Ive been reading about WW2 planes since I was a child, and playing WW2 flight sims for a long time , since Ien Warbirds came along and blew my mind.
Everything I've ever read about the P-51 in cambat has pointed to the fact that the FLAPS were everything in its being able to manuever in combat. I've read many acounts of pilots turning inside 109s (let alone 190s). The trick was deploying flaps(which were incremental). Flap use had to be done very judiciously, as they bled energy like mad. The trick was to only deploy them when pulling for angles at the proper moments and pulling lead for the shot.
Effective ACM is all about WHEN to pull G's, with regard to where in the RELATIVE circles you are with the enemy and what attitude your nose is in at the moment. Its not just about which circle has a smaller radius, but where in 3-D space these circles intersect, and the relative position of the circles on the horizontal vs. vertical plane.An energy fighter rolling out vertically can easily turn INSIDE a smaller horizontal radius. =eadg= was the master of this tactic in Warbirds and dominated the old dueling ladders using this tactic. Just pulling G's in an ongoing circle is ineffective in an energy fighter like the P-51. But accounts Ive read say that it could turn VERY tighly for a quarter or half-circle, but then you need to back off the stick, or E-bleed will slow you to doom level very quickly! Unfortunately, flaps are not available in realistic mode which I fly for the immersion factor of the 'target lock' view. I've spent years using the old static hat views and can use them well, but the visual immersion of seeing the smooth 'pan' is something I can't go back from now. Just beautiful to behold!
Hopefully the new P-51 fixes will help keep this fighter flying online. Be a shame to do without her beautifull lines
in my sights

I've always been a 'knife-fighter' myself.