Aerodynamic Turning Model
Q500,
Perhaps you would define "d" for me.
My sole purpose in recommending a minimum taper ratio of 0.75 was to avoid tip stall by providing plenty of stall margin when turning almost as tightly as possible with flaps.
Example 1: At a coefficient of lift of 0.86 (with flaps), the taper ratio of 0.5 yields an induced drag of 0.024 and with a taper ratio of 0.75 the induced drag goes up to 0.029. The wing with a smaller taper ratio has an advantage unless the pilot over does it, tries for too much and, snaprolls. If the piloting is good enough to never snaproll then the more tapered wing is best down to a taper ratio of between 0.3 and 0.4. Such wings will have vicious snap roll tendencies when trying for high lift coefficients by pulling a bit too hard or encountering a gust in the turn.
Example 2: At a coefficient of lift of .4 (without flaps), the taper ratio of 0.5 yields an induced drag of 0.0066 and with a taper ratio of 0.75 the induced drag goes up to 0.0068 which is hardly a significant increase compared to the total drag.
So, the choice of taper ratios boils down to a matter of sqeezing the last bit of drag reduction out of the design versus a design that is more forgiving of pilot error and gusty air. Obviously, highly tapered wings are best for pylon racing by top notch pilots. I should think less tapered wings would be better for combat.