From news Wed Apr 4 16:41:03 2001 Path: ditka!bounce-back Newsgroups: sci.aeronautics.airliners Date: 04 Apr 2001 16:41:04 From: "Paul Palmer" Subject: Re: Boeing's Sonic Cruiser - a Boeing stealth aircraft References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: iad-read.news.verio.net 986426792 199.103.191.46 (Wed, 04 Apr 2001 23:26:32 GMT) Organization: Verio X-Newsreader: Microsoft Outlook Express 5.50.4133.2400 NNTP-Posting-Host: 199.103.191.46 "Damon Hill" wrote in message news:airliners.2001.83@ditka.Chicago.COM... > Will it fly? Will the airlines buy? I hope so! Commercial > aircraft design has been SO boring for the past couple of > decades. > > How fast WILL it go? It already looks supersonic, with the right > engines. > > http://www.boeing.com/news/feature/concept/ I believe Boeing is fibbing. Why go to the lengths of a canard and double-delta wing for Mach .95? Cessna's Citation X does Mach .92 in a standard configuration. So add some more wing sweep and burn a bit more kerosene, big deal. I worked on General Dynamics' F-16XL, which had a double-delta "cranked arrow" wing. The program was originally called SCAMP, which was an acronym for 'supersonic cruise at mil power'. Mil power is without afterburner, and SS cruise without it is something that could not be done on the 1980's generation of engines. During the program, we found out that the configuration was also structurally efficient, and could carry a lot of load. Hmmm, sounds like an airliner.... At Mach .95, the Sonic Cruiser vs. A380 debate becomes, on my NYC-Tokyo flight, where do I want to take my shower? With the sonic cruiser, I take it at the airline club at the airport; on the A380, I take it on the plane. Either way, I get to my meeting at the same time. At Mach 1.5, about the max speed standard aluminum and 350 degree F cure composites will allow, I get to Narita with enough time for a side trip to the Ginza. I'll go to great lengths to get my company to swing for the increased fare for that (...but boss, I'll be so refreshed...) Combine Boeing's announcement with the AvWeek articles a few weeks back about GE working on a combined cycle engine. Excuse me, why would a profit-motivated enterprise like GE work on such a thing, if not for a supersonic commercial aircraft? For the military? Give me a break, Pratt's been working on the F119 engine for 20 years and hasn't put that into production yet, while ceding commercial market share to GE. The USAF hasn't been able to get the F-22 into production despite all of its efforts. GE would no more pour its own money into an unfunded military program than it would admit that it wasn't number 1 or a strong number 2 in some market. The 'Sonic Cruiser' has got to be a low cost Mach 1.4-1.5 bird that can cruise economically subsonically over land. If it ain't, Boeing's just putting out word of the Sonic Cruiser because it's getting its butt kicked by Airbus in the tin-can airliner battle, and somehow that makes it feel good. How about it, anonymous Boeing engineers? Paul Palmer From news Wed Apr 4 16:41:03 2001 Path: ditka!bounce-back Newsgroups: sci.aeronautics.airliners Date: 04 Apr 2001 16:41:05 From: Eric Hagerstrom Subject: Re: Wing vs. tail-mounted engines? References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: news.abs.net 986347469 64.50.179.169 (Tue, 03 Apr 2001 21:24:29 EDT) X-Newsreader: Forte Agent 1.8/32.548 NNTP-Posting-Host: 64.50.179.169 On 31 Mar 2001 16:43:19 , robinjohnson@bigfoot.com (Robin Johnson) wrote: >On 23 Mar 2001 17:40:08 , Wolfgang Keller told us: > >Engines these days are very reliable. It is not unknown for an engine >to remain in position for five years. >On the other hand, more and more ETOPS flights are being undertaken - >the majority of North Atlantic crossings for example. Despite this, >there have been very few ditchings. Well, actually no ETOPS flight has ever ditched. The Ethopian ditched while struggling with a hijacker in the vcockpit, certaily not because of ETOPS operations. >Just this month a United 767 on the climb-out from Lihue and bound for >California, had a loss of power on both engines. No harm done, >but..... >I'm a little concerned about the dynamics of a ditching with >underslung engines, though. The Ethiopian 767 off the Comores, >although a hijack situation with armed men on the flightdeck, looked >good on the video until the last minute, when it seemed that the >engines dug in asymmetrically, causing the fuselage to break up. >Does anyone know of a successful ditching by a jet? 13 January 1969, An SAS DC8-62 (four-engines under the wing) ditched in the ocean off Los Angeles (apparently after running out of fuel). 15 fatalities. I don't recall how many were aboard but the aircraft stayed afloat for hours. From news Wed Apr 4 16:41:03 2001 Path: ditka!bounce-back Newsgroups: sci.aeronautics.airliners Date: 04 Apr 2001 16:41:06 From: Thaddeus Beier Subject: Re: Boeing's Sonic Cruiser References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: news.pacbell.net 986340432 216.102.153.252 (Tue, 03 Apr 2001 16:27:12 PDT) Organization: SBC Internet Services NNTP-Posting-Host: 216.102.153.252 Damon Hill wrote: > > Will it fly? Will the airlines buy? I hope so! Commercial > aircraft design has been SO boring for the past couple of > decades. > > How fast WILL it go? It already looks supersonic, with the right > engines. > > http://www.boeing.com/news/feature/concept/ > > --Damon I really have to hand it to Boeing -- after decades of new designs of airliners that all look more and more the same; and are tuned to getting the most cattle on board for the lowest possible price per seat-mile; Boeing proposes something completely different. The nice thing is that these planes will appeal most to business travelers, who provide probably 90% of the profit for airlines. No matter how many people you shove in an A380 -- if all of the businesspeople are flying in a faster plane you will lose money on the A380. Very clever. And Airbus can't possibly compete, now that they've committed to building the A380. If Boeing had made this announcement a couple of months ago, before Airbus committed, then they might have had a chance. I have to say that the painting that Boeing presented doesn't look like a transonic plane to me; it should be visciously area-ruled, but the cross-section swells very quickly in the front and then is constant for a good long way, then grows again when the strakes start. Putting the fuel in the strakes is a great idea; of course, Rutan has been doing that for decades for all the same reasons. Still, if the strakes are going to be fat enough to carry the fuel then you're going to have to cut down your cross sectional area from somewhere else. My guess is that the final design won't look too much like the painting that Boeing has presented. I had been hoping that they'd build a blended wing-body plane, but I have to say that this makes much more sense. A BWB might get you another 5 to 10% efficiency, but it wouldn't be nearly as 'cool' as this airplane; and I think that they'll be able to sell the 'cool' for quite a premium. that, and speed, of course. thad From news Wed Apr 4 16:41:03 2001 Path: ditka!bounce-back Newsgroups: sci.aeronautics.airliners Date: 04 Apr 2001 16:41:07 From: Steve Subject: Re: Wing vs. tail-mounted engines? References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM Content-Type: text/plain; charset=us-ascii; x-mac-type="54455854"; x-mac-creator="4D4F5353" Content-Transfer-Encoding: 7bit X-Trace: ns3.arlut.utexas.edu 986325851 4912 129.116.176.203 (3 Apr 2001 19:24:11 GMT) Organization: I only wish.... NNTP-Posting-Host: roadrunner.arlut.utexas.edu Daniele Procida wrote: > ) > > As someone who is scared out of his wits by aeroplanes, I much prefer > MD-80s and the like, because the sight of those enormous heavy engines > making those delicate wings bend up and down in that terrifying fashion > is something I can really do without. At least on a MD-80 I don't spend > the entire flight checking to see if the wings are going fall off. Ahh, but looks are deceiving ;-) the biggest *drag* force on an aircraft comes from the wing- whether the engines are on the tail or on the wing. Also, its the wing that holds the plane *up* in the first place. So, if the engines are on the wing, there's actually less stress overall since the thrust of the engines has to be transmitted through less structure to counter the drag on the wings. And besides, thats all trivial compared to holding the whole thing up anyway. > Instead I worry about an uncontained blade failure ripping into the > fuselage or destroying the tailplane. It happens... but so do car wrecks, strokes, heart attacks, and meteor strikes. No sense living in terror of everything.... From news Wed Apr 4 16:41:03 2001 Path: ditka!bounce-back Newsgroups: sci.aeronautics.airliners Date: 04 Apr 2001 16:41:08 From: jthorn@galileo.thp.univie.ac.at (Jonathan Thornburg) Subject: Re: A fascinating tidbit from Boeing References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM Organization: Universitaet Wien (Vienna, Austria) / Institut fuer Theoretische Physik In article , Robert H. Nielsen wrote: >Check out this link to a story about a Boeing design for a high-subsonic >airliner: > >http://biz.yahoo.com/rf/010326/n26655542_2.html > >Wouldn't his give the A380 market a case of the fits! Not really, they target different market segments: A "fastjet" only matters on long-range flights (otherwise the travel time isn't significantly different). A large part of the airliner market is short- and medium- -range. And a small plane (100-150 seats) only makes sense for relativly "thin" routes (low number of passengers/week). The operating costs are a big > Operating costs would not be > all that different from similar-sized airplanes,'' Callan continued. In other words [translating from PR-speak to engineer/accountant-speak], they'd be a bit higher than competing airplanes (whether Boeing or Airbus). This looks like a product aimed at a (admittedly very lucrative) niche market, basically long-range 1st/business-class travellers on "thin" routes who care more about travel time than ticket price. I don't think anything but the absolute lowest operating costs (--> ticket prices) is going to win over the cattle-class travellers who (continue to) account for most of the seat-miles flown. Maybe Boeing can pull this off, but as the Concorde experience has shown, "premium" jets are a tough sell. [Concorde makes an operating profit... but with only 10ish airplanes sold to only 2 airlines, it was a huge money-loser if you count the R&D costs. Boeing abandoned its 2707 SST project when Uncle Sam (the Nixon administration) refused to subsidize its costs.] [The Convair 990 was another failed "premium" jet, but that was more a technical botch: the manufacturer promised the C990's high cruise speed before a prototype flew, but the actual hardware didn't deliver, so the airline orders disappeared. I suspect computers + wind-tunnel tests are good enough today that Boeing could indeed deliver what their engineers say thy could.] > ``The jet would use more fuel, but it could offer airlines savings in =========================== > the form of better crew and asset utilization.'' This means that this project represents an even-greater-than-usual-for-airliner-projects gamble on future oil prices. I'm sure they've thought of this, but if I owned Boeing stock, I'd be a bit nervous about trying to 2nd-guess OPEC this way... -- -- Jonathan Thornburg http://www.thp.univie.ac.at/~jthorn/home.html Universitaet Wien (Vienna, Austria) / Institut fuer Theoretische Physik "When you find that your views match [those of] the majority, it's time to pause and reflect." -- Samuel L. Clemens, a.k.a. Mark Twain From news Wed Apr 4 16:41:03 2001 Path: ditka!bounce-back Newsgroups: sci.aeronautics.airliners Date: 04 Apr 2001 16:41:09 From: jthorn@galileo.thp.univie.ac.at (Jonathan Thornburg) Subject: Re: Wing vs. tail-mounted engines? References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM Organization: Universitaet Wien (Vienna, Austria) / Institut fuer Theoretische Physik In article , Wolfgang Keller writes: >What are the actual design tradeoffs today and how did the situation >evolve over the past decades to favor wing-mounted engines that much? In article , JohnMcGrew wrote: >Weight: Putting engines in the back requires extra load carrying structure, >both for the thrust and the weight of the engine itself. On the other hand, >little extra structure is required for the wing mounted engine since there's >structure already there; the wing is mostly structure. Advantage: Wing Mount. [[...]] >However, most rear engine configurations necessitate a T-Tail configuration for >the horizontal stabilizer, which requires extra weight for structure at the top >of the vertical stabilizer, as opposed to conventional horizontal stabilizers >attached to existing structure at the end of the fuselage. [[...]] >Maintenance: Most maintenance on wing-mounted engines can be performed at >ground level without lifts or scaffolding. Significant appeal to maintenance >staffs. Advantage: Wing. These are the big reasons in practice, especially the lower weight (--> lower drag at the same lift/drag ratio --> lower fuel burn). >Aerodynamics: Rear-mount allows for a cleaner wing design, and less conflicts >with airflow and mechanics for slats and flaps. Advantage: Rear. With modern design techniques (computer + wind-tunnel) the aerodynamic difficulties of wing-mount (podded) engines can be dealt with without serious difficulty. The industry doesn't care much about it, but safety is another big advantage of wing-mounted engines: What kills people in a jet crash is often not the crash itself, but the ensuing fire. Tail-mounted engines mean fuel pipes running from the wing (where the fuel tanks are) aft through the fuselage to the engines, i.e. you've got fuel right in the fuselage with the passengers. In contrast, wing-mounted engines allow all the fuel to be kept in the wings, some distance away from the passengers. (Some designs do put fuel tanks in the wing center sections anyway.) -- -- Jonathan Thornburg http://www.thp.univie.ac.at/~jthorn/home.html Universitaet Wien (Vienna, Austria) / Institut fuer Theoretische Physik Q: Only 6 countries have the death penalty for children. Which are they? A: Congo, Iran, Nigeria, (Pakistan[*]), Saudi Arabia, United States, Yemen [*] Pakistan reportedly ended it in July 2000. -- Amnesty International http://www.web.amnesty.org/ai.nsf/index/AMR511392000 From news Wed Apr 4 16:41:03 2001 Path: ditka!bounce-back Newsgroups: sci.aeronautics.airliners Date: 04 Apr 2001 16:41:10 From: "AirEcGrp" Subject: Re: Deice Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Newsreader: Microsoft Outlook Express 5.00.2919.6700 Organization: Posted via Supernews, http://www.supernews.com Flt Tech Online www.flttechonline.com published the following story regarding a new deicing system developed by Radiant Aviation Services last week: New De-Ice System Uses Infrared Radiation Instead Of Glycol Radiant Aviation Services has introduced a new de-icing system this winter, that uses heat instead of chemicals to melt ice containments from an aircraft. Radiant says the system, dubbed InfraTek, de-ices an aircraft by using directed infrared radiation in place of the usual 50-50 mix of glycol and hot water. InfraTek requires the an airplane to be taxied, or towed, into a tent-like hangar, which is open at both ends. While inside the structure, natural gas burners are used to bathe the airplane with infrared radiation which melts the frozen containments. Radiant says the infrared radiation is a benign form of heat energy that has been used for more than 40 years to safely heat gymnasiums, auditoriums and aircraft hangars. The energy reflects off the aircraft skin and melts ice but won't raise the temperature inside the plane, the company said. In 500 tests with Continental Airlines at Newark International Airport over the past two years, the InfraTek system cleaned aircraft in an average 7.2 minutes, which is 30% to 40% faster than conventional de-icing, according to Radiant. Furthermore, a typical de-icing with glycol costs between $1,000 and $5,000 per plane, while the cost with InfraTek is "a couple hundred dollars," the company claims. During the tests, Continental initially used a redundant glycol application along with the infrared heat procedure as a precaution. This follow-up procedure was discontinued after a review of InfraTek's efficacy. Radiant says Continental is now using InfraTek as its primary defrosting method at Newark. The company plans to build three sizes of hangars to accommodate several aircraft sizes ranging from commuter planes to a B-747. Radiant says it can install the system on its own cost, and then contract out their use. 03-30-2001. From news Wed Apr 4 16:41:03 2001 Path: ditka!bounce-back Newsgroups: sci.aeronautics.airliners Date: 04 Apr 2001 16:41:11 From: don@news.daedalus.co.nz (Don Stokes) Subject: Re: Wing vs. tail-mounted engines? References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: raewyn.paradise.net.nz 986256347 41668 203.96.144.16 (3 Apr 2001 00:05:47 GMT) X-Newsreader: trn 4.0-test72 (19 April 1999) Organization: Daedalus Consulting NNTP-Posting-Host: 203-96-144-16.cable.paradise.net.nz Don Stokes wrote: >(I can't think of any case of failure of the wing box or root structure >causing an accident on a post-war commercial airliner -- can anyone?) To answer my own question: The Aviation Safety Network has a list of airframe failure accidents at: http://aviation-safety.net/events/afw.shtml It seems that the L-188 Electra and Vickers Viscount had a number of "wings falling off" accidents due to actual design flaws. Pre-war designs like the DC-3 and C-46 seem to have fallen out of the sky in seriously bad weather on a fairly regular basis. There are few jet aircraft in this list. They are: 15.07.1964 Boeing 720 Aircraft overstressed and disintegrated Ansbach, DE Lufthansa after loss of control by training crew performing a (deliberate) roll. 03.06.1973 Tupolev Tu-144 Canard failed in demonstration flight Paris, FR Aeroflot 09.05.1976 Boeing 747-131F Lightning strike to wing caused fuel Madrid, ES Iran Air Force explosion that unravelled wing structure 14.05.1977 Boeing 707-321C Separation of horizontal stabilizer due Nairobi, KE IAS Cargo to metal fatigue and inadequate inspection 06.10.1981 Fokker F28 Aircraft disintegrated in tornado Moerdijk, NL NLM Cityhopper 12.08.1985 Boeing 747-SR46 Poorly repaired pressure bulkhead failed Tokyo, JP JAL in flight, causing loss of hydraulic control Of these, only the Lufthansa 720 and NLM F28 count as stress failures of the main wing -- I'm not even sure about the 720 as to what failed first -- and in both cases the overstresses were pretty extreme -- it's not considered normal procedure in commercial ops to fly aerobatics or into tornadoes... -- don From news Wed Apr 4 16:41:03 2001 Path: ditka!bounce-back Newsgroups: sci.aeronautics.airliners Date: 04 Apr 2001 16:41:12 From: Ian Barclay Subject: Re: Wing vs. tail-mounted engines? References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Newsreader: Turnpike Integrated Version 4.02 S Wolfgang Keller writes, >What are the actual design tradeoffs today and how did the situation >evolve over the past decades to favor wing-mounted engines that much? Others have covered most of the main issues (wing bending relief, clean wing aerodynamics, ground clearance, FOD ingestion, etc) but a few other considerations are :- Wing mounted engines put mass in front of the flexural axis of the wing. This damps out the aeroelastic forces & gives greater flutter margins or allows lighter wing structures. Rear mounting moves the cg aft reducing tail moment arms thus requiring a larger tailplane and maybe even fin. Rear mounted engines require heavier rear fuselage structure. Rear mounted engines can be fitted with bucket reversers which tend to be cheaper and more effective than cascade or 4 door reversers used on wing mounted engines. External noise levels are generally less for rear engine installations as the fuselage partially shields one engine for sideline noise measurements and the wings partially shield both engines for approach measurements. Wing mounted engines can easily