The Harrier and the Yak-38 were the first operational examples of VTOL fixed-wing aircraft
A vertical take-off and landing (VTOL) aircraft is one that can hover, take off, and land vertically. This classification can include a variety of types of aircraft including fixed-wing aircraft as well as helicopters and other aircraft with powered rotors, such as cyclogyros/cyclocopters and tiltrotors. 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). Some lighter-than-air aircraft also qualify as VTOL aircraft, as they can hover, takeoff, and land with vertical approach/departure profiles.
Besides the ubiquitous helicopter, there are currently two types of VTOL aircraft in military service: craft using a tiltrotor, such as the Bell Boeing V-22 Osprey, and another using directed jet thrust, such as the Harrier family and new F-35B Lightning II Joint strike Fighter (JSF). In the civilian sector currently only helicopters are in general use (some other types of commercial VTOL aircraft have been proposed and are under development as of 2017). Generally speaking, VTOL aircraft capable of STOVL use it wherever possible, since it typically significantly increases takeoff weight, range or payload compared to pure VTOL.
The idea of vertical flight has been around for thousands of years and sketches for a VTOL (helicopter) shows up in Leonardo da Vinci's sketch book. Manned VTOL aircraft, in the form of primitive helicopters, first flew in 1907 but would take until after World War Two to perfect.
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 a tilting engines. In the late 1930s British aircraft designer Leslie Everett Baynes was issued a patent for the Baynes Heliplane, another tilt rotor aircraft. 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.
In May 1951, both Lockheed and Convair were awarded contracts in the attempt to design, construct, and test two experimental VTOL fighters. Lockheed produced the XFV, and Convair producing the Convair XFY Pogo. Both experimental programs proceeded to flight status and completed test flights 1954–1955, when the contracts were cancelled. Similarly, the X-13 flew a series of test flights between 1955 and 1957, but also suffered the same fate.
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.
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.
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.
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. During testing, two of the CL-84s crashed due to mechanical failures, but no loss of life occurred as a result of these accidents. No production contracts resulted.
Although tiltrotors such as the Focke-Achgelis Fa 269 of the mid-1940s and the Centro Técnico Aeroespacial "Convertiplano" of the 1950s reached testing or mock-up stages, the V-22 Osprey is considered the world's first production tiltrotor aircraft. It has one three-bladed proprotor, turboprop engine, and transmission nacelle mounted on each wingtip. The Osprey is a multi-mission 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.
Attempts were made in the 1960s to develop a commercial passenger aircraft with VTOL capability. The Hawker Siddeley Inter-City Vertical-Lift proposal had two rows of lifting fans on either side. However, none of these aircraft made it to production after they were dismissed as too heavy and expensive to operate.
In 2018 Opener Aero demonstrated an electrically-powered fixed-wing VTOL aircraft, the Blackfly, which the manufacturer claims is the world's first ultralight fixed-wing, all-electric, vertical take-off and landing aircraft.
In 1947, Ryan X-13 Vertijet, a tailsitter design, was ordered by the US Navy, who then further issued a proposal in 1948 for an aircraft capable of vertical takeoff and landing (VTOL) aboard platforms mounted on the afterdecks of conventional ships. 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.
Another more influential 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), Short Brothers and Harland, Belfast which used four vertical lift engines with a horizontal one for forward thrust.
The Short SC.1 was the first British fixed-wing VTOL aircraft. The SC.1 was designed to study the problems with VTOL flight and the transition to and from forward flight. 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 design was accepted by the ministry and a contract was placed for two aircraft (XG900 and XG905) to meet Specification ER.143D dated 15 October 1954. The SC.1 was also equipped with the first "fly-by-wire" control system for a VTOL aircraft. This permitted three modes of control of the aerodynamic surfaces and/or the nozzle controls.
The Yakovlev Yak-38 was a Soviet Navy VTOL aircraft intended for use aboard their light carriers, cargoships, and capital ships. It was developed from the Yakovlev Yak-36 experimental aircraft in the 1970s. Before the Soviet Union broke up, a supersonic VTOL aircraft was developed as the Yak-38's successor, the Yak-141, which never went into production.
In the 1960s and early 1970s, Germany planned three different VTOL aircraft. One used the Lockheed F-104 Starfighter as a basis 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 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. 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 aircraft, and the Dornier Do 31E-3 (troop) transport.
