Lift varies with, amongst many other things, angle of attack - looseley, the amount by which the leading edge of the wing is pitched up relative to the air. So, to increase lift, pull the nose up. The first thing that happens (before the aircraft goes anywhere since we haven't yet generated any additional force) is that the leading edge pitches up relative to the air passing over it. Result - increased lift. The aircraft now accelerates at right-angles to the wing - increased G. if you don't add power at this point, speed will reduce (increased lift => increased drag) and since lift also depends on speed, the excess lift will diminish until the forces come into balance. Pull some more and the angle of attack again increases, and the manoeuvre continues. The limiting factor is the stalling angle of the wing, or the point you run out of speed, which in turn depends on how powerful the engine is, or the extent you are trading height (= energy) for turning performance.
This works whether the aircraft is initially level - entry to a loop, for example, or whether it is banked - entry to a break.
Health warning. I'm not a QFI so that may be overly simple / just plain rwong.
Last edited by Sven Sixtoo; 29th Aug 2011 at 10:43.