This AM got a kill that made the other guy made, because he thought there was no way I could have kept up with him. There were very good reasons why I did, and they're worth sharing....so see if this helps.
1) The most important reason a slow plane can catch a fast one is hard to see when you're newer -- ENERGY. Think of energy as being speed times altitude, so a very high slow plane may have more potential speed than a fast one on the deck. In the past, I've been caught by a miserable IL2 even though I was in a P-51, because he dove from a big altitude advantage.
In my fight this morning, the P-47N actually started higher than my F4U-1C, but I caught up to him right away and he never was able to pull away over my 2 minute chase. He thought it was BS, but it wasnt - because -----
2) How you maneuver affects speed. Hard, sharp maneuvers kill speed fast. When the chase started, the P-47 dove nearly straight down to drop bombs. That meant that he had a hard pull out, using lots of elevator, to keep from augering. Meanwhile, my dive angle was more shallow, and I could slide onto his 6 gently without burning as much energy. I might have hit WEP sooner than he did too, since I knew he was faster and he thought he'd get away....but the biggest factor was how we used controls at the start.
I was 600 back once the tail chase got set up. I closed a little, then stayed steady at about 500 -- I'd see 600, then 400, then 600 on the icon. I shot some, and landed a few hits, spread out so they werent lethal.
Elevators cost more speed than airelons, and rudders are worse than either. He maneuvered to keep me from having an easy 6 straight shot, so he kept sliding from side to side in my gunsight. BUT he used elevatrors for some sharper moves, pulling back on the stick. I did as little as possible, rolling rather than pulling. That let me stay closer.
3) Straight line is shorter than a curved one! Once I hit him again, he made wider evasions. I made sure I did straighter ones, which meant that his more curved "S" moves drew longer lines than my flatter, smoother ones. I had a shorter distance to fly, so my slower plane could keep up.
[EDIT] The straight line thing is even more important with turns and half loops. When you make any curved flight path, be aware that pursuers can cut inside you and close quickly to get a shot. Think of how the bowstring is shorter than the bow itself![/EDIT]
I closed to right at 400, got another ping on his wing, and it fell off. The pilot, who's played a long time, was upset because he was thinking only about pure top speed and didnt understand how my slower plane coudl keep up -- but the chase wasnt BS, it was speed management.
EDIT
4) Fuel and Ordinance status make a difference Bombs and rockets add drag plus more weight, and even internal fuel tanks are heavy! When a plane is heavier, the engine has to pull more mass forward, so the same power means slower acceleration and lower top speed. My C-Hog was low on fuel (arent they always!), and but I dont know how much gas he was lugging. [/EDIT]
So, if you manage your plane well, you'll start to see why vets say "It's not the plane, its the pilot!"