be struck and damaged in a misjudged crosswind landing. The downwash from the wing varies with angle of attack and tends to result in a relatively small variation in AoA at the engine inlet of rear mounted engines making the inlet aerodynamics more closely optimised across the flight envelope. Rear mounted engines often require soft (rubber/fluid) engine mounts to absorb vibration and blade off loads. For wing mounted engines the flexible wings act as effective dampers thus allowing engines to use cheaper hard mount arrangements. Wing mounted engines are ideally located to supply bleed air for wing LE anti-ice. If the APU is tail mounted, bleed piping can be simplified with rear mounted engines. The length of fuel lines is minimised for wing mounted engines. Ice shed from the wing can be ingested into rear mounted engines. Wing mounting may limit the flap span to allow for the exhaust stream. There is the possibility of high drag from the convergent/divergent channel formed between the nacelle and the fuselage wall on rear mounted engine installations. More available fuel volume for rear mounted engines as no dry bays in the wing fuel tanks to cater for disc bursts are required. It may be possible for engine nacelles to be common port and starboard for wing mounted engines. It is easier to make accessories, piping & harnesses common on port and starboard sides for wing mounted engines. At the end of the day its pretty evenly balanced. Hence the popularity of both configurations. I think the two factors that tend to swing the decision are the manufacturers experience (e.g. Boeing & Airbus go for wing mounted, McDonnell Douglas used to go for rear mounted because that was what they had done before, they had the engineers with that design knowledge, it was the low risk approach) and ground clearance (e.g. regional jets want to be able to load baggage holds from the ground and passengers without jetways so rear mounted is better for this case). -- Ian Barclay Salwick, UK From news Wed Apr 4 16:41:03 2001 Path: ditka!bounce-back Newsgroups: sci.aeronautics.airliners Date: 04 Apr 2001 16:41:13 From: Robert Briggs Subject: Re: Wing vs. tail-mounted engines? References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: newsfeed.pit.comms.marconi.com 986232134 26570 87.0.21.1 (2 Apr 2001 17:22:14 GMT) Organization: Marconi NNTP-Posting-Host: 87.0.21.1 Robin Johnson wrote: > I'm a little concerned about the dynamics of a ditching with > underslung engines, though. > Does anyone know of a successful ditching by a jet? Yes. In May of 1995, the Royal Air Force did quite a neat job with Comet - correction, Nimrod - XW666 of 51 Squadron near Lossiemouth. I've not found a picture on the Web (perhaps no big surprise for an event that long ago), but the incident is mentioned at: http://www.morayairnet.co.uk/News/Crashes.htm Of course, that answers your actual question about a successful ditching by a jet, but doesn't address your concern about underslung engines in such circumstances. :-) From news Wed Apr 4 16:41:03 2001 Path: ditka!bounce-back Newsgroups: sci.aeronautics.airliners Date: 04 Apr 2001 16:41:14 From: westin*nospam@graphics.cornell.edu (Stephen H. Westin) Subject: Re: Boeing's Sonic Cruiser References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: news01.cit.cornell.edu 986225611 28559 128.84.247.211 (2 Apr 2001 15:33:31 GMT) X-Newsreader: Gnus v5.7/Emacs 20.6 Organization: Cornell University NNTP-Posting-Host: diesel.graphics.cornell.edu damon@halcyon.com (Damon Hill) writes: > Will it fly? Will the airlines buy? I hope so! Commercial > aircraft design has been SO boring for the past couple of > decades. > > How fast WILL it go? It already looks supersonic, with the right > engines. > > http://www.boeing.com/news/feature/concept/ Humph. "faster, higher, farther flight than any current airplane"? I suppose if you demand the range, then that's true. Concorde, of course, is faster and flies higher. I think they're talking about a transsonic aircraft, which has certainly been suggested before. Far less demanding than Mach 2 or so, and more likely to meet noise and pollution requirements. Not to mention easier on fuel, cheaper to build, etc. The "fact sheet" seems pretty shour on facts; this is obviously a blue-sky concept. But not a bad one... -- -Stephen H. Westin Any information or opinions in this message are mine: they do not represent the position of Cornell University or any of its sponsors. From news Wed Apr 4 16:41:03 2001 Path: ditka!bounce-back Newsgroups: sci.aeronautics.airliners Date: 04 Apr 2001 16:41:15 From: jgh@uk.sun.com (Jeremy Harris [RU-UK]) Subject: Re: Air France Concorde crashes after departing Paris CDG References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: new-usenet.uk.sun.com 986216585 19430 129.156.199.109 (2 Apr 2001 13:03:05 GMT) X-Newsreader: knews 1.0b.1 Organization: Sun Microsystems NNTP-Posting-Host: watford-109.uk.sun.com In article , FilipPC.DeVos@rug.ac.be (Filip De Vos) writes: > Part of that drag is the rudder, deflected to compensate for the > assymetric thrust. So my question is, is it possible to make a climbing > turn at a lower speed than 275kt? (turning towards the dead engines) Uh, to first order, planes don't turn thanks to the rudder, but thanks to having been banked. - Jeremy From news Wed Apr 4 16:41:03 2001 Path: ditka!bounce-back Newsgroups: sci.aeronautics.airliners Date: 04 Apr 2001 16:41:16 From: johnmcgrew@aol.com (JohnMcGrew) Subject: Re: Boeing's Sonic Cruiser References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Newsreader: Session Scheduler Organization: AOL http://www.aol.com In article , damon@halcyon.com (Damon Hill) writes: >Will it fly? Will the airlines buy? I hope so! Commercial >aircraft design has been SO boring for the past couple of >decades. That's a tough call. The real quesion will be if the economics make it worthwhile. Perhaps it will find a niche on international routes of flight times more than 7 or 8 hours. It's pretty much a foregone conclusion that the Concorde isn't going to be with us much longer. However, I doubt that airlines will be interested in using it domestically. Considering that airport congestion now consumes at least 20 minutes of every flight, a mere 10% increase in speed in the air isn't going to get pax anywhere that much faster. John From news Wed Apr 4 16:41:03 2001 Path: ditka!bounce-back Newsgroups: sci.aeronautics.airliners Date: 04 Apr 2001 16:41:17 From: johnmcgrew@aol.com (JohnMcGrew) Subject: Re: Wing vs. tail-mounted engines? References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Newsreader: Session Scheduler Organization: AOL http://www.aol.com In article , westin*nospam@graphics.cornell.edu (Stephen H. Westin) writes: >I think the DC-9 and 727 got rear-mounted engines in part so they >could sit lower to the tarmac for easy access at primitive >airports. Actually, primitive airports were a major consideration for both these planes, as they were being sold as short and medium range "feeders" to replace places that were still being served by DC-3s in the early '60s. The 727 was actually certified for and used on gravel runways in Alaska; conditions that a under-slung engine could not survive. John From news Wed Apr 4 16:41:03 2001 Path: ditka!bounce-back Newsgroups: sci.aeronautics.airliners Date: 04 Apr 2001 16:41:18 From: FilipPC.DeVos@rug.ac.be (Filip De Vos) Subject: Re: Wing vs. tail-mounted engines? References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Newsreader: TIN [version 1.2 PL2] Organization: University of Ghent, Belgium NNTP-Posting-Host: eduserv1.rug.ac.be Robin Johnson (robinjohnson@bigfoot.com) wrote: : Engines these days are very reliable. It is not unknown for an engine : to remain in position for five years. : On the other hand, more and more ETOPS flights are being undertaken - : the majority of North Atlantic crossings for example. Despite this, : there have been very few ditchings. I am aware of exactly no ditchings caused by ETOPS. In fact, I am aware of no mid-ocean ditchings in the jet age. All jets lost at sea came apart in mid-air (TW800, AI182, KL007) or shattered on impact (SR111) : Just this month a United 767 on the climb-out from Lihue and bound for : California, had a loss of power on both engines. No harm done, Engines require a continuous flow of fuel :) : but..... : I'm a little concerned about the dynamics of a ditching with : underslung engines, though. The Ethiopian 767 off the Comores, : although a hijack situation with armed men on the flightdeck, looked : good on the video until the last minute, when it seemed that the : engines dug in asymmetrically, causing the fuselage to break up. : Does anyone know of a successful ditching by a jet? A SAS DC-8 at San Fransisco or LA (pilots were preoccupied with a faulty landing gear light) A JAL DC-8 Super sixty pulled reverse thrust on approach to Haneda, pilot heard voices in his head. Not really a ditching. 24 killed. More recently, a 707 cargo in Lake Victoria. Engines and landing gear was sheared off, but the aircraft kept on floating, crew safe. : I would feel safer in a rear-engined model. In a ditching, I do not know. The engines do not hang down, and therefore cannot 'dig in', but aircraft with tail-mounted engines tend to have wings that are straight instead of pointing slightly upward, so instead of digging in an engine, they can dig in the wingtip, with potentially the same results. -- "Who needs credibility around | Filip De Vos here?" -- T. L. Elifritz | FilipPC.DeVos@rug.ac.be From news Wed Apr 4 16:41:03 2001 Path: ditka!bounce-back Newsgroups: sci.aeronautics.airliners Date: 04 Apr 2001 16:41:19 From: "Tim J Lee" Subject: Re: Wing vs. tail-mounted engines? References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Newsreader: Microsoft Outlook Express 5.50.4522.1200 Organization: BT Internet NNTP-Posting-Host: host213-123-154-151.btopenworld.com "ME Incorporated" wrote in message news:airliners.2001.65@ditka.Chicago.COM... > "Wolfgang Keller" wrote in message > > > What are the actual design tradeoffs today and how did the situation > > evolve over the past decades to favor wing-mounted engines that much? What > > would be the impact of, for example, drastically increased fuel prices > > and/or significantly more strict noise regulations (=> engines with bypass > > ratio >>10)? > And so, with more powerful engines, and the complaints/requests of big > clients such as American, United, etc, these tail mounted engines are > becoming a non desired design. Hence, the design of the 777. Very much an > airplane designed by and with the airlines, and not just the plane makers > designing around a spec. You can bet that Boeing wanted more engines, and > maybe in the tail, but because of that maintenance thing, two is cheaper, > and wing mounted cheaper still. An engineer writes..... Structurally, underwing engines are a better bet. Reason? If you put the weight of the engines on the fuselage (a la DC9), this adds to the weight that the wing root has to transmit - leading to a more complex wing/fuselage interface and carry-through structure. The object is to make the wing as heavy as possible (so it carries it's own weight) and the fuse as light as possible. It's the same reason that on aircraft with centre fuel tanks, they use this first (usually for take off) - get the fuse light, keep the weight on the wings. As an aside, it also makes maintenance easier, but this is a secondary consideration against airframe efficiency. There are good reasons for tail mounted engines - the VC10 had the best - it was designed with the hot and high airports that BOAC were serving in East Africa in mind, and so an efficient and highly flapped wing was created. Fouling the trailing edge up with engine exhaust was not considered a good bet, due to the loss of flap section. As for containment - the bit of the engine most likely to go bang is the large fan at the front - which in any case is mounted ahead of the wing and fuel. T From news Wed Apr 4 16:41:03 2001 Path: ditka!bounce-back Newsgroups: sci.aeronautics.airliners Date: 04 Apr 2001 16:41:20 From: RF-X Subject: Re: Wing vs. tail-mounted engines? References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: news.pacbell.net 986193586 63.195.112.9 (Sun, 01 Apr 2001 23:39:46 PDT) Organization: SBC Internet Services NNTP-Posting-Host: 63.195.112.9 In article , robinjohnson@bigfoot.com wrote: > I'm a little concerned about the dynamics of a ditching with > underslung engines, though. The Ethiopian 767 off the Comores, > although a hijack situation with armed men on the flightdeck, looked > good on the video until the last minute, when it seemed that the > engines dug in asymmetrically, causing the fuselage to break up. > Does anyone know of a successful ditching by a jet? > I would feel safer in a rear-engined model. I was under the impression that jets with underslung engines had a method of jettisoning said engines in a ditch scenario, and this wasn't employed in the Ethiopian 767 due to the hijackers' complete ignorance of their situation - insufficient fuel for post-hijack voyage, incomplete understanding of commercial flight realities, not to mention rejection of the ditch inevitability, etc... From news Wed Apr 4 16:41:03 2001 Path: ditka!bounce-back Newsgroups: sci.aeronautics.airliners Date: 04 Apr 2001 16:41:21 From: Tom Digby Subject: Re: Aircraft design question References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: nntp1.ba.best.com 986175186 69786 206.184.139.150 (2 Apr 2001 01:33:06 GMT) Organization: The ISP formerly known as Best NNTP-Posting-Host: shell18.ba.best.com Ken Ishiguro wrote: > Part of engineering is capturing and meeting requirements in cost effective > or unique ways. Why is there a requirement for a window? Presumably so the > passenger can see out, and also so people don't become claustrophobic. As > you and others have stated, there's a lot of factors involved. > ISTM that an ergonomically designed cabin and lighting will provide an > illusion of spaciousness. Airframe manufacturers and airlines put a lot of > effort into cabin design to accomplish this. As far as seeing out, a camera > system and an in-seat LCD display with individually selectable / changeable > views will meet the "see out" requirement. As a potential passenger, I want a "real" window, not just a TV hookup. If I'm looking at the Grand Canyon or the Rock of Gibraltar or maybe just the curvature of the Earth or a sunset or something, I want to actually see it with my own eyes. It's like the difference between seeing your favorite performer at a live concert and staying home and watching on TV. It may not be a rational feeling, but it's there. If the window has to be small with a limited view, a TV hookeup might be good to supplement it. But I still want the real window. -- Tom Digby bubbles@well.com http://www.well.com/~bubbles/ From news Wed Apr 4 16:41:03 2001 Path: ditka!bounce-back Newsgroups: sci.aeronautics.airliners Date: 04 Apr 2001 16:41:22 From: don@news.daedalus.co.nz (Don Stokes) Subject: Re: Wing vs. tail-mounted engines? References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: raewyn.paradise.net.nz 986130195 96309 203.96.144.16 (1 Apr 2001 13:03:15 GMT) X-Newsreader: trn 4.0-test72 (19 April 1999) Organization: Daedalus Consulting NNTP-Posting-Host: 203-96-144-16.cable.paradise.net.nz In article , Robin Johnson wrote: >I'm a little concerned about the dynamics of a ditching with >underslung engines, though. The Ethiopian 767 off the Comores, >although a hijack situation with armed men on the flightdeck, looked >good on the video until the last minute, when it seemed that the >engines dug in asymmetrically, causing the fuselage to break up. >Does anyone know of a successful ditching by a jet? >I would feel safer in a rear-engined model. If you watch the video again, you'll notice the wingtip went into the water first, and the fuselage went in more or less sideways. Not good for the structure, that. Engines have "fuse pins" that will shear them off given the kind of stresses involved in a water landing. This was demonstrated a year or two ago by a 707 freighter crew that rather badly misjudged the approach to Mwanza, Tanzania and put the bird into Lake Victoria. There's photos somewhere around on the net (Aviation Week reprinted 'em) of the 707 floating in the lake, more or less intact but minus all four engines, having been towed to shallow water and unloaded. -- don From news Wed Apr 4 16:41:03 2001 Path: ditka!bounce-back Newsgroups: sci.aeronautics.airliners Date: 04 Apr 2001 16:41:23 From: don@news.daedalus.co.nz (Don Stokes) Subject: Re: Wing vs. tail-mounted engines? References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: raewyn.paradise.net.nz 986129615 96050 203.96.144.16 (1 Apr 2001 12:53:35 GMT) X-Newsreader: trn 4.0-test72 (19 April 1999) Organization: Daedalus Consulting NNTP-Posting-Host: 203-96-144-16.cable.paradise.net.nz JohnMcGrew wrote: >Noise: Clearly, advantage rear, except perhaps for those sitting in the back. >Advantage: Rear Mount. I don't think it's quite that clear-cut. Vibration from rear-mounted engines is transmitted directly into the rear of the cabin, rather than into the wing and wing root, and the wing itself protects the cabin from exhaust noise (at least on most designs -- the 737-100/200 have exhausts behind the wing, but modern designs are well underneath). Intake noise is also closer to the cabin in tail-mounted designs. The wing probably directs more noise groundward from the exhaust. >Aerodynamics: Rear-mount allows for a cleaner wing design, and less conflicts >with airflow and mechanics for slats and flaps. Advantage: Rear. But at the expense of putting the engines in a messy place. Wing mounted designs put the intakes in more or less clear air, whereas tail mounted have aerodynamic effects from the wing and fuselage to contend with. I believe this is why you don't see high bypass engines mounted on the sides of the tail on any aircraft -- the big fans tend to be more touchy about screwball intake flow than their lower bypass brethren. (This doesn't seem to have stopped the DC-10 and L-1011 from having top mounted intakes.) -- don From news Wed Apr 4 16:41:03 2001 Path: ditka!bounce-back Newsgroups: sci.aeronautics.airliners Date: 04 Apr 2001 16:41:24 From: Michael Butler Subject: Re: Wing vs. tail-mounted engines? References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: lust.ihug.co.nz 986123207 13808 203.173.230.205 (1 Apr 2001 11:06:47 GMT) Organization: ihug ( New Zealand ) NNTP-Posting-Host: p13-max4.wlg.ihug.co.nz Don Stokes wrote: > (I can't think of any case of failure of the wing box or root structure > causing an accident on a post-war commercial airliner -- can anyone?) I think it was either a Viscount or a Convair with batteries in the wing to make it self starting and the heat from the battery caused the wing failure - but even then it was a mod to the original design. -- Mike Butler Wellington NZ Ben BC X New Zealand Dog Agility on the Web Ella Kelpie http://homepages.ihug.co.nz/~mbutler/nala/ From news Wed Apr 4 16:41:03 2001 Path: ditka!bounce-back Newsgroups: sci.aeronautics.airliners Date: 04 Apr 2001 16:41:25 From: b.domke@coruscant.b.shuttle.de (Burkhard Domke) Subject: Re: Boeing's Sonic Cruiser References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: ulm.shuttle.de 986122323 29839 194.95.246.75 (1 Apr 2001 10:52:03 GMT) X-Newsreader: Forte Free Agent 1.1/32.230 Organization: WiNShuttle, DFN - German Research Network NNTP-Posting-Host: p75.b.shuttle.de On 31 Mar 2001 16:43:07 , damon@halcyon.com (Damon Hill) wrote: >Will it fly? Will the airlines buy? I hope so! Commercial >aircraft design has been SO boring for the past couple of >decades. > >How fast WILL it go? It already looks supersonic, with the right >engines. The main wing is mounted way aft on the fuselage. This rules out the installation of effective high-lift devices, as the canards won't be able to compensate the resulting nose-down moment. That puts a severe limit on takeoff and landing performance. So it won't go at all, as airlines to rate good takeoff and landing performance essential. Burkhard From news Wed Apr 4 16:41:03 2001 Path: ditka!bounce-back Newsgroups: sci.aeronautics.airliners,rec.travel.air Date: 04 Apr 2001 16:41:26 From: