Question

1. (18%) A certain thin, symmetric airfoil stalls at angles of attack greater than α-16". At α 16", it produces a lift per unit span of L' 2,000 Nm at standard sea-level conditions; its chord length is c m. a) Use thin airfoil theory to calculate the airfoil speed, Vp, just prior to stall, i.e. at a 16 b) For this real airfoil, will the a at which stall occurs depend on the Reynolds number? Why? c) Use thin airfoil theory to calculate the moment coefficient about the airfoil leading edge, caLE, at a 16. Is the direction of the moment "nose up" (pitch up) or "nose down" (pitch down)? d) If the speed, V, of the airfoil is varied so that it produces the same L' at all angles ofattack α below stall, at what α will the speed be the slowesr? (Do not worry about α-f or compressibility effects, just consider the question and come up with the most sensible answer.)

Answer 1

180 L'= 2000 N/m- L 2. L' 2x 200o 1.,. 2.SX ↓×1.7S 43.195m s mpor when aud hau an airLai e.

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