Lockheed began private research into ejector augmention systems for VTOL aircraft in 1959. They received a US Army contract in July 1961 to build two of their Hummingbird aircraft as the XV-4A. The Hummingbird had a wingspan of 26 ft, and a length of 32 ft, primarily consisting of a boxy fuselage that housed the ejectors and augmentors. Along each side of the aircraft, a Pratt & Whitney JT12A turbojet engine produced 3,300 lb thrust either for horizontal flight, or diverted into the augmentor ejectors for vertical take-off and landing. The two engines fed interleaved ejectors in case of engine failure. In transition, one engine was diverted from the ejectors to providing forward thrust, until wing-borne lift allowed the second engine to do the same; the augmentors doors were then closed. The augmentors were constructed of stainless steel and titanium, accounting for a significant portion of the 5,000 lb empty weight and the 7,200 lb gross weight. Actual vertical thrust after installation losses was about 7,500 lb for a 1.04 thrust-to-weight. This was only a 14% net augmentation.

First conventional flight was on 7 July 1962. First tethered hover on 30 November of that year was followed by first free hover on 24 May 1963. First transition was not completed until 8 November 1963. The first aircraft crashed on 10 June 1964, killing the pilot.

Source: AHS V/STOL Wheel


Data on design, manufacture and status

Design authority: Lockheed Aircraft Corporation

Primary manufacturer: Lockheed Aircraft Corporation

Parent type: Lockheed XV-4

Aircraft status: No longer flying


Primary flight and mechanical characteristics

VTOL type: Jet lift VTOL

Compound type: N/A

Lift configuration: Lift augmentation (x2)

Dedicated control device: Other

Crew required: 1

Crew seating: Single seater

Landing gear: Wheels (all retractable)

Layout and Dimensions

Data on aircraft size

Overall Dimensions
Overall Height:  
Overall Length:  
Overall Width:  
Airframe Dimensions
Airframe Length:  
Airframe Width:  
Airframe Height:  
Landing Gear Dimensions
Landing Gear Base:  
Landing Gear Track:  
Cabin Dimensions
Cabin Internal Height:  
Cabin Internal Length:  
Cabin Internal Width:  

Weights and Performance

Data on aircraft weight and flight characteristics

Max Gross Weight (ground): 3,266 kg 7,200 lb
Max Gross Weight (airborne):  
Max Take-off Weight: 3,266 kg 7,200 lb
Empty Weight: 2,268 kg 5,000 lb
Useful Load: 998 kg 2,200 lb
Empty Weight Fraction: 0.694
Climb Performance
Max Rate of Climb:  
Hover Performance
Hover Ceiling IGE:  
Hover Ceiling OGE:  
Max Level Flight Speed:  
Never Exceed Speed:  
Service Ceiling:  
Range and Endurance
Max Range:  
Max Endurance:  

Engine Details

Aircraft powerplant (lift and/or propulsion)

Provided powerplant data is for uninstalled, sea level, static operations.

Number of engines: 2
Normal Ratings
Max continuous:  
Take-off / rated:  
OEI Ratings
OEI contingency:  
OEI continuous:  
OEI 30-second:  
OEI intermediate:  

Primary Lift Device

Data on primary lift devices such as main rotors

Main Rotor Characteristics
Direction of Rotation: Unknown
Hub Type:  
Main Rotor Blade Characteristics
Blade Construction:  
Blade Chord:  
Blade Tip Geometry:  
Blade Twist:  
Number of Blades:  
Main Rotor Derived Characteristics
Disc Area:  
Disc Loading:  
Main Rotor Blade Derived Characteristics
Blade area per blade:  
Tip Speed:  

Primary Control Device

Data on primary control devices such as tail rotors

Tail Rotor Characteristics
Configuration: Unknown
Direction of Rotation: Unknown
Tail Rotor Blade Characteristics
Number of Blades:  
Blade Construction: N/A
Blade Chord:  
Blade Twist:  
Tail Rotor Derived Characteristics
Disc Area:  
Tail Rotor Blade Derived Characteristics
Tip Speed:  
Blade Area (per blade):  

Related VFS Resources

Resources related to the XV-4A Hummingbird, provided by the Vertical Flight Society.
Forum Proceedings
Vertiflite articles
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Web files from vtol.org
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Related Public Resources

Resources related to the XV-4A Hummingbird, provided by public sources across the internet.