what position of flaps causes slots to extend as well in 767 ?Michael J.

For 767:Flap1 selection puts slats to mid-range positions, where they remain through flap5, flap15 and flap20. Flap25 moves them to fully extended position, where they remain in flap30 as well. Note that, unlike in the 757, the 767 flaps remain retracted in flap1 selection, where ONLY slats move in the 767. The 767 flaps start moving only at flap5.Tero

Thanks. So slots extend gradually ? I thought they only had two positions - extended and retracted.Michael J.http://www.reality-xp.com/community/nr/rsc/rxp-higher.jpg

"I thought they only had two positions - extended and retracted."As Tero says, they have two extended positions. The first extended position is called the "sealed" (or "takeoff") position. In this position, the slats don't have any air slipping between them and the wind leading edge. The second extended position is called the "gapped" (or "landing") position and air will flow between the slat and the wing leading edge.Cheers.Ian.

Thanks. Most obliged.Michael J.http://www.reality-xp.com/community/nr/rsc/rxp-higher.jpg

i may sound daft here .. but just FYI .. they're called Slats .. ;)

>i may sound daft here .. but just FYI .. they're called Slats>.. ;)Of course. I saw this question posted on a foreign-language aviation forum. In that other language slats are called "sloty" - I mixed up two langauges. Ooops.Michael J.

So in effect when the "slats" are fully extended at flaps 25, then the air flows through the "slot" to move the centre of pressure rearward, stopping airflow separation that would lead to stalling?(just thought I would through in correct terminology there)

I'll leave this one for the aerodynamicists to answer ;-) (I'm not one).Cheers.Ian.

Actually, according to everything I've ever studied, the point of the slot is to allow high-pressure air from below the wing to move out over the top of the wing which reduces boundary layer separation. It's a lot like the way a jib works on a sailboat.