Windmill Planes
February 1939 Popular Science

February 1939 Popular Science [Table of Contents] Wax nostalgic about and learn from the history of early electronics. See articles from Popular Science, published 1872-2021. All copyrights hereby acknowledged.

Leonardo da Vinci is usually credited with producing the first illustration of a helicopter concept. It employed a rotating helical corkscrew device at the top in order to enable the craft and occupant to "screw his way aloft, in much the same manner as Archimedes designed his eponymous helical screw device to lift water from a lower level to a higher level. Water, being dense and cohesive with itself, was easily elevated, whilst air, not being dense or cohesive, did not yield to the same technique. In fact, if the "aerial screw" were able to spin rapidly enough and was of an efficient aerodynamic design, it would work. Here is a 4-screw drone to prove it. These "Windmill Planes" presented in the February 1939 issue of Popular Science magazine represent the state of the art at the time. Surprisingly omitted is an example of Igor Sikorsky's helicopter design, which he first flew successfully in September of that year.

Windmill Planes

Whirring gyro-planes, and amazing wingless air machines that soar straight up, hover motionless, and even fly backward, may soon open a new chapter in the history of aviation. That is the prediction of 150 engineers and scientists, gathered a few weeks ago at Philadelphia, Pa., to discuss the remarkable recent advances of rotating-wing aircraft, and the problems that still confront their builders, in the first meeting of its kind ever held.

Nor was this mere prophecy. Spurred on by a $2,000,000 grant from Congress for the study of all types of "whirligig" aircraft, for possible use by the Army, Navy, Coast Guard, Department of Agriculture, and a dozen Government bureaus, active production is soon to boom again.

The first machines to be developed in the big program will probably be gyroplanes, the fantastic "flying windmill" type of craft introduced in this country by the late Juan de la Cierva, in 1929. Holding forth a brilliant future, the autogiro and similar machines were beset with technical shortcoming that had to be solved before they could become a commercial success. After ten years of quiet experimentation and development, the knottiest problems have been overcome. Strength and efficiency have been increased, and control has been made easier and more certain. Speed has been increased from seventy or eighty miles an hour to 135.

Where greater speed is required, without sacrificing the ability to land slowly and safely on the roughest or most restricted terrain, a convertible plane, designed by Gerard P. Herrick, New York engineer, is the answer. Normally a biplane of conventional appearance, it has the upper wing mounted on a single pivot bearing at its center. This wing may be released and set rotating at will by the pilot, converting the ship instantly from an airplane to a gyroplane.

One of the greatest hopes of the new program, however, is the helicopter, until recently considered a dream almost as wild as that of perpetual motion. Now, it is here. Since the middle of 1937, a machine that can dart straight up, stand motionless in still air, fly sideways and backward, has been flying all over Europe. E. Burke Wilford, of Philadelphia, has developed a similar machine, and expects to begin production of helico-gyres - machines that ascend as helicopters and fly or land as gyroplanes - within a few years.

Louis Breguet, famous French aeronautical designer, goes even farther. Before the French Academy of Science he recently presented a design for a helicopter transport that would lift a total load of sixteen tons, fly 310 miles an hour, and excel the efficiency of a conventional airplane!

It is the Focke helicopter, however, that opens the most amazing field of development. Until 1936, many helicopters had managed to get into the air, but once there they lacked control almost completely. Either the torque produced by the spinning rotor whirled the machine around, or a gust of wind overturned the whole thing and crashed it to the ground.

Unlike most previous machines, the Focke helicopter is the result of years of theoretical research, of experiments in wind tunnels and in "flights" while the machine was tied to the ground. On June 26, 1936, it made its first free flight. A year later it won all existing world's records - rising to an altitude of 8,600 feet, hovering motionless, flying forward at ninety miles an hour, and backward at twenty! So perfect was its control, that in February 1938, a girl flew the machine successfully throughout a Berlin hall, at times hovering only eight feet off the floor while leaning out the cockpit and talking with her associates!

Both Biplane and Gyroplane: Concept drawing.

Prototype gyrplane.

This queer hybrid is a convertible biplane-gyroplane. The upper wing is mounted on a pivot so that it can be released and set rotating at will, thus converting the craft into a gyroplane

Still another approach to the problem is revealed in the plans of a California inventor for a helicopter having a gas-filled corkscrew wing that whirls on a vertical axis above a globe-shaped fuselage. In this odd ship, rudder and stabilizing surface are mounted on a yoke that pivots on the poles of the spherical gondola to guide the craft in any desired direction. In case of engine failure in flight, the base containing the motor and the fuel tanks can be dropped, allowing the rest of the craft to drift safely down like a parachute.

Somewhat slower, inherently safer, and capable of making landings and take-offs in extremely restricted areas, the rotating-wing machine does not compete with the airplane but supplements it in a field of its own. Among suggested uses are for air taxi or bus service from suburbs to city, military observation, mapping, forestry work, sea rescues, and ship-to-shore service. For private flying, of course, its safety and ease of landing make it ideal.