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I am trying to make a concept for a small UAV. The UAV shall be flying at Mach=0.75 , shortly 0.9

For this, I am looking for an adequate airfoil, which allows me, to avoid Mach=1 on the airfoil. From airfoiltools I have chosen the rae2822 , said to have a high critical mach number. I plotted my cp curve for alpha=0 and calculated the critical mach number which is 0.736 for sweep angle=5 degree.

So I this will not work. I also tested the sc2 0714, originally made as supercritical airfoil, which gives me a value of Mach=0,56 as critical mach number.

Either I made a mistake in calculation or I do not know how commercial aircraft fly at 0.8 or 0.9 ? I do not want to have a big sweep angle in order to have a good lift/drag ratio.

Can you recommend any airfoil?

Thanks Lucas

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    $\begingroup$ Second sentence is unclear. $\endgroup$ – quiet flyer Mar 18 at 14:50
  • $\begingroup$ Critical Mach number isn't the biggest driver (unless it affects Cm wildly). Drag divergence Mach number is the real driver. $\endgroup$ – JZYL Mar 18 at 15:49
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    $\begingroup$ when asking for an airfoil, are you asking for a profile, for dieadral parameters, sweep angles, aspect ratio, shape,...? I think putting more clues about your thinking can help us guide you. $\endgroup$ – Manu H Mar 18 at 19:22

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