Military Factory logo

Kellett KD-1

United States (1935)
Picture of Kellett KD-1 Two-Seat Observation Autogiro Aircraft

The Kellett KD autogiro design primarily served the United States Army Air Force heading into World War 2.


Detailing the development and operational history of the Kellett KD-1 Two-Seat Observation Autogiro Aircraft.  Entry last updated on 11/18/2017. Authored by Staff Writer. Content ©www.MilitaryFactory.com

The Kellett Autogiro Company was founded during the "Golden Age of Flight" in 1929. Its early work involved licensed production of Cierva autogyro aircraft. Despite their appearance, autogyros were not true helicopters as their main rotor masts were not driven under normal power. Instead an "autorotation" effect was used to develop vertical lift while an engine-driven propeller provided the needed forward pull / push. The concept was developed by Spaniard Juan de la Cierva and an example first-flown in January of 1923.

Kellett produced several of the early-form Cierva products before shifting attention to a more internally-oriented design. This work produced the Kellett "KD-1" which held attributes akin to the Cierva C.30 model autogyro. The aircraft carried a traditionally-arranged airframe which sat the engine at the nose and two open-air cockpits directly aft of this. The engine (Jacobs L-4 radial unit of 225 horsepower) drove a two-bladed propeller. The tail unit incorporated the necessary horizontal and vertical planes while the undercarriage was fixed in flight and wheeled for ground-running actions. The notable physical characteristic of the aircraft was its three-bladed, mast-mounted main rotor which was installed over and ahead of the crew positions and over the engine compartment.

The prototype emerged as the KD-1 and only a single example was built. Upon completing the needed testing and certification, the KD-1 was brought to the commercial sector as the "KD-1A". Three were built to this standard. The "KD-1B" was similar in form and function but offered enclosed cockpits. Two of this mark were built.
United States Army interest in the design was enough to warrant formal evaluation of the product. This led to the developmental designation of "YG-1" being issued and covered a single KD-1A example. The follow-up "YG-1A" was given a radio suite and the first U.S. Army production model became "YG-1B" and seven were acquired. One was modified with a constant-speed propeller for testing purposes and became the "YG-1C" (later the XR-2).

An additional seven examples followed in the "XO-60" guise which carried the Jacobs R-755 radial piston engine of 225 horsepower. The "YO-60" differed in its use of a Jacobs R0915-3 radial engine of 300 horsepower. Six were produced to this standard.

The "XR-2" was the YG-1C redesignated but also carried the R-915-3 engine of 300hp. The "XR-3" was a one-off YG-1B model modified to the XR-2 standard but only ever reached the evaluation stage and was never furthered.

In practical service, the KD-1 proved a successful autogyro attempt. It was responsible for the first-ever scheduled delivery of mail by air by a rotary-wing aircraft when it completed such a flight on July 6th, 1939. For the U.S. Army, it also served as the service's first viable rotary-wing platform before more advanced types were eventually acquired. A few variants also emerged from Kabaya in Japan: "Ka-Go" was a prototype based on the KD-1A and Ka-1 was given an Argus As 10 engine of 240 horsepower. Ka-2 carried a Jacobs L-4MA-7 engine of 245 horsepower.






Our Data Modules allow for quick visual reference when comparing a single entry against contemporary designs. Areas covered include general ratings, speed assessments, and relative ranges based on distances between major cities.

Image of collection of graph types

Relative Maximum Speed Rating
Hi: 150mph
Lo: 75mph
    This entry's maximum listed speed (128mph).

    Graph average of 112.5 miles-per-hour.
City-to-City Ranges
NYC
 
  LON
LON
 
  PAR
PAR
 
  BER
BER
 
  MOS
MOS
 
  TOK
TOK
 
  SYD
SYD
 
  LAX
LAX
 
  NYC
Graph showcases the Kellett KD-1B's operational range (on internal fuel) when compared to distances between major cities.
Aviation Era
Pie graph section
Pie graph section
Pie graph section
Pie graph section
Pie graph section
Useful in showcasing the era cross-over of particular aircraft/aerospace designs.
Unit Production Comparison
Comm. Market HI*: 44,000 units
Military Market HI**: 36,183 units
21
21


  * Commercial Market High belongs to Cessna 172.

