Have you noticed the speed of the F15 only goes around 600kt when in reality it should be 1433kt max which is about 1640mph?
I incorporated the F16(since you did the F15) using the default structure and engine specs in JSBSIM I only get around 600kt as well. I did a straight dive and was able to get 800kt but the aircraft started shaking.
It may be some setting to change since the default pawn was made on a 787-8 basis. Or there could be something incorrect in the HUD calculations and I was actually doing the 1660kt of the F16 which is about Mach 2 for it.
I’ll probably start looking tomorrow, just curious if you noticed it as well.