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1922

De Bothezat

In January 1921, the US Army Air Corps awarded a contract to Dr. George de Bothezat and Ivan Jerome to develop a vertical flight machine. The 1678kg "X"-shaped structure supported a 8.1m diameter six-blade rotor at each end of the 9m arms. At the ends of the lateral arms, two small propellers with variable pitch were used for thrusting and yaw control. A small lifting rotor was also mounted above the 180hp Le Rhone radial engine (which it also cooled) at the junction of the frames, but was later removed as unnecessary. Each rotor had individual collective pitch control to produce differential thrust through vehicle inclination for translation. The aircraft weighed 1700kg at take-off and made its first flight in October 1922. The engine was soon upgraded to a 220hp Bentley BR-2 rotary. About 100 flights were made by the end of 1923 at what would eventually be known as Wright Field near Dayton, Ohio, including one with three "passengers" hanging onto the airframe. Although the contract called for a 100m hover, the highest it ever reached was about 5m. After expending $200,000, de Bothezat demonstrated that his vehicle could be quite stable and that the practical helicopter was theoretically possible. It was, however, underpowered, unresponsive, mechanically complex and susceptible to reliability problems. Pilot workload was too high during hover to attempt lateral motion.

In the late 1930s, de Bothezat built a single seat, coaxial helicopter with even less success.

De Bothezat

The first rotorcraft ordered by the United States Army was made by de Bothezat. This Russian engineer who had emigrated to the United States started in July 1921 to build a helicopter at Dayton under the auspices of the United States Air Service.

The helicopter had four six-bladed rotors mounted at the ends of beams 20 metres in length, forming a cross and intersecting in all directions. The rotor axes were not parallel but slightly inclined inwards so that if prolonged they would have met at a point directly above the centre of gravity. Besides the rotors with variable-pitch blades, the helicopter had two horizontal propellers called 'steering airscrews' as well as two small airscrews placed above the gearbox and acting as regulators for the 220hp engine. Ready for flight, the helicopter weighed 1610kg.

On 18th December 1922 during a test by the Technical Section at McCook Field (now known as Wright Field), the aircraft rose 1.8 metres from the ground and remained airborne for 1 minute 42 seconds. On 19th January 1923 it lifted two persons to a height of 1.2 metres, and on 17th April 1923 it lifted not only the pilot but also four people hanging on to the framework. Because of its great moment of inertia, the helicopter proved quite stable, yet despite the series of sustained flights which it performed, the Air Corps rapidly lost interest in it.

P.Lambermont "Helicopters and Autogyros of the World", 1958

De Bothezat

A machine which was less complex than Sikorsky's first prototype but equally heavy - almost a 1922 version of the famous Breguet No.1 - was flown by a Russian emigre to the United States, de Bothezat, on 18 December of that year. The 1600kg vehicle, with a 220hp engine, lifted itself to a height of 1.80m and stayed in the air for one minute, 42 seconds. But the US Air Force was more interested in autogyros and blocked funds to de Bothezat, who was thus obliged to give up his experiments.

G.Apostolo "The Illustrated Encyclopedia of Helicopters", 1984

Technical data for Bothezat helicopter

Engine: 1 x Rhone rated at 135kW, rotor diameter: 8.08m, length and width: 19.8m, height: 3.05m, take-off weight: 1700kg

Comments 
iki, e-mail, 20.10.2011

wow like the helicoters

shoes, e-mail, 15.06.2011

Thank you for your attention,
but I don't need it. So you may put it on E-bay ;)

p, e-mail, 10.06.2011

Thank you for your attention,

vimal, e-mail, 20.10.2010

helo am doing the quad rotor project any one can give some structural design ideas and relative analysis.

Business Gifts, e-mail, 21.08.2010

The site is very well-planned, informative, and easy to browse. It is a good thing that you posted articles for cuisin

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Jobba, 20.05.2010

I reeeally want one of these helos

Manohar, e-mail, 21.02.2009

I am B A Manohar from Bangalore(India).I am doing my M Tech project on quadcopter and needed to know how to design the blade for the same. If you can provide the details it would help me in my project work

Devon Blaine, e-mail, 30.04.2008

Hi it's me devon again that conner kid doesn't have any money. I'm rich.

Connor Miles, e-mail, 30.04.2008

i will buy this aircraft who ever has the heliocopter

Devon Blaine, e-mail, 30.04.2008

I will buy that picture. My first offer is $750 cash

Alexandra, e-mail, 20.10.2007

In you're article you are saying that George de Bothezat is a Russian engineer. After doing some researches, I didn't find any relation between his parents and the Russian people. Apparently, and as I knew before reading you article, he is Romanian, born in 1883 in Iasi, România, where he actually began school then University studies then moved to Petrograd, Russia to finish his studies. Otherwise, liked your articles.

avia.russian.ee, 24.02.2007

Thank you for your attention,
but I don't need it. So you may put it on E-bay ;)

Claudine, e-mail, 24.02.2007

My late Uncle has left me an original 5x7 (approx. size) black & white picture of"De Bothezat Helicopter" flight of April 17,1923, 2 min.45 sec.of flight time McCook Field, Ohio. Do you have a museum for these pictures?
Please respond,as I'm thinking about putting it on E-bay.
Regards, Claudine

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