The Isacco Helicogyre

Updated: 20 Oct 2009
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This extraordinary machine was found in Volume 4 of "Newne's Pictorial Knowledge" an indispensable reference for those concerned with unusual means of transport. The Associate Editor was... Enid Blyton.

Left: The Helicogyre. I have not yet located an actual photograph.

The Helicogyre was a form of autogyro, with special arrangements for driving the rotor for vertical takeoff and landing. (VTOL) The designer was an Italian called V Isacco.

In level flight the rotor of an autogyro autorotates to provide lift and is not driven by an engine. Conventional autogyros used a shaft drive from the main engine to spin up the rotor for takeoff, but the unique feature of the Helicogyre was the provision of four small piston-engines at the rotor tips to turn the rotor. The 32hp Bristol Cherub appears to have been chosen.

This has some advantages- for example, there is no torque reaction on the body of the aircraft as it does not provide the rotor drive, and so a tail-rotor is not required. (though there must presumably still be some tendency to rotate due to bearing friction)

On the downside, there are five engines to go wrong instead of one. The consequences of one of the four rotor engines stopping in mid-flight are not entirely clear; is the rotor head built strongly enough to redistribute the torque from the remaining engines?
There would also be some interesting problems to be solved in getting throttle control to the engines and instrumentation readings back.

The picture shows a pilot and observer, which seems to indicate intended military use.

Unlikely as it may appear, one of these was built in 1929 under the auspices of the British Air Ministry. They had previously encouraged the Brennan helicopter, from 1919 to 1926, at the Royal Aircraft Establishment, Farnborough.

It was not successful (who would have thought it?) and Isacco worked on other projects until after the Second World War when he came to England from France to work with Bevan Brothers on a jet-powered version of the Helicogyre, the Jetcopter. The Jetcopter project (specification E.1/48.) was abandoned in 1951.

The concept of the tip-driven rotor reappeared with considerable success in the Fairey Jet Gyrodyne of 1955 and the Fairey Rotodyne in 1957. The Rotodyne was an entirely sound design with two wing mounted Napier Eland turbo-props, mounted on stub wings, for forward flight. Air bled from the compressor stages was fed to rotor-tip combustors for take-off and landing. For various reasons, including tightening noise regulations, (the rotor-drive system was not quiet) this design did not enter quantity production.

Left: The Fairey Rotodyne of 1957.

I built an Airfix kit of one of these. It must have been a very long time ago, as I seem to recall that it was stil regarded as "transport of the future" at the time.

The rear doors were tricky to assemble, I remember...

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