Wind tunnels have afforded the best potential for studying regions of aerodynamic uniqueness of V/STOL aircraft, but they have been of limited value because of the magnitude of the flow interference they introduce. A new wind tunnel concept is described for covering the spectrum of transition testing from hover throughout wing sustained flight. The wall interference corrections are physically produced by the structure of the wall. A small scale tunnel was designed, constructed, and tested employing this concept. Data from a small rotor model were obtained in the new tunnel and a large conventional one as a basis for comparative evaluation. (Author).

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A compilation of available experimental and analytical data is presented, dealing with the effects of propellers (and rotors) on V/STOL take-off and transition flight. Since the majority of the experimental work was conducted with small-scale propellers/rotors, considerable effort was expended to demonstrate the applicability of these data to full-scale propellers. The dependence of take-off performance on blade Reynold's number and tip Mach number is described. Recent results from the Navy flying wind tunnel have conclusively indicated the dependence of model V/STOL transition flight data on the character of the model test facility. Therefore, the correlation of model vs. fullscale propeller/rotor transition data was impossible because of the non-availability of accurate full-scale results. Data are presented describing identical tests run on the airship and in three different wind tunnels. A brief analytical treatment is described which might enable more work to proceed to correct for wall interference. In addition, the experimental techniques used to obtain accurate low velocity measurements and to obtain vibration-free straingage traces are briefly described. (Author).