Dave,

This is a really interesting question. In your previous thread, I noted that flying banked required the wing to fly at a higher coefficient of lift, which would increase induced drag. I still think this is true, but it occurred to me that something more important is probably happening as well, which is that some surfaces other than the wing start providing the lift. In particular, the side of the fuselage and the vertical stabilizer. These are lifting surfaces which are certain to produce much more induced drag than any decent wing, including one with ailerons deflected. I have not done a quantitative analysis, but I would bet that maximum speed ( straight & level ) would be achieved with no bank. This does not necessarily mean that flying the pylon course with zero bank is best, because a pilot that overshoots when coming out of the bank could end up flying a very nonoptimal trajectory, and come out worse than if he/she had stayed banked.

Hmmm....

banktoturn