  ** Military Market High belongs to Ilyushin Il-2.


Altitude Visualization
Small airplane graphic
  Compare this entry against other aircraft using our Comparison Tool  
National Flag Graphic
Origin: United States
Year: 1935
Type: Two-Seat Observation Autogiro Aircraft
Manufacturer(s): Kellett Autogiro Company - USA
Production: 21
Status: Retired, Out-of-Service
Global Operators:
Imperial Japan; United States
Historical Commitments / Honors:

Military lapel ribbon for Operation Allied Force
Military lapel ribbon for the Arab-Israeli War
Military lapel ribbon for the Battle of Britain
Military lapel ribbon for the Battle of Midway
Military lapel ribbon for the Berlin Airlift
Military lapel ribbon for the Chaco War
Military lapel ribbon for the Cold War
Military lapel ribbon for the Cuban Missile Crisis
Military lapel ribbon for the Falklands War
Military lapel ribbon for the French-Indochina War
Military lapel ribbon for the Golden Age of Flight
Military lapel ribbon for the 1991 Gulf War
Military lapel ribbon for the Indo-Pak Wars
Military lapel ribbon for the Iran-Iraq War
Military lapel ribbon for the Korean War
Military lapel ribbon for the 1982 Lebanon War
Military lapel ribbon for the Malayan Emergency
Military lapel ribbon for the attack on Pearl Harbor
Military lapel ribbon for the Six Day War
Military lapel ribbon for the Soviet-Afghan War
Military lapel ribbon for the Spanish Civil War
Military lapel ribbon for the Suez Crisis
Military lapel ribbon for the Vietnam War
Military lapel ribbon for Warsaw Pact of the Cold War-era
Military lapel ribbon for the WASP (WW2)
Military lapel ribbon for the World War 1
Military lapel ribbon for the World War 2
Military lapel ribbon for the Yom Kippur
* Ribbons not necessarily indicative of actual historical campaign ribbons. Ribbons are clickable to their respective campaigns/operations.
Measurements and Weights icon
Structural - Crew, Dimensions, and Weights:
Unless otherwise noted the presented statistics below pertain to the Kellett KD-1B model. Common measurements, and their respective conversions, are shown when possible.

Operational
CREW


Personnel
2


Dimension
LENGTH


Feet
28.84 ft


Meters
8.79 m


Dimension
WIDTH


Feet
40.03 ft


Meters
12.2 m


Dimension
HEIGHT


Feet
10.30 ft


Meters
3.14 m


Weight
EMPTY


Pounds
1,581 lb


Kilograms
717 kg


Weight
LOADED


Pounds
2,249 lb


Kilograms
1,020 kg

Engine icon
Installed Power - Standard Day Performance:
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.

Performance
SPEED


Miles-per-Hour
128 mph


Kilometers-per-Hour
206 kph


Knots
111 kts


Performance
RANGE


Miles
200 mi


Kilometers
322 km


Nautical Miles
174 nm


Performance
CEILING


Feet
12,500 ft


Meters
3,810 m


Miles
2.37 mi

Armament - Hardpoints (0):

None.
Variants: Series Model Variants
• KD-1 - Prototype; single example
• KD-1A - Fitted with Jacobs L-4 radial engine of 225 horsepower; three examples completed.
• KD-1B - KD-1A model with enclosed cockpits; two examples completed.
• YG-1 - KD-1A for evaluation by U.S. Army
• YG-1A - YG-1 fitted with radio equipment
• YG-1B - U.S. Army production model; seven examples completed.
• YG-1C - One-off YG-1B fitted with constant-speed propeller for testing; redesignated to XR-2.
• XO-60 - Fitted with Jacobs R-755 radial of 225 horsepower; seven examples completed.
• YO-60 - XO-60 model with Jacob R-915-3 radial of 300 horsepower; six modified to this standard.
• XR-2 - Redesignation of YG-1C; Jacobs R-915-3 radial of 300 horsepower.
• XR-3 - One-off YG-1B modified to XR-2 standard
• Kayaba Ka-Go - Prototype by Kayaba of Japan; based on KD-1A model.
• Kayaba Ka-1 - Fitted with Argus As 10 engine of 240 horsepower.
• Kayaba Ka-2 - Fitted with Jacobs L-4MA-7 engine of 245 horsepower.