Let's not confuse BnZ with E-Fighting as, in my opinion, they're different animals. I hope the following doesn't hijack this thread.
BnZ is really a series of very short engagements by a plane with far superior energy over another plane or planes. The attacker "booms" in from above at a high rate of speed (relative his target), shoots very quickly at a hopefully unwary or otherwise engaged target and then "zooms" back up rebuilding his energy advantage for another pass. The engagement might be only a few seconds really as the time spent in effective guns range is short due to the high speed involved. The idea is to go in fast, hit hard and get out. The "zoom" part might involve a fairly long extension whether is be up or away or both. This technique is largely ineffective vs a single pilot that sees it coming as it's easily ducked using a well timed turn. The much faster plane likely won't be able to follow and will have to break off his attack and zoom away. It becomes a "lather, rinse, repeat" sort of thing. Quite boring. This would absolutely be the technique of choice tho in a 1 vs many environment where locking on to one target's tail might put you into a bad position vs the other NME in the area. Better to stay fast and out of their guns range, zoom in--possibly picking a guy off here or there--while in time other friendlies might arrive in the area.
Energy fighting is much different. Energy fighting lacks the long extension part of BnZ. Here you gauge your E state versus your target's E state taking into account your plane's zooming ability and climbing ability versus the other guy's plane or planes. The idea is to manage your energy and get the other guy to blow his by following you in a generally upwards direction. The trick here is being able to identify the other guy's energy state. It's hard to do and if you guess wrong--you're dead. You want to start with a height or speed advantage over your target. It need not be excessive tho. You want to entice your target into this type of engagement. Make him want to follow you. Keep him close but below you. A turn fight can evolve into an energy fight if for example your plane can climb much better than your target's can. Get his nose turned up to a point he can't follow and you've now done a good job of managing his energy. Now reverse and kill him as he wallows on the edge of a stall beneath you. That's the general idea. At the least if you've maintained your energy advantage you're "safe" from being killed which is almost as good as getting the kill. Live to fight another day. Find another target and kill him. Can't do that from the tower.
Remember, there are differences with a plane's verticle performance. Don't confuse climbing ability with zooming ability. Climb rate has to do with the plane's power to weight ratio and wing design. Zoom is a product of forward momentum coupled with mass. That whole object in motion will tend to stay in motion until it's acted upon by an opposing force (s). In our case--that's gravity and drag. A plane like a Zero is an excellent climber but as it's very lightly constructed, lacks the weight to zoom well. A P-47, for example doesn't climb well but it's heavy and zooms like pretty much nothing else once it gets up a head of steam.
Now regarding the P-38. Good choice by the way. I've settled on that one myself. I'm generally of the energy fighting tribe too and I find it excels there. The P-38s combine a good but not spectacular climb rate with good but not great speed with excellent turn rates in both directions (due to the counter rotating props) if you get the hang of the flaps. So if things go bad you can still turn well with most but not all planes. They zoom very, very well. Reason being they're both aerodynamically clean and have a lot of mass because of the two engines. However, the mass and cleanliness both giveth and taketh away. While great for heading up in a zoom you really have to watch it heading downhill as it builds up speed quick and will compress. It gets worse at higher alts in thinner air. This is a problem with BnZ as your controls will get sluggish as you speed up and you might not be able to make corrections with your guns quickly. At worst you'll end up below your target before you can correct and now you have to get out of dodge. So have your elevator trim control handy when heading downhill in the P-38. Because of this I'd pick another ride if you were looking to purely BnZ. Think about the FWs or one of the Jugs or even a Pony. Very fast, great guns, great high speed control. Better tool for that job.
Hope I didn't go on too long for ya.
Good luck
