VTOL

VTOL is an abbreviation for Vertical Take-Off and Landing. VTOL describes fixed-wing aircraft that can lift off vertically. 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:

• Using a tiltrotor — the Bell Boeing V-22 Osprey
• Using directed jet thrust — 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 of 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.

A German V/STOL VJ101 "Starfighter" on display at the Deutsches Museum, Munich, Germany.

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[1], and the Dornier Do 31E-3 (troop) transport[2], prototypes of the two can be seen at the Deutsches Museum branch at Oberschleißheim Airfield.

Canadair CL-84 Dynavert

File:CanadairCL-84DynavertSerialCX8402.jpg

CL-84-1 (CX8402) on display at the Canada Aviation Museum in Ottawa, Ontario

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

File:Aircraft.osprey.678pix.jpg

U.S. Marines jump from a V-22 Osprey, the first production tiltrotor aircraft.

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). 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.

F-35B

The most spectacular demonstration of the JSF qualifying flight trials was the X-35B's STOVL demonstration where it took off in less than 500 feet, went supersonic, and landed vertically -- a feat that Boeing's entry was unable to achieve.

The JSF program was created to replace various aircraft while keeping development, production, and operating costs down. This was pursued by building three variants of one aircraft, sharing 80% of their parts:

• F-35A, a conventional takeoff and landing (CTOL) variant.
• F-35B, a short-takeoff and vertical-landing (STOVL) variant.
• F-35C, a carrier-based variant.

File:F-l3 lift fan.jpg

X-35B lift fan; the VTOL propulsion system is designed and manufactured by Rolls-Royce plc

The F-35B is the short-takeoff and vertical-landing (STOVL) variant aircraft. The F-35B is similar in size to the Air Force F-35A, trading fuel volume for vertical flight systems. Like the AV-8 Harrier II, guns will be carried in a ventral pod. Vertical flight is by far the riskiest, and in the end, a decisive factor in design.

Instead of lift engines, or rotating nozzles on the engine fan and exhaust like the Pegasus-powered Harrier, the F-35B uses an innovative shaft-driven Lift Fan, patented by Lockheed Martin and developed by Rolls-Royce. Somewhat like a turboprop embedded into the fuselage, engine shaft power is diverted forward via a clutch-and-bevel gearbox to a vertically mounted, contra-rotating lift fan located forward of the main engine in the center of the aircraft. Bypass air from the cruise engine turbofan exhausts through a pair of roll-post nozzles in the wings on either side of the fuselage, while the lift fan balances the vectoring cruise nozzle at the tail. This system is more similar to the Russian Yak-141 than previous STOVL designs, such as the Harrier with thrust vectoring.

Demonstrator X-35 aircraft flew in 2000; a production model first took flight on 15 December 2006.

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

External links

• Doak VZ-4 image

Media

• F-35 compilation.ogg

  F-35 flight, transition to VTOL configuration, vertical take off, inflight re-fueling, vertical hover and landing

• F-35 verticle landing.ogg

  F-35 vertical landing

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "VTOL".