From kls Fri Dec 17 01:57:43 1999 Path: bounce-back Newsgroups: sci.aeronautics.airliners Date: 17 Dec 99 01:57:43 From: burkhard.domke@pace.de (Burkhard Domke) Subject: Re: 2 Vs 4 engines - CFM56 Engineering Dept Costs References: Message-ID: Approved: kls@ohare.Chicago.COM Sender: kls@ohare.Chicago.COM X-Trace: crusher.de.colt.net 944835047 1086 62.96.200.90 (10 Dec 1999 14:10:47 GMT) Organization: Colt Telecom GmbH X-Newsreader: Forte Free Agent 1.11/32.235 NNTP-Posting-Host: h-62.96.200.90.host.de.colt.net On 03 Dec 99 02:10:12 , Ernie Fidgeon wrote: >rhay10@scu.edu.au wrote: >> If you were an airline running a CFM56 fleet B737 / A320 etc. and you >> wanted to buy a wide bodied Airbus would the A340 cominality (sp?) with >> the CFM56 be much of an advantage when compared to the greater fuel >> burn etc. of a 4 engined aircraft? > >If you do your own engine mtce and already are familiar with the CFM, it >would be an advantage to do this. In addition, IMHO the CFM family of >engines is extremely operation friendly and very reliable compared to other >types available. Also, for its size, the 4 engined A340 is extremely >efficient. The fan area is smaller than othe 4 engined beasts and offers >drag benefits therein. Two large engines should yield less overall drag than 4 smaller engines and also weigh and cost less, but then wing weight will be considerably lower with 4 engines due to a more favourable load distribution and inherently enhanced flutter resistance. Hard to compare though, because wing area is a function of the number of engines installed to begin with (takeoff considerations, much higher wing loadings possible with number of engines going up), this in turn having a major impact on cruise (altitude) capabilities (initial cruise ALT of 777 much better than A340's FL270 at max weight). Burkhard Domke Berlin, Germany