VTOL

VTOL is an abbreviation for Vertical Take-Off and Landing. VTOL describes fixed-wing aircraft that can lift off vertically. "Vertical lift” is the capability to execute a controlled vertical take-off and vertical landing with a mission payload [Rhett Flater, AHS International Executive Director and Michael Hirschberg, DARPA Aerospace Engineer] . This classification includes only a very few aircraft; helicopters, autogyros; balloons and airships are not normally considered VTOL. Some aircraft can operate in VTOL mode in addition to others, such as CTOL (Conventional Take-off and Landing) and/or STOL (Short Take-Off and Landing). Others can only operate by VTOL, due to the aircraft lacking landing gear that can handle horizontal motion.

Currently there are two types of practical VTOL aircraft in military service: craft using a tiltrotor, such as the Bell Boeing V-22 Osprey, and craft using directed jet thrust such as the Harrier family.

History

In 1928, Nikola Tesla received patents for an apparatus for aerial transportation. Tesla called it the "Flivver". It is one of the earliest examples of VTOL aircraft.

In late World War II, German designers studied the possibility of a VTOL aircraft, the Heinkel Lerche, but the plan never got off the drawing board.

An early contribution to VTOL was Rolls-Royce's Thrust Measuring Rig ("flying bedstead") of 1953 . This led to the first VTOL engines as used in the first British VTOL aircraft, the Short SC.1 (1957) which used 4 vertical lift engines with a horizontal one for forward thrust.

The idea of using the same engine for vertical and horizontal flight by altering the path of the thrust led to the Bristol Siddeley Pegasus engine which used rotating ducts to direct thrust over a range of angles. This was developed side by side with an airframe, the Hawker P.1127, which became subsequently the Kestrel and then entered production as the Hawker Siddeley Harrier though the supersonic Hawker Siddeley P.1154 was cancelled in 1965 .

The Harrier is often flown in STOVL mode which enables it to carry a higher fuel or weapon load over a given distance. The Indian Navy operates Sea Harriers mainly from its aircraft carrier INS Viraat. The United States Marine Corps, and the Italian and Spanish Navies use the AV-8 Harrier II, an advanced derivative of the Harrier. The Harrier II will be replaced in the air arms of the US and UK by a STOVL variant of the F-35 Joint Strike Fighter.

NASA has flown other VTOL craft such as the XV-15 research craft (1977), as have the Soviet Navy and "Luftwaffe". Sikorsky tested an aircraft dubbed the X-Wing, which took off in the manner of a helicopter. The rotors would become stationary in mid-flight, and function as wings, providing lift in addition to the static wings. Boeing X-50 is a Canard Rotor/Wing prototype that utilizes a similar concept.

In the 1960s France developed a version of the Dassault Mirage III capable of attaining Mach 1. The Dassault Mirage IIIV (not to be confused with the Mirage 5) achieved transition from vertical to horizontal flight in March 1966 and reached Mach 1.3 in level flight a short time later.

The Soviet Yak-38 Forger was the Soviet Navy's VTOL aircraft for their light carriers, cargoships, and capital ships. It was developed from the Yak-36 Freehand experimental aircraft. Before the Soviet Union collapsed, a supersonic VTOL aircraft was developed as the Yak-38's successor, the Yak-141, which never went into production. The Yak-141, also called Yak-41 was further developed into the Yak-43.

In the 1960s and early 70s Germany planned three different VTOL planes. One used the F-104 as a base for research for a V/STOL aircraft. 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 Luftwaffe 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. One of the test-aircraft is preserved in the Deutsches Museum in Munich, Germany. The others were the VFW-Fokker VAK 191B light fighter and reconnaissance plane [http://www.deutsches-museum.de/flugwerft/sammlungen/senkrechtstarter/vak-191/] , and the Dornier Do 31E-3 (troop) transport [http://www.deutsches-museum.de/flugwerft/sammlungen/senkrechtstarter/do-31/] , prototypes of the two can be seen at the Deutsches Museum branch at Oberschleißheim Airfield.

Canadair CL-84 Dynavert

The CL-84 was a Canadian V/STOL turbine tilt-wing monoplane designed and manufactured by Canadair between 1964 and 1972. The Canadian government ordered three updated CL-84s for military evaluation in 1968, designated the CL-84-1. From 1972 to 1974, this version was demonstrated and evaluated in the United States aboard the aircraft carriers USS Guam and USS Guadalcanal, and at various other centres. These trials involved military pilots from the United States, the United Kingdom and Canada. Two of the CL-84s crashed due to mechanical failures, but no loss of life occurred as a result of these accidents. Despite the fact that the CL-84 was very successful in the experimental and operational trials carried out between 1972 and 1974, no production contracts resulted.

The Moller Skycar is a prototype personal VTOL aircraft -- literally, a "flying air vehicle" (PAV). It has, as of this date, never made the transition to level flight, nor has it ever flown with anybody on board.

Aircraft designed to operate in extraterrestrial environments often utilize VTOL. An example of this type of aircraft is the LLRV. Spacecraft typically operate in environments where runways or even a suitably flat surface for skids is nonexistent.

V-22

The V-22 Osprey is the world's first production tiltrotor aircraft, with one three-bladed proprotor, turboprop engine, and transmission nacelle mounted on each wingtip. The Osprey is a joint service, multimission, military tiltrotor aircraft with both a vertical takeoff and landing (VTOL) and short takeoff and landing capability (STOL)(Vertical or Short Takeoff and Landing(V/STOL)) . It is designed to perform missions like a conventional helicopter with the long-range, high-speed cruise performance of a turboprop aircraft. The FAA classifies the Osprey as a model of powered lift aircraft.Fact|date=May 2007

See also

* STOL
* List of VTOL aircraft
* Military flying saucers
* Tiltrotor
* Tiltwing
* Tailsitter
*Bristol Siddeley BS100 - a ducted turbofan engine for VTOL use
*Rolls-Royce RB.108 - one of the first dedicated lift engines
*Masten Space Systems - an aerospace company that that is developing a VTVL (Vertical Takeoff Vertical Landing) Spacecraft

References

External links

* [http://www.militaryimages.net/photopost/data/520/Doak_VZ-4.jpgDoak VZ-4 image]

Media