Just a little clarification in relation to the rolling harriers. If, while rolling, the aircraft is descending, you simply add some throttle to bring the aircraft up. Really simple to do. It is also a timing and coordination trick which is rather easy.

In a rolling circle (no matter how many rolls, as long as they are COUNTED and DETERMINED before the roller even starts) if you want to gain some altitude you may need to input elevator, up or down and/or rudder left or right. You have four distinc possibilities and combination of each also. Soooo gaining altitude is no simple thing, it is a combination of all disponible inputs in a controlled manner, not timed manner.