Originally Posted by
VinRouge
High lift wings can have transonic (and also >M 1.0) flow at aircraft subsonic speeds as low as M0.5-0.6, as all those high lift devices do wonders to pressure differentials. In other words, the wing goes transonic WELL before the aircraft does.
Agree, but it can be even lower than the speeds quoted. Think of the gap between slat and fixed portion of the wing. it's a nice accelerating channel. Thing what's going to happen at even moderate Mach numbers to the flow in that channel.
Hell, even non-slatted aircraft can generate transonic flow locally at VERY low free stream Mach numbers, under the right conditions (CL etc).