Changes

A '''leading edge stall ''' happens when the angle of attack is so large that the boundary layer separates straight away at the leading edge under a very steep adverse pressure gradient. This stalling behaviour is very unpleasant as very little warning is given and the loss of lift is sudden and drastic. This is usually avoided by designing a thick aerofoil where the steep adverse pressure gradient around the leading edge is smoothed out.

A '''trailing edge stall ''' happens when the boundary layer separation point near the trailing edge moves forward because the adverse pressure gradient is increased due to an increased angle of attack. This type of stall is more gentle with plenty of warning signs and a gradual loss of lift. This is the stall behaviour observed on training gliders, e.g. K21s.