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Old 31st July 2008, 16:30
Graham Boak Graham Boak is offline
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Re: Performance of the Fw 190A on the Deck?

Actually, fuel state is not that important with regard to maximum speed. Drag is made up of two components, the lift-induced drag and the rest, or zero-lift drag. Weight has no effect on zero-lift drag. At cruise, the two components are equal. The lift-induced drag increases with the lift coefficient, which is high at low speed and low at high speed. So at high speeds, and at sea-level, the lift-induced drag would only be a small proportion of the overall drag (of the order of 15%, perhaps). Lift-induced drag goes up with weight (because the aircraft needs greater lift to equal this weight) but you are only looking at the difference in weight of the fuel, compared with the overall weight of the aircraft. So you are only looking at a small proportion of the smaller part of the drag.

In most combats the opposing aircraft will be at similar fuel states, around half: after such a jabo attack the escaping aircraft might well be at a lighter state, the interceptor heavier. This sort of difference might show in a long steady chase, as did occur over the Channel after some Jabo attacks, but a few mph would not normally be noticed.

Weight is much more important in manoeuvre and climb, there the fuel state could be more important. Most of all near the ceiling.