I'm not a F4U driver, and never droven F4Us seriously, but maybe my little experience in other fighters such as 190A-5s against N1K2s and Spitfires would suggest some useful tips.
Now, "Fight when you are faster, and higher than him" is a truth that applies to all fighters, and a bit vague. Clearly you seem to be asking the situations where you are forced to fight them in simular altitudes.
The problem with the 'bad turner' planes is that no matter how fast you are capable of, the superior turners are always one step.. no, make that three four steps above of you after the merge. Let's say a 190A-5 is at an equal altitude with an enemy Spitfire9. Both approaching at Head-On direction.
The first Head-On merge happens, and two foes pass each other. Look back, and start to reverse directions to engage again. The speed of both planes after they passed each other Head-On might have been equal, the A-5 might even have been faster.. but the problem is when the 190 tries a reversal, it's turn performance is bad so it takes a long time. If you do a Immelmann turn right after the merge, you will notice the Spitfire has also done the same, but has already finished its move and is pointing his guns at you. By this time the 190A-5 has but just finished, or is about to finish his Immelmann.
Thus, when two planes meet at the same alt, both having simular speeds, the better turn fighter always has advantage. To win comfortably in these situations, the 190A-5 has to have either looooots of speed or the Spit pilot has to be very inexperienced. Thus, in a bad turner, after a HO merge, you have to go easy on the reversal and extend. What does this mean?? For example, read carefully this scenario and imagine the fight within your head:
* A Spitfire9 and 190A-5 meet, both near same speed, simular altitude.
* A head on pass occurs, the Spitfire, after passing the 190A-5, begins to turn.
* 190A-5, seeing this, just plain extends away straight.
* Now, the Spit9 has turned right after the HO merge quickly. With that move, he lost a lot of speed. He has to build up his speed again, and that takes time.
* So, the 190A-5 passes and just goes straight to about 3.0 - 4.0 distance.
* In this safe distance, the 190A-5 does an easy Immelmann.
* Now the distance closes again, 190A-5 finished the Immelmann. 190A-5 is slow. The Spitfire gained some of his speed he lost, but not all of it. Two foes again, are facing each other with some distance, but this time, the Spitfire a little faster than 190A-5, but the 190A-5 higher than the Spitfire.
* The 190A-5 dives shallowly down to the Spitfire. The Spitfire, if he wants to have his guns on the 190A-5, has to point his nose up shallow.
* Now, as the distance closes much, the Spitfire loses speed again. In contrast, the 190A-5 picks up speed.
* Just when a Spitfire is attempting a Head-On shot, the 190A-5 moves away from the Head-On again, and goes vertically up.
* The Spitfire cannot follow the 190A-5.
* Now, the Spit9 has to nose down and try to dive away, and the 190A-5, after going vertically up, will nose down and start chasing the Spitfire. Two planes started at equal terms, one was energy wise, the other spent his energy in vain. This is what people call "energy fighting"
Think it as sort of a 'joust'. But after each pass you have to trick the opponent into making bit more extreme maneuvers, while you do the least maneuvers. After many passes, the small mistakes some up to a big one. Such as in the scenario of the Spit9 vs 190A-5. Keep note that in that scenario, the 190A-5 gained the critical advantage when the Spitfire, trusting his good turn capability, turned and reversed after the first pass. It took time for the Spitfire to regain some of the energy he lost, and during that time the 190A-5 ran away to a safe distance, and gained an altitude advantage and came back.
Fighting in a Corsair against supreme turners at the same altitude, unless the Corsair pilot is extremely talented, is always a disadvantaged game for reasons I have stated in the beginning. Make long extensions, pass after pass, and see if the pilot in the turn fighter is a hasty guy, reversing not long after each pass. If he is, he can be shot down with patience and good energy management. If the pilot you see is a cautious one, seemingly experienced, and makes his reversals after passes carefully, then run. He mocks you or not, just run. That is the time when you should run and come back later with higher altitude and speed.
