I will not attempt to give a comprehensive guide to aerobatic training. Horvath’s book on sailplane aerobatics is an excellent place to start. However, of all the post-licence training, aerobatics probably requires the most expertise relative to possible negative outcomes when mistakes are made. The simple facts are that our senses are not very accurate in judging g-forces, and most of the aerobatic manoeuvres are very disorienting. As such any execution of aerobatics without expert training and a properly equipped aircraft is foolhardy.
In the beginning stages, negative g loadings should be avoided as much as possible. These are more troublesome for humans to handle and most aircraft are not stressed as strongly in this regard. The first manoeuvre that can be taught by most instructors is the wingover. The wingover starts with a 45 degree dive until the entry speed recommended in the operating manual is reached (usually 80-90 knots). The pilot then starts to pull up and immediately begins a turn. As the aircraft comes about to a heading 180 degrees from the initial entry point the aircraft enters another dive and the wings are levelled. The aircraft is then smoothly recovered from this dive and returned to the normal gliding attitude. The pullup during the dive recovery only brings the nose to the horizon until the speed bleeds off to just above the normal gliding attitude speed before returning the aircraft to the normal gliding attitude. The characteristic of the wingover is that positive loads are maintained at all times, and at no time is the aircraft stalled. As long as the turn is started with the initial pull up, then mistakes still result in positive loadings. Linked wingovers are called lazy eights. When the initial move is not followed by a dive but rather just a level turn, this is known as a chandelle.
Not all ‘simple’ manoeuvres have the same margins for safety. The stall turn or ‘hammerhead’ has real risks of developing into a tailslide, which is not well tolerated by most aircraft. The stall turn requires the aircraft to be brought to a vertical nose up attitude and before the forward motion stops, the aircraft is yawed and essentially flops on its side and then to a nose down attitude. Standard dive recovery is then done to complete the manoeuvre. It is foolish for any pilot to attempt this or any similar manoeuvres in any aircraft not rated for a tailslide. Both inexperienced and experienced aerobatics pilots have been killed attempting these.
The next simple exercise is the loop. The key again is positive loading as much as possible. The common mistake is not using high enough entry speeds and pulling insufficient g’s to carry the speed properly through the top of the loop. Basic aerobatics training programs usually require 4 g pullups. This kind of loading is hard to judge so a g-meter is essential. Those trying to teach themselves rarely will pull up hard enough to develop more than 3 g’s, and again the major risk is the tailslide.
From this point on the exercises usually progress to rolling manoeuvres. Rolls represent a significant increase in orientation and control problems. Simple rolls mark the endpoint for the basic aerobatics instructor. Any combination of looping and rolling manoeuvres should be left to those who instruct regularly and have more than introductory abilities. This is certainly an area where casual instructing should not be allowed. Pilots learn not only what they are told, but what they observe and feel, and the instructional demonstrations should be as perfect as possible.
Hopefully pilots will perform aerobatics for the shear joy of doing them well as opposed to showing off their talents. There is a definite link between accidents and incidents, and ‘shows’.