The first thing you need to know (it took me at least a year to figure this out) is that a "zoom climb" is not necessarily made at a steep angle. With most aircraft, unless you have a great energy advantage, it's far more efficient to simply raise the nose thirty degrees or so (not losing sight of the gyro horizon) instead of yanking the stick back and hurtling your ship straight up. Hold the airplane in this shallow zoom climb until your speed reaches your best climb speed (a good average is 160 M.P.H., although it is different for every aircraft and varies with weight, power, and altitude). When you are at your best climb speed, and you are about three miles away, you can begin a careful reversal. If you have enough speed, an Immelmann is the best, but a combat turn (climbing and turning in equal measure) made at or near your best climb speed is the next best thing.