I'm trying to model characteristics of various aircraft for a WWII air combat game, and need to know how turns affect speed for various aircraft profiles; ex, light aircraft like the Japanese ki-27 Nate or Zero vs heavier aircraft like the F4F Wildcat or P-40 Warhawk. Thanks.

The angle of bank determines the amount of speed the aircraft loses during a turn. Shallow turns = very little loss of airspeed. Steep banked turns = higher loss of speed due to loss of lift from the wings. The vertical component of lift shifts from the vertical axis to a more horizontal axis as the angle of bank increases. Aerodynamically speaking, the steeper the turn, the greater the loss of the vertical component of lift that's needed to maintain a straight-and-level speed.