North American P-51 Mustang one of the best ww2 fighters why so "crappy" on bop?

[Robotic Pope]

I will add that it doesn't help that the constant speed propellor in BoP is allways set on max engine RPM which is best for acceleration and climbing but creates more drag because the blades are more face on to the airstream.

In a Mustang once you got to altitude you would lower the prop rpm and the blades would become less face on, causing less drag so you could then dive faster and better retain that speed once you leveled out. You'd then put the prop rpm back at max when you needed more power from the engine for aceleration or for gaining altitude again.