Kayaba's Cessna-based « Heliplane » compound helicopter

Until World War II, the Kayaba company manufactured autogiros and aircraft undercarriages in Japan. In 1952, Shiro Kayaba, the founder of the firm, returned to rotary wing experimentation with the Heliplane compound helicopter. He obtained the fuselage of a Cessna 170B and, during the following two years, turned it into quite a presentable convertiplane.

The Kayaba Heliplane was a curious machine, expected to be able to climb vertically and then cruise horizontally under the power of its piston-engine alone. The normal 180 h.p. Continental engine, driving a fixed-pitch airscrew, was retained. The Heliplane's three-blade rotor had a 36 foot-diameter and was mounted above the cabin roof. Each blade of this rotor was driven by a small Ishikawajima ramjet used for takeoff and landing. In horizontal flight, when the Heliplane was being driven by the normal propeller, the rotor would rotate freely. The undercarriage was attached to low-set stub wings.

It is known that tied-down testing took place late in 1954, but no reports exist to indicate that the machine ever flew untethered.

Good stuff, i had never heard of this one...

It was mentioned in Aviation Week 1952 (don't know the exact issue in the moment) with the same photo
(but in lower res), as the first one in Stéphans post. The caption states, that top speed would have been
105 mph, range about 250 miles and, especially interesting, I think, that the rotor was connected to the
Continental engine, too.

Hi Stéphane
Nice one, the Kayabe Heliplane. What has bothered me over the years is the engine.
If the C170B engine was retained this was not a 180hp unit, since the C170B had a 145hp (C145/O-300) six-cilinder. My notes talk of a 180-hp Continental E185, but it could have been a 180hp Lycoming O-360.
The Handbook of Japanese Aircraft 1951-1989 mentions engine O-360, 180hp and that could indicate at the Lycoming engine.
Keep posting these rare ones!

Some figures on the Kayabe Heli-Plane (as they call it) from the Handbook of Japanese Aircraft 1951-1989:
Rotor diameter 11,00m, length 7,40m, (Projected) max. speed 170km/h, cruise 120km/h, ceiling 4,000m, range 360km

Hi! Kayaba began to develop heliplane which combined the merit of autogyro and helicopter. Fuselage, engine and propeller were taken from second hand cessna 170B. Three ramjet engines which developed by IHI were installed at rotor tip. Rotor blades were made of bonded metal. Before the first flight, engine was changed to 180hp one, propeller was changed to variable pitch type. Tie down test was held in February 1954, but ramjet engine did not work well. In April 1954, ramjet engine destroyed the fuselage at tie down test. It's neccesary to increase engine power, to exchange ramjet engine and basical modification of the fuselage structure, so development was terminated.

Awesome pic and source document... Thank you so much!!

Hi! Kayaba heliplane type1.
I can see the word オスナ(osuna) at the wing leading edge. The meanig of this word is "Don't push here".
In japanese language, Cessna pronounce セスナ(sesuna). This word is a Joke.
https://www.kyb.co.jp/company/media/history80_2015_11.pdf