The LLRV was a spacecraft simulator for the Apollo lunar lander. It was designed to mimic the flight characteristics of the lunar 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 led to the Bristol Siddeley Pegasus engine which used four rotating nozzles 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 canceled in 1965. The French in competition with the P.1154 had developed a version of the Dassault Mirage III capable of attaining Mach 1. 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 usually flown in STOVL mode, which enables it to carry a higher fuel or weapon load over a given distance. In V/STOL the VTOL aircraft moves horizontally along the runway before taking off using vertical thrust. This gives aerodynamic lift as well as thrust lift and permits taking off with heavier loads and is more efficient. When landing the aircraft is much lighter due to the loss of propellant weight and a controlled vertical landing is possible.
Now retired from British Royal 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 has also been retired in December 2010, after being 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 Lockheed Martin F-35 Lightning II. An important aspect of Harrier STOL operations aboard Naval carriers was the "ski jump" raised forward deck, which gave the craft additional vertical momentum at takeoff.
In the 21st century, unmanned drones are becoming increasingly commonplace. Many of these have VTOL capability, especially the quadcopter type.
Grasshopper was a VTVL first-stage booster test vehicle SpaceX developed to validate various low-altitude, low-velocity engineering aspects of its large-vehicle reusable rocket technology. The test vehicle made eight successful test flights in 2012–2013. Grasshopper v1.0 made its eighth, and final, test flight on October 7, 2013, flying to an altitude of 744 metres (2,441 ft) (0.46 miles) before making its eighth successful VTVL landing.
On November 23, 2015, Blue Origin's New Shepard booster rocket made the first successful vertical landing following an unmanned suborbital test flight that reached space. On December 21, 2015, SpaceX's 20th Falcon 9 first stage made a successful landing after boosting 11 commercial satellites to low earth orbit on Falcon 9 Flight 20. These demonstrations potentially open the way for substantial reductions in space flight costs.
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. The capability to efficiently hover for extended periods of time is due to the helicopter's relatively long, and hence efficient rotor blades, and allows a helicopter to accomplish tasks that fixed-wing aircraft and other forms of vertical takeoff and landing aircraft could not perform at least as well until 2011.
On the other hand, the long rotor blades restrict the maximum speed to about 250 miles per hour (400 km/h) of at least conventional helicopters, as retreating blade stall causes lateral instability.
Autogyros are also known as gyroplanes or gyrocopters. The rotor is unpowered and rotates freely in the airflow as the craft travels forward, so the craft needs a conventional powerplant to provide thrust. An autogyro is not intrinsically capable of VTOL: for VTO the rotor must be spun up to speed by an auxiliary drive, and vertical landing requires precise control of rotor momentum and pitch.
Gyrodynes are also known as compound helicopters or compound gyroplanes. A gyrodyne has the powered rotor of a helicopter with a separate forward thrust system of an autogyro. Apart from take-off and landing the rotor may be unpowered and autorotate. Designs may also include stub wings for added lift.
A cyclogyro or cyclocopter has a rotary wing whose axis and surfaces remain sideways across the airflow, as with a conventional wing.
A convertiplane takes off under rotor lift like a helicopter, then transitions to fixed-wing lift in forward flight.
A tiltrotor or proprotor tilts its propellers or rotors vertically for VTOL and then tilts them forwards for horizontal wing-borne flight, while the main wing remains fixed in place.
Similar to tiltrotor concept, but with ducted fans. As it can be seen in the Bell X-22.
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.
Thrust vectoring is a technique used for jet and rocket engines, where the direction of the engine exhaust is varied. In VTOL, the exhaust can be varied between vertical and horizontal thrust.
Similar to tiltrotor concept, but with turbojet or turbofan engines instead of ones with propellers.
A lift jet is an auxiliary jet engine used to provide lift for VTOL operation, but may be shut down for normal wing-borne flight.
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 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 entered into production.
Aircraft in which VTOL is achieved by exploiting the Coandă effect are capable of redirecting air much like thrust vectoring, but rather than routing airflow through a duct, the airflow is simply routed along an existing surface, which is usually the body of the craft allowing less material and weight. The Avro Canada VZ-9 Avrocar, or simply the VZ-9, was a Canadian VTOL aircraft developed by Avro Aircraft Ltd. which utilizes this phenomenon by blowing air into a central area, then it is directed down over the top surface, which is parabolic and resembles a bowed flying saucer. Due to the Coandă effect, the airflow is attracted to the nearest surface and continues to move along that surface despite the change in the surface's direction away from the airflow. The craft is designed to direct the airflow downward to provide lift.
