An aerobatic aircraft does not fly the way a normal aeroplane does. It flies the way a dart does, with the wing acting as a steering surface rather than a lifting one. Conventional wings use cambered aerofoils. Curved on top, flatter below. They generate lift efficiently at low angles of attack, but only in one direction. Turn that wing upside down and the camber works against you. Sustained inverted flight becomes a fight. Competition aircraft such as the Extra 330 and Sukhoi Su-31 use symmetrical aerofoils instead. Identical curvature above and below. At zero angle of attack they produce zero lift, which sounds useless until you realise what it buys. - Lift becomes purely a function of angle of attack, not orientation - Inverted performance mirrors upright performance almost exactly - The pilot pushes the stick forward and holds a negative angle of attack - Pitch response stays linear and predictable across the whole envelope The trade is efficiency. Symmetrical wings need more a...