Why flaps are deflected downwards?
Lowering the flaps increases K and therefore also the lift, but the flaps need to be raised when the aircraft has reached its cruising altitude because they cause undesirable drag. Flaps are extensions of the trailing edge of the wing and can be deflected downward as much as 45°.
How did the trailing edge flaps affect the airfoil lift curve?
The flaps and slats move along metal tracks built into the wings. Moving the flaps aft (toward the tail) and the slats forward increases the wing area. Pivoting the leading edge of the slat and the trailing edge of the flap downward increases the effective camber of the airfoil, which increases the lift.
Why is the trailing edge of an airfoil mostly pointing downward?
The trailing edge of and airfoil is mostly pointing downward. Is there any reason for that? Down wash increases drag and down wash is due to the direction of air pointing down. If the trailing edge is made horizontal (or maybe pointing upward), they can produce less down wash and Kutta Condition can still be satisfied.
Where is the rear stagnation point on an airfoil?
The rear stagnation point is usually located at the trailing edge of the airfoil, thanks to the Kutta Condition which says that, “A body with a sharp trailing edge which is moving through a fluid will create about itself a circulation of sufficient strength to hold the rear stagnation point at the trailing edge.”
Do you have to have a trailing edge to fly?
You are right, the trailing edge does not need to point down. Take symmetric airfoils – here the trailing edge runs parallel to the airfoil chord. Or take reflex airfoils (like the HQ 34 of the SB-13 tailless glider ): Here the trailing edge is indeed pointing upwards, and still this aircraft flies.
Why does the trailing edge not point down?
Down wash increases drag and down wash is due to the direction of air pointing down. If the trailing edge is made horizontal (or maybe pointing upward), they can produce less down wash and Kutta Condition can still be satisfied. What are the specific reasons for this shape? You are right, the trailing edge does not need to point down.