VTOL
[5][6] In addition to helicopter development, many approaches have been tried to develop practical aircraft with vertical take-off and landing capabilities, including Henry Berliner's 1922–1925 experimental horizontal-rotor fixed-wing aircraft, and Nikola Tesla's 1928 patent, and George Lehberger's 1930 patent for relatively impractical VTOL fixed wing airplanes with tilting engines.
In 1941, German designer Heinrich Focke's began work on the Focke-Achgelis Fa 269, which had two rotors that tilted downward for vertical takeoff, but wartime bombing halted development.
[12] A different British VTOL project was the gyrodyne, where a rotor is powered during take-off and landing but which then freewheels during flight, with separate propulsion engines providing forward thrust.
Starting with the Fairey Gyrodyne, this type of aircraft later evolved into the much larger twin-engined Fairey Rotodyne, that used tipjets to power the rotor on take-off and landing but which then used two Napier Eland turboprops driving conventional propellers mounted on substantial wings to provide propulsion, the wings serving to unload the rotor during horizontal flight.
The Rotodyne was developed to combine the efficiency of a fixed-wing aircraft at cruise with the VTOL capability of a helicopter to provide short-haul airliner service from city centres to airports.
Both Convair and Lockheed competed for the contract but in 1950, the requirement was revised, with a call for a research aircraft capable of eventually evolving into a VTOL ship-based convoy escort fighter.
At the end of 1958, the French SNECMA Coléoptère, a tailsitter annular wing design, performed its maiden flight.
Another more influential early functional contribution to VTOL was Rolls-Royce's Thrust Measuring Rig ("flying bedstead") of 1953.
The SC.1 was designed to meet a Ministry of Supply (MoS) request for tender (ER.143T) for a vertical take-off research aircraft issued in September 1953.
The Republic Aviation AP-100 was a prototype VTOL 6x General Electric J85 turbojet-engined nuclear-capable strike fighter concept designed by Alexander Kartveli that had three ducted fans in the centre of its fuselage and tail as a possible contender for the TFX Program.
The Yakovlev Yak-38 was a Soviet Navy VTOL aircraft intended for use aboard their light carriers, cargoships, and capital ships.
Although two models (X1 and X2) were built, the project was canceled due to high costs and political problems as well as changed needs in the German Air Force and NATO.
The EWR VJ 101C did perform free VTOL take-offs and landings, as well as test flights beyond mach 1 in the mid- and late 60s.
[25] It was designed to mimic the flight characteristics of the lunar exploration module (LEM), which had to rely on a reaction engine to land on the Moon.
The idea of using the same engine for vertical and horizontal flight by altering the path of the thrust was conceived by Michel Wibault.
The Harrier is usually flown in STOVL mode, which enables it to carry a higher fuel or weapon load over a given distance.
An important aspect of Harrier STOL operations aboard naval carriers is the "ski jump" raised forward deck, which gives the craft additional vertical momentum at takeoff.
The United States Marine Corps and the Italian and Spanish navies all continue to use the AV-8B Harrier II, an American-British variant.
Replacing the Harrier II/AV-8B in the air arms of the US and UK is the STOVL variant of the Lockheed Martin F-35 Lightning II, the F-35B.
On November 23, 2015, Blue Origin's New Shepard booster rocket made the first successful vertical landing following an uncrewed suborbital test flight that reached space.
[40] The helicopter's form of VTOL allows it to take off and land vertically, to hover, and to fly forwards, backwards, and laterally.
These attributes allow helicopters to be used in congested or isolated areas where fixed-wing aircraft would usually not be able to take off or land.
A tiltwing has its propellers or rotors fixed to a conventional wing and tilts the whole assembly to transition between vertical and horizontal flight.
A tail-sitter sits vertically on its tail for takeoff and landing, then tilts the whole aircraft forward for horizontal flight.
Jetoptera announced a proposed line of aircraft based on what it called fluidic propulsion that employs the Coandă effect.
[41][42] Jetoptera says its approach yields thrust augmentation ratios exceeding 2.0 and 50% fuel savings when compared to a turbofan in static or hovering conditions.