Matthew Sheren Subject: Re: Long-distance direct flights References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: carnaval.risq.qc.ca 986114522 132.216.36.46 (Sun, 01 Apr 2001 04:42:02 EDT) NNTP-Posting-Host: 132.216.36.46 Robin Johnson wrote: > Helsinki is one of the smaller hub cities: but I can see it being > developed further in the oneWorld context for traffic from the East to > Western Europe, and for traffic from the West to Eastern Europe/CIS/ > and possibly Middle East, as London gets more congested than ever. A good call, except that oW already has Dublin to use as a reliever hub to LHR, provided Ireland gets rid of the 'all flights from the West going into Dublin have to stop in Shannon' rule. Dublin is closer to the great circle from pretty much any point in the US to Europe (save the 2 main cities in Russia). > The home market is insufficient, as you indicate, for frequent operation to > most US/Canadian centres. What are the main centres of the Finnish diaspora? Eeh, a few professionals and academics in nearly every city and major university; no real centre, maybe Minneapolis because of the high Scandinavian population, but there's isn't exactly a 'Little Helsinki' in many cities :> According to the 1990 Census (see, someone *cares* about this stuff), there's 659,000 Americans who claim themselves of Finnish heritage [not actual Finns, but it'll give an indication], 47% in the Midwest, 27% in the West, 14% in the Northeast, and 11% in the South. Sharp-eyed viewers will note that these percentages add up to 99%. The remaining 1% were told by their grandfathers that they were from Turku, but heard 'Turkey,' and are in Istanbul trying to rediscover their heritage. Matthew :) [who used to babysit for this wonderful Finnish kid who taught me the virtues of eating pizza with a knife and fork] From news Wed Apr 4 16:41:04 2001 Path: ditka!bounce-back Newsgroups: sci.aeronautics.airliners Date: 04 Apr 2001 16:41:27 From: gbeaman@pei.sympatico.ca (Gord Beaman) Subject: Re: How Important Is Cross-section Shape Of Wing? References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: sapphire.mtt.net 986105531 142.176.73.200 (Sun, 01 Apr 2001 03:12:11 ADT) X-Newsreader: Forte Free Agent 1.21/32.243 Organization: ISLAND TEL NNTP-Posting-Host: 142.176.73.200 cp@panix.com wrote: >BBarksdl wrote: >> In the April issue of Discover magazine, Robert Kunzig challanges the textbook >> explanation of the principles of flight. > >Personally I found the article less explicit (and more confusing) than >this. It seemed to suggest that the mass of an aircraft must be supported >by displacing an equal mass of air downward (at least, if the aircraft is >gliding without engine power). But the article did acknowledge that a >classic airfoil section does result in lower density air above the wing; >and therefore I conclude from this that it's another way of saying that >air mass has been displaced downward. Sure...the 'path' over the top of the wing is longer than the path under it so the pressure has to be lower on the top inflight. So as the AOA increases the pressure 'under' the wing increases while the pressure on top decreases therefore the wing wants to move up. As you say, this pressure differential is basically the result of displacing air mass downward but it's the pressure differential that provided lift. >The article was more explicit in renouncing the idea that lower density >air pulls the aircraft upward. Fair enough; a vacuum, or partial vacuum, >doesn't pull anything anywhere unless there is a higher density pushing on >the opposite side. > Of course...people say "A window burst and a passenger was sucked out of the a/c". The pax was 'pushed' out of the a/c by the higher air pressure inside. To prove that just imagine an unpressurized fuselage when a window falls out, not too many pax will be 'sucked' out then I'll wager. From news Wed Apr 4 16:41:04 2001 Path: ditka!bounce-back Newsgroups: sci.aeronautics.airliners Date: 04 Apr 2001 16:41:28 From: R J Carpenter Subject: Re: Wing vs. tail-mounted engines? References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: UmFuZG9tSVZYxq09+qKP98VQm/BEklOD9a+mJE81yXSrY8o0KoY78utcI9dEgjhH Stephen H. Westin wrote: > > 2. Structure. Instead of carrying the weight of the engines > through the wing roots and fuselage, they are attached to the > part that holds them up, the wing. Am I naive in thinking that a "flying" tail could support the rear engines without any of their weight being supported by the wings??? The first rear-engined jet, the Caravelle, didn't have a true T-tail. The horizontal tail surface was still fairly low on the fin. Bob C. From news Wed Apr 4 16:41:04 2001 Path: ditka!bounce-back Newsgroups: sci.aeronautics.airliners Date: 04 Apr 2001 16:41:29 From: gbeaman@pei.sympatico.ca (Gord Beaman) Subject: Re: Wing vs. tail-mounted engines? References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: sapphire.mtt.net 986103722 142.176.73.200 (Sun, 01 Apr 2001 01:42:02 AST) X-Newsreader: Forte Free Agent 1.21/32.243 Organization: ISLAND TEL NNTP-Posting-Host: 142.176.73.200 {$usenet$}@apple-juice.co.uk (Daniele Procida) wrote: --cut-- >As someone who is scared out of his wits by aeroplanes, I much prefer >MD-80s and the like, because the sight of those enormous heavy engines >making those delicate wings bend up and down in that terrifying fashion >is something I can really do without. At least on a MD-80 I don't spend >the entire flight checking to see if the wings are going fall off. > >Instead I worry about an uncontained blade failure ripping into the >fuselage or destroying the tailplane. > >Daniele Daniele, it might ease your mind to think that the engines are lifted -by- the wing and because they're mounted -out- on it will contribute much less stress on it than if they were mounted on the fuselage and their weight had to be carried by the wing root. You shouldn't worry about safety, after all, you did survive the trip to the airport didn't you?...you're much safer in flight than on the highway. From news Wed Apr 4 16:41:04 2001 Path: ditka!bounce-back Newsgroups: sci.aeronautics.airliners,rec.travel.air Date: 04 Apr 2001 16:41:30 From: gbeaman@pei.sympatico.ca (Gord Beaman) Subject: Re: Long-distance direct flights References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: sapphire.mtt.net 986103695 142.176.73.200 (Sun, 01 Apr 2001 01:41:35 AST) X-Newsreader: Forte Free Agent 1.21/32.243 Organization: ISLAND TEL NNTP-Posting-Host: 142.176.73.200 >On 23 Mar 2001 17:40:12 , robinjohnson@bigfoot.com (Robin Johnson) >wrote: >>The longest flight stages at present operated by scheduled airlines >>run about 15 hours, at which range payload is limited. Where >>practicable, aircraft configurations biased towards premium fares are >>used. This will probably still be true when 18-hour stages start, if >>they do, in a few years. London-Perth might be one such, or New >>York-Singapore. Aircrew rest positions away from the main deck are >>being on the drawing boards - they already exist on some 747-400s. I'd think that 'if' is the operative word here...I flew for many years in Maritime Patrol Aviation where our average Long Range Patrol was around 18-20 hours and I can tell you that having extra crew available doesn't do much to alleviate fatigue. Even though you get used to sleeping in short bursts (couple of hours at a time) you're nearly as tired as if you had worked straight through. Personally, I think that I'd get somewhat apprehensive as a passenger on an airline flight of over about 12 hours. From news Wed Apr 4 16:41:04 2001 Path: ditka!bounce-back Newsgroups: sci.aeronautics.airliners Date: 04 Apr 2001 16:41:31 From: gbeaman@pei.sympatico.ca (Gord Beaman) Subject: Re: How Important Is Cross-section Shape Of Wing? References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: sapphire.mtt.net 986103654 142.176.73.200 (Sun, 01 Apr 2001 01:40:54 AST) X-Newsreader: Forte Free Agent 1.21/32.243 Organization: ISLAND TEL NNTP-Posting-Host: 142.176.73.200 bbarksdl@aol.com (BBarksdl) wrote: >In the April issue of Discover magazine, Robert Kunzig challanges the textbook >explanation of the principles of flight. I have always felt the books were >wrong on this when they say that the shape of the wing invokes Bernoulli's >Principle to provide the lift required. Kunzig refutes the role of Bernoulli's >Principle. He says that planes fly by pushing air down, getting lift from the >equal and opposite reaction that pushes the plane up. I'm trying to reconcile >that with my own thoughts on the subject - that the forces that cause an >airplane to fly are essentially the same as those that cause a kite to fly. >Either way you look at it, the shape of the wing is not the main element. >Otherwise, how could a plane fly upside-down? As an old barnstormer was >reported to have said, "Give me enough power, and I'll fly a barn door." Sure, I agree with that, I think that the wing shape just augments the forces that actually provide lift, which, as you say, is the reaction of the wings 'pushing' the airmass down. From news Wed Apr 4 16:41:04 2001 Path: ditka!bounce-back Newsgroups: sci.aeronautics.airliners Date: 04 Apr 2001 16:41:32 From: gbeaman@pei.sympatico.ca (Gord Beaman) Subject: Re: Air France Concorde crashes after departing Paris CDG References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: sapphire.mtt.net 986103624 142.176.73.200 (Sun, 01 Apr 2001 01:40:24 AST) X-Newsreader: Forte Free Agent 1.21/32.243 Organization: ISLAND TEL NNTP-Posting-Host: 142.176.73.200 FilipPC.DeVos@rug.ac.be (Filip De Vos) wrote: >matt weber (mattheww50@home.com) wrote: > >: Flyable only in a very narrow sense of the word. Concorde is a strange >: airliner in that minimum drag at MGTOW on most aircraft is pretty close to >: V2, on Concorde it is at 415kt. The full thrust of 2 engines on Concorde is >: roughly equal to drag at 275kt. Below 275kt, drag exceeds thrust, >: consequently flight at speeds below 275kt on 2 engines is a black hole in > >Part of that drag is the rudder, deflected to compensate for the >assymetric thrust. So my question is, is it possible to make a climbing >turn at a lower speed than 275kt? (turning towards the dead engines) Wouldn't that be sort of self defeating?...if you roll any aircraft from level then you reduce the lift that the wings produce, so I'd think that to maintain your altitude in other than level flight you'd need to increase your AOA which would replace the drag that you saved from the rudder deflection... From news Wed Apr 4 16:41:04 2001 Path: ditka!bounce-back Newsgroups: sci.aeronautics.airliners Date: 04 Apr 2001 16:41:33 From: matt weber Subject: Re: Air France Concorde crashes after departing Paris CDG References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM Content-Type: text/plain; charset="us-ascii"; format=flowed At 04:43 PM 3/31/01 +0000, you wrote: >matt weber (mattheww50@home.com) wrote: > >: Flyable only in a very narrow sense of the word. Concorde is a strange >: airliner in that minimum drag at MGTOW on most aircraft is pretty close to >: V2, on Concorde it is at 415kt. The full thrust of 2 engines on Concorde is >: roughly equal to drag at 275kt. Below 275kt, drag exceeds thrust, >: consequently flight at speeds below 275kt on 2 engines is a black hole in > >Part of that drag is the rudder, deflected to compensate for the >assymetric thrust. So my question is, is it possible to make a climbing >turn at a lower speed than 275kt? (turning towards the dead engines) The information I have seen says the rudder just made things worse, i.e. effectively the minimum safe airspeed with two engines on one side out is higher then 275kt. The preliminary investigation however suggests that the need for large amounts of rudder on the runway was a result of the wheel assembly being incorrectly assembled after repair, rather then assymetric thrust. It was missing a spacer on the wheel assembly, and as a result, would not track straight down the runway. The engines are close enough together, and far enough from the CG that rudder authority isn't much of an issue. Matt Weber From news Wed Apr 4 16:41:04 2001 Path: ditka!bounce-back Newsgroups: sci.aeronautics.airliners Date: 04 Apr 2001 16:41:34 From: matt weber Subject: Re: Wing vs. tail-mounted engines? References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM Content-Type: text/plain; charset="us-ascii"; format=flowed At 04:43 PM 3/31/01 +0000, Don Stokes wrote: >Daniele Procida <{$usenet$}@apple-juice.co.uk> wrote: > >As someone who is scared out of his wits by aeroplanes, I much prefer > >MD-80s and the like, because the sight of those enormous heavy engines > >making those delicate wings bend up and down in that terrifying fashion > >is something I can really do without. At least on a MD-80 I don't spend > >the entire flight checking to see if the wings are going fall off. > >Actually, the wing stresses are lower with the engines on the wing >because the wing root is not carrying the weight of the engines as well >as the fuselage. Remember that the wings carry the plane, not the other >way around. > >Of course, the tail mounted aircraft have correspondingly stronger wing >root and tail structures to deal with the higher stresses, so the chances >of the wings falling off are about the same: vanishingly small. > >(I can't think of any case of failure of the wing box or root structure >causing an accident on a post-war commercial airliner -- can anyone?) That what caused the Two Electra accidents indirectly. The whirl mode failure of the engine mounts caused the wingbox loading to exeed the design limits, and the actual failure was the wings came off the aircraft. The fix was to stiffen the wing, and make the engine mounts stronger. Matt Weber From news Wed Apr 4 16:41:04 2001 Path: ditka!bounce-back Newsgroups: sci.aeronautics.airliners Date: 04 Apr 2001 16:41:35 From: "matt weber" Subject: Re: Wing vs. tail-mounted engines? References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit ----- Original Message ----- From: "Robin Johnson" To: Sent: Saturday, March 31, 2001 4:43 PM Subject: Re: Wing vs. tail-mounted engines? > On the other hand, more and more ETOPS flights are being undertaken - > the majority of North Atlantic crossings for example. Despite this, > there have been very few ditchings. > Just this month a United 767 on the climb-out from Lihue and bound for > California, had a loss of power on both engines. No harm done, > but..... > I'm a little concerned about the dynamics of a ditching with > underslung engines, though. The Ethiopian 767 off the Comores, > although a hijack situation with armed men on the flightdeck, looked > good on the video until the last minute, when it seemed that the > engines dug in asymmetrically, causing the fuselage to break up. You have to remember that at that point, both engines had failed (fuel starvation), and I doubt there was time to deploy the RAT, and with no fuel, the APU isn't going to be helpful either... > Does anyone know of a successful ditching by a jet? In the 1960's, a JAL DC8 freighter ended up well short of the runway at SFO, and in the bay. It was fished out, overhauled, and flew until the mid 1980's when it was finally retired.... From hrose-saa@ckdhr.com Mon Apr 9 15:36:56 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 09 Apr 2001 15:36:56 From: Joe Castleman Subject: Re: Boeing's Sonic Cruiser References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: sv3-1moN4dzIDHX2OLNxl4LV7aIQ+0z6Yn345NPd3Q7hpY+RXN7m8UyVu8tITJfsEMEPJmqV43MABg6qWVl!weZR3zJ45JZnZKEM7ICJBjLt5CFvA8aqTr/KvrJCTXlOLNBIJs/ygelani2w0sttSiaH5AknwQFe!5TlT3yMx Organization: Giganews.Com - Premium News Outsourcing Damon Hill wrote: > Will it fly? Will the airlines buy? I hope so! Commercial > aircraft design has been SO boring for the past couple of > decades. I know there are Rutan airplanes, as well as a Beech aircraft, that look like this... I've wondered for years if they would ever apply such a design to commercial airliners. I figure that one problem with this is how to pull the jetway up to the fuselage. If they move the horizontal stabilizer (or is it canard?) to the front, it will be in the way. How far back on the fuselage could they mount the stabilizer? -- --- Joe Castleman -- jcastle@io.com - gyrofrog@gyrofrog.com Gyrofrog Communications -- http://www.gyrofrog.com/ Austin, Texas, U.S.A. From hrose-saa@ckdhr.com Mon Apr 9 15:36:57 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 09 Apr 2001 15:36:57 From: "Matthew Willshee" Subject: Re: How Important Is Cross-section Shape Of Wing? References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: newsg3.svr.pol.co.uk 986631550 950 217.134.155.56 (7 Apr 2001 08:19:10 GMT) X-Newsreader: Microsoft Outlook Express 5.00.2314.1300 NNTP-Posting-Host: modem-824.sponger.dialup.pol.co.uk Gord Beaman wrote in message news:airliners.2001.124@ditka.Chicago.COM... > cp@panix.com wrote: > > Sure...the 'path' over the top of the wing is longer than the > path under it so the pressure has to be lower on the top > inflight. So as the AOA increases the pressure 'under' the wing > increases while the pressure on top decreases therefore the wing > wants to move up. As you say, this pressure differential is > basically the result of displacing air mass downward but it's the > pressure differential that provided lift. Here's my take on this one. Bernoulli's principle says that faster flowing air has lower pressure. This is because as the air flow accelerates some of the pressure energy is converted to movement energy. Bernoulli's principle is a law of physics. You can use Bernoulli's equation itself in incompressible flow (water or very low Mach number air) but you must use compressible flow equations to get accurate results at higher speeds. Where every "popular science" text gets it wrong is that they say the air must move faster over the top section of the wing because it has farther to go (therefore pressure is lower hence net force on wing). The problem is that the air on the top doesn't know that it has to take the same time to get across the wing as the air on the bottom. It doesn't even know what the air on the bottom is doing. It might get to the trailing edge at the same time, earlier or later. What is going on then? Newton's Third Law says that every action must have an equal and opposite reaction. In the vertical sense there are two forces acting on the plane. First gravity - the Earth pulls the plane down (reaction - plane pulls earth up). Second lift - the air is pushing the plane up to counteract gravity. There must be a reaction - the air must be pushed downwards. So any successful lift device displaces air downwards. We could use wings, a rotor or some sort of jet. At the wing itself this exchange of forces is via pressure differences. The wing feels higher pressure on the bottom than the top. The air on the top feels a pressure gradient from ambient away from the wing to the lower pressure on the wing surface - and so is deflected downwards. The air on the bottom feels a pressure gradient from the higher pressure on the wing surface to ambient below the wing - and is also deflected downwards. Other posters have already talked about different ways of achieving this situation with a wing design - either a symmetrical wing at an angle of attack or a curved wing. Regards, Matthew Willshee From hrose-saa@ckdhr.com Mon Apr 9 15:36:58 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 09 Apr 2001 15:36:58 From: "Frank Jenkins" Subject: Re: Boeing's Sonic Cruiser References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: nntp1.ba.best.com 986591649 79983 206.184.163.161 (6 Apr 2001 21:14:09 GMT) X-Newsreader: Microsoft Outlook Express 5.50.4133.2400 Organization: The ISP formerly known as Best NNTP-Posting-Host: fjenkins.vip.best.com "Damon Hill" wrote in message news:airliners.2001.83@ditka.Chicago.COM... > Will it fly? Will the airlines buy? I hope so! Commercial > aircraft design has been SO boring for the past couple of > decades. > > How fast WILL it go? It already looks supersonic, with the right > engines. > > http://www.boeing.com/news/feature/concept/ With the main landing gear mounted so far back, the pilots are going to be really high off the runway on touchdown. Likely more than even the Concorde or 747. If Boeing can keep the fuel burn/mile