Kaman K-225

The Kaman K-225 is an American experimental helicopter developed by Kaman Aircraft. One example was modified to become the world's first gas turbine-powered helicopter.

K-225
XHTK-1 modified with a Boeing 502 (YT50) turboshaft engine
Role	Experimental helicopter
National origin	United States
Manufacturer	Kaman Aircraft
First flight	15 January 1947 (K-125)
Status	Retired
Primary users	United States Navy United States Coast Guard
Number built	7

Design and development

The K-125 was Charles Kaman's first helicopter, which utilized intermeshing rotors and Kaman's patented servo-flap stability control.^[1] The K-125 first flew on 15 January 1947.

The K-190 and K-225 were an improved versions of the K-125, which first flew in April and July 1949 respectively. The U.S. Navy bought two and the Coast Guard one for $25,000 each. The United States Air Force evaluated one K-225 with the designation YH-22.

A modified K-225 equipped with a Boeing 502 (YT50) turboshaft engine became the first gas turbine-powered helicopter in December 1951.^[2] This aircraft is now at the Smithsonian Institution in Washington, D.C.

A standard K-225 is preserved in the New England Air Museum at Windsor Locks Connecticut.

In 1953, the Turkish Army purchased one Kaman K-225 helicopter and a K-225 was the first helicopter flown in Turkey.^[3]

Variants

K-225

The fifth K-225 to be built displayed at the New England Air Museum, Windsor Locks, Connecticut, in June 2005

K-125

first two-seat prototype with 125 hp (93 kW) Lycoming O-390-3 engine and moulded plywood fuselage and bubble canopy.

K-190

improved prototype with 190 hp (140 kW) Lycoming engine, marketed as an open cockpit crop-duster, certified in April 1949^[4]

K-190A

open frame three-seat helicopter, powered by a 175 hp (130 kW) Lycoming O-435-C engine. Type certified on April 15, 1949.^[5]

K-190B

four-seat version.

K-225

improved model, powered by a 225 hp (168 kW) Lycoming O-435-A2 engine, certified on September 16, 1949.^[5]

K-5

designation for K-225 with Boeing T50-BO-2 model 502 engine.

YH-22

United States Air Force designation for one K-225 bought for evaluation.

Specifications (K-225)

3-view line drawing of the Kaman K-225

Data from ^[6][7]

General characteristics

• Crew: two
• Length: 22 ft 5 in (6.83 m)
• Height: 11 ft 0 in (3.35 m)
• Empty weight: 1,799 lb (816 kg)
• Gross weight: 2,703 lb (1,226 kg)
• Powerplant: 1 × Lycoming O-435-2 6-cyl. air-cooled horizontally opposed piston engine, 225 hp (168 kW)
• Main rotor diameter: 2 × 38 ft 0 in (11.58 m)

Performance

• Maximum speed: 73 mph (117 km/h, 63 kn)

See also

Related development

• Kaman HH-43 Huskie

Aircraft of comparable role, configuration, and era

• Flettner Fl 282

References

Notes

1. "Hall of Fame/Inventor Profile: Charles Kaman"
2. Boeing Model 502 Gas Turbine Engine Archived 2011-06-22 at the Wayback Machine
3. "Turkish Kaman 225".
4. "Kaman K-225". National Air and Space Museum. Retrieved 21 November 2024.
5. Federal Aviation Administration (September 26, 1950). "Helicopter Specification No. 1H1" (PDF). faa.gov. Archived (PDF) from the original on April 19, 2021. Retrieved September 2, 2022.
6. Eckland, K.O. (2009-03-07). "American Airplane Ka-Ku". usa: Aerofiles.com. Retrieved 8 May 2012.
7. Kaman K-225 Archived 2016-03-04 at the Wayback Machine, Smithsonian National Air and Space Museum, cit. 28. 1. 2013

Bibliography

• "Hall of Fame/Inventor Profile: Charles Kaman". National Inventors Hall of Fame. Archived from the original on 2009-01-06. Retrieved 2009-01-27.