Full-scale-tunnel Investigation of the Static-thrust Performance of a Coaxial Helicopter Rotor

An investigation to determine the static-thrust performance of a coaxial helicopter rotor having blades tapered both in plan form and thickness ratio has been conducted in the Langley full-scale tunnel. Tests of both the coaxial-rotor and single-rotor configurations were made for a range' of blade-pitch setting and for a range of tip speed up to 500 feet per second. Several tests were also conducted to determine the effect of variation in directional control on the hovering performance of the coaxial rotor.