the same as a 767 (a *big* if), they could have a winner. Here's hoping. Frank From hrose-saa@ckdhr.com Mon Apr 9 15:36:59 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 09 Apr 2001 15:36:59 From: "Doug Holik" Subject: Re: Air France Concorde crashes after departing Paris CDG References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: newssvr06-en0.news.prodigy.com 986566320 4758050 63.252.158.179 (6 Apr 2001 14:12:00 GMT) X-Newsreader: Microsoft Outlook Express 5.50.4133.2400 Organization: Prodigy http://www.prodigy.com NNTP-Posting-Host: a010-0687.ipls.splitrock.net "Jeremy Harris [RU-UK]" wrote in message news:airliners.2001.112@ditka.Chicago.COM... > In article , > FilipPC.DeVos@rug.ac.be (Filip De Vos) writes: > > Part of that drag is the rudder, deflected to compensate for the > > assymetric thrust. So my question is, is it possible to make a climbing > > turn at a lower speed than 275kt? (turning towards the dead engines) > Uh, to first order, planes don't turn thanks to the rudder, but thanks > to having been banked. Actually they do turn because of the rudder, why do you think its there? Ordinarrily you are correct, commercial aircraft turn primarily through banking, but, only because it is an uncomfortable sensation for the passengers if a plane turns through use of the rudder. To them the plane feels like it is sliding back and forth. The ruder is always used to make turns though. It is merely used in conjunction with a degree of bank in order to make the passengers more comfortable. In an assymetrical thrust situation the rudder would be dialed to a pre-determined setting to account for the missing engine thrust. The worst possible case is to be left with only engines on one side of the aircraft, then you would need almost full turn to be dialed in on the rudder. If you have ever felt the pilots make a turn with the rudder it is a most uncomfortable feeling... it is easy to see why the airlines try to avoid it. Doug Holik From hrose-saa@ckdhr.com Mon Apr 9 15:37:00 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 09 Apr 2001 15:37:00 From: "Doug Holik" Subject: Re: Wing vs. tail-mounted engines? References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: newssvr05-en0.news.prodigy.com 986557213 4758050 63.252.158.181 (6 Apr 2001 11:40:13 GMT) X-Newsreader: Microsoft Outlook Express 5.50.4133.2400 Organization: Prodigy http://www.prodigy.com NNTP-Posting-Host: a010-0689.ipls.splitrock.net "RF-X" wrote in message news:airliners.2001.117@ditka.Chicago.COM... > In article , > robinjohnson@bigfoot.com wrote: > > > I'm a little concerned about the dynamics of a ditching with > > underslung engines, though. The Ethiopian 767 off the Comores, > > although a hijack situation with armed men on the flightdeck, looked > > good on the video until the last minute, when it seemed that the > > engines dug in asymmetrically, causing the fuselage to break up. > > Does anyone know of a successful ditching by a jet? > > I would feel safer in a rear-engined model. > > I was under the impression that jets with underslung engines had a > method of jettisoning said engines in a ditch scenario, and this wasn't Not sure where you heard that but there is no way to jettison the engines. Some commercial aircraft, notably the MD-11 feature a "ditching" switch. All this switch does is close up the holes on the skin of the aircraft, APU Ports, Outflow Valve, etc... A means to jettison the engines does not sound like a good idea anyway, what if someone accidentally pressed the wrong button? Doug Holik From hrose-saa@ckdhr.com Mon Apr 9 15:37:01 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners,misc.transport.air-industry Date: 09 Apr 2001 15:37:01 From: "AirEcGrp" Subject: Growing traffic delay problems Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Newsreader: Microsoft Outlook Express 5.00.2919.6700 Organization: Posted via Supernews, http://www.supernews.com In the last few years we have been witnessing a growing air traffic delay problem in the US. There is a great deal of debate regarding the solutions to these problems and a great deal of finger pointing. While the airlines point the finger at ATC and the weather, a recent editorial points the finger back at the airlines themselves. I thought the peice offered some pretty valid suggestions, what do you all think? Ten Things Airlines Should Do About Airspace Capacity Problem The long simmering airspace capacity problem is coming to a boil in the U.S., after years of warnings. Recently, the Air Transport Association of America listed a "Top Ten List" of things the airlines want the FAA to do to help turn things around. Wingman thinks the airlines, themselves, could do more to help. Here's Wingman's list of ten things the airlines should do as quickly as possible to ensure the continuing viability of their industry: 1.. Take back the responsibility for the basic purpose for their business: transporting passengers safely, efficiently and reliably by air. This includes not taking for granted what happens between gate push-back and gate arrival - and it goes beyond collaborative decision making. While airline safety is still exceptional, airline flight efficiency is declining and its flight schedule reliability is rapidly deteriorating. Hoping someone else (read FAA) will fix it, is wishful dreaming. 2.. Install a high-level manager to oversee airspace improvement within each airline. This person - who needs to be an innovative manager with experience in airspace operations - might come from the airline's pilot ranks, but that is not absolutely necessary. Such a person could come from an airlines' dispatch and operational planning function, or its engineering group. Whatever the person's background, it is important that the person be intimately knowledgeable about how the airspace system works. What is even more important, is that each airline clearly send a message, internally and to outsiders, that it intends to take the problem of airspace improvement seriously. Therefore, this manager needs to report to, at least, the airline 's highest ranking operational executive. 3.. Show up at industry airspace operational meetings. These certainly include RTCA's Free Flight effort and airspace redefinition. For too long, airlines have been absent from important industry deliberations on the concepts and procedures for managing tomorrow's airspace. (There have been a few notable exceptions to this, such as American's Robert Baker chairing the Free Flight Steering Committee.) This has been unfortunate, because the airlines lack of interest has retarded the process of introducing the new technology and techniques that could have helped prevent the present problem - first, because it creates doubts about airline buy-in, and second, because it restricts airline input on how things actually work in the real world. 4.. Participate in industry standards activities. There is little debate about the need for standards in aviation. Global flight would be nearly impossible without the worldwide operational requirements of ICAO, the minimum operational and performance standards of RTCA and Eurocae, along with the form, fit and function specifications of AEEC, which make avionics both practical and affordable. Yet, in recent years airlines seem to take these necessary functions for granted. Unfortunately, the airlines' lack of interest has slowed the decision-making of these groups and may have inhibited the quality of their work as well. 5.. Take more initiative in conducting trials, demonstrations and other activities to develop, evaluate and prove the value of new procedures and technologies. Airlines have access to the expertise, facilities and equipment necessary to do some of the required proof-of-concept work and evaluations required to develop both the equipment and procedures needed for real, worthwhile modernization. The Ohio Valley operational surveillance evaluations over the last two years have been one example of this. U.S. airlines are currently participating in new datalink communications work, as well. But these aren't enough to affect the necessary changes which must be implemented much faster. Compared to the losses (both direct and intangible) airlines suffer from airspace-related disruptions and poor service, these contributions to help understand and validate improvements are minor. 6.. Don't be stymied by faulty competitive concerns or the not-invented-here syndrome. Each airline cannot and should not invent an improved airspace system by itself. Nor should new flight procedures be proprietary if they have synergistic effects by mass adoption. On the other hand, there are self-help and competitive opportunities which innovative airlines can successfully exploit to gain competitive advantages. These might be especially possible at hub-dominated airports. 7.. Reconstitute the divisions in flight operations and engineering that keep track of and contribute to what's going on in the airspace. Airlines have too long neglected their "sky factory." This assertion may seem strange, but very few airline people really know much about it - even line pilots. (This is not meant to disparage their professionalism, but day-to-day flying is not the same as becoming really expert about airspace technology, management and innovation. Still, the airline people who know the most about the sky factory are pilots and dispatchers, but for a number of reasons - some cost-related - they're often not consulted. Qualified pilots, engineers and operational control managers within airlines need to be identified, nurtured and supported. And the job is to big, important and complex to handed off as subsidiary duty for a training pilot or check airman. A big problem for many airlines, however, is that pilots and dispatchers are union members and therefore excluded from management roles for contractual and cultural reasons. 8.. Collect and share operational data with more detail, using flight operations quality assurance (FOQA) recorders and other data gathering and analytical devices. We hear more and more about the need of data to understand what is happening in our airspace and to validate steps to improve it. Some of it is relatively easy and inexpensive to get. Today's airplanes have a myriad of sensors that can collect that data, and there are retrieval systems and data reduction programs which can economically analyze the resulting information. These data need to be collected, shared and analyzed as quickly as possible for the benefit of all. 9.. Become more realistic about payback requirements. For too long, airlines have cowed avionics suppliers with unreasonable investment payback hurdles. It may be understandable, that managers need simple formulas to sift through an overwhelming number of capital budget requests. But investments in the sky factory cannot be treated the same way as typical requests for new equipment. Investments in airspace infrastructure needs the same long-term view as purchases of new airplanes. 10.. Be open to new ideas. The airlines' we're-not-interested response to the idea of ATC privatization, as publicized by the Air Transport Association, was disappointing. There may seem to be good reasons for this: fear of labor's reaction, fear of losing some relative near-term cost advantage, a vain hope that former President Clinton's new ATC management structure will somehow change things, or even fear of the unknown. But airlines in particular have a vested interest in solving "sky factory" problems. Their unwillingness to question the ATC status quo doesn't inspire confidence that they have enough awareness of their perilous future. 03-25-2001. This editorial appeared in Flt Tech Online in the editorial Wingman section. From hrose-saa@ckdhr.com Mon Apr 9 15:37:02 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 09 Apr 2001 15:37:02 From: gbeaman@pei.sympatico.ca (Gord Beaman) Subject: Re: Wing vs. tail-mounted engines? References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: sapphire.mtt.net 986518874 142.176.117.32 (Thu, 05 Apr 2001 22:01:14 ADT) X-Newsreader: Forte Free Agent 1.21/32.243 Organization: ISLAND TEL Reply-To: ve1eo@rac.ca NNTP-Posting-Host: 142.176.117.32 matt weber wrote: --cut-- >> >>(I can't think of any case of failure of the wing box or root structure >>causing an accident on a post-war commercial airliner -- can anyone?) >That what caused the Two Electra accidents indirectly. The whirl mode >failure of the engine mounts caused the wingbox loading to exeed the design >limits, and the actual failure was the wings came off the aircraft. The >fix was to stiffen the wing, and make the engine mounts stronger. Bit more than that Matt,,,they discovered that the 'whirl mode' problem was causing sympathetic vibration of certain stiffeners and support structures in the wings and that the fix was to add syncronization and syncrophasing of the propellers. This system is now used on all twin and four engined a/c using Allison T-56 type engines. C-130, P-3, and Convair 580's are the types that I know about, there's likely others. This system has the added benefit of reducing crew fatigue due to less engine induced vibration. From hrose-saa@ckdhr.com Mon Apr 9 15:37:03 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 09 Apr 2001 15:37:03 From: gbeaman@pei.sympatico.ca (Gord Beaman) Subject: Re: Wing vs. tail-mounted engines? References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: sapphire.mtt.net 986518868 142.176.117.32 (Thu, 05 Apr 2001 22:01:08 ADT) X-Newsreader: Forte Free Agent 1.21/32.243 Organization: ISLAND TEL Reply-To: ve1eo@rac.ca NNTP-Posting-Host: 142.176.117.32 R J Carpenter wrote: --cut-- > >Am I naive in thinking that a "flying" tail could support the rear >engines without any of their weight being supported by the wings??? Yes, I'm afraid so, -all- of any a/c's weight is supported by the wings (or canards), none is supported by the tail surfaces at all. They're there -only- to control (along with the ailerons) the a/c in flight. As a matter of fact, in normal flight, the horizontal tail surfaces actually have a net downward force which is used in the 'vertical stability department'. >The first rear-engined jet, the Caravelle, didn't have a true T-tail. >The horizontal tail surface was still fairly low on the fin. The reason for the T tail config is to get the horizontal stab. up out of the turbulance of the rear mounted engines. When in a very nose high position the a/c can get into what's known as a 'deep stall' where the elevators are in such turbulent air from the engines that you cannot get the nose down...this apparently happened to a Trident (?) in the UK many years ago. From hrose-saa@ckdhr.com Mon Apr 9 15:37:04 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 09 Apr 2001 15:37:04 From: Geno Rice Subject: Re: Wing vs. tail-mounted engines? References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM Organization: Monmouth Internet NNTP-Posting-Host: bg-tc-ppp648.monmouth.com R J Carpenter wrote: > Am I naive in thinking that a "flying" tail could support the rear > engines without any of their weight being supported by the wings??? > The first rear-engined jet, the Caravelle, didn't have a true T-tail. > The horizontal tail surface was still fairly low on the fin. I thought that for stability the tail is required to provide negative lift. Geno Rice From hrose-saa@ckdhr.com Mon Apr 9 15:37:05 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 09 Apr 2001 15:37:05 From: Malcolm Weir Subject: Re: Boeing's Sonic Cruiser - a Boeing stealth aircraft References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM Organization: Little to None X-Newsreader: Forte Agent 1.8/32.548 NNTP-Posting-Host: !]Mt^1k-YI`csm/G]aU:FDGgF (Encoded at Airnews!) On 04 Apr 2001 16:41:04 , "Paul Palmer" caused to appear as if it was written: [ Snip ] >I worked on General Dynamics' F-16XL, which had a double-delta "cranked >arrow" wing. The program was originally called SCAMP, which was an acronym >for 'supersonic cruise at mil power'. Mil power is without afterburner, and >SS cruise without it is something that could not be done on the 1980's >generation of engines. Errr... actually, you need 1960's generation of engines for supercruise! Rolls-Royce/SNECMA Olympus 593, anyone? Still, I don't disagree with your real point! [ Snip ] >Paul Palmer Malc. From hrose-saa@ckdhr.com Mon Apr 9 15:37:06 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 09 Apr 2001 15:37:06 From: Malcolm Weir Subject: Re: A fascinating tidbit from Boeing References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM Organization: Little to None X-Newsreader: Forte Agent 1.8/32.548 NNTP-Posting-Host: !]Mt^1k-YI`csm/G]aU:FDGgF (Encoded at Airnews!) On 04 Apr 2001 16:41:08 , jthorn@galileo.thp.univie.ac.at (Jonathan Thornburg) caused to appear as if it was written: [ Snip ] >> Operating costs would not be >> all that different from similar-sized airplanes,'' Callan continued. > >In other words [translating from PR-speak to engineer/accountant-speak], >they'd be a bit higher than competing airplanes (whether Boeing or Airbus). Actually, the translation is slightly less favorable: Operating costs would be a bit higher than the operating costs of the currently flying aircraft of comparable size, most of which were designed in the 1980s. This is not to say that the operating costs would be very close to the costs of a hypothetical new design that Boeing _could_ make. It is no secret that one of the biggest problems that the 747X faced was that its costs were only slightly better than those of the 747-400. By contrast, the costs of the 777 are much better. Airlines wanted 777-style costs in a 747-400+ sized package; this is apparently technically possible based on things like the GE90, extended use of composites, etc. but you have to start with a mostly clean sheet of paper. Malc. From hrose-saa@ckdhr.com Mon Apr 9 15:37:07 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 09 Apr 2001 15:37:07 From: Pete Finlay Subject: Re: Boeing's Sonic Cruiser References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM Organization: Expensive Desktop Paperweights X-Newsreader: Turnpike (32) Version 4.01 Reply-To: Pete Finlay In article , JohnMcGrew writes >It's pretty much a foregone conclusion that the Concorde isn't >going to be with us much longer. Not so. BA plans on getting another 8 - 10 years out of them. -- Pete Finlay From hrose-saa@ckdhr.com Mon Apr 9 15:37:08 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 09 Apr 2001 15:37:08 From: Pete Finlay Subject: Re: Boeing's Sonic Cruiser - a Boeing stealth aircraft References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM Organization: Expensive Desktop Paperweights X-Newsreader: Turnpike (32) Version 4.01 Reply-To: Pete Finlay In article , Paul Palmer writes >At Mach 1.5, about the max speed standard aluminum and 350 degree F cure >composites will allow, Concorde's skin is aluminium, and we fly at Mach 2.0 In fact, the maximum speed of Concorde is limited by the temperature which aluminium doesn't like. If the nose probe temperature reaches 127 degrees C, we slow down. -- Pete Finlay From hrose-saa@ckdhr.com Mon Apr 9 15:37:09 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 09 Apr 2001 15:37:09 From: Pete Finlay Subject: Re: Air France Concorde crashes after departing Paris CDG References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM Organization: Expensive Desktop Paperweights X-Newsreader: Turnpike (32) Version 4.01 Reply-To: Pete Finlay In article , Jeremy Harris [RU-UK] writes >In article , > FilipPC.DeVos@rug.ac.be (Filip De Vos) writes: >> Part of that drag is the rudder, deflected to compensate for the >> assymetric thrust. So my question is, is it possible to make a climbing >> turn at a lower speed than 275kt? (turning towards the dead engines) > >Uh, to first order, planes don't turn thanks to the rudder, but thanks >to having been banked. > >- Jeremy Jeremy, I don't think Philip was stating that the pilots put rudder in so they could turn. When you are assymetric, you *need* rudder to fly straight. -- Pete Finlay From hrose-saa@ckdhr.com Mon Apr 9 15:37:10 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 09 Apr 2001 15:37:10 From: jgh@uk.sun.com (Jeremy Harris [RU-UK]) Subject: Re: Boeing's Sonic Cruiser - a Boeing stealth aircraft