leading edge lift devices

[1515Blue]

...what's the difference between slats and krueger flaps? i'm a bit confused. and if anyone has a link with pictures and explanations.? thanks

['%MAC']

A slat is a small airfoil, positioned near the leading edge of a larger airfoil. Air flowing through the slot created by the slat :) infuses kinetic energy into the flow and so delays separation. A slat provides a high local lift (however, lift of the main surface is reduced some what – you can’t get something for nothing. That said, total lift is increased, just lift of the main surface is decreased.). The Kruger flap (as all flaps) is a method to change camber. At high alpha the boundary layer is suppressed and the stall alpha is increased. As for pictures, the inboard section of 737s have Kruger flaps while slats exist outboard of the nacelles. (ref: Stinton)

[Keith.Williams.]

A slat is an aerofoil attached to the leading edge of the wing. In most cases it can be moved forward to produce a convergent slot. Air flowing up through this slot is accelerated, causing the boundary layer on the upper surface of the wing to be energised. This delays boundary layer separation and so increases the stalling angle of the wing. In some cases the slats also move downards to act as leading edge flaps, increasing wing leading edge camber.

Krueger flaps are small panels fitted to the underside of the leading edge. They are hinged at the front and deploy downwards into the airflow. This increases the camber of the wing, which in turn increases CL. But in most cases the resulting shape is fairly crude. This decreases the stalling angle of the wing
By fitting kruegers inboard and slats outboard, it is possible to ensure that the wing root stalls before the tips. This effect is often the subject of JAR ATPL POF questions.