Re: Efficiency of commercial planes

From:         kls@ohare.Chicago.COM (Karl Swartz)
Organization: Chicago Software Works
Date:         05 Oct 93 13:18:23 PDT
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>Shorter distances, depending on what you mean by that, may not yield
>better fuel efficiency, because the machines don't operate very
>efficiently at low altitudes.

That's why I said "up to a point."  More important than low altitudes,
takeoff and climb use a tremendous amount of fuel, while cruise uses
relatively little in comparison.

But, in my 737-500 example, at maximum range it can only carry about
65 passengers, well under its 100-130 seat capacity.  Trading enough
of that 2,500 nm range to bring the passenger count up to capacity
will undoubtedly produce a poorer fuel/nm figure, but you get to
amortize it over quite a few more passengers.  I don't have numbers
to prove it but my guess would be that the best performance in terms
of passenger miles per gallon will be found near the longest flight
with a full payload, at least for most aircraft.

Anyone have hard numbers to substantiate this?

Karl Swartz	|INet		
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