References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: new-usenet.uk.sun.com 986490331 11871 129.156.199.109 (5 Apr 2001 17:05:31 GMT) Organization: Sun Microsystems X-Newsreader: knews 1.0b.1 NNTP-Posting-Host: watford-109.uk.sun.com In article , "Paul Palmer" writes: > Mil power is without afterburner, and > SS cruise without it is something that could not be done on the 1980's > generation of engines. What, did engine design go that far backwards from the 1960's to the 1980's ? Take a look at the R-R Olympus, mate. - Jeremy From hrose-saa@ckdhr.com Mon Apr 9 15:37:11 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 09 Apr 2001 15:37:11 From: John Liebson Subject: Re: Wing vs. tail-mounted engines? References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: reader.nmix.net 986475750 82690 198.59.168.109 (5 Apr 2001 13:02:30 GMT) Organization: NMIX X-Newsreader: Forte Agent 1.8/32.548 NNTP-Posting-Host: dialup9.nets.com johnmcgrew@aol.com (JohnMcGrew) wrote: >Actually, primitive airports were a major consideration for both these planes, >as they were being sold as short and medium range "feeders" to replace places >that were still being served by DC-3s in the early '60s. The 727 was actually >certified for and used on gravel runways in Alaska; conditions that a >under-slung engine could not survive. B737s could have, as a factory-option, gravel kits installed, and aircraft with this option operate from gravel runways. I suspect that these 737s have under-slung engines and that they survive such operations.... From hrose-saa@ckdhr.com Mon Apr 9 15:37:12 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 09 Apr 2001 15:37:12 From: John Liebson Subject: Re: Wing vs. tail-mounted engines? References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: reader.nmix.net 986475549 82678 198.59.168.109 (5 Apr 2001 12:59:09 GMT) Organization: NMIX X-Newsreader: Forte Agent 1.8/32.548 NNTP-Posting-Host: dialup9.nets.com jthorn@galileo.thp.univie.ac.at (Jonathan Thornburg) wrote: >The industry doesn't care much about it, but safety is another big >advantage of wing-mounted engines: What kills people in a jet crash >is often not the crash itself, but the ensuing fire. Tail-mounted >engines mean fuel pipes running from the wing (where the fuel tanks are) >aft through the fuselage to the engines, i.e. you've got fuel right >in the fuselage with the passengers. In contrast, wing-mounted engines >allow all the fuel to be kept in the wings, some distance away from the >passengers. (Some designs do put fuel tanks in the wing center sections >anyway.) What about wing-mounted-engine aircraft that _also_ have tail-mounted fuel tanks? From hrose-saa@ckdhr.com Mon Apr 9 15:37:13 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 09 Apr 2001 15:37:13 From: JF Mezei Subject: Re: Boeing's Sonic Cruiser References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: wagner.videotron.net 986439234 24.201.176.173 (Wed, 04 Apr 2001 22:53:54 EDT) NNTP-Posting-Host: 24.201.176.173 OK, Boeing only mentions mach 0.95, but many think that this will in fact be a supersonic plane. >From a certification and regulations point of view, what would be involved if Boeing decided to uprate that plane to Mach 1.5 ? Would there be a major difference in terms of FARs , regulations and approvals ? Also, Airbus stated that it needed to build 250 of the A380s to break even. What sort of numbers would Boeing have to build to make its Sonic Cruiser a money maker ? From hrose-saa@ckdhr.com Mon Apr 9 15:37:14 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 09 Apr 2001 15:37:14 From: "John R Weiss" Subject: Re: A fascinating tidbit from Boeing References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM Content-Type: text/plain; charset="Windows-1252" Content-Transfer-Encoding: 7bit X-Trace: news1.sttls1.wa.home.com 986436984 24.20.159.158 (Wed, 04 Apr 2001 19:16:24 PDT) Organization: Excite@Home - The Leader in Broadband http://home.com/faster X-Newsreader: Microsoft Outlook Express 5.50.4133.2400 NNTP-Posting-Host: 24.20.159.158 Reply-To: "John R Weiss" "Jonathan Thornburg" wrote in message news:airliners.2001.105@ditka.Chicago.COM... > Not really, they target different market segments: A "fastjet" only > matters on long-range flights (otherwise the travel time isn't > significantly different). A large part of the airliner market is > short- and medium-range. And a small plane (100-150 seats) > only makes sense for relativly "thin" routes (low number of > passengers/week). Hmmm... Why is Alaska Air campaigning vigorously for a DCA slot, only to put a direct SEA-DCA 737-700 in it, if the small plane isn't perceived to make a profit on the longer-range route? Long range (domestically speaking) and low body count aren't mutually exclusive. Besides, frequency of flights is apparently a better sell than bigger planes taking more bodies per [less frequent] flight. Also, a Mach 0.95 airplane will be a LOT cheaper to fly than an SST. The business customer who believes he MUST get from LA to DC 15 minutes faster than the other guy will be willing to pay the premium. The casual customer will be attracted for several years (because there are a LOT of them compared to the number of airplanes) to the gee-whiz, high-tech looks of the new airplane ("Heidi, look what's taking us on our honeymoon!). -- John Weiss Seattle, WA remove *nospam* from reply address From hrose-saa@ckdhr.com Mon Apr 9 15:37:15 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 09 Apr 2001 15:37:15 From: don@news.daedalus.co.nz (Don Stokes) Subject: Re: Boeing's Sonic Cruiser References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: raewyn.paradise.net.nz 986435851 14879 203.96.144.16 (5 Apr 2001 01:57:31 GMT) Organization: Daedalus Consulting X-Newsreader: trn 4.0-test72 (19 April 1999) NNTP-Posting-Host: 203-96-144-16.cable.paradise.net.nz In article , Damon Hill wrote: >Will it fly? Will the airlines buy? I hope so! Commercial >aircraft design has been SO boring for the past couple of >decades. > >How fast WILL it go? It already looks supersonic, with the right >engines. > >http://www.boeing.com/news/feature/concept/ Doesn't look supersonic to me. Note: - Large engine pods to house high-bypass engines -- not efficient for supersonic cruise - Decidedly sub-sonic looking nose section - Large canards -- the Tu-144 used (smaller) canards to keep the nose up at low speed, but retracted them for supersonic flight. Also note that the painting looks heavily area-ruled, and I suspect the fuselage would provide significant lift -- it appears to have a low floor although it's hard to tell from the published painting. That would move the centre of lift further forward than would appear from just looking at the wing planform. Does anyone else think it looks like a grown-up version of the Starship? -- don From hrose-saa@ckdhr.com Mon Apr 9 15:37:16 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 09 Apr 2001 15:37:16 From: "Ken Ishiguro" Subject: Re: Aircraft design question References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: newsread2.prod.itd.earthlink.net 986433273 209.179.238.3 (Wed, 04 Apr 2001 18:14:33 PDT) Organization: EarthLink Inc. -- http://www.EarthLink.net X-Newsreader: Microsoft Outlook Express 5.50.4133.2400 NNTP-Posting-Host: 209.179.238.3 "Tom Digby" wrote in message news:airliners.2001.118@ditka.Chicago.COM... > Ken Ishiguro wrote: > > As a potential passenger, I want a "real" window, not just a TV hookup. > If I'm looking at the Grand Canyon or the Rock of Gibraltar or maybe just > the curvature of the Earth or a sunset or something, I want to actually > see it with my own eyes. It's like the difference between seeing your > favorite performer at a live concert and staying home and watching on TV. > It may not be a rational feeling, but it's there. > I personally agree with you. However, if a camera/screen ends up way cheaper than a real window, see how long windows stay in a design. :-) Also, we probably aren't *most* passengers. The most popular seats on an airliner are aisles, followed by windows. You've probably observed that window passengers spend little or no time looking out the window. They choose it because they only share one armrest, and because they couldn't get the aisle. Looking out the window simply isn't important to most pax. Ken Ishiguro From hrose-saa@ckdhr.com Mon Apr 9 15:37:17 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 09 Apr 2001 15:37:17 From: don@news.daedalus.co.nz (Don Stokes) Subject: Re: Wing vs. tail-mounted engines? References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: raewyn.paradise.net.nz 986433030 14368 203.96.144.16 (5 Apr 2001 01:10:30 GMT) Organization: Daedalus Consulting X-Newsreader: trn 4.0-test72 (19 April 1999) NNTP-Posting-Host: 203-96-144-16.cable.paradise.net.nz JohnMcGrew wrote: >Actually, primitive airports were a major consideration for both these planes, >as they were being sold as short and medium range "feeders" to replace places >that were still being served by DC-3s in the early '60s. The 727 was actually >certified for and used on gravel runways in Alaska; conditions that a >under-slung engine could not survive. Actually, they can with a bit of imaginative engineering -- 737-200s were (are?) used for the same runways, with the aid of a "gravel kit" consisting of a deflector on the nose gear and small bleed air pipes pointing forward to disrupt any vortexes forming in front of the intakes that might suck stuff into the engines. -- don From hrose-saa@ckdhr.com Thu Apr 19 16:40:13 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 19 Apr 2001 16:40:13 From: David Simpson Subject: Re: Lightning Strike out of Dorval ? References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: typhoon.we.rr.com 987528461 24.130.197.114 (Tue, 17 Apr 2001 10:27:41 PDT) Organization: Road Runner NNTP-Posting-Host: 24.130.197.114 Joe wrote: > > Can anyone elaborate on this?It scared the dickens out of me.I heard > one of the stewardesses say. " I heve never experienced anything like > this in 32 years of flying" > > Spooked Frequent Flyer A static discharge is exactly the same as when you scoot your feet across a carpet and touch a doorknob. You build up a static charge, and when you get close enough to something conductive, it discharges. An airplane can do the same thing under the right conditions, and it throws a "spark" (lightning bolt) when the charge gets high enough. USUALLY, there is little or no damage. Certainly not enough to break the airplane, and any damage would likely be limited to localized scorching or pitting. About the worst-case scenario would be to have the radome knocked off. Not a problem structurally, but you would have no airspeed indications, since the airflow over the sensors is all fouled up. (Like the American EP-3 that went down in China). I did experience a lightning strike while sitting on the ground at O'Hare in a 727 years ago. Observers in the terminal said it hit the tail. No damage whatsoever to the structure or electronics. There are actually quite a few lightning strikes every year, and usually there is little or no damage. You asked if the captain should have returned to Dorval, and what the procedures were. There probably isn't any specific procedure for a strike/discharge at Air Canada, there is none at my airline. You'll know very quickly if something is wrong, and there will be a procedure for whatever that problem is, regardless of the cause. Obviously your flight crew saw that their electronic equipment was working properly, and there were no other abnormalities, so they decided to press on. Much the same as with a bird strike, which also happens quite frequently. Lightning strikes and static discharges are very spectacular, and certainly scary, but highly unlikely to do any real damage. A search of the NTSB (US National Transportation Safety Board) database for the last thirty years showed not a single accident that could be attributed to a lightning strike or static discharge. At worst, one airplane (a small one) had "significant" damage, but still landed with no one being hurt. (http://www.ntsb.gov/ntsb/query.asp) Most people's anxiety over flying is due to being in an environment where they have little or no knowledge of how things work or what's going on, and it's the fear of the unknown that is always the worst. I hope I was able to demystify the situation somewhat for you, and you can relax on your next flight! Dave Simpson Captain, American Airlines From hrose-saa@ckdhr.com Thu Apr 19 16:40:14 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 19 Apr 2001 16:40:14 From: westin*nospam@graphics.cornell.edu (Stephen H. Westin) Subject: Re: Air France Concorde crashes after departing Paris CDG References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: news01.cit.cornell.edu 987437599 22388 128.84.247.211 (16 Apr 2001 16:13:19 GMT) X-Newsreader: Gnus v5.7/Emacs 20.6 Organization: Cornell University NNTP-Posting-Host: diesel.graphics.cornell.edu "Doug Holik" writes: > "Jeremy Harris [RU-UK]" wrote in message > news:airliners.2001.112@ditka.Chicago.COM... > > In article , > > FilipPC.DeVos@rug.ac.be (Filip De Vos) writes: > > > Part of that drag is the rudder, deflected to compensate for the > > > assymetric thrust. So my question is, is it possible to make a climbing > > > turn at a lower speed than 275kt? (turning towards the dead engines) > > > Uh, to first order, planes don't turn thanks to the rudder, but thanks > > to having been banked. > > Actually they do turn because of the rudder, why do you think its there? To keep things pointing in the right direction. The Wright brothers developed a glider that would turn by warping the wings: one wing went up, the other down, and the lift vector would make the aircraft turn. Unfortunately, the high-lift wing would also have increased drag, so the whole plane would yaw back the wrong way. They fixed this problem by adding vertical fins at the rear, first fixed ones and finally the rudder we know today. So banking is what makes the plane turn (i.e. accelerates it off of a straight path), but the rudder keeps it pointed in the right direction. -- -Stephen H. Westin Any information or opinions in this message are mine: they do not represent the position of Cornell University or any of its sponsors. From hrose-saa@ckdhr.com Thu Apr 19 16:40:15 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 19 Apr 2001 16:40:15 From: "Paul Palmer" Subject: Re: Boeing's Sonic Cruiser - a Boeing stealth aircraft - too shay! References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: iad-read.news.verio.net 987434067 199.103.191.49 (Mon, 16 Apr 2001 15:14:27 GMT) X-Newsreader: Microsoft Outlook Express 5.50.4133.2400 Organization: Verio NNTP-Posting-Host: 199.103.191.49 Malcolm: Too shay! Of course, I believe with the right aerodynamic design, other 1960's engines could go supersonic without reheat...North American packed 6 J79's side by side on the XB70, which I believe went sonic without afterburn? Anybody? (Hey, XB-70 Valkyrie: ...canard...delta wing....) I think those 80s engines had to worry about fuel consumption...too bad! Paul "Malcolm Weir" wrote in message news:airliners.2001.142@ditka.Chicago.COM... > On 04 Apr 2001 16:41:04 , "Paul Palmer" caused to > appear as if it was written: > > [ Snip ] > > >I worked on General Dynamics' F-16XL, which had a double-delta "cranked > >arrow" wing. The program was originally called SCAMP, which was an acronym > >for 'supersonic cruise at mil power'. Mil power is without afterburner, and > >SS cruise without it is something that could not be done on the 1980's > >generation of engines. > > Errr... actually, you need 1960's generation of engines for supercruise! > > Rolls-Royce/SNECMA Olympus 593, anyone? > > Still, I don't disagree with your real point! > > [ Snip ] > > >Paul Palmer > > Malc. From hrose-saa@ckdhr.com Thu Apr 19 16:40:16 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 19 Apr 2001 16:40:16 From: "Scotty" Subject: Re: Boeing's Sonic Cruiser References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: bgtnsc04-news.ops.worldnet.att.net 987385441 12.77.135.236 (Mon, 16 Apr 2001 01:44:01 GMT) X-Newsreader: Microsoft Outlook Express 5.50.4522.1200 Organization: remove X's to reply NNTP-Posting-Host: 12.77.135.236 I sort of doubt that this is an engineering-representative design drawing. At least, it seems apparent the systems-E folks have not had a good hack at it yet. "Don Stokes" wrote in message news:airliners.2001.152@ditka.Chicago.COM... > In article , > Damon Hill wrote: > >Will it fly? Will the airlines buy? I hope so! Commercial > >aircraft design has been SO boring for the past couple of > >decades. > > > >How fast WILL it go? It already looks supersonic, with the right > >engines. > > > >http://www.boeing.com/news/feature/concept/ > > Doesn't look supersonic to me. Note: > > - Large engine pods to house high-bypass engines -- not efficient for > supersonic cruise > > - Decidedly sub-sonic looking nose section > > - Large canards -- the Tu-144 used (smaller) canards to keep the nose up > at low speed, but retracted them for supersonic flight. > > Also note that the painting looks heavily area-ruled, and I suspect the > fuselage would provide significant lift -- it appears to have a low floor > although it's hard to tell from the published painting. That would move > the centre of lift further forward than would appear from just looking > at the wing planform. > > Does anyone else think it looks like a grown-up version of the Starship? > > -- don From hrose-saa@ckdhr.com Thu Apr 19 16:40:17 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 19 Apr 2001 16:40:17 From: JP Caputa Subject: High wing vs. low wing Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: news1.gvcl1.bc.home.com 987307277 24.64.214.46 (Sat, 14 Apr 2001 21:01:17 PDT) Organization: Excite@Home - The Leader in Broadband http://home.com/faster NNTP-Posting-Host: 24.64.214.46 Why is it that all commercial airliners, aside from perhaps turbo-prop feeder liners and the BAe 146 are low winged, where as most military cargo planes are high winged. Both types of aircravet serve very similar roles, and travel over similar ranges. I can understand that the purpose of the high winged cargo transports is to have the floor of the plane closer to the ground for easier loading of cargo, but I'd figure this should be an equally important factor for the airlines. So essencially, the question is: WHAT ARE THE BENEFITS OF LOW WINGED AIRCRAFT (if any) AS OPPOSED TO HIGH WINGED AIRCRAFT? =================================================== JP Caputa ***** jcaputa@engr.uvic.ca =================================================== From hrose-saa@ckdhr.com Thu Apr 19 16:40:18 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 19 Apr 2001 16:40:18 From: Eric George Subject: McDonnel Douglas name still in use? Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: bgtnsc06-news.ops.worldnet.att.net 987219597 12.74.131.221 (Sat, 14 Apr 2001 03:39:57 GMT) Organization: AT&T Worldnet NNTP-Posting-Host: 12.74.131.221 Hi All, I hnow McDonnell Douglas was bought out (ok merged) with Boeing back in Aug. 1997. Does anybody know if any vestige of the company still uses the McDonnel Douglas name? ie. could somebody say they work for McDonnell Douglas? Thanks From hrose-saa@ckdhr.com Thu Apr 19 16:40:19 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 19 Apr 2001 16:40:19 From: jwizardc@aol.com (JWizardC) Subject: Re: Growing traffic delay problems References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM Organization: AOL http://www.aol.com I would like to point to the simplest solution: decrease the number of flights scheduled during the peak hours! Until the reality of multiple objects attempting to occupy the same physical space at the same time it corrected (which is going to take some serious ammendments to the laws of physics), the airspace corridors are going to continue to have the same problems as our highway system. IMHO, the problem isn't FAA, ATC, or 'free flight'. It is simply that the airplanes sooner or later have to come home to roost, and everyone is trying to do so at the same time! Look at any airline schedule -- I don't care what airport you are talking about -- note tha number of flights during the 0500 - 1000 local, 1600 - 2000, and compare against the rest of the times. It is no accident that most of the airlines' cut rate specials are for flights outside those peak times. Having to fly empty (or nearly empty) planes around to have them in place for the next rush is a drain on profits. We the travelling public aren't demanding flight times, we are demanding departure and arrival times! Of course, I don't have any strong feelings on this topic... TheFNG From hrose-saa@ckdhr.com Thu Apr 19 16:40:20 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 19 Apr 2001 16:40:20 From: jwizardc@aol.com (JWizardC) Subject: Re: How Important Is Cross-section Shape Of Wing? References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM Organization: AOL http://www.aol.com Okay, here's another simian torquer (monkey wrench): When I got to advanced aero design classes, I learned that Bernoulli is mostly a convient fiction to help explain a mind numbingly difficult truth. In actuality, as a wing-shaped object begins to move forward in a fluid (like air), an amazing phenomenon takes place. A vortex begins to form behind the wing, creating a partial suction, which pulls more air over the top of the wing -- here's the hard part -- from underneath it! Wander over to http://www.geocities.com/galemcraig/ for a discussion far better than I can provide here. TheFNG From hrose-saa@ckdhr.com Thu Apr 19 16:40:21 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 19 Apr 2001 16:40:21 From: robinjohnson@bigfoot.com (Robin Johnson) Subject: Re: Wing vs. tail-mounted engines? References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: 13 Apr 2001 00:17:50 +1000, 202.138.58.243 X-Newsreader: Forte Agent 1.5/32.451 Organization: North Antarctica Reply-To: robinjohnson@bigfoot.com NNTP-Posting-Host: 202.138.58.243 On 09 Apr 2001 15:37:00 , "Doug Holik" told us: >"RF-X" wrote in message >news:airliners.2001.117@ditka.Chicago.COM... >> In article , >> robinjohnson@bigfoot.com wrote: >> >> > I'm a little concerned about the dynamics of a ditching with >> > underslung engines, though. The Ethiopian 767 off the Comores, >> > although a hijack situation with armed men on the flightdeck, looked >> > good on the video until the last minute, when it seemed that the >> > engines dug in asymmetrically, causing the fuselage to break up. >> > Does anyone know of a successful ditching by a jet? >> > I would feel safer in a rear-engined model. >> >> I was under the impression that jets with underslung engines had a >> method of jettisoning said engines in a ditch scenario, and this wasn't > >Not sure where you heard that but there is no way to jettison the engines. >Some commercial aircraft, notably the MD-11 feature a "ditching" switch. >All this switch does is close up the holes on the skin of the aircraft, APU >Ports, Outflow Valve, etc... >A means to jettison the engines does not sound like a good idea anyway, what >if someone accidentally pressed the wrong button? I didn't get much response to the above question in another ng (about successful ditchings). But I do remember that some of the early jets with underslung engines, specifically the DC-8, had a pylon arrangement that disconnected easily in the event of increased resistance. The example I saw was a DC-8-50 that overran into a soft ploughed field on attempted takeoff at Heathrow sometime in the mid-60s. One engine (or more) had completely severed connection. I was told at the time it was arranged so to avoid smashing into the wing fuel tanks: it presumably did not happen to the ET 767. Which aircraft had/have that as a feature, and why was it dropped? --Robin Johnson > >Doug Holik From hrose-saa@ckdhr.com Thu Apr 19 16:40:22 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 19 Apr 2001 16:40:22 From: robinjohnson@bigfoot.com (Robin Johnson) Subject: Re: Boeing's Sonic Cruiser References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: 13 Apr 2001 00:03:44 +1000, 202.138.58.243 X-Newsreader: Forte Agent 1.5/32.451 Organization: North Antarctica Reply-To: robinjohnson@bigfoot.com NNTP-Posting-Host: 202.138.58.243 On 09 Apr 2001 15:37:07 , Pete Finlay told us: >In article , JohnMcGrew > writes >>It's pretty much a foregone conclusion that the Concorde isn't >>going to be with us much longer. > >Not so. BA plans on getting another 8 - 10 years out of them. What is the high time/cycles on the BA Concorde fleet? The only figures I have seen were dated Sept 1999 and the high timer was under 22,000 hours. --Robin Johnson From hrose-saa@ckdhr.com Thu Apr 19 16:40:23 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 19 Apr 2001 16:40:23 From: jwizardc@aol.com (JWizardC) Subject: Re: Wing vs. tail-mounted engines? References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM Organization: AOL http://www.aol.com The biggest disadvantage to the wing-mounted engines in the Comet was the complexity of the wing main spar/load box. Also, the engines take up a bunch of room that could have been used by fuel. As far as the T-tail goes, a 'conventional' empannage can also stall under certain circumstances. On the other hand, the t-tail allows a slightly longer moment arm from the center of gravity. TheFNG From hrose-saa@ckdhr.com Thu Apr 19 16:40:24 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 19 Apr 2001 16:40:24 From: "Keith Willshaw" Subject: Re: Aircraft design question References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: sshuraac-i-1.production.compuserve.com 987030464 10863 158.152.112.50 (11 Apr 2001 23:07:44 GMT) X-Newsreader: Microsoft Outlook Express 5.50.4133.2400 Organization: CompuServe Interactive Services NNTP-Posting-Host: kwillshaw.demon.co.uk "Ken Ishiguro" wrote in message news:airliners.2001.153@ditka.Chicago.COM... > > "Tom Digby" wrote in message > news:airliners.2001.118@ditka.Chicago.COM... > > Ken Ishiguro wrote: > > > > As a potential passenger, I want a "real" window, not just a TV hookup. > > If I'm looking at the Grand Canyon or the Rock of Gibraltar or maybe just > > the curvature of the Earth or a sunset or something, I want to actually > > see it with my own eyes. It's like the difference between seeing your > > favorite performer at a live concert and staying home and watching on TV. > > It may not be a rational feeling, but it's there. > > > I personally agree with you. However, if a camera/screen ends up way > cheaper than a real window, see how long windows stay in a design. :-) > > Also, we probably aren't *most* passengers. The most popular seats on an > airliner are aisles, followed by windows. You've probably observed that > window passengers spend little or no time looking out the window. They > choose it because they only share one armrest, and because they couldn't get > the aisle. Looking out the window simply isn't important to most pax. > > Ken Ishiguro Lets be honest there just isnt anything much to see on most flights. You are typically over the Ocean , flying at night or over cloud cover. If I'm flying in daytime on on commuter planes I'll go for a window seat otherwise its the aisle every time. Keith From hrose-saa@ckdhr.com Thu Apr 19 16:40:25 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 19 Apr 2001 16:40:25 From: JP Caputa Subject: Re: Wing vs. tail-mounted engines? References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: news1.gvcl1.bc.home.com 986950876 24.64.214.46 (Tue, 10 Apr 2001 18:01:16 PDT) Organization: Excite@Home - The Leader in Broadband http://home.com/faster NNTP-Posting-Host: 24.64.214.46 Mad Monks wrote: > Daniele Procida <{$usenet$}@apple-juice.co.uk> wrote: > >As someone who is scared out of his wits by aeroplanes, I much prefer > >MD-80s and the like, because the sight of those enormous heavy engines > >making those delicate wings bend up and down in that terrifying fashion > >is something I can really do without. At least on a MD-80 I don't spend > >the entire flight checking to see if the wings are going fall off. > > The wing mounted engines are there because it makes for easier > lengthening and shortening of the a/c. The chief engineer for the 747 > pushed through the wing-mounted engine for the 737 so that the a/c > could be better balanced and also lengthened (so we now have a/c as > short as the 737-500 and as long as the -900). A tail-mounted engine > would have limited this flexiblity. What about the DC9/MD 80-95/717 series, those came in lengths between 46.5 m for an MD-90 to 37.2 m for an MD-95, seems pritty strechable to me! -JP jcaputa@engr.uvic.ca From hrose-saa@ckdhr.com Thu Apr 19 16:40:26 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 19 Apr 2001 16:40:26 From: mitch21@northkent.freeserve.co.uk (Michael Mitchell) Subject: AN 225 to fly soon. Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: newsg3.svr.pol.co.uk 986926683 19667 62.136.167.182 (10 Apr 2001 18:18:03 GMT) Reply-To: mitch21@northkent.freeserve.co.uk NNTP-Posting-Host: modem-54.echuir.dialup.pol.co.uk The AN 225 is nearing the end of a $20m overhaul and is due to return to the air next week. See:- http://www.aero-news.net/ Also:- http://www.airfoyle.co.uk/banner/970255462g.html Regards, Mike Mitchell. From hrose-saa@ckdhr.com Thu Apr 19 16:40:27 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 19 Apr 2001 16:40:27 From: John Wright Subject: Re: Air France Concorde crashes after departing Paris CDG References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: news.demon.co.uk 986926636 nnrp-13:12217 NO-IDENT pegase.demon.co.uk:158.152.238.141 X-Newsreader: Forte Agent 1.8/32.548 Organization: None that I'm aware of. Reply-To: news@pegase.demon.co.uk NNTP-Posting-Host: pegase.demon.co.uk On 09 Apr 2001 15:36:59 , "Doug Holik" wrote: >Jeremy Harris wrote in >>Filip De Vos writes: >> > Part of that drag is the rudder, deflected to compensate for the >> > assymetric thrust. So my question is, is it possible to make a climbing >> > turn at a lower speed than 275kt? (turning towards the dead engines) > >> Uh, to first order, planes don't turn thanks to the rudder, but thanks >> to having been banked. > >Actually they do turn because of the rudder, why do you think its there? >Ordinarrily you are correct, commercial aircraft turn primarily through >banking, but, only because it is an uncomfortable sensation for the >passengers if a plane turns through use of the rudder. To them the plane >feels like it is sliding back and forth. The ruder is always used to make >turns though. It is merely used in conjunction with a degree of bank in >order to make the passengers more comfortable. In an assymetrical thrust >situation the rudder would be dialed to a pre-determined setting to account >for the missing engine thrust. The worst possible case is to be left with >only engines on one side of the aircraft, then you would need almost full >turn to be dialed in on the rudder. If you have ever felt the pilots make a >turn with the rudder it is a most uncomfortable feeling... it is easy to see >why the airlines try to avoid it. You do that in any kind of aircraft and it will "skid". A lot of people will find that more uncomfortable than turning properly, i.e with the ailerons or spoilers. The rudder is primarily used to balance out the differential yaw induced by use of ailerons. -- John Wright From hrose-saa@ckdhr.com Thu Apr 19 16:40:28 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 19 Apr 2001 16:40:28 From: jthorn@galileo.thp.univie.ac.at (Jonathan Thornburg) Subject: Re: Wing vs. tail-mounted engines? References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM Organization: Universitaet Wien (Vienna, Austria) / Institut fuer Theoretische Physik In article , John Liebson wrote: >B737s could have, as a factory-option, gravel kits installed, and >aircraft with this option operate from gravel runways. I suspect that >these 737s have under-slung engines and that they survive such >operations.... Indeed, ISTR DC-9 engines being rather prone to damage from ingesting gravel or dirt flung up by the main wheels. Wing-mount engines may well be *preferable* in this regard. -- -- Jonathan Thornburg http://www.thp.univie.ac.at/~jthorn/home.html Universitaet Wien (Vienna, Austria) / Institut fuer Theoretische Physik Moore's Law: computer hardware speed doubles every 18 months Gates' Law: computer software speed halves every 18 months From hrose-saa@ckdhr.com Thu Apr 19 16:40:29 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 19 Apr 2001 16:40:29 From: jthorn@galileo.thp.univie.ac.at (Jonathan Thornburg) Subject: Re: Wing vs. tail-mounted engines? References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM Organization: Universitaet Wien (Vienna, Austria) / Institut fuer Theoretische Physik I wrote | The industry doesn't care much about it, but safety is another big | advantage of wing-mounted engines: What kills people in a jet crash | is often not the crash itself, but the ensuing fire. Tail-mounted | engines mean fuel pipes running from the wing (where the fuel tanks are) | aft through the fuselage to the engines, i.e. you've got fuel right | in the fuselage with the passengers. In contrast, wing-mounted engines | allow all the fuel to be kept in the wings, some distance away from the | passengers. (Some designs do put fuel tanks in the wing center sections | anyway.) In article , John Liebson asked >What about wing-mounted-engine aircraft that _also_ have tail-mounted >fuel tanks? Not nice: * fuel pipes in the aft fuselage (--> big fire risk in crashes) * fuel tanks far from center of gravity --> big trim change as you burn that fuel --> hurts aerodynamic efficiency (fighting that trim change will cost extra drag) -- -- Jonathan Thornburg http://www.thp.univie.ac.at/~jthorn/home.html Universitaet Wien (Vienna, Austria) / Institut fuer Theoretische Physik Q: Only 6 countries have the death penalty for children. Which are they? A: Congo, Iran, Nigeria, (Pakistan[*]), Saudi Arabia, United States, Yemen [*] Pakistan reportedly ended it in July 2000. -- Amnesty International http://www.web.amnesty.org/ai.nsf/index/AMR511392000 From hrose-saa@ckdhr.com Thu Apr 19 16:40:30 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 19 Apr 2001 16:40:30 From: FilipPC.DeVos@rug.ac.be (Filip De Vos) Subject: Re: Air France Concorde crashes after departing Paris CDG References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Newsreader: TIN [version 1.2 PL2] Organization: University of Ghent, Belgium NNTP-Posting-Host: eduserv1.rug.ac.be Pete Finlay (Pete@zzzmeads.demon.co.uk) wrote: : In article , Jeremy Harris [RU-UK] : writes : >In article , : > FilipPC.DeVos@rug.ac.be (Filip De Vos) writes: : >> Part of that drag is the rudder, deflected to compensate for the : >> assymetric thrust. So my question is, is it possible to make a climbing : >> turn at a lower speed than 275kt? (turning towards the dead engines) : > : >Uh, to first order, planes don't turn thanks to the rudder, but thanks : >to having been banked. : > : >- Jeremy : Jeremy, I don't think Philip was stating that the pilots put rudder in : so they could turn. When you are assymetric, you *need* rudder to fly : straight. Indeed. And this causes drag, which which Concorde could not overcome. So I am asking whether it is possible for the pilots to use slightly less rudder than necessary to counter the assymetric thrust, and accepting a turn (in the direction of the dead engines), to experience less rudder-induced drag, and hopefully climb or accelerate. -- "Who needs credibility around | Filip De Vos here?" -- T. L. Elifritz | FilipPC.DeVos@rug.ac.be From hrose-saa@ckdhr.com Thu Apr 19 16:40:31 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 19 Apr 2001 16:40:31 From: gbeaman@pei.sympatico.ca (Gord Beaman) Subject: Re: Wing vs. tail-mounted engines? References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: sapphire.mtt.net 986872590 142.176.125.196 (Tue, 10 Apr 2001 00:16:30 ADT) X-Newsreader: Forte Free Agent 1.21/32.243 Organization: ISLAND TEL Reply-To: ve1eo@rac.ca NNTP-Posting-Host: 142.176.125.196 Geno Rice wrote: >R J Carpenter wrote: > >> Am I naive in thinking that a "flying" tail could support the rear >> engines without any of their weight being supported by the wings??? > >> The first rear-engined jet, the Caravelle, didn't have a true T-tail. >> The horizontal tail surface was still fairly low on the fin. > >I thought that for stability the tail is required to provide negative >lift. > >Geno Rice > Indeed that's correct Gino... From hrose-saa@ckdhr.com Thu Apr 19 16:40:32 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 19 Apr 2001 16:40:32 From: gbeaman@pei.sympatico.ca (Gord Beaman) Subject: Re: Wing vs. tail-mounted engines? References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: sapphire.mtt.net 986872543 142.176.125.196 (Tue, 10 Apr 2001 00:15:43 ADT) X-Newsreader: Forte Free Agent 1.21/32.243 Organization: ISLAND TEL Reply-To: ve1eo@rac.ca NNTP-Posting-Host: 142.176.125.196 John Liebson wrote: --cut-- > >What about wing-mounted-engine aircraft that _also_ have tail-mounted >fuel tanks? But those tanks are comparatively very small John, their purpose is for trimming out the aerodynamic drag of the aircraft's 'stability system' when it's not essential. It's only used in stabilized cruise conditions, so for takeoff and landings these tanks are always empty. The engines are not fed from them. From hrose-saa@ckdhr.com Thu Apr 19 16:40:33 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 19 Apr 2001 16:40:33 From: CptKrell@aol.com Subject: Re: Rudder stuff 101 Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM Content-Type: multipart/alternative; boundary="part1_44.cd9339a.2803b639_boundary" --part1_44.cd9339a.2803b639_boundary Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Not to offend anyone, but Mr. Doug Houk is incorrect when he states "Actually they (airplanes) do turn because of the rudder, why do you think its (sic) there?" Jack Northrop plus the guys'n girls that designed the current stealth bomber would take you to task. *Conventional* airplanes turn the same way flying wings turn. Aerodynamics 101. One wing is reconfigured to have more lift than the other This is accomplished by changing the shape of the wings via the ailerons. The rudder (which is just a movable portion of the vertical stabilizer) keeps the airplane from "skidding", or, helps the airplane TO "skid", ie: desired *crabbing* in a cross-wind, etc. If you relied on only rudder input to turn, you'd pretty much just skid sideways (yaw) without doing a lot of turning. You'd also lose a lot of lift and airspeed which is a no-no. The rudder is commonly used in conjunction with the ailerons because lift (and therefore drag) is increased on the same wing and and the airplane will want to to be "pushed" in that direction. This is compensated to the desired degree by the good ol' rudder pedal. As for "dialing in the rudder" for engines out on one side, you better work at changing the wings and messing with the remaining throttles while you are "dialing". ........Jack (Detroit) DTW / YIP --part1_44.cd9339a.2803b639_boundary Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: 7bit Not to offend anyone, but Mr. Doug Houk is incorrect when he states
"Actually they (airplanes) do turn because of the rudder, why do you
think its (sic) there?"   

Jack Northrop plus the guys'n girls that designed  the current stealth
bomber would take you to task. *Conventional* airplanes turn the same
way flying wings turn.  Aerodynamics 101. One wing is reconfigured to
have more lift than the other  This is accomplished by changing the shape
of the wings via the ailerons. The rudder (which is just a movable portion of
the vertical stabilizer) keeps the airplane from "skidding", or, helps the
airplane TO "skid", ie: desired *crabbing* in a cross-wind, etc.  If you
relied on only rudder input to turn, you'd pretty much just skid sideways
(yaw) without doing a lot of turning. You'd also lose a lot of lift and
airspeed
which is  a no-no.  The rudder is commonly used in conjunction with the
ailerons because lift (and therefore drag) is increased on the same wing and
and the airplane will want to to be "pushed" in that direction.  This is
compensated to the desired degree by the good ol' rudder pedal.

As for "dialing in the rudder" for engines out on one side, you better
work at changing the wings and messing with the remaining throttles
while you are "dialing".