SpaceX has constructed a half-acre concrete launch facility in McGregor, and the Grasshopper rocket is already standing on the pad, outfitted with four insect-like silver landing legs.
WATCH: Grasshopper flies to its highest height to date – 744 m (2441 ft) into the Texas sky. http://youtu.be/9ZDkItO-0a4 This was the last scheduled test for the Grasshopper rig; next up will be low altitude tests of the Falcon 9 Reusable (F9R) development vehicle in Texas followed by high altitude testing in New Mexico.
The Airbus CityAirbus is a multinational project by Airbus Helicopters to produce an electrically-powered VTOL aircraft demonstrator. It is intended for the air taxi role, to avoid ground traffic congestion.Armstrong Whitworth AW.681
The Armstrong Whitworth AW.681, also known as the Whitworth Gloster 681 or Hawker Siddeley HS.681, was a projected British long-range STOL military transport aircraft design of the early-1960s by Armstrong Whitworth Aircraft and was to be capable of development to VTOL performance. The AW.681 was designed to meet the NATO specification NBMR-4.Bell D-188A
The Bell D-188A (unofficial military designations XF-109/XF3L) was a proposed eight-engine Mach 2–capable vertical take-off and landing (VTOL) tiltjet fighter that never proceeded past the mock-up stage.Bell X-14
The Bell X-14 (Bell Type 68) is an experimental VTOL aircraft flown in the United States in the 1950s. The main objective of the project was to demonstrate vectored thrust horizontal and vertical takeoff, hover, transition to forward flight, and vertical landing.Convair XFY Pogo
The Convair XFY Pogo was an experiment in vertical takeoff and landing (VTOL) tail-sitter. The Pogo had delta wings and three-bladed contra-rotating propellers powered by a turboprop engine. It was intended to be a high-performance fighter aircraft capable of operating from small warships. Landing the XFY-1 was difficult, as the pilot had to look over his shoulder while carefully working the throttle to land.Fairchild VZ-5
The Fairchild VZ-5 (or Model M-224-1) was a 1950s American experimental VTOL research aircraft built by Fairchild Aircraft for the United States Army.Focke-Achgelis Fa 269
The Focke-Achgelis Fa 269 was a tiltrotor VTOL aircraft project designed by Henrich Focke.Harrier Jump Jet
The Harrier, informally referred to as the Harrier Jump Jet, is a family of jet-powered attack aircraft capable of vertical/short takeoff and landing operations (V/STOL). Named after a bird of prey, it was originally developed by British manufacturer Hawker Siddeley in the 1960s. The Harrier emerged as the only truly successful V/STOL design of the many attempted during that era, despite being a subsonic aircraft, unlike most of its competitors. It was conceived to operate from improvised bases, such as car parks or forest clearings, without requiring large and vulnerable air bases. Later, the design was adapted for use from aircraft carriers.
There are two generations and four main variants of the Harrier family, developed by both UK and US manufacturers:
The Hawker Siddeley Harrier is the first generation-version and is also known as the AV-8A Harrier; it was used by multiple air forces, including the Royal Air Force (RAF) and the United States Marine Corps (USMC). The Sea Harrier is a naval strike/air defence fighter derived from the Hawker Siddeley Harrier; it was operated by both the Royal Navy and the Indian Navy. During the 1980s, a second generation Harrier emerged; manufactured in the United States as the AV-8B and in Britain as the British Aerospace Harrier II respectively. By the start of the 21st century, the majority of the first generation Harriers had been withdrawn, many operators having chosen to procure the second generation as a replacement. In the long term, several operators have announced their intention to supplement or replace their Harrier fleets with the STOVL variant of the F-35 Lightning II, designated as the F-35B.Helicopter carrier
A helicopter carrier is a type of aircraft carrier whose primary purpose is to operate helicopters. A helicopter carrier has a large flight deck that occupies a large part of the ship, which can extend the full length of the ship like HMS Ocean of the Royal Navy (RN), or only partway, usually aft, as in the Soviet Navy's Moskva class, the Chinese Navy's Type 0891A or the RN's RFA Argus. It often also has a hangar deck for the storage of aircraft.
