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XV-4 Hummingbird
First prototype XV-4 Hummingbird
Type	VTOL
Manufacturer	Lockheed
Maiden flight	7 July 1962
Status	Retired
Primary user	United States Army
Number built	2

The Lockheed XV-4 Hummingbird (originally designated VZ-10) was a U.S. Army project in the 1960s, one of many, to produce a V/STOL vertical take off / landing jet. At a design speed of 336 mph, the Hummingbird was slower than some propeller-powered transports.

The design used doors at the top and bottom of the fuselage intended to augment thrust ejected into this area with cold air. In theory, a 11,607 lb aircraft could be lifted by a 6,600 lbf engine. Unfortunately, performance was far below the estimates only 1.04 thrust-to-weight in practice and the prototype crashed on 10 June 1964, killing the pilot. The second aircraft was converted to lift jets instead, also crashing after several tests.

Rockwell's XFV-12 would be even less successful at venting cold air to augment thrust through the wings. The Lockheed F-35 Joint Strike Fighter would later employ a shaft-driven lift fan, also located in the fuselage and drawing on the lessons of the Hummingbird.

None of the early American V/STOL designs would result in a production plane. The British Hawker Siddeley Harrier used vectoring nozzles, while the Russian Yakovlev Yak-38 Forger attack jet used lift jets in conjunction with rotating rear nozzles.

General characteristics

• Length: 32 ft (10.3 m)
• Wingspan: 26 ft (7.9 m)
• Height: 11 ft 8 in (3.58 m)
• Loaded weight: 11,607 lb ()
• Powerplant: 2× Pratt & Whitney JT12A turbojets, 3,300 lbf () each

Performance

• Maximum speed: 336 mph (541km/h)

• X-Planes and Prototypes by Jim Winchester
• Lockheed VZ-10 Hummingbird/XV-4
• VSTOL.org Wheel

 

Comparable aircraft

• XV-5 Vertifan
• XFV-12
• Hawker P.1127

Designation sequence

OV-1 - CV-2 - XV-3 - XV-4 - XV-5 - XV-6 - CV-7

Related lists

• List of military aircraft of the United States
• List of Lockheed aircraft
• List of VTOL aircraft