........Jack (Detroit) DTW / YIP
--part1_44.cd9339a.2803b639_boundary-- From hrose-saa@ckdhr.com Thu Apr 19 16:40:34 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 19 Apr 2001 16:40:34 From: don@news.daedalus.co.nz (Don Stokes) Subject: Re: Boeing's Sonic Cruiser - a Boeing stealth aircraft References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: raewyn.paradise.net.nz 986860347 89824 203.96.144.16 (9 Apr 2001 23:52:27 GMT) X-Newsreader: trn 4.0-test72 (19 April 1999) Organization: Daedalus Consulting NNTP-Posting-Host: 203-96-144-16.cable.paradise.net.nz In article , Malcolm Weir wrote: >Errr... actually, you need 1960's generation of engines for supercruise! > >Rolls-Royce/SNECMA Olympus 593, anyone? Concorde accelerates through M1 with the afterburners lit. Supercruise involves leaving the afterburners off. -- don From hrose-saa@ckdhr.com Thu Apr 19 16:40:35 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 19 Apr 2001 16:40:35 From: don@news.daedalus.co.nz (Don Stokes) Subject: Re: Air France Concorde crashes after departing Paris CDG References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: raewyn.paradise.net.nz 986859889 89763 203.96.144.16 (9 Apr 2001 23:44:49 GMT) X-Newsreader: trn 4.0-test72 (19 April 1999) Organization: Daedalus Consulting NNTP-Posting-Host: 203-96-144-16.cable.paradise.net.nz In article , Doug Holik wrote: > >"Jeremy Harris [RU-UK]" wrote in message >news:airliners.2001.112@ditka.Chicago.COM... >> In article , >> FilipPC.DeVos@rug.ac.be (Filip De Vos) writes: >> > Part of that drag is the rudder, deflected to compensate for the >> > assymetric thrust. So my question is, is it possible to make a climbing >> > turn at a lower speed than 275kt? (turning towards the dead engines) > >> Uh, to first order, planes don't turn thanks to the rudder, but thanks >> to having been banked. > >Actually they do turn because of the rudder, why do you think its there? Turning the rudder just changes where the aircraft is poitinng; it doesn't change its direction of travel. If you do this (especially with swept wings) with the rudder, the aiflow over the wings becomess assymetric and you risk flipping the thing over. The rudder is there to control the yaw axis to keep the airflow straight down the aircraft. The turn itself is done by banking as the previous poster said. Basically, the aircraft's lift, in straight level flight, is pushing the plane straight up against gravity. By banking the aircraft, you adjust the direction of that force so that there's a sideways component to the force applied. This sideways force is what changes the direction of travel and makes the turn. Without banking, there's very little force being applied to the aircraft to actually change the direction of flight -- just that applied to the fuselage and tail, that latter will be just trying to pull the aircraft straight again. Mostly the aircraft will be naturally stable and will turn itself with the changing airflow without help from the rudder. But for tighter turns, a bit of rudder input helps keep the aircraft from entering a dangerous yaw. The rudder has other uses -- it can offset assymetric power, or with help from the ailerons actually be used to fly the aircraft in a slight yaw where you (for example) want to fly straight with respect to the ground rather than the air, as in the final approach in a crosswind. -- don From hrose-saa@ckdhr.com Thu Apr 19 16:40:36 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 19 Apr 2001 16:40:36 From: "matt weber" Subject: Re: Wing vs. tail-mounted engines? References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM Content-Type: text/plain; charset="us-ascii"; format=flowed At 03:37 PM 4/9/01 +0000, you wrote: >matt weber wrote: >--cut-- > >> > >>(I can't think of any case of failure of the wing box or root structure > >>causing an accident on a post-war commercial airliner -- can anyone?) > >That what caused the Two Electra accidents indirectly. The whirl mode > >failure of the engine mounts caused the wingbox loading to exeed the design > >limits, and the actual failure was the wings came off the aircraft. The > >fix was to stiffen the wing, and make the engine mounts stronger. > >Bit more than that Matt,,,they discovered that the 'whirl mode' >problem was causing sympathetic vibration of certain stiffeners >and support structures in the wings and that the fix was to add >syncronization and syncrophasing of the propellers. This system >is now used on all twin and four engined a/c using Allison T-56 >type engines. C-130, P-3, and Convair 580's are the types that I >know about, there's likely others. This system has the added >benefit of reducing crew fatigue due to less engine induced >vibration. Synching up the props is a lot older then the Electra. The L1049 (Constellation) has it. However had the wing been adequately stiff in the first place, it would have damped out the sympathetic vibrations in the first place, and raised the frequency at which the wing would resonate to a frequency well beyond what could be generated by precession caused by partial engine mount failure.. Matt Weber From hrose-saa@ckdhr.com Wed May 16 17:45:09 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 16 May 2001 17:45:09 From: johnmcgrew@aol.com (JohnMcGrew) Subject: Re: Wing vs. tail-mounted engines? References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Newsreader: Session Scheduler Organization: AOL http://www.aol.com In article , jthorn@galileo.thp.univie.ac.at (Jonathan Thornburg) writes: >The industry doesn't care much about it, but safety is another big >advantage of wing-mounted engines: What kills people in a jet crash >is often not the crash itself, but the ensuing fire. Tail-mounted >engines mean fuel pipes running from the wing (where the fuel tanks are) >aft through the fuselage to the engines, i.e. you've got fuel right >in the fuselage with the passengers. In contrast, wing-mounted engines >allow all the fuel to be kept in the wings, some distance away from the >passengers. (Some designs do put fuel tanks in the wing center sections >anyway.) I doubt there is much in the way of actual crash data to justify that opinion. Any accident serious enough to compromise the fuel system almost certainly will compromise the fuel tanks as well. And with many longer-range planes today, that argument is moot since fuel is now being stored in tanks other than in the wings or at the spar, and even the horizontal stabilizer, resulting in fuel lines, pumps, etc all over the airframe. John From hrose-saa@ckdhr.com Wed May 16 17:45:10 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 16 May 2001 17:45:10 From: "JohnB" Subject: Re: Boeing's Sonic Cruiser - a Boeing stealth aircraft References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: 2 May 2001 09:56:05 GMT, 193.119.52.130 X-Newsreader: Microsoft Outlook Express 5.50.4133.2400 NNTP-Posting-Host: 193.119.52.130 Concorde uses afterburner to accelreate through the transonic drag rise. After about M1.5 the afterburners are cut and the supersonic cruise is done without afterburner. "Don Stokes" wrote in message news:airliners.2001.176@ditka.Chicago.COM... > In article , > Malcolm Weir wrote: > >Errr... actually, you need 1960's generation of engines for supercruise! > > > >Rolls-Royce/SNECMA Olympus 593, anyone? > > Concorde accelerates through M1 with the afterburners lit. Supercruise > involves leaving the afterburners off. > > -- don From hrose-saa@ckdhr.com Wed May 16 17:45:11 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 16 May 2001 17:45:11 From: gfoley@gcfn.org (Gerard Foley) Subject: Re: Lightning Strike out of Dorval ? References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Newsreader: TIN [version 1.2 PL2] Organization: The Greater Columbus Free-Net David Simpson (dsimpson@dsimpson.net) wrote: snip> : Lightning strikes and static discharges are very spectacular, and certainly : scary, but highly unlikely to do any real damage. A search of the NTSB (US : National Transportation Safety Board) database for the last thirty years showed : not a single accident that could be attributed to a lightning strike or static : discharge. At worst, one airplane (a small one) had "significant" damage, but : still landed with no one being hurt. : (http://www.ntsb.gov/ntsb/query.asp) I thought that the crash of a PanAm 707 in the Washington-Balitimore area 30-40 years ago was blamed on a lightning strike. -- Gerry From hrose-saa@ckdhr.com Wed May 16 17:45:12 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 16 May 2001 17:45:12 From: "John McLaren" Subject: Re: High wing vs. low wing References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: /wq5/f55pLhJjRzV8Q6wqbnb08CDT6MZNjYfIo787jj5H2AJlhfZXmiCWnTVuJNbEV1evIqGylhC!P6LQSVM50S1G3zuc1y7jH4UG5Zvmo+9wjLOHvE43WCMJg49fXoqwthWjouTZGLVpGLyWt/aT/Ou5!tuPKeEA= X-Newsreader: Microsoft Outlook Express 5.00.2919.6600 This is just a guess since I am not a structures person. I wonder it there is a weight savings to the low wing airplane. By attaching the main landing gear to the wing, the wing to body joint carries the load of the airplane on the ground or in flight. With a high wing plane there has to be structure to transfer the wing to fuselage load in flight and a second set of structural members to carry the landing gear to fuselage load on the ground (if the gear attaches to the body line on a C-5. On airpanes like a Dash-8 where the gear still attaches to the wing, the high wing may not matter. From hrose-saa@ckdhr.com Wed May 16 17:45:13 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 16 May 2001 17:45:13 From: westin*nospam@graphics.cornell.edu (Stephen H. Westin) Subject: Re: Wing vs. tail-mounted engines? References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: news01.cit.cornell.edu 988151204 3513 128.84.247.211 (24 Apr 2001 22:26:44 GMT) X-Newsreader: Gnus v5.7/Emacs 20.6 Organization: Cornell University NNTP-Posting-Host: diesel.graphics.cornell.edu jwizardc@aol.com (JWizardC) writes: > The biggest disadvantage to the wing-mounted engines in the Comet > was the complexity of the wing main spar/load box. Also, the engines > take up a bunch of room that could have been used by fuel. And something that I'm sure wasn't considered in the '50s: the complexity of upgrading to other engines. Though the RAF Nimrods are slated to be fitted with BR700's soon; I wonder how they managed that. -- -Stephen H. Westin Any information or opinions in this message are mine: they do not represent the position of Cornell University or any of its sponsors. From hrose-saa@ckdhr.com Wed May 16 17:45:14 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 16 May 2001 17:45:14 From: "Christopher St. Peter" Subject: Re: McDonnel Douglas name still in use? References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: news1.rdc1.il.home.com 988063648 24.22.252.70 (Mon, 23 Apr 2001 15:07:28 PDT) X-Newsreader: Microsoft Outlook Express 5.00.2919.6700 Organization: Excite@Home - The Leader in Broadband http://home.com/faster NNTP-Posting-Host: 24.22.252.70 It was initially called the McDonnell Douglas Products Division of Boeing. But the MD-90 type is called the Boeing 717 and the MD-11 is no longer being produced. "Eric George" wrote in message news:airliners.2001.160@ditka.Chicago.COM... > Hi All, > I hnow McDonnell Douglas was bought out (ok merged) with Boeing back in > Aug. 1997. Does anybody know if any vestige of the company still uses > the McDonnel Douglas name? ie. could somebody say they work for > McDonnell Douglas? > Thanks From hrose-saa@ckdhr.com Wed May 16 17:45:15 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 16 May 2001 17:45:15 From: "Johan Eertink" Subject: Re: How Important Is Cross-section Shape Of Wing? References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: simian.nlr.nl 988008555 135663 137.17.196.216 (23 Apr 2001 06:49:15 GMT) X-Newsreader: Microsoft Outlook Express 5.50.4522.1200 Organization: National Aerospace Laboratory NLR NNTP-Posting-Host: pcvo048a.nlr.nl For what I've learned in aerodynamics classes, the vortex is a by-product of the lift producing characteristics of the wing: High pressure underneath, low(er) pressure on top => At the wingtip, the air flows from underneath to top, thus producing a vortex as the aircraft moves forward. This is basically an unwanted process, since you loose energy that you want to use to lift the aircraft. The "winglets" you find on many modern airliners are helpful to minimise this. As for Bernouilli: This is not fiction (as confirmed in the webpage you refer to). B's law only states that moving air has lower pressure when it moves faster. No doubt about that. The question is about how to make air move faster over the top of a wing. This is achieved by placing the wing at an angle of attack w.r.t. the airflow. Rounding the nose and pointing the trailing edge helps the flow in staying attached to the wing. Johan "JWizardC" wrote in message news:airliners.2001.162@ditka.Chicago.COM... > Okay, here's another simian torquer (monkey wrench): When I got to advanced > aero design classes, I learned that Bernoulli is mostly a convient fiction to > help explain a mind numbingly difficult truth. In actuality, as a wing-shaped > object begins to move forward in a fluid (like air), an amazing phenomenon > takes place. A vortex begins to form behind the wing, creating a partial > suction, which pulls more air over the top of the wing -- here's the hard part > -- from underneath it! > Wander over to http://www.geocities.com/galemcraig/ for a discussion far better > than I can provide here. > TheFNG From hrose-saa@ckdhr.com Wed May 16 17:45:16 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 16 May 2001 17:45:16 From: wzman1@aol.comnojunk (WZMan1) Subject: Re: High wing vs. low wing References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM Organization: AOL http://www.aol.com In addition to having the cargo deck low to the ground, an additional design feature of most military cargo aircraft is an uninteruppted cargo compartment which allows cargo to be rolled on and rolled off. On a low wing aircraft, the wing carrythrough structure would require the cargo deck to be installed above the structure or would result in a hump spanning the cargo compartment. On aircraft like the C-130, C141, C-5, & C-17, the wing structure passes through the fuselage overhead, reducing headroom but leaving a huge flat cargo deck. Additional considerations include requirements for operations from unimproved airfields. The C-130 and C-17 were built to meet requirements for operations on short, unimproved runways. A high wing provides engines with greater clearance from FOD than a low wing. In the case of the '130, the high wing gives additional clearance for the props! As for airliner operations, a low wing configuration permits the passenger deck to be mounted above the wing box, leaving an uninterrupted passenger floor and no compromise on head room. The baggage area is invaded by the wing structure, but the baggage doesn't mind. W Zelenski From hrose-saa@ckdhr.com Wed May 16 17:45:17 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 16 May 2001 17:45:17 From: inet@intellisys.net (brian whatcott) Subject: Wing Warp (was Re: Air France Concorde ...) References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Newsreader: Forte Free Agent 1.21/32.243 Organization: BWInc Reply-To: inet@intellisys.net NNTP-Posting-Host: news.newsdawg.com Hmmm.... on the Wright Flyer, the trailing edge which was warped lower dropped, and the other wing lifted. This was a design feature revived for another low power low stall airplane: Gossamer Condor, whose designer tipped his cap towards the Wrights. Brian Whatcott On 19 Apr 2001 16:40:14 , westin*nospam@graphics.cornell.edu (Stephen H. Westin) wrote: >> > Uh, to first order, planes don't turn thanks to the rudder, but thanks >> > to having been banked. >> >> Actually they do turn because of the rudder, why do you think its there? > >To keep things pointing in the right direction. The Wright brothers >developed a glider that would turn by warping the wings: one wing went >up, the other down, and the lift vector would make the aircraft >turn. Unfortunately, the high-lift wing would also have increased >drag, so the whole plane would yaw back the wrong way. /snip/ >-Stephen H. Westin Brian Whatcott Altus OK Eureka! From hrose-saa@ckdhr.com Wed May 16 17:45:18 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 16 May 2001 17:45:18 From: Merlin Dorfman Subject: Re: McDonnel Douglas name still in use? References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Newsreader: TIN [version 1.2 PL2] Organization: a2i network NNTP-Posting-Host: waltz.rahul.net Eric George (ergeorge@worldnet.att.net) wrote: : Hi All, : I hnow McDonnell Douglas was bought out (ok merged) with Boeing back in : Aug. 1997. Does anybody know if any vestige of the company still uses : the McDonnel Douglas name? ie. could somebody say they work for : McDonnell Douglas? All my friends who used to work for McDonnell Douglas (or Rockwell) now have Boeing on their business cards, e-mail addresses, etc. I don't think any of them still say they work for McD-D. From hrose-saa@ckdhr.com Wed May 16 17:45:19 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 16 May 2001 17:45:19 From: jdwill68@aol.com (JDWill68) Subject: Re: High wing vs. low wing References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM Organization: AOL http://www.aol.com JP Caputa asked: >Why is it that all commercial airliners, aside from perhaps turbo-prop >feeder liners and the BAe 146 are low winged, where as most military >cargo planes are high winged. Both types of aircravet serve very similar >roles, and travel over similar ranges. > >I can understand that the purpose of the high winged cargo transports is >to have the floor of the plane closer to the ground for easier loading >of cargo, but I'd figure this should be an equally important factor for >the airlines. > >So essencially, the question is: > >WHAT ARE THE BENEFITS OF LOW WINGED AIRCRAFT (if any) AS OPPOSED TO HIGH >WINGED AIRCRAFT? The military likes getting the engines away from the ground as well, since the ability to operate from rough airfields is a standard requirement. Higher engines are less likely to suck gravel into the blades. Having the cargo deck close to the ground but also having the engines further away from it leads to the high wing. Civil cargo aircraft like to have the engines near enough to the ground to work on easily. Also, they operate from large airports where there is adequate cargo-handling equipment to deal with having the deck up high-unlike the military, which may have to deal with primitive facilities. This leads to the main reason: civil air cargo companies use standard airliners converted to cargo use, regardless of whether or not they are optimal when compared to military a/c. The production runs are longer and they are much cheaper to buy and operate. It's easier to work around the high-deck problem with inexpensive ground equipment than to invest in very expensive military planes. Note that military tankers and EW aircraft are all converted from civil airliners for the same reason. There are probably lots of reasons why civil airliners have a low wing, but maintainance is likely near the top of the list. From hrose-saa@ckdhr.com Wed May 16 17:45:20 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 16 May 2001 17:45:20 From: Matt Maurano Subject: Re: High wing vs. low wing References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: agate.berkeley.edu 987899799 27116 169.229.88.103 (22 Apr 2001 00:36:39 GMT) Organization: University of California at Berkeley X-Newsreader: Forte Agent 1.8/32.548 NNTP-Posting-Host: ida-88-103.reshall.berkeley.edu On 19 Apr 2001 16:40:17 , JP Caputa wrote: >Why is it that all commercial airliners, aside from perhaps turbo-prop >feeder liners and the BAe 146 are low winged, where as most military >cargo planes are high winged. Both types of aircravet serve very similar >roles, and travel over similar ranges. I seem to recall the following: Passenger jets always land on a prepared tarmac. Some military cargo jets have the requirement to land in less prepared areas which might have bushes or something sticking out of the ground. The high wing allows greater clearance. I also think it is structurally easier to put the wing down low. -- Remove "GARBAGE" to send email From hrose-saa@ckdhr.com Wed May 16 17:45:21 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 16 May 2001 17:45:21 From: robinjohnson@bigfoot.com (Robin Johnson) Subject: Re: McDonnel Douglas name still in use? References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: 21 Apr 2001 16:13:49 +1000, 202.138.58.219 Organization: North Antarctica X-Newsreader: Forte Agent 1.5/32.451 NNTP-Posting-Host: 202.138.58.219 Reply-To: robinjohnson@bigfoot.com On 19 Apr 2001 16:40:18 , Eric George told us: >Hi All, >I hnow McDonnell Douglas was bought out (ok merged) with Boeing back in >Aug. 1997. Does anybody know if any vestige of the company still uses >the McDonnel Douglas name? ie. could somebody say they work for >McDonnell Douglas? >Thanks I'm not sure how recent this was, but I have seen medical computer hardware and software with the McD D name. --Robin From hrose-saa@ckdhr.com Wed May 16 17:45:22 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 16 May 2001 17:45:22 From: robinjohnson@bigfoot.com (Robin Johnson) Subject: Re: Boeing's Sonic Cruiser - a Boeing stealth aircraft References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: 21 Apr 2001 16:13:48 +1000, 202.138.58.219 Organization: North Antarctica X-Newsreader: Forte Agent 1.5/32.451 NNTP-Posting-Host: 202.138.58.219 Reply-To: robinjohnson@bigfoot.com On 19 Apr 2001 16:40:34 , don@news.daedalus.co.nz (Don Stokes) told us: >In article , >Malcolm Weir wrote: >>Errr... actually, you need 1960's generation of engines for supercruise! >> >>Rolls-Royce/SNECMA Olympus 593, anyone? > >Concorde accelerates through M1 with the afterburners lit. Supercruise >involves leaving the afterburners off. > >-- don As I'm sure Pete will confirm, one of the biggest design problems with Concorde was the engine air intakes. Supersonic airflow has to be slowed down to subsonic before entering the engine. It is only now that supersonic combustion engines are being designed. --Robin From hrose-saa@ckdhr.com Wed May 16 17:45:23 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 16 May 2001 17:45:23 From: Malcolm Weir Subject: Re: Boeing's Sonic Cruiser - a Boeing stealth aircraft References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM Organization: Little to None X-Newsreader: Forte Agent 1.8/32.548 NNTP-Posting-Host: !Z2n&1k-Y"l->P[A9`26B7+5U (Encoded at Airnews!) On 19 Apr 