Built under a US Air Force contract, the X-14 used a planar array of diverter vanes to vector the exhaust of two Armstrong Siddeley ASV.8 Viper engines (1,750 lb thrust each) at the center of gravity (c.g.). The vanes could be rotated to direct the exhaust from vertical to nearly horizontal. The 25 ft fuselage and tail were from a Beech T-34; the 34 ft span wing was from a Beech Bonanza. The lack of a ejection seat limited hover testing to very low and very high altitudes. The gross weight was originally only 3,100 lb. The landing gear had to be lengthened when the phenomenon of suck-down was first discovered. Engine gyroscopic effects and exhaust gas reingestion were also encountered.

First hover flight was achieved on 17 February 1957; first transition was made on 24 May 1958. The Viper engines were replaced with higher power GE J85 engines when it was transferred to NASA in 1960. It was eventually fitted with a digital fly-by-wire control system and continued flying as a V/STOL testbed until 1981!

Note: The method of low-speed control and the no. of control devices are unknown.

Source: AHS V/STOL Wheel


Data on design, manufacture and status

Design authority: Bell Aircraft Corporation

Primary manufacturer: Bell Aircraft Corporation

Parent type: No type defined

Aircraft status: No longer flying


Primary flight and mechanical characteristics

VTOL type: Jet lift VTOL

Compound type: N/A

Lift configuration: Vectored thrust (x2)

Dedicated control device: Other (x99)

Crew required: 1-2

Crew seating: Side-by-side

Landing gear: Wheels (non-retractable)

Layout and Dimensions

Data on aircraft size

Overall Dimensions
Overall Height: 2.43 m 8.0 ft
Overall Length: 7.62 m 25.0 ft
Overall Width: 10.36 m 34.0 ft
Airframe Dimensions
Airframe Length: 7.62 m 25.0 ft
Airframe Width: 10.36 m 34.0 ft
Airframe Height: 2.43 m 8.0 ft
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): 1,406 kg 3,100 lb
Max Gross Weight (airborne):  
Max Take-off Weight: 1,406 kg 3,100 lb
Empty Weight:  
Useful Load:  
Empty Weight Fraction:  
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
Designation: Armstrong Siddeley ASV.8 Viper turbine
Manufacturer: Armstrong Siddeley
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 X-14 , 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 X-14 , provided by public sources across the internet.