Flight, March 1923
THE DE BOTHEZAT HELICOPTER
JUST recently reports have been coming along of several successful flights of some of the experimental helicopters with which various inventors, in different parts of the world, are attempting to solve the problem
of direct lift and hovering. One of these, which appears to be making a certain amount of progress towards success, is the de Bothezat. According to our American contemporary Aviation, it accomplished its first free flight at the Headquarters of the Engineering Division at McCook Field, Dayton, Ohio, on December 18 last. The duration of this flight was 1 min. 42 secs., and the altitude reached about 6 ft. The helicopter rose straight from the ground, and then was manoeuvred at the will of the pilot, and then descended, landing safely and easily. The machine was steady during this flight, showing a high degree of stability, and no difficulty was experienced in landing. The flight was witnessed by many Army officials and others.
This helicopter was designed by Dr. G. de Bothezat and built, under his personal supervision, by the U.S. Air Service.
As may be seen from the accompanying illustrations, the de Bothezat helicopter consists of a cruciform framework, or fuselage, supported on a four-wheel chassis, and having at the extremity of each arm of the “body" a large six-bladed lifting screw - or, practically speaking, six lifting planes arranged radially. These are rotated through a special shaft gearing designed by Dr. de Bothezat by a 170 h.p. Le Rhone engine mounted in the centre of the body. The working of this gearing has been quite satisfactory. The total blade area of the lifting screws is 900 sq. ft., and their diameter 25 ft. The total weight of the helicopter is 3,600 lbs., including pilot and fuel. This machine was built full size, without preliminary models or tests of any kind, all of the details of the construction being based upon computations made by Dr. de Bothezat and in accordance with his general theory of helicopter stability.
The construction of the helicopter took only eighteen months, including the work of designing, building and all adjustments and tests. During its first successful flight it was piloted by Major T. H. Bane, who had been in charge of the Engineering Division while the machine was being designed and built.
During further trials, on January 19, it lifted two persons - Major Bane, the pilot, and Art Smith, the well-known civilian pilot - to a height of about 4 ft. In this weight the total weight lifted was 3,750 lbs., or 450 lbs. in excess of its designed gross weight. After this test several other flights were made by Major Bane and Art Smith individually. The maximum height reached was 10 ft. The engine, it may be noted, was never given full throttle. It is claimed that this machine can travel horizontally as well as vertically, and that it will glide to earth without danger in the event of engine trouble, as the projected area of the blades, when turning free, slow down the descent to a safe speed.