2001 16:40:34 , don@news.daedalus.co.nz (Don Stokes) caused to appear as if it was written: >In article , >Malcolm Weir wrote: >>Errr... actually, you need 1960's generation of engines for supercruise! >> >>Rolls-Royce/SNECMA Olympus 593, anyone? > >Concorde accelerates through M1 with the afterburners lit. Supercruise >involves leaving the afterburners off. ... which is exactly what happens once they reach M1.7 or so. Then the engines are conventional, not using afterburners/reheat, and the thing is trundling along at M2. Supercruise. Seems to me acceleration, like climb out, isn't cruise. Super or otherwise. >-- don Malc. From hrose-saa@ckdhr.com Wed May 16 17:45:24 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 16 May 2001 17:45:24 From: "ME Incorporated" Subject: Re: Wing vs. tail-mounted engines? References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: 20 Apr 2001 16:20:10 -0500, 216-119-139-117.ipset19.wt.net Organization: World Trade Network, Inc. (WT.net) X-Newsreader: Microsoft Outlook Express 5.50.4133.2400 NNTP-Posting-Host: 216-119-139-117.ipset19.wt.net "Jonathan Thornburg" wrote in message news:airliners.2001.106@ditka.Chicago.COM... > The industry doesn't care much about it, but safety is another big > advantage of wing-mounted engines: What kills people in a jet crash > is often not the crash itself, but the ensuing fire. Tail-mounted > engines mean fuel pipes running from the wing (where the fuel tanks are) > aft through the fuselage to the engines, i.e. you've got fuel right > in the fuselage with the passengers. In contrast, wing-mounted engines > allow all the fuel to be kept in the wings, some distance away from the > passengers. (Some designs do put fuel tanks in the wing center sections > anyway.) That's all well and good, but ya still have center wing tanks on most airliners. That's potentially gonna get into the cabin as well. While it's not piping, true, I wonder how much of the fuel in a CWT can get into the cabin. Or outright just explode due to vapors... From hrose-saa@ckdhr.com Wed May 16 17:45:25 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 16 May 2001 17:45:25 From: "MJ" Subject: Re: How Important Is Cross-section Shape Of Wing? References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM Organization: Posted via Supernews, http://www.supernews.com X-Newsreader: Microsoft Outlook Express 5.00.2919.6700 See also http://www.monmouth.com/~jsd/how/title.html Section 3 for another good treatment. Also debunks coanda effect relative to lift production (section 18.4), and the notion that a tail plane must always act downward (somewhere in there). Mike Jones "JWizardC" wrote in message news:airliners.2001.162@ditka.Chicago.COM... > Okay, here's another simian torquer (monkey wrench): When I got to advanced > aero design classes, I learned that Bernoulli is mostly a convient fiction to > help explain a mind numbingly difficult truth. In actuality, as a wing-shaped > object begins to move forward in a fluid (like air), an amazing phenomenon > takes place. A vortex begins to form behind the wing, creating a partial > suction, which pulls more air over the top of the wing -- here's the hard part > -- from underneath it! > Wander over to http://www.geocities.com/galemcraig/ for a discussion far better > than I can provide here. > TheFNG From hrose-saa@ckdhr.com Wed May 16 17:45:26 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 16 May 2001 17:45:26 From: jthorn@galileo.thp.univie.ac.at (Jonathan Thornburg) Subject: Re: High wing vs. low wing References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM Organization: Universitaet Wien (Vienna, Austria) / Institut fuer Theoretische Physik In article , JP Caputa wrote: >WHAT ARE THE BENEFITS OF LOW WINGED AIRCRAFT (if any) AS OPPOSED TO HIGH >WINGED AIRCRAFT? + more ground effect --> shorter takeoff/landing distances and/or --> higher maximum takeoff gross weights + wing-mounted engines lower to the ground --> easier servicing + fuel tanks in wings are lower to the ground --> easier refueling + wing-mounted landing gear needs shorter struts --> stronger/lighter Of course, there are drawbacks, too: - wing-mounted engines may be *too* close to the ground --> risk of foreign-object damage if unpaved runways are used (though the 737 was certified for gravel runways) --> max bank angle on landing ( ==> max crosswind for landing) might be limited by nacelles hitting the ground instead of wingtips hitting the ground (dihedral alleviates wintip-hitting) - more risk of ground servicing vehicles hitting/damaging wings/engines As the original poster noted, empirically low-wing wins for civilian use. -- -- Jonathan Thornburg http://www.thp.univie.ac.at/~jthorn/home.html Universitaet Wien (Vienna, Austria) / Institut fuer Theoretische Physik Only 6 countries in the world have the death penalty for children: Congo, Iran, Nigeria, (Pakistan[*]), Saudi Arabia, United States, Yemen [*] Pakistan reportedly ended it in July 2000. -- Amnesty International http://www.web.amnesty.org/ai.nsf/index/AMR511392000 From hrose-saa@ckdhr.com Wed May 16 17:45:27 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 16 May 2001 17:45:27 From: westin*nospam@graphics.cornell.edu (Stephen H. Westin) Subject: Re: Wing vs. tail-mounted engines? References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: news01.cit.cornell.edu 987780029 28716 128.84.247.211 (20 Apr 2001 15:20:29 GMT) Organization: Cornell University X-Newsreader: Gnus v5.7/Emacs 20.6 NNTP-Posting-Host: diesel.graphics.cornell.edu jthorn@galileo.thp.univie.ac.at (Jonathan Thornburg) writes: > In article , > John Liebson asked > >What about wing-mounted-engine aircraft that _also_ have tail-mounted > >fuel tanks? > > Not nice: > * fuel pipes in the aft fuselage (--> big fire risk in crashes) > * fuel tanks far from center of gravity --> big trim change as you burn > that fuel --> hurts aerodynamic efficiency (fighting that trim change > will cost extra drag) I believe the 747-400 offers optional fuel storage in the horizontal stabilizer. I suspect that this could be used to trim CG during cruise; it might even wind up as a net advantage, as with Concorde. -- -Stephen H. Westin Any information or opinions in this message are mine: they do not represent the position of Cornell University or any of its sponsors. From hrose-saa@ckdhr.com Wed May 16 17:45:28 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 16 May 2001 17:45:28 From: westin*nospam@graphics.cornell.edu (Stephen H. Westin) Subject: Re: High wing vs. low wing References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: news01.cit.cornell.edu 987779441 27392 128.84.247.211 (20 Apr 2001 15:10:41 GMT) Organization: Cornell University X-Newsreader: Gnus v5.7/Emacs 20.6 NNTP-Posting-Host: diesel.graphics.cornell.edu JP Caputa writes: > Why is it that all commercial airliners, aside from perhaps > turbo-prop feeder liners and the BAe 146 are low winged, where as > most military cargo planes are high winged. Both types of aircravet > serve very similar roles, and travel over similar ranges. Nope, their roles are quite different. Airliners fly in to nice, civilized airports with jetways, paved runways, and the like. Military transports might have to fly into dirt strips. They also may have no tugs to push them back, so reverse thrust will be needed for ground maneuvering. So getting the engines far from the ground is a Good Thing to avoid having them inhale something solid. And cargo is unloaded from airliners by lots of nice machinery, rather than being driven or towed off. So a low cabin floor is very nice to have in a military plane. > I can understand that the purpose of the high winged cargo transports is > to have the floor of the plane closer to the ground for easier loading > of cargo, but I'd figure this should be an equally important factor for > the airlines. Not as important as making it convenient for passengers. Actually, I suspect that mechanized cargo handling systems (especially for containerized freight) make this point moot. The equipment is bought for efficiency, and would be there in any case; it just reduces the advantage of a low cargo deck. > So essencially, the question is: > > WHAT ARE THE BENEFITS OF LOW WINGED AIRCRAFT (if any) AS OPPOSED TO HIGH > WINGED AIRCRAFT? Well, a low-wing aircraft gets more benefit from ground effect at takeoff and landing. It lets the wing spar pass through the cargo area, rather than intruding into cabin headroom. It also is compatible with worldwide infrastructure built up over the past 45 years or so. Not to mention the chance to mount landing gear on a low wing, giving a nice wide stance without lots of extra structure. Regional airliners have a mission much more similar to that of military transports: more primitive airfields with less infrastructure for ground handling. So it makes sense for them to use high wings. -- -Stephen H. Westin Any information or opinions in this message are mine: they do not represent the position of Cornell University or any of its sponsors. From hrose-saa@ckdhr.com Wed May 16 17:45:29 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 16 May 2001 17:45:29 From: John Liebson Subject: Re: Wing vs. tail-mounted engines? References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: reader.nmix.net 987772038 39315 198.59.168.167 (20 Apr 2001 13:07:18 GMT) Organization: NMIX X-Newsreader: Forte Agent 1.8/32.548 NNTP-Posting-Host: dialup67.nets.com gbeaman@pei.sympatico.ca (Gord Beaman) wrote: >But those tanks are comparatively very small John, their purpose >is for trimming out the aerodynamic drag of the aircraft's >'stability system' when it's not essential. It's only used in >stabilized cruise conditions, so for takeoff and landings these >tanks are always empty. The engines are not fed from them. True, but that does not detract from my original comment, which is that fuel can be present and sometimes _is_ present, a fact which contradicts the first statement that wing-mounted aircraft don't have fuel where tail-mounted ones do. The tail tanks are never completely empty, nor is the piping from them to the main tanks. A reminder (from someone, namely me, who happens to be a retired fire chief), empty tanks may be considerably more dangerous than full ones! Adding to that, there are also, on some aircraft, auxiliary fuel tanks that are mounted in the cargo areas, and those tanks are used on aircraft with wing-mounted engines. So, to conclude, the theory of the message that started this, namely that wing-mounted-engine airliners are inherently safer in regards to fuel than rear-mounted-engine airlines is, I submit, somewhat of a canard. (And, yes, the pun IS intentional ...). From hrose-saa@ckdhr.com Wed May 16 17:45:30 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 16 May 2001 17:45:30 From: Pete Mellor Subject: Re: Wing vs. tail-mounted engines? Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM > In article , > John Liebson asked > >What about wing-mounted-engine aircraft that _also_ have tail-mounted > >fuel tanks? > > Not nice: > * fuel pipes in the aft fuselage (--> big fire risk in crashes) > * fuel tanks far from center of gravity --> big trim change as you burn > that fuel --> hurts aerodynamic efficiency (fighting that trim change > will cost extra drag) Exactly the opposite, in fact. This misrepresents the purpose of the tail tank, which is not to store masses of fuel, but precisely to effect a trim change. (In fact, the tail tank is often referred to as the "trim tank".) This is used on long-haul aircraft for which efficient cruising at high altitude is desirable. Examples are A300, A310, A330, A340 and (I think) most Boeings in the medium to long haul range. (Note that it does *not* apply to the A320, A319, A321, and similar, which are short haul.) As an example of the size of the tail tank, that on the A330 holds about 7000 units compared to around 25000 in the wing and centre. (I am going by memory from the last time I rode in the jump seat of an A330 several years ago. I think the units the crew quoted were gallons. If I'm wrong, please correct me.) During cruise, fuel is pumped between the tail and wing/centre tanks in order to move the CoG as close to the Centre of Lift as possible while still retaining marginal static stability. The result is that elevator trim and hence drag is reduced to the minimum compatible with safe cruising. Therefore fuel burn is reduced with a significant cost saving. On modern aircraft, this transfer is (surprise! :-) controlled by computer. A similar feature exists on Concorde, and as it goes supersonic, the centre of lift changes, hence the fraction of the fuel load required in the tail changes also, but the transfer is performed under the manual control of the flight engineer. The disadvantage of the system is that the aircraft *must* be controlled by the autopilot while in this trimmed-back configuration. The reason is fairly obvious. The aircraft is up in coffin corner where the stall speed approaches the cruising speed *and* it is only marginally stable. The suddent disconnection of AP can therefore lead to a spectacular upset. This is thought to have been a factor in the crash in Russia a few years back (the A300 or 310 in which it was suspected that the captain's teenage son was at the controls). I think there is now some doubt about the "kid at the controls" theory, but even an experienced pilot has great difficulty retaining control if the AP is unexpectedly disconnected. (A Lufthansa pilot was quoted to that effect in Der Spiegel at the time of the Russian crash.) I would be very interested to hear any other thoughts/information on this topic. Pete ---------------------------------------------------------------- Peter Mellor, Centre for Software Reliability, City University, Northampton Square, London EC1V 0HB Tel.: +44 (0)20 7040 8422 ) NOTE: Code recently changed from Fax.: +44 (0)20 7040 8585 ) 7477 to 7040 e-mail: Pete Mellor ---------------------------------------------------------------- From hrose-saa@ckdhr.com Wed May 16 17:45:31 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 16 May 2001 17:45:31 From: "David" Subject: Re: Air France Concorde crashes after departing Paris CDG References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: cswtrans.cos.agilent.com 987721189 15231 130.29.252.172 (19 Apr 2001 22:59:49 GMT) Organization: Agilent Laboratories, Palo Alto X-Newsreader: Microsoft Outlook Express 5.00.2919.6600 NNTP-Posting-Host: emperor.labs.agilent.com "Filip De Vos" wrote in message news:airliners.2001.172@ditka.Chicago.COM... > Indeed. And this causes drag, which which Concorde could not overcome. So > I am asking whether it is possible for the pilots to use slightly less > rudder than necessary to counter the assymetric thrust, and accepting a > turn (in the direction of the dead engines), to experience less > rudder-induced drag, and hopefully climb or accelerate. I would doubt it. The Concorde was severely on the backside of the power curve. AW&ST reported that its best L/D comes at about 400 kts CAS. At 200 kts, the induced drag would be much worse than the rudder drag. David Smith From hrose-saa@ckdhr.com Wed May 16 17:45:32 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 16 May 2001 17:45:32 From: don@news.daedalus.co.nz (Don Stokes) Subject: Re: Lightning Strike out of Dorval ? References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM X-Trace: raewyn.paradise.net.nz 987727959 78233 203.96.144.16 (20 Apr 2001 00:52:39 GMT) Organization: Daedalus Consulting X-Newsreader: trn 4.0-test72 (19 April 1999) NNTP-Posting-Host: 203-96-144-16.cable.paradise.net.nz David Simpson wrote: >Lightning strikes and static discharges are very spectacular, and certainly >scary, but highly unlikely to do any real damage. A search of the NTSB (US >National Transportation Safety Board) database for the last thirty years showed >not a single accident that could be attributed to a lightning strike or static >discharge. At worst, one airplane (a small one) had "significant" damage, but >still landed with no one being hurt. >(http://www.ntsb.gov/ntsb/query.asp) The National Ligntening Safety Institute lists a few serious aircraft accidents relating to lightning at: http://www.lightningsafety.com/nlsi_lls/avaition_losses.html including a lighning initiated wing failure on a 747-131F; ... It appeared that the aircraft had been struck by lightning, entering a forward part of the aircraft and exiting from a static discharger on the left wingtip. The lightning current's conductive path to the static discharger at the tip was through a bond strap along the trailing edge. Concentration of current at the riveted joint between this bond strap and a wing rib were sufficient conductive to cause the flash to reattach to this rivet and to leave the discharger. Fuel vapors in the no.1 fuel tank then ignited. The explosion caused the upper wing skin panel to separate, causing a drastic altering of the aeroelastic properties of the wing, and especially the outboard section of wing. The outer wing began to oscillate, developing loads which caused the high-frequency antenna and outer tip to separate. The whole wing failed a little later. -- don From hrose-saa@ckdhr.com Wed May 16 17:45:33 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 16 May 2001 17:45:33 From: matt weber Subject: Re: Air France Concorde crashes after departing Paris CDG References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM Content-Type: text/plain; charset="us-ascii"; format=flowed > > >Indeed. And this causes drag, which which Concorde could not overcome. So >I am asking whether it is possible for the pilots to use slightly less >rudder than necessary to counter the assymetric thrust, and accepting a >turn (in the direction of the dead engines), to experience less >rudder-induced drag, and hopefully climb or accelerate. The box for Concorde is that L/D at low speed is pretty horrible (less then 5:1), and below 275kt, the D component exceeds the output of two engines even with the emergency thrust augmentation system operating (gets you about 105% of rated thrust), Aircraft cannot climb on two engines below 275kt period.. Matt Weber From hrose-saa@ckdhr.com Wed May 16 17:45:34 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 16 May 2001 17:45:34 From: matt weber Subject: Re: Boeing's Sonic Cruiser - a Boeing stealth aircraft References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM Content-Type: text/plain; charset="us-ascii"; format=flowed At 04:40 PM 4/19/01 +0000, you wrote: >In article , >Malcolm Weir wrote: > >Errr... actually, you need 1960's generation of engines for supercruise! > > > >Rolls-Royce/SNECMA Olympus 593, anyone? > >Concorde accelerates through M1 with the afterburners lit. Supercruise >involves leaving the afterburners off. > >-- don Actually the burners go off at about M1.7. That's apparently the point at which drag starts to drop off, and the afterburners are no longer needed. It is very noticeable on the aircraft, not so much because of the change in acceleration as change in cabin noise level and vibration. The pumps that feed the afterburners are probably the largest single source of noise on board. Matt Weber From hrose-saa@ckdhr.com Wed May 16 17:45:35 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 16 May 2001 17:45:35 From: matt weber Subject: Re: Wing vs. tail-mounted engines? References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM Content-Type: text/plain; charset="us-ascii"; format=flowed At 04:40 PM 4/19/01 +0000, you wrote: >The biggest disadvantage to the wing-mounted engines in the Comet was the >complexity of the wing main spar/load box. Also, the engines take up a >bunch of >room that could have been used by fuel. It is also impossible to fit a high bypass (read fuel efficient) engine inside the wing..... Matt Weber From hrose-saa@ckdhr.com Wed May 16 17:45:36 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 16 May 2001 17:45:36 From: matt weber Subject: Re: Wing vs. tail-mounted engines? References: Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM Content-Type: text/plain; charset="us-ascii"; format=flowed All underslung engines have fuse pins, and they will allow the engine to separate if loaded enough in the correct direction. If you examine the ET accident, the aircraft was not under control when it went in, and frankly whether the engines were still attached when it went in or not, would probably have made very little difference. On the other hand, in the early 1960's JAL put a DC8 freighter down in San Franciso Bay. Engines remained attached, in fact the aircraft was fished out, rebuilt, and flew for 20+ more years with JAL before being retired in the 1980's Matt Weber From hrose-saa@ckdhr.com Wed May 16 17:45:37 1901 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 16 May 2001 17:45:37 From: matt weber Subject: Re: High wing vs. low wing Message-ID: Approved: hrose-saa@ckdhr.com@ditka.Chicago.COM Sender: hrose-saa@ckdhr.com@ditka.Chicago.COM Content-Type: text/plain; charset="us-ascii"; format=flowed At 04:40 PM 4/19/01 +0000, you wrote: >Why is it that all commercial airliners, aside from perhaps turbo-prop >feeder liners and the BAe 146 are low winged, where as most military >cargo planes are high winged. Both types of aircravet serve very similar >roles, and travel over similar ranges. > >I can understand that the purpose of the high winged cargo transports is >to have the floor of the plane closer to the ground for easier loading >of cargo, but I'd figure this should be an equally important factor for >the airlines. > >So essencially, the question is: > >WHAT ARE THE BENEFITS OF LOW WINGED AIRCRAFT (if any) AS OPPOSED TO HIGH >WINGED AIRCRAFT? Most materials take compression loads better (and fail much more gracefully under them) then they take tension loads, consequently a low wing aircraft does not need as strong a wingbox or fuselage as a high wing (lower weight). The aircraft load is being carried as a compression load with a low wing as opposed to a tension load on a high wing. Cracks cause far less trouble in compression loads then they do with tension loads. Other issues, high wing gets you more engine clearance, which if you want to run on not so good air fields (gravel/dirt and shell fragments), is probably desireable. The impact is very real. When you compare lift capacity as a percentage of Empty weight, the low wing commercial airlines do much better then the Military airlifters. Most commercial cargo is palletized or containerized, so it is easily loaded with automated loading equipment. A lot of military cargo is outsize, so it has to be driven on board, so the higher cabin floor really isn't much of a draw back for a commercial airliner, but is for a military cargo aircraft. Matt Weber