Model Size

You say from "technical drawings" using a .40. You don't say what kind of OS

1. Is it like LA, older FSR, or FX?

To design your own with a .40 you should look for somewhere in the 500 square inches wing area at a weight of not more than 1 pound per 100 sq. inches of wing area. You can get down to 400 sq. ins, however remember that the engine/radio weight is fixed and you will most likely exceed the 1 lb. per 100 sq. ins. rule of thumb for smaller models. OTOH if you can keep the weight to 5#, and get a 600 sq. ins. w/aera, then you will have a fun/trainer/scale machine with fine flying ability. That would be very difficult with a P-40 (relatively small wing) however 100 years ago today, there was another difficult flying machine feat accomplished. So go for it. If total scale is not the ultimate goal, and since the P-40 had a very tapered wing, one could cheat a tad. Add 1/2" to the root chord, plus 1" to the tip chord, thus picking up some 36 square inches on a 48" wingspan aircraft without too much apparent change. The lighter the wing loading, the better the flying. Good luck

HC

I'd say build it smaller and keep it light. So it has bags of power but still stalls at a sensible speed, and doesn't tip stall because of high wing loading.

Many "sport scale" models have thicker airfoils than the full size versions to decrease the stall speed and give the model scale-like speeds. You will want to thicken the airfoil if you're designing from full scale drawings.

Morris

So true. To add to the specificity of your comment, I'd suggest that the NACA 0018 is a perfect airfoil for WWII warbird models of around that size. It will give good scale speed but still be as aerobatic as you probably want for full scale looks.

MJC