[Graham Boak]

You are right, I haven't been an Aerodynamicist for twenty years. I had worked on performance aerodynamics for the previous nineteen. Like riding a bicycle, I believe you said? Some things you don't forget.

You want a more academic source. I offer you "Design for Air Combat", by Ray Whitford C.Eng MRAeS. Page 13, "Trailing vortex drag typically represents 75% of the total drag in maximum sustained manoeuvre flight.........only 5 to 10% in the low altitude high speed flight." Trailing vortex drag is his term for induced drag. This value is for modern combat jets: for WW2 fighters at about half the speed the induced drag proportion will be higher, about 10-20%.

You might also wish to consider his Fig 16, where the 1g and 4g flight envelopes for the F-5E can be seen to be very close together, at max speed at sea level. That's very little change for a 300% increase in weight. You can see why the change in level speed due to a 5% increase in weight is regarded as insignificant.

In combat, every little helps, of course. In this sense, insignificance can be claimed as the effect is less than the variation to other causes such as surface finish, fit of panels, age of engine, excrescence standard. And indeed, pilot handling. A mis-set trim will create more drag than a couple of mph. If the radiator shutters are set too open they will create more drag.

Re comments from actual pilots: They were referred to much earlier in the thread, at least indirectly. Every kill of a fleeing Jabo proved that other fighters could outrun an Fw 190, so the basic statement was untrue. Yet many Fw 190s did escape their pursuers, and the question how such differences arose led to discussions of basic aerodynamics.

Which I suspect has gone far enough now.