Was asked a question the other day about old style flaps(727, 737 classic, 737-400 v new style, A380 etc. Hitting the internet has come up with all sorts of graphs, but not the answer.
Classic aircraft have 3 stage Fowler flaps that at take-off setting extend a large distance behind the trailing edge of the wing. The 727 take-off flap setting is a good example.
New aircraft, especially A380, 777, 737NG has at a guess 1/3 of the Fowler action.
Can someone explain to a simple instructor how the the new design of flap provides the same amount of lift. I have searched but there's nothign that explains the answer.
While I'm it, the A380 has a noticeably slower Vr and Vref. Is that a function of the huge wing, or wing design (airfoil tech) or am I missing something.
Take-off, flap retraction schedule. Old aircraft 727,707 it seems their acceleration during the acceleration phase (3 stage?) takes ages. Heavy takeoffs can take 7 mins to get to flaps up (watched over dozens of videos). A380 gets to clean speed in 2 mins or so. My guess better thrust to weight of new aircraft resulting in better 3rd stage segment.