The Cyclogyros.

Updated: 14 Oct 2004
Planned paddle-wheel aeroplanes

A cyclogyro (or cyclogyre) is an aeroplane propelled and given lift by horizontal assemblies of rotating wings. Very few prototypes were built, and those that were constructed were completely unsuccessful.

Above: An artists conception of a two-passenger cyclogyre. Picture dated 1935.

The essential principle is that the angle of attack of the rotating wings is altered as they go round, allowing the lift/thrust vector to be altered. This (in theory) allows the craft to rise vertically, hover, and even go backwards.

Above: How to fly a cyclogyre. Sorry about the poor picture quality; I've done the best I can.

The picture above describes the cyclogyro principle better than I could: I hope it is readable. The lowest part of the diagram shows (possibly rather optimistically) how a cyclogyro suffering engine failure could still glide to a forced landing. Personally, I think it would have glided like a grand-piano.

Left: Another speculative view of the cyclogyre, apparently by the same artist.

In 1935 NACA wind-tunnel tests were done on a cyclogyro wing, and it was found that theory and reality were somewhat out of line. The power required to turn the rotary wings was much greater than calculated, and would have been impractical.

The Schroeder S1 Cyclogyro: 1930.
The Schroeder machine retained its normal wings, and so looked like an ordinary high-wing monoplane, except there were two large paddle-wheels in front instead of a propeller. The aircraft was powered by a Henderson engine. Vertical takeoff would be out of the question with the lift concentrated at the front, and so it appears that Schroeder was merely planning to use the rotary wings as a more efficient alternative to a propellor. In this he would have been sadly disappointed.
E A Schroeder was based in San Francisco, USA.

The Rohrbach Cyclogyro: 1933.
This proposal was based on experiments in Germany by Adolf Rohrbach with the paddle-wheel wing arrangement. As in the big picture above, the wings were altered from positive to negative angles of attack during each revolution, and would in theory produce any combination of horizontal and vertical forces. There appears to be no evidence that this design was ever built, let alone flown.
Note the tall thin fuselage required to lift the rotary wings clear of the ground.

Cyclogyro by the Rahn Aircraft Corp, 1935.
This experimental aircraft was only 15 feet long, and carried two 6-foot span rotating wings on each side; once again these would theoretically allow the aircraft to rise or descend vertically, and fly forwards at up to 100 mph without the aid of a normal propeller. It was powered by a 240 hp supercharged Wright Whirlwind. No information appears to exist on whether it ever got off the ground.

Well, despite every thing, it looks like this concept still lives: see the Korean cyclocopter.

Thanks to Paul Dunlop for pointing this one out.