B757 LE high lift devices
How can you tell the difference between LE flaps and Slats?
DLEs may be hinged at the lower surface and have linear actuators or jackscrews attached near the upper. When extended, the leading edge of the wing surface appears to droop, adding camber to the upper surface of the airfoil. The Lockheed Jetstar has nearly full-span DLEs.
Krueger flaps are hinged to the lower wing near the leading edge. When retracted, they fit into the lower surface of the wing. Linear actuators extend them down and forward, effectively making the leading edge of the wing much thicker in the areas where they are installed. The B-727 has them inboard near the wing roots.
Slats differ from L/E flaps primarily in that they actually extend the leading edge forward on rollered rails or tracks that curve downward. This forward and downward movement increases both the upper surface camber and the actual wing area by extending the cord length of the wing in the areas of the wing L/E where they are installed. They are normally slotted when fully extended to allow higher energy air from behind the lower leading edge to spill into the upper surface airflow behind the slat to reduce airfow separation-induced turbulent flow on the upper surface. In conjunction with T/E Fowler flaps, these high-lift devices signifigantly decrease stall speed and required angle of attack at a given speed/weight combination. Slats are by far the most common and efficient L/E lift augmentation device in use today.
I hope this helps.
Here is a link to a NASA page with diagrams and pictures of some high-lift devices.
http://www.hq.nasa.gov/office/pao/Hi...468/ch10-5.htm
Best regards,
Westhawk
Last edited by westhawk; 12th Oct 2005 at 09:40.
