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The Convair Pogo was one tailsitter design.

A tail-sitter or tailsitter is a type of VTOL aircraft that takes off and lands on its tail, then tilts horizontally for forward flight.


A tail-sitter sits vertically on its tail for takeoff and landing, then tilts the whole aircraft forward for horizontal flight. This is very different from the many other kinds of VTOL technologies, which have horizontally-oriented fuselages.

Tail-sitters change fuselage orientation after take-off. They start of with the back of the aircraft to the ground (...a vertical orientation), and then reorient to a horizontal orientation in flight.

Some tail-sitters then landed conventionally in horizontally-oriented configuration, while others had a much more ambitious goal of landing vertically with the aircraft's back to the ground, a highly hazardous procedure for many reasons, prime of which was increased fuel consumption and limited pilot visibility.


The concept of a tail-sitting aircraft was included in a patent by Nikola Tesla in 1928.[1]

The Focke-Wulf Triebflügel (wing-driven) fighter was a German tail-sitter project during the Second World War. Three wings were mounted radially as a rotor on a rotating section of the fuselage and driven by small jet engines on the wingtips. The aircraft was to be propelled by this wing rotation. For takeoff and landing it would fly vertically as a helicopter, then tilt over horizontally to fly as a self-propelled wing generating both lift and thrust. The contemporary Heinkel Lerche project had an annular wing forming a duct around a conventional propeller, and in the transition from vertical to forward flight the lift would have transferred to the wing. [2]

The SNECMA Coléoptère was a postwar French development of the annular wing concept, but powered by a turbojet. It flew in both vertical and horizontal flight modes but never achieved the transition between the two.[citation needed]

Meanwhile, the USA was experimenting with propeller-driven design configurations with relatively conventional fixed wings. The Convair XFY Pogo had a delta wing with cruciform tail and successfully demonstrated the full transition between flight modes, while the Lockheed XFV Salmon had a straight wing with X tail but never achieved the flight transition.

A later jet-powered design, the Ryan X-13 Vertijet, first flew in 1955. Two prototypes were made, both flew, made successful transitions to and from horizontal flight, and landed. The final test flight was near Washington DC in 1957.[3]

An inherent problem with all these tail-sitter designs was poor pilot visibility, especially of the ground, during vertical descent and landing. This led to the concept being abandoned once a more practical form of VTOL appeared, in the form of thrust vectoring.[citation needed]

An UAV does not suffer the problem of pilot attitude. The Dornier Aerodyne is of ducted-fan configuration similar to a coleopter, and a test UAV flew successfully in hover mode in 1972, before development was discontinued.

Studies and wind tunnel models were made of a tail-sitting version of the F-16 that would be ship based, but any further development was abandoned due to the large thrust requirement, and the need for extensive apparatus to handle take-off and landing.[4]

List of tail-sitters[edit]

Type Country Date Role Status Description
AeroVironment SkyTote USA 2010 UAV Prototype None
Bachem Ba 349 Germany 1944 Interceptor Prototype Launched up a vertical tower, landed using parachutes.
Bell Apt USA 2019 UAV Prototype Planned for delivering[5]
Bolköw P 110.1 West Germany 1950s VTOL Fighter Project None [6]
Sukhoi Shkval USSR 1960 Interceptor Development ceased,partial Mockup equipped with a conventional Landing gear.side-by-side afterburner engines.
CDADI VD200 China 2014 UAV Project None
Convair XFY-1 Pogo USA 1954 Fighter Prototype None
Dornier Aerodyne Germany 1972 UAV Prototype None
Focke-Wulf Triebflügel Germany 1944 Interceptor Project Rotor wing around middle of fuselage. In-flight transition never resolved.
Focke Wulf Fw 860 West Germany 1950s VTOL Fighter Project None [7]
Heinkel Lerche Germany 1944 Fighter Project None
Heinkel He 231 West Germany 1950s VTOL Fighter Project None
Lockheed Martin Cormorant USA 2008 UAV Prototype None
Lockheed XFV-1 USA 1954 Fighter Prototype None
Messerschmitt Me X1-21 West Germany 1950s VTOL Fighter Project None [8]
NASA Puffin USA 2010 Private Project None [9]
Northrop Grumman Tern USA 2018 UCAV Prototype None
NSRDC BQM-108 USA 1976 UAV None None
Rotary Rocket Roton ATV USA 1999 Experimental Prototype Rotorcraft test vehicle for proposed SSO space launcher.
Ryan X-13 Vertijet USA 1955 Experimental Prototype None
SNECMA Coléoptère France 1959 Experimental Prototype Never achieved transition.

See also[edit]


  1. ^ "Nikola Tesla U.S. Patent 1,655,114 - Apparatus for Aerial Transportation". 2015-03-01. Retrieved 2016-08-07., Tesla Universe.
  2. ^ Dan Sharp, Luftwaffe: Secret Weapons of the Third Reich, Mortons, 2015
  3. ^ Darling, Jeff (2011-06-13). "Ryan X-13 Vertijet". Diseno. Archived from the original on 2014-01-28. Retrieved 2014-02-09.
  4. ^ Newsom, William A.; Anglin, Ernie L. (September 1975). "FREE-FLIGHT MODEL INVESTIGATION OF A VERTICAL-ATTITUDE VTOL FIGHTER" (PDF). National Aeronautics and Space Administration. Retrieved October 16, 2016.
  5. ^ "Bell APT". Bell Flight. Retrieved 2019-10-14.
  6. ^ http://www.robertcmason.com/textdocs/GermanVSTOLFighters.pdf
  7. ^ http://www.robertcmason.com/textdocs/GermanVSTOLFighters.pdf
  8. ^ http://www.robertcmason.com/textdocs/GermanVSTOLFighters.pdf
  9. ^ Choi, Charles Q. (2010-01-19). "Electric Icarus: NASA Designs a One-Man Stealth Plane". Scientific American. Retrieved 2010-02-27.