I recently performed an aerodynamic analysis of a fixed-wing UAV with a pusher propeller configuration. I found out that the L/D reduced by about 15% when compared to the body alone without propeller. I am investigating methods to mitigate this problem.

The following are some details about the aircraft, Wing Span = 2.5 m

Fuselage length = 2 m

MTOW = 25 kgs

Tandem wing configuration. The following image is a representative image.

Courtesy: Raytheon Coyote

Tandem wing UAV

Any suggestions will really be helpful.

  • $\begingroup$ With a spinning propeller, or propeller at standstill? $\endgroup$
    – Koyovis
    Aug 11, 2019 at 5:37
  • $\begingroup$ Please explain how you measured that L/D reduction. Was the propeller spinning or fixed? How did the end of the aircraft look like initially, without the prop? $\endgroup$ Nov 26, 2019 at 17:57

1 Answer 1


You need to fair in the tail with a carbon fibre fairing/spinner such that the prop folds back and nests into it. Like below.

enter image description here

  • $\begingroup$ Thanks for the reply @John K. I have incorporating such a fairing mechanism at the rear portion and the above problem I mentioned is still persistent. Are there any other methods to decrease the negative impact of the propeller? $\endgroup$ Jun 11, 2019 at 12:21
  • 1
    $\begingroup$ The only other thing that might help is the extend the spinner in a way that lets the blades lie completely flush in the spinner profile when folded. $\endgroup$
    – John K
    Jun 11, 2019 at 12:27
  • $\begingroup$ Noted. Will try to push that to the greatest extent possible. $\endgroup$ Jun 11, 2019 at 12:30

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