For many years I thought the 747-400 had many slats on the leading edge. Recently I've read that they are Krueger flaps since they fold out from under the wing whereas a true slat is supposed to be the whole front edge of the wing that goes forward and downward. Now I am reading about the Queen having variable camber flaps at the leading edge.What does the Queen have and what actually is the difference between these slats (or flaps?!). I always thought a slat was whatever protruded at the leading edge to enable greater lift and delay a stall. Appreciate any further ed on this matter, thanks.Merry Xmas to all too !Jonathan

Johnathanhttp://en.wikipedia.org/wiki/SlatsSlats and flaps are both 'High Lift Devices or HLDs', but go about their work differently. Flaps increase the curve or camber of the wing's chord - slats keep the airflow stuck onto the top surface of the wing over a higher angle of attack.(Lift increases with angle of attack, but so does drag). The objective of all the HLD's is to provice the needed lift at a lower speed for landing or takeoff.A stall normally develops as the angle of attack increases - beginning from the rear of the wing with the airflow over the top of the wing breaking away (and resulting in zero lift, mega turbulence and drag). This phenomenon known as boundary layer breakaway.The true slat is positioned forwards of the wing, and a little below the centre line. Have a whole bunch of reference data on this if you'd like to study it more... used to mess about designing model planes and miniature gas turbines before the kids got old enough to absorb all the leisure funds...All the best for 08.Peter Lloyd

Dear Peter and Q:Thank you both for your kind replies. This helps me quite a bit and I can go from here now. Seasons' Greetings!Jonathan