Date: 15 Apr 97 03:22:41 From: firstname.lastname@example.org (matt weber) Organization: 1st Solutions Inc. Followups: 1 2 3 4 5
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Why no new Super-Jumbo? This piece involves a certain amount of speculation, and is condensed from several private E-mail's. I think it sheds considerable light on what is going on, and what is likely to happen. 1). The current state of Computational Fluid Dynamics is such that I seriously doubt that any substantial improvement in overall airframe efficiency is possible within the current regulatory environment. I think that has probably pretty much been the case since the 757/767 era. Larger airframes tend to be more efficient because they have more favorable surface to volume ratio's. While there was vast difference in size between the 707 era and 747 era in which the number of passengers you could carry on the aircraft almost tripled, no one is talking about more than doubling the capacity of the current generation, and 747 derivatives were only a 40-60% increase. 2). Engine Performance. Larger engines have tended to more efficient. The differences in specific fuel consumption between the JT8 class engines that flew the 707/727/737 etc. and thegeneration that followed (JT9/CF6/RB211) that flew the next generation were enormous.The JT8's were typically around .61pounds of fuel/pound hour of thrust. The JT9's are typically about .36, a roughly 40% improvement in Fuel Economy. I suspect that class of engines was the firstto benefit from real computer aided designs (not necessary in the drawings, in the fluid dynamics calculations ). Since that time Engine improvements have been much harder to obtain. As best I can tell the best of the available engines today have specific fuel consumption of about .31. Unfortunately data on the current engines (PW4084/PW4090/GE90/Trent800) is not readily available. (Source for engine data is Aviation Week & Space Technology Aerospace Source Book, January 1997). While the improvement form .36 to .31 is about 14%, it has taken 20+ years to do it. It only took about 12 years to go from .61 to .36. This suggests to me that within the current environment, there isn't a lot of room left for improvement in engine efficiency. 3). The cost of the people to design and build these things has gone up immensely. In spite of immense investments in computer technology in the industry (and for that matter everywhere), there appear to have been only very limited productivity gains. The guy with the 200 million instructions per second computer on his desk doesn't get 200 times as much work done as he did 10 years ago when he had a 1 million instruction per second computer on his desk! It is a little like the computer industry. Used to be we gave away the software because all the money was in the hardware. Now we give away the hardware, all the money goes into the software. If you look at the relationship between R&D cost and aircraft selling price, the problem becomes a little clearer. I think the 747 incurred R&D costs of several hundred million, the cost of perhaps 10 copies of the aircraft. The projected R&D costs on A3XX are 8-10 billion, at 250 million a copy that comes to the selling price of 40 aircraft, and current press reports say 200 million is the threshold of serious buyer resistance. 4). The improvements in operating costs of the next generation of aircraft cannot come from engine efficiency or air frame aerodynamic efficiency. There just isn't much left to be gained there. What is left are improvments in weight, which is being done. However the use of relatively exotic materials to produce the weight reductions are expensive and often difficult to work with. In short they drive up the costs substantially. 5). I am not normally involved in the finance side of this business, and I admit my involvement in the industry is on the periphery. However some relatively straight forward calculations lead me to believe the capital costs on these aircraft are what is killing the super jumbo. As best I can tell, the current cost per available seat mile on 747-400 or 777 is on the order of 1.5 cents. On the 747-500/600 based upon the data that was published in Avaiation Week last year, it is probably on the order of 1.8 cents per available seat mile. An all new aircraft such as A3xx will incur even higher R&D costs, and I doubt Airbus can build such an aircraft at a cost that is materially different than Boeing's costs, and in fact there is good data to suggest that Airbus because of its structure, may not even be able to do it as efficiently as Boeing. What that really says is that A3xx's Available seat mile costs are likely to be at least as high as 747-500/600, and quite probably even higher. Given that these costs now appear to represent close to 20% of the total Available Seat Mile costs, this is a very troubling development. In the past, each new generation of aircraft has offered a substantial improvement in Available Seat Mile costs. This analysis suggests that within the current environment, those days may be over. 6), Will such an aircraft be built? My own suspicion is yes, but in order to make it attractive, it is not going to be anytime soon, and it will not look anything at all like the current generation of aircraft. The current regulatory environment places severe requirements on the stability of commercial aircraft. We make the aircraft stable by putting drag in the right places. It makes the aircraft stable, it also does nasty things to the overall aerodynamic efficiency of the airframe. It should come as no surprise that it is likely that the most aerodynamically efficient aircraft are likely to be aircraft that are inherently unstable. That kind of tradeoff is acceptable at the moment in military aircraft such as the F117 and B2. It is not acceptable in a commercial passenger liner today. A brief review of the B2 versus the B1 is quite enlightening, and suggest that a super jumbo in the form of a blended wing, or flying wing might be very attractive. The B1 and B2 have similar payload capacities as best I can tell, however the B2 probably flies further, and weighs about 140,000 pounds less. By civilian standards, the B2 engines are very inefficient. (Specfic fuel consumption is quoted as .66, a CFM56 engine used on an A319 is quoted as .31.This at least suggests to me that such an aircraft design with high efficiency engines might be capable of substantially improved operating costs over any current civilian design. Flying wings however have a reputation for not being especially stable. One of the reason the B47 was selected over the flying wing was the wing apparently made a poor bombing platform. Improvements in control systems and computers apparently make the B2 a stable platform, however I doubt that relying on computers and automation for so much of the basic handling and flight characteristics of an airframe would make people like the FAA very comfortable. Again, a tradeoff that is acceptable in a military environment, not so acceptable in today's civil environment. I think it is going to require a good deal more experience with inherently unstable aircraft before the rules are going to be changed to allow an inherently unstable aircraft to be used for a civilian transport. While I don't doubt it is going to happen, I do doubt it will happen in the immediate future. Until that does happen, I think the prospects for a commercially viable super jumbo are not good. The opinion expressed here are my own.