Does anyone know of any study that provides/obtains experimental values for the slipstream contraction factor, and for the slipstream heigth of a rotor? I am trying to modulate the slipstream using the expression V=Vc+Vi+Vi*tanh(s*k/h), from Seddon's Basic Helicopter Aerodynamics, but I am not finding a way to evaluate k (wake contraction factor) and h (slipstream height). I think I only need the value for the upper rotor, so values from a single rotor might work. And if they were regarding small propellers (unmanned aircraft prop) it would be better. I believe I can get a value for k from theoretical assumptions (as Leishman does), but if I would like to try with experimental values.
Thank you.
Have you tried here:
Coleman, Colin P. "A Survey of Theoretical and Experimental Coaxial Rotor Aerodynamic Research." (1997).
?
Thank you for your reply.
Yes,I did. In fact Coleman refers to studies by Nagashima and Nakanishi ("Optimum performance and wake geometry of coaxial rotor in hover. Proceedings of the 7th European Rotorcraft and Powered Lift Forum", Paper No.41, Sept. 1981 and "Optimum performance and wake geometry of a coaxial rotor in hover", Vertica, vol.7, 1983) and by Andrew, M.J. ("Coaxial Rotor Aerodynamics in Hover", Vertica, vol.5, 1981) which seem to explore this question.
Unfortunately, I was not able to find either one of them...
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