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 A vertical and/or short take-off and landing (V/STOL) aircraft is an airplane able to take-off or land vertically or on short runways. Vertical takeoff and landing (VTOL) aircraft are a subset of V/STOL craft that do not require runways at al ...

operation. The aircraft takes off using the fans to provide lift, then transitions to fixed-wing lift in forward flight. Several experimental craft have been flown, but only the

F-35 Lightning II The Lockheed Martin F-35 Lightning II is an American family of single-seat, single-engine, all-weather stealth multirole combat aircraft that is intended to perform both air superiority and strike missions. It is also able to provide ele ...

entered into production.

History

A number of experimental aircraft were evaluated in the USA during the late 1950s and throughout much of the 1960s. The

Republic Aviation The Republic Aviation Corporation was an American aircraft manufacturer based in Farmingdale, New York, on Long Island, New York, Long Island. Originally known as the Seversky Aircraft Company, the company was responsible for the design and produc ...

AP-100 was a prototype VTOL 6x

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

Turbojet engined nuclear capable strike fighter concept designed by

Alexander Kartveli Alexander Kartveli, born Aleksandre Kartvelishvili, ( ka, ალექსანდრე ქართველიშვილი) (September 9, 1896 – July 20, 1974) was a Georgian aeronautical engineer and an aviation pioneer in the United ...

that had 3x ducted fans in the centre of its fuselage and tail as a possible contender for the

TFX Program The United States Air Force and Navy were both seeking new aircraft when Robert McNamara was appointed U.S. Secretary of Defense in January 1961. The aircraft sought by the two armed services shared the need to carry heavy armament and fuel loads, ...

. The

Avro Canada Avrocar The Avro Canada VZ-9 Avrocar was a VTOL aircraft developed by Avro Canada as part of a secret U.S. military project carried out in the early years of the Cold War. The Avrocar intended to exploit the Coandă effect to provide lift and thrust ...

, commissioned by the USA, was intended to be a technology demonstrator for a supersonic VTOL aircraft. It featured a single central fan in a circular flying wing, with engine thrust directed rearwards for forward flight. It underwent trials between 1958 and 1961 but, due to its unstable "flying saucer" aerodynamics and lower than expected thrust, never flew out of ground effect. The Verticraft Verticar of 1961 was a similar single-fan, directed-thrust, all-wing (or lifting body) aircraft, of conventional but very low-aspect-ratio wing planform. It failed to fly. A tandem-fan version was proposed but never built.Retro Mechanix
(retrieved 11 March 2014 ) By contrast the

Ryan XV-5 Vertifan The Ryan XV-5 Vertifan was a jet-powered V/STOL experimental aircraft in the 1960s. The United States Army (US Army) commissioned the Ryan VZ-11-RY (re-designated XV-5A in 1962) in 1961, along with the Lockheed VZ-10 Hummingbird (re-designated ...

of 1964 was an otherwise conventional delta-wing jet. It had a large fan in each wing and a third, smaller fan in the nose to provide balance in pitch. It was more successful, with one of the two prototypes flying until 1971. The Vanguard C2 and C2D Omniplane had two fans side by side, with one in each wing. It underwent tethered trials between 1959 and 1962 but never flew untethered. In the late 1960s NASA conducted wind tunnel experiments on a series of larger aircraft designs using different numbers of fans in the wings. Beginning with a one-sixth scale model in 1962, Paul Moller has been experimenting with the flying saucer configuration ever since. All have had a central cockpit but have varied between a single lift fan surrounding the cockpit, twin fans behind the cockpit or, more recently, eight individual fans distributed around it. Some examples such as the XM-2 of 1965 have been able to hover within ground effect. The artificially stabilised M200X was re-engined in 1989 and can fly out of ground effect, but has not entered production. AW Project Zero 2013

Several projects were announced in 2010 and 2011. The Ray passenger aircraft had four fans arranged approximately in a square, similarly to a

quadrotor A quadcopter or quadrotor is a type of helicopter with four rotors. Although quadrotor helicopters and convertiplanes have long been flown experimentally, the configuration remained a curiosity until the arrival of the modern UAV or drone. T ...

, with a small fan in front of a larger one behind it in each wing.Ray Research
/ref>On Fans and Wings - Switzerland's VTOL Ray
Aviation Week, 2010AeroRevue, "Ray" - new life for Vertical Takeoff Aircraft (English translation from German

/ref> The Lockheed Martin VARIOUS was a multi-role military UAV with twin fans side by side, one in each wing.Lockheed Martin: VARIOUS
/ref>Lockheed VARIOUS UCAV concept
/ref> The Northrop MUVR ship-to-shore resupply aircraft similarly had a fan in each wing.Wraps Off Northrop's Fan-in-Wing MUVR
Aviation Week, 2011 Unlike these the Anglo-Italian

AgustaWestland Project Zero The AgustaWestland Project Zero is a hybrid tiltrotor/ Lift fan aircraft. It has been developed by AgustaWestland as a technology demonstrator, and is used to investigate all-electric propulsion and other advanced technologies. It is the world' ...

hybrid tiltrotor/lift-fan unmanned technology demonstrator was actually built and flew successfully in 2011. It has side by side twin fans which can rotate into a vertical plane to act as propellers in forward flight, while still located within the wing structure. The

uses the

Rolls-Royce LiftSystem The Rolls-Royce LiftSystem, together with the F135 engine, is an aircraft propulsion system designed for use in the STOVL variant of the F-35 Lightning II. The complete system, known as the Integrated Lift Fan Propulsion System (ILFPS), was aw ...

, in which 29,000 hpLockheed Propulsion System
''VTOL.org''. Retrieved: 19 September 2010. is diverted forward through a driveshaft from the engine's low-pressure (LP) turbine via a clutch and bevel-gearbox to a vertically mounted,

contra-rotating Contra-rotating, also referred to as coaxial contra-rotating, is a technique whereby parts of a mechanism rotate in opposite directions about a common axis, usually to minimise the effect of torque. Examples include some aircraft propellers, res ...

lift fan located forward of the main engine. Israeli enterprise Urban Aeronautics is developing a wingless drone that uses a pair of lift fans to ensure lift by ground effect and another pair of fans for forward flight.

Table of lift fan aircraft

References

{{reflist. VTOL aircraft Aircraft configurations

History

Table of lift fan aircraft

See also

References