VTOL History

HISTORY OF VTOL [VETICAL TAKEOFF AND LANDING

VTOL is an acronym for vertical take-off and landing aircraft. This classification includes fixed-wing aircraft that can hover, take off and land vertically as well as helicopters and other aircraft with powered rotors, such as tiltrotors.[1][2][3][4] The terminology for spacecraft and rockets isVTVL (vertical takeoff with vertical landing).[5]

Click on the image to know more about balloons, airships, etc.

Autogyros, balloons, and airships are not normally considered VTOL Some VTOL aircraft can operate in other modes as well, such as CTOL (conventional take-off and landing), STOL (short take-off and landing), and/or STOVL(short take-off and vertical landing). Others, such as some helicopters, can only operate by VTOL, due to the aircraft lacking landing gear that can handle horizontal motion. VTOL is a subset of V/STOL (vertical and/or short take-off and landing).

Besides the ubiquitous helicopter, there are currently two types of VTOL aircraft in military service: craft using a tiltrotor, such as the BellBoeing V-22 Osprey, and aircraft using directed jet thrust such as the Harrier family.

BellBoeing V-22 Osprey Harrier Jump Jet

In addition to the helicopter, many approaches have been tried to develop practical aircraft with vertical take-off and landing capabilities.Nokila Tesla patented[6] a vertical take-off and landing vehicle concept in 1928. An early functional 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 Short SC.1 was the first British fixed-wing vertical take-off and landing (VTOL) aircraft

Another 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 turbopropsdriving 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.

The use of vertical fans driven by engines was investigated in the 1950s. The US built an aircraft where the jet exhaust drove the fans, while British projects not built included fans driven by mechanical drives from the jet engines.

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.1154was anceled in 1965. The French in competition with the P.1154 had developed a version of the Dassault Mirage III capable of attaining Mach1. The Dassault Mirage IIIV achieved transition from vertical to horizontal flight in March 1966, reaching Mach 1.3 in level flight a short time later.

The Harrier is often flown in STOVL mode which enables it to carry a higher fuel or weapon load over a given distance. Now retired from BritishRoyal Navy service, the Indian Navy operates Sea Harriers mainly from its aircraft carrier INS Viraat. The latest version of the Harrier, the BAE Harrier II is operated by the British Royal Air Force and Royal Navy. The United States Marine Corps, and the Italian and Spanish Navies use the AV-8B Harrier II, an equivalent derivative of the Harrier II. The Harrier II/AV-8 will be replaced in the air arms of the US and UK by a STOVL variant of the F-35 Lightning II.

NASA has flown other VTOL craft such as the Bell 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.

The Yakovlev Yak-38 was the Soviet Navy's VTOL aircraft for their light carriers, cargoships, and capital ships. It was developed from theYakovlev Yak-36 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.A German V/STOL VJ101 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 theLuftwaffe 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, and the dornier d31 (troop) transport.

REFERANCE:

1. "Vertical Takeoff & Landing Aircraft," John P. Campbell, The MacMillan Company, New York, 1962.

2. "VTOL – Military Research Aircraft," Mike Rogers, Orion Books, New York, 1989.

3. "Vertical Take-Off and Landing (VTOL) Aircraft," edited by I.B.Laskowitz, Annals of the New York Academy of Sciences, Vol 107,Art.1, March 25, 1963.

4. "Straight Up - A History of Vertical Flight," Steve Markman and Bill Holder, Schiffer Publishing, 2000.

5. "Masten Space Systems Achieves First-Ever VTVL Midair Engine Relight Milestone on Path to Space". SpaceRef.com. May 29, 2010.

6. U.S. Patent 1,655,113