AERO 325 AERODYNAMICS I, WINTER 2008,
PROBLEM SET V
Handed out 02/18/08, Due in 03/05/08
We saw in class that the best way to distribute the lift across the span of a wing is to do
so elliptically. This is optimal in the sense that if the wing needs to generate a given lift,
this distribution minimizes the induced drag.
However, drag is not the only penalty for generating lift. Weight can also be a problem,
especially that of the structure needed to withstand bending moment at the root of each
wing. This can be an important consideration in the design of very flimsy aircraft, such as
those powered by humans, and we will investigate this.
Assume that the lift distribution across the span is given by the usual Fourier series;
so that
Work out a corresponding expression for the bending moment at the root of each wing.
Be careful. A symmetrically loaded wing experiences no rolling moment because the left
and right halves cancel.
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 Winter '08
 Roe
 Fluid Dynamics, Aerodynamics, Wing, Lift

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