Deflecting an aileron will increase or decrease the camber of the outer wing where the aileron is attached. I learnt on this platform that centre of pressure (c.p.) moves fore and aft with aileron deflection.

Is the c.p. movement as a result of aileron deflection significant? If it is significant, how does one calculate the difference in c.p. with respect to aileron upward or downward deflection?

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    $\begingroup$ Probably you refer to ailerons used as flaperon when flaps are extended. Yes in this case the c.p. displacement is comparable to what happens with flaps. Calculations are beyond my scope but extremely complicated without much much more information and data $\endgroup$ – user40476 Jun 14 at 18:16
  • $\begingroup$ I think you forgot a link in along with the sentence "I learnt on this platform". Which platform are you talking about? $\endgroup$ – Manu H Jul 6 at 8:46

The CP of local sections where the ailerons are deflected should shift aft. In an asymmetric deflection case, very little pitch moment would be generated. For symmetric deflection (e.g. maneuver load alleviation, flaperon), there will be a net pitch moment, but should be small due to the outboard location of the panels, unless the wing is highly swept.

To estimate the effect, you can view ailerons as part-span plain flaps. You can use any of the semi-analytical methods from ESDU, DATCOM or Roskam. You can also use any vortex lattice method to get the answer. The estimates should agree fairly well for small deflections and low Mach.

  • $\begingroup$ Thank you for your answer,I'm trying to design an ultralight and can I safely conclude from your answer that the movement of c.p caused by deflected ailerons are negligible in a slow,light weight,low performance ultralight airplane?@Jimmy $\endgroup$ – David Teahay Sep 5 at 8:46
  • $\begingroup$ @DavidTeahay If you're talking about asymmetric aileron deflection, there should be very little pitching moment. Is that what you're ultimately interested in? $\endgroup$ – Jimmy Sep 5 at 12:58

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