A few random thoughts on AoA and vertical maneuvers. Please forgive me, but I do like to chat about aerodynamics:
AoA is defined as the angle between the wing chord line and the relative wind.
A plane must have a positive AoA to generate lift, so anytime a plane is flying it has AoA. Airspeed and AoA determine the size of the lift vector.
You turn by pointing the lift vector where you want to go, and increasing the size of the lift vector. You do this by pulling the stick, which increases the AoA.
Greater AoA means greater induced drag. Greater induced drag means you lose more E.
Put it all together: to turn, you bank and pull the stick. Pulling the stick increases the AoA, which increases the lift vector, pushing the plane in the direction you want to go. But it also increases induced drag, which bleeds Energy.
What can you do about this? Some simple rules:
1. Turn gentle. Slower turns require less force = less AoA = less drag = more E.
2. Turn at cornering velocity. If you are going faster, you have to pull harder to get the same radius of turn. In most late-WWII fighters, cornering velocity is around 210 mph. Anything faster, you are wasting E if you try to turn hard.
3. Turn in the vertical, as explained by several guys above. This helps you two ways. First, you get gravity on your side, helping you to turn instead of working against you. Second, pulling vertical puts you closer to cornering velocity, which means less wasted energy in your turns.
So, bottom line is this: When you dive for the attack, you'll be fast. If you turn hard, you'll bleed your energy. Pull gently up and exchange that airspeed for altitude, until you are near cornering velocity. Then turn. Or go completely vertical with a hammerhead or humpty-bump. Once you have turned in the desired direction, exchange altitude for airspeed, and repeat.