How can I calculate upwash angle(alpha u) at the wing? I notice at every position upwash angle is different, which angle is chosen as the reference upwash angle?

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1 Answer 1


For a preliminary estimation of the upwash in front of the wing, the following plot¹ can be used:

 Upwash in front of a wing

Given the distance in front of the wing (x-axis) and the aspect ratio $A$, the plot returns $\frac{\partial \epsilon_u}{\partial \alpha}$ (y-axis), where $\epsilon_u$ is the upwash angle. The value $\frac{\partial \epsilon_u}{\partial \alpha}$ from the plot has to be multiplied by the wing's AoA to get $\epsilon_u$.

¹from: Daniel P. Raymer, Aircraft Design: A Conceptual Approach; in turn taken from: Hoak D. et al., USAF DATCOM.

  • $\begingroup$ Camber line at the bottom right is contour of wing? $\endgroup$
    – user0422
    Commented Dec 11, 2022 at 16:43
  • $\begingroup$ Yes, from 0.25 till -0.75 $\endgroup$
    – sophit
    Commented Dec 11, 2022 at 17:03
  • $\begingroup$ Where can I find how to calculate upwash angles, lifting line, lifting surface theory? $\endgroup$
    – user0422
    Commented Dec 14, 2022 at 14:35
  • $\begingroup$ Regarding upwash any book about general airplane design contains some method to estimate it. Regarding lifting line/surface theory any book about aerodynamics contains an explanation about it. $\endgroup$
    – sophit
    Commented Dec 14, 2022 at 16:30

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