Question

Why do we provide upsweep to the lower surface at aft fuselage?

(a) To reduce drag

(b) To increase drag

(c) To increase lift

(d) To maximize drag

I have been asked this question by my school teacher while I was bunking the class.

This key question is from Configuration Layout in portion Configuration Layout Considerations of Aircraft Design

Answer 1

The correct answer is (a) To reduce drag

Explanation: Fuselage is primary drag generating component of aircraft. A lower surface upsweep is provided to reduce drag penalty for typical aircraft. This upsweep will induce vortex flow pattern at the lower surface which can reduce the drag. However, for high speed aircraft it should be as low as possible.