Lockheed XH-51

Lockheed Corporation · United States · first flew 1962 · helicopter

The Lockheed XH-51 was a research helicopter developed to investigate rigid rotor technology, achieving speeds well above conventional helicopter limits in its compound configuration. It helped establish the data needed for future high-speed rotorcraft designs.

Recognition (WEFT)

WEFT is AircraftIQ's four-point recognition method — how it works.

Spot it by:

• Rigid rotor research helicopter reaching 280 km/h+
• Sleek streamlined fuselage for high-speed tests
• Optional stub wings and auxiliary jet for compound configurations

Distinguish by the unusually slim, streamlined fuselage, rigid three-blade rotor, and (on the Compound) the distinctive stub wings and jet exhaust nozzle.

Specifications

• The Lockheed XH-51 has a length of 12.42 m (41 ft).
• It has a wingspan of 10.67 m (35 ft).
• Its maximum speed is 280 km/h (174 mph).
• Typical crew: 2.

Figures are for the representative variant described above; marks differ. See how AircraftIQ sources figures.

History

Lockheed flew the XH-51 from 1962, using a stiff rotor system that offered better high-speed stability than articulated rotors. In its XH-51A Compound form with a stub wing and auxiliary Pratt & Whitney J60 jet, it set unofficial rotorcraft speed records exceeding 480 km/h. The programme contributed significantly to understanding compressibility effects on rotors.

Variants

The XH-51A Compound added a stub wing and auxiliary jet for speed record attempts; the AH-51 was a proposed armed derivative.

Where you'll see it

Used exclusively as a US Army and Lockheed research aircraft; never entered operational service.

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