c) A helicopter rotor has radius R = 5.0m, uniform rotor blade chord c = 0.390m and rotates at n = 5.5 revolutions per s

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C A Helicopter Rotor Has Radius R 5 0m Uniform Rotor Blade Chord C 0 390m And Rotates At N 5 5 Revolutions Per S 1 (52.85 KiB) Viewed 36 times

c) A helicopter rotor has radius R = 5.0m, uniform rotor blade chord c = 0.390m and rotates at n = 5.5 revolutions per second. At a given angle of attack the two dimensional aerofoil lift coefficient in incompressible flow is Cli = 0.52. The rotor lift in hover is required (i.e. due to rotor rotation only). Derive an expression for the rotor blade lift, 1, per unit span at radial position r (in terms of the lift coefficient in incompressible flow, C1, ambient air density, p. ambient speed of sound, aco, rotor blade chord, c, and local Mach number, M, at radial position r). Then evaluate the rotor lift per blade. [15] Assume uniform angle of attack along the span and ignore any finite wing effects. You should use standard sea level temperature T = 288.1K and density p = 1.225kgm-3, and the gas constant for air is R = 0.287kJkg1K 1.