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Comment by teamonkey | Hacker News Reader

The wings are two sandwiched pieces of foam with only the slightest bit of trimming on the leading edge. Certainly not anything like the smooth upper surface I’d assume was necessary for a wing to be aerodynamic. I guess it doesn’t matter too much for a plane this size, but would a smoother wing surface actually perform better?

I’m also fascinated by the variety of shapes of RC planes, compared to your traditional passenger aircraft. Is there a good primer on model plane design?

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Even a flat piece of foam will generate lift [1]. The only requirement per se is that the trailing edge of the wing is somewhat sharp. A more optimized shape would allow the plane to fly at a lower angle of attack and would reduce drag, but drag isn’t exactly your problem if your thrust to weight ratio is 2:1.

1- https://www.av8n.com/how/htm/airfoils.html#fig-barn20

Yeah, a proper airfoil would absolutely perform better, and people use hot wire cutters on foam like this to produce airfoils [1][2], but that's more of an advanced craft and not necessary for getting something which flies well.

  1: https://www.youtube.com/watch?v=yIxyyTnT-hM
  2: https://www.youtube.com/watch?v=JIRzQO4F8ck

The power to weight ratio on these machines is very high indeed. They can accelerate straight up. In horizontal flight you can get plenty of lift from angle of attack without careful wing shaping. You might get more efficiency with better shaping, but these things are already so outrageously flyable that the demand on the pilot is the limiting factor.

Normally the foam core board is cunningly bent over to form a pretty darned good airfoil.

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