How many approximate g can aircraft structure/aircrew withstand during flight?
It depends on what kind of aircraft and aircrew. Normal category aircraft are designed to withstand 3.8G positive and 1.52G negative. Most have a lower limitation with flaps down. Utility aircraft can go up to 4.4G positive and many aerobatic aircraft are stressed to 6G positive and 3G negative. Some extremely aerobatic aircraft can withstand 9G positive and 9G negative. During certification the aircraft must withstand 150% of the maximum loading for a few seconds and not have structural failure, but they are usually wrinkled and deformed after these tests. Pilots must be fit and do special maneuvers to withstand high positive G unaided (typically tensing up lower and mid muscle groups and having the seat in a semi-reclined position. To withstand anything higher than about 5Gs, you need a G suit which uses a fluid to squeeze the lower body. Rapid of prolonged exposure to high positive G leads to tunnel-vision, grey-out, black-out, and loss of conciousness. Negative G isn’t as easy to h
