Re: 757 highest thrust to weight ratio ?

From:         gregory@halcyon.com (Gregory Wright)
Organization: The 23:00 News and Mail Service
Date:         10 Dec 92 02:09:23 PST
References:   1 2 3
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In article <airliners.1992.113@ohare.Chicago.COM> fredch@phx.mcd.mot.com (Fred Christiansen) writes:
>In article <airliners.1992.71@ohare.Chicago.COM> kls@chicago.com (Karl Swartz) writes:
>>Not surprisingly, the top 11 were all twins.
>
>Why "not surprisingly"?  As a layman with no background in this stuff,
>I would have tho't that manufacturers would keep the thrust-to-weight
>in some ballpark range (for economic reasons).  And that the advent
>of larger twins is because more powerful engines have become available,
>eliminating the need for a 3rd (or in the case of, say, MD-10 class
>aircraft, the need for a 4th).
>-- 

  The reason for the this may, as you say, may not be so obvious so 
alow me to put in my two cents. The FAA, along with the CAA and others,
require that we demonstrate a minimum climb out gradient with one engine
inoperative. In the case of a two engine aircraft this requires that
the airplane be able to climb out with a 50% reduction in gross thrust.
For a four engine platform this one engine out condition represents only
a 25% reduction in thrust. You can see then, that for a two engine plane
it is required to "over" engine the plane...

Hope this helps to clear things up,
greg
HIgh lift development



>Fred Christiansen, Motorola, 2900 S Diablo Way, Tempe, AZ 85282  "Canajun, eh?"
>fredch@phx.mcd.mot.com  ||  uunet!phx.mcd.mot.com!fredch  ||  +1 602-438-3464
>  ".. I have set before you Life and Death, blessing and cursing;  therefore
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>


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