The Lockheed XV-4 Hummingbird (originally designated VZ-10) was a

U.S. Army The United States Army (USA) is the primary land service branch of the United States Department of Defense. It is designated as the Army of the United States in the United States Constitution.Article II, section 2, clause 1 of the United Stat ...

project to demonstrate the feasibility of using VTOL for a surveillance aircraft carrying target-acquisition and sensory equipment.Hummingbird A Promising Augmented-Jet VTOL Aircraft
''

Flight International ''Flight International'', formerly ''Flight'', is a monthly magazine focused on aerospace. Published in the United Kingdom and founded in 1909 as "A Journal devoted to the Interests, Practice, and Progress of Aerial Locomotion and Transport", i ...

'', 3 April 1962 It was designed and built by the

Lockheed Corporation The Lockheed Corporation was an American aerospace manufacturer. Lockheed was founded in 1926 and merged in 1995 with Martin Marietta to form Lockheed Martin. Its founder, Allan Lockheed, had earlier founded the similarly named but otherwise-u ...

in the 1960s, one of many attempts to produce a

V/STOL A vertical and/or short take-off and landing (V/STOL) aircraft is an airplane able to takeoff and landing, take-off or land vertically or on short runways. VTOL, Vertical takeoff and landing (VTOL) aircraft are a subset of V/STOL craft that do ...

vertical take off/landing jet. Both prototype aircraft were destroyed in accidents.

Design and development

Vertical take-off lift was obtained by exhausting the engine flow downward through multiple nozzles, augmented by a secondary flow of cold air. But the performance was far below estimates with only a 1.04 thrust-to-weight ratio, and the prototype crashed on 10 June 1966, killing the pilot. The second aircraft was converted to

lift jet A lift jet is a lightweight jet engine installed only for upward thrust.{{cite book , url=https://archive.org/details/cambridgeaerospa0000guns/page/346/mode/2up , isbn=978-0-521-84140-5 , title=The Cambridge aerospace dictionary , date=2004 , ...

s instead, yet also crashed after several tests. Rockwell's

XFV-12 The Rockwell XFV-12 was a prototype supersonic United States Navy fighter which was built in 1977. The XFV-12 design attempted to combine the Mach 2 speed and AIM-7 Sparrow armament of the McDonnell Douglas F-4 Phantom II in a VTOL (vertical t ...

would be even less successful at producing lift by using engine exhaust to entrain cold air, in this case through flaps on the wings. None of the early American V/STOL designs would result in a production aircraft. The British

Hawker Siddeley Harrier The Hawker Siddeley Harrier is a British jet-powered attack aircraft designed and produced by the British aerospace company Hawker Siddeley. It was the first operational ground attack and reconnaissance aircraft with vertical/short takeo ...

used vectoring nozzles, while the Russian

Yakovlev Yak-38 The Yakovlev Yak-38 (; NATO reporting name: "Forger") was Soviet Naval Aviation's only operational VTOL strike fighter aircraft in addition to being its first operational carrier-based fixed-wing aircraft. It was developed specifically for, and ...

Forger attack jet used lift jets in conjunction with rotating rear nozzles. The Lockheed F-35 Lightning II would later employ a shaft-driven

lift fan Lift fan is an aircraft configuration in which lifting fans are located in large holes in an otherwise conventional fixed wing or fuselage. It is used for V/STOL operation. The aircraft takes off using the fans to provide lift, then transitions ...

located in the fuselage.

Testing

The first conventional takeoff flight of the first prototype, XV-4A ''(62–4503),'' took place on 7 July 1962. Initial tethered flight tests were carried out on 30 November 1962 with the first free hovering flight occurring on 24 May 1963. The first flight to transition from hovering to forward flight took place on 8 November 1963. ''62–4503'' was destroyed in a fatal crash in

Cobb County Cobb County is a county in the U.S. state of Georgia, and is a core county of the Atlanta metropolitan area in the north-central portion of the state. As of the 2020 Census, the population was 766,149. It is the state's third most populous cou ...

on 10 June 1966. 1-32ScaleModelofXV-4

Lockheed modified the second prototype aircraft between 1966 and 1968 to XV-4B standard. The two

Pratt & Whitney JT12 The Pratt & Whitney JT12 (US military designation J60) is a small turbojet engine. The Pratt & Whitney T73 (Pratt & Whitney JFTD12) is a related turboshaft engine. Design and development The J60 conception and project design began in July 1957 ...

engines were replaced with six

General Electric J85 The General Electric J85 is a small single-shaft turbojet engine. Military versions produce up to of thrust dry; Afterburner, afterburning variants can reach up to . The engine, depending upon additional equipment and specific model, weighs fro ...

turbojet The turbojet is an airbreathing jet engine which is typically used in aircraft. It consists of a gas turbine with a propelling nozzle. The gas turbine has an air inlet which includes inlet guide vanes, a compressor, a combustion chamber, and ...

s, four of these units acting as

s. This aircraft crashed in

Georgia Georgia most commonly refers to: * Georgia (country), a country in the South Caucasus * Georgia (U.S. state), a state in the southeastern United States Georgia may also refer to: People and fictional characters * Georgia (name), a list of pe ...

on 14 March 1969; pilot Harlan J. Quamme escaped uninjured, using the

ejection seat In aircraft, an ejection seat or ejector seat is a system designed to rescue the aircraft pilot, pilot or other aircrew, crew of an aircraft (usually military) in an emergency. In most designs, the seat is propelled out of the aircraft by an exp ...

Variants

* XV-4A: * XV-4B:

Specifications (XV-4A)

Notes

References

* ''X-Planes and Prototypes'' by Jim Winchester

External links

VSTOL.org Wheel
{{DEFAULTSORT:Lockheed Xv-4 Hummingbird V-004 1960s United States experimental aircraft Twinjets Aircraft with auxiliary jet engines Lift jet Cancelled military aircraft projects of the United States Mid-wing aircraft Aircraft first flown in 1962 T-tail aircraft Six-engined jet aircraft