https://en.wikipedia.org/wiki/Kellett_KD-1

http://www.militaryfactory.com/aircr...rcraft_id=1319

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.

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 225 hp (168 kW) 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 300 hp (224 kW) Jacobs R-915-3s
and re-designated YO-60. 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.


Role
Autogyro

Production Total: 21

National origin
United States

Manufacturer
Kellett Autogiro Company

First flight
1934

Primary users
United States Army Air Forces
Eastern Airlines

Variants
Kayaba Ka-1

Specifications (KD-1B)

General characteristics

Operating Crew: 2
Length: 28.84 feet (8.79 meters)
Width: 40.03 feet (12.20 meters)
Height: 10.30 feet (3.14 meters)

Weight (Empty): 1,581 lb (717 kg)
Weight (MTOW): 2,249 lb (1,020 kg)

Installed Power and Standard Day Performance

Engine(s): 1 x Jacobs L-4 radial engine developing 225 horsepower driving a
two-bladed nose-mounted propeller unit;
Autorotation managed the three-bladed, mast-mounted main rotor.

Maximum Speed: 128 mph (206 kph; 111 knots)
Maximum Range: 200 miles (322 km)
Service Ceiling: 12,500 feet (3,810 meters; 2.37 miles)






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