Kellett KD-1

The Kellett KD-1 was a 1930s American autogyro built by the Kellett Autogiro Company. It had the distinction of being the first practical rotary-wing aircraft used by the United States Army and inaugurated the first scheduled air-mail service using a rotary-wing aircraft.

Development

Using the experience gained in building Cierva autogyros under licence the Kellett Autogiro Company developed the KD-1 which was similar to the contemporary Cierva C.30. It had two open cockpits, a fixed tailwheel landing gear and was powered by a 225hp (168kW) Jacobs L-4 radial engine. After testing of the prototype a commercial variant designated the KD-1A was put into production. The KD-1A had a three-bladed rotor with folding blades and a number of minor detail improvements. A KD-1B which was a KD-1A with an enclosed cockpit for the pilot was operated by Eastern Airlines and inaugurated the first scheduled rotary-wing air-mail service on 6 July 1939.

In 1935 the United States Army bought a KD-1 for evaluation and designated it the YG-1, a second aircraft followed which had additional radio equipment and was designated the YG-1A. These two aircraft were followed by a batch of seven designated YG-1B. In 1942 seven more were bought for use in the observation role as the XO-60. Six XO-60s were re-engined with 300hp (224kW) Jacobs R-915-3s and re-designated YO-60.^[1] One YG-1B was modified with a constant-speed rotor and was re-designated the YG-1C, it was later re-engined with the more powerful R-915 and re-designated again as the XR-2. The XR-2 was destroyed by rotor ground resonance problems and the evaluation was continued with another modified YG-1B designated the XR-3.

Variants

KD-1

Prototype, one built

KD-1A

Commercial variant with open cockpit and a 225hp (168kW) Jacobs L-4 radial engine, three built

KD-1B

Commercial variant with enclosed cockpit two built.

YG-1

United States Army designation for one KD-1A acquired for evaluation.

YG-1A

One aircraft as YG-1 with the addition of radio equipment.

YG-1B

Production aircraft for the United States Army, seven built.

YG-1C

One YG-1B modified with a constant-speed rotor for evaluation, later designated the XR-2.

XO-60

Production aircraft for the United States Army with a 225hp (168kW) Jacobs R-755 radial engine, seven built.

YO-60

Six XO-60s re-engined with a 300hp (224kW) Jacob R-915-3 radial engine.

XR-2

The YG-1C re-designated after being re-engined with a 300hp (224kW) Jacobs R-915-3 radial engine.

XR-3

One YG-1B modifed to XR-2 standard for evaluation.

Kayaba Ka-Go Prototype

Prototype, It was an airframe which had repaired KD-1A by Kayaba.

Kayaba Ka-1

Imperial Japanese Army developed referring to KD-1A. Powered by a 240hp (179kW) Argus As 10 engine, Airframe that changed engine of prototype.

Kayaba Ka-2

Imperial Japanese Army developed referring to KD-1A. Powered by a 245 hp (183 kW) Jacobs L-4MA-7 engine, Airframe that changed engine of Ka-1 for the same thing as prototype.

Operators

 Japan

 United States

• Eastern Airlines
• United States Army Air Force

Specifications (KD-1B)

General characteristics

• Crew: 2
• Length: 28 ft 10 in (8.79 m)

Performance

See also

Aircraft of comparable role, configuration and era

• Cierva C.30
  

Related lists

• List of helicopters
• List of military aircraft of the United States
  

References

• Taylor, Michael J. H. (1989). Jane's Encyclopedia of Aviation. London: Studio Editions. 
• The Illustrated Encyclopedia of Aircraft (Part Work 1982-1985). Orbis Publishing. 
• Andrade, John (1979). U.S.Military Aircraft Designations and Serials since 1909. Midland Counties Publications. ISBN ISBN 0-904597-22-9.