Experience The skill and know-how of our engineering staff and shop personnel, developed during the past few years, in experimental and production work on parts and sub-assemblies for leading HELICOPTER manufacturers, enable us to competently handle your work. Complete facilities for machining and assembling under Army Air Forces "Approved Quality Control" procedures. SPECIAL MACHINE TOOL ENGINEERING WORKS Established 1910 "Specialists in Special Machining" 132 Lafayette St. New York 13, N. Y. ROTOR CRAFT CORPORATION SPECIALlZING IN The Tandem Helicopter NOW CONSTRUCTING THE ARMY XR-11 THE PROTOTYPE OF YOUR PRIVATE HELICOPTER OF THE FUTURE ALSO UNDER DEVELOPMENT MODEL X-20 FOR 20 PASSENGERS OR CARGO 4358 W. 3RD STREET LOS ANGELES 5 CALIFORNIA NEWS VIEWS AIMS SIMPLIFIED HYDRAULIC DAMPER Vibradamp Incorporated of New Brunswick, N. J., have designed and manufactured a rotor blade damper which has been tested for Kellett's XR-8 and XR-10 helicopters. Infinite life for this unit was predicted through the results of a 500 hour fatigue test at 250 cycles per minute, which proceeded Kellett's successful flight program. Former difficulty of maintaining concentricity in manufacture, is eliminated by the simplified design culminating in extraordinary performance. The damper is mounted in a horizontal position, simulating flight attitude, on a shock absorber testing machine which permits varying cycle frequency from 50 to 300 rpm, and stroke limits from 1/16" to 3 1/2". NEW SUPERSONIC WIND TUNNEL Problems of high-speed flight will be conducted upon accurately constructed steel models mounted in the threesquare-foot test section of the 1500 mile-per-hour wind tunnel, located at the Ames Aeronautical laboratory of the NACA at Moffet Field, California. This new supersonic tunnel has been designed to operate exclusively beyond the velocity of sound, which is approximately 760 mph. Conditions corresponding to those encountered by supersonic aircraft will be simulated by air being forced through the constricted channel equivalent to twice the speed of sound. Heat generated in the compression of this air is removed by passing the air through large water-cooled radiators built in the tunnel circuit. Power will be provided by electric motors totalling 10,000 hp driving four three-stage centrifugal compressors which rotate at a constant speed of 5350 rpm. The models are supported in the stream of air on a slender boom extending from a balance which weighs the aerodynamic forces. Acting lift, drag, and pitching moment are transmitted to springs whose deflections are measured by electric strain gauges. Simultaneously, a sensitive optical apparatus permits the flow of air past the model to be observed and photographed, providing a valuable aid in interpreting the numerical balance data. UNITED HELICOPTERS "COMMUTER" PROGRESSES Production plans concerning the two-passenger "Commuter" helicopter manufactured by United Helicopters, Inc., has been released by Stanley Hiller, Jr., founder of the firm. Designed primarily for the private-owner market, it will be priced at approximately the same figure as an airplane of equal horsepower. One of the outstanding features of this model is the greatly simplified technique of helicopter control, which makes practical the piloting of rotary wing craft by persons with limited flying experience.