What determines the amount of speed a turning aircraft loses?
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.
All the answers so far have been helpful. Nobody mentions weight as a factor – so I assume that given the same bank, angle of attack, etc, a heavy plane will decelerate at the same rate as a light one?

when an aircraft turns it loses lift, and so it requires more lift (created by pitching up) this pitch up motion creates more drag and changes the angle of attack which in effect reduces airspeed. The steeper the bank, the more loss of lift, the more loss of airspeed.
Weight is a factor only to the point where the aircraft will require more lift to counteract the force of weight, but weight will not be added while in a turn. However that begins to get into G’s so I’lls top there.
Good luck.