Helicopter Trials In Paris

Northern Advocate, 18 February 1939, Page 5 (Supplement)

Helicopter Trials In Paris

The most promising of the helicopters, offered years ago to Great Britain and declined after the inventor had been encouraged to transfer his work to London, is now pursuing its course of development in Paris. The first of a series has begun its flying trials in the yard of a London factory, and has made hovering flights of 30 minutes’ duration (says “The Times”). It is the forerunner of other models calculated to give a fast rate of climb, a high ceiling, and high forward speed in combination with the ability to make slt»w descents through the lift generated by autorotation. / The principle applied to these helicopters is that on which the Hungarian inventor, Mr Oscar von Asboth, has been working for more than 10 years. In 1931 an official of the British Air Ministry flew one of the early models in Budapest, and gave a favourable report of its stability and its power of vertical ascent. Work in Paris. In 1936 the Air Ministry purchased the, drawings of the invention and

contemplated the construction of a helicopter, but various circumstances impeded the plan, and eventually the work was transferred to Paris. There the lirst machine, fitted with a 180 h.p. engine driving two co-axial lifting airscrews, has flown at a loaded weight of 13201b5. and has developed an initial rate of climb of about 14 feet a second.

One feature of this helicopter is the small diameter of the lifting screws. It is no more than 16 feet four inches. In the next model of similar power, the diameter will be increased to 36 feet, the loaded weight to 2210 lbs.," and the rate of vertical ascent to 29 feet a second. This makes an interesting comparison with the Focke-Wulf helicopter, which has rotors of 65 feet diameter and an initial rate of climb of about eight feet a second.

In the biggest model he has yet projected, Mr von Asboth proposes to use screws of only 55 feet diameter, and these, driven by engines of 2000 h.p., are estimated to lift 10,0001 b. (of which 43001 b. will be useful load) to 20,000 feet in 9 h minutes. This type is estimated to have a top forward speed, obtained by tilting the rotors, of 270 miles an hour. The efficiency of this type of heli-

copter in lift and stability has been fairly well proved. The claim of efficient autorotation is also made, but the method of securing control in those circumstances has not been re-- ■ -.'3 vealed. In his earlier models, the inventor made no use of the system of altering the angles of the rotor blades which has been developed in the autogiro and in the Focke-Wuif helicopter.

Instead, he relied for control on,g movable surfaces placed in the down •» I wash of the rotors, and they proved admirable so long as the engine was running to create the downwash. The condition of descent with engine I slopped involves consideration of the control, surfaces, which apparently ho longer have powerful downwash in which to operate. Slow Descent. i In none of the models now in use v or projected is the rate of autorota- ■ tional descent to be more than 16 feet > a second. This would enable forced | landings to be made in very small fields, provided sufficient control ttgm mained at service of the pilot to enable him to choose his landing .i| place. If Mr von Asboth has dealt i with this matter in his neiv models, | they should prove of the utmost im-|| portance. J