Pure helicopter carriers are difficult to define in the 21st century. The advent of STOVL aircraft such as the Harrier Jump Jet, and now the F-35, have complicated the classification; the United States Navy's Wasp class, for instance, carries six to eight Harriers as well as over 20 helicopters. Only smaller carriers unable to operate the Harrier and older pre-Harrier-era carriers can be regarded as true helicopter carriers. In many cases, other carriers, able to operate STOVL aircraft, are classified as "light aircraft carriers". Other vessels, such as the Wasp class, are also capable of embarking troops such as marines and landing them ashore; they are classified as amphibious assault ships.
Helicopter carriers have been used as anti-submarine warfare carriers and amphibious assault ships.
HMS Hermes and two of her sisters were 22,000 ton fleet carriers converted to "commando carriers" only able to operate helicopters. Hermes was later converted to a STOVL carrier.List of VTOL aircraft
This is a list of fixed-wing aircraft capable of vertical take-off and landing arranged under manufacturer. The list excludes helicopters, including compound helicopters and gyrocopters, because they are assumed to have this capability.
For more detail on subtypes of VTOL, see List of tiltrotor aircraft.List of experimental aircraft
This is a list of experimental aircraft, or aircraft used or built to conduct experiments involving aerodynamics, structural materials, propulsion systems, configuration and equipment. Prototypes, pre-production and homebuilt aircraft described as experimental but which were not used in this manner outside their own development are excluded.Lockheed XFV
The Lockheed XFV (sometimes referred to as the "Salmon") was an American experimental tailsitter prototype aircraft built by Lockheed in the early 1950s to demonstrate the operation of a vertical takeoff and landing (VTOL) fighter for protecting convoys.Rattler (G.I. Joe)
The Cobra Rattler is a fictional VTOL attack aircraft from the universe of G.I. Joe.STOVL
A short take-off and vertical landing aircraft (STOVL aircraft) is a fixed-wing aircraft that is able to take off from a short runway (or take off vertically if it does not have a heavy payload) and land vertically (i.e. with no runway). The formal NATO definition (since 1991) is:
A Short Take-Off and Vertical Landing aircraft is a fixed-wing aircraft capable of clearing a 15 m (50 ft) obstacle within 450 m (1,500 ft) of commencing take-off run, and capable of landing vertically.
On aircraft carriers, non-catapult-assisted, fixed-wing short takeoffs are accomplished with the use of thrust vectoring, which may also be used in conjunction with a runway "ski-jump". Use of STOVL tends to allow aircraft to carry a larger payload as compared to during VTOL use, while still only requiring a short runway. The most famous examples are the Hawker Siddeley Harrier and the Sea Harrier. Although technically VTOL aircraft, they are operationally STOVL aircraft due to the extra weight carried at take-off for fuel and armaments. The same is true of the F-35B Lightning II, which demonstrated VTOL capability in test flights but is operationally STOVL.Short SC.1
The Short SC.1 was the first British fixed-wing vertical take-off and landing (VTOL) jet aircraft. It was developed by Short Brothers. It was powered by an arrangement of five Rolls-Royce RB108 turbojets, four of which were used for vertical flight and one for conventional horizontal flight. The SC.1 had the distinction of being the first British fixed-wing VTOL aircraft and the first one to transition between vertical and horizontal flight modes; it was also the first VTOL-capable aircraft with a fly-by-wire control system.
The SC.1 was designed and produced in response to a Ministry of Supply (MoS) requirement for a suitable aircraft for conducting flight studies into VTOL flight, as well as specifically into the transition between vertical and horizontal flight. Two prototypes were used for flight testing between 1957 and 1971. Research data from the SC.1 test programme contributed to the development of the Hawker Siddeley P.1127 and the subsequent Hawker Siddeley Harrier, the first operational VTOL aircraft.
In October 2012, the Short SC.1 received Northern Ireland's first Engineering Heritage Award as a recognition of its significant achievement in the engineering field.Takeoff
Takeoff is the phase of flight in which an aerospace vehicle goes from the ground to flying in the air.
For aircraft that take off horizontally, this usually involves starting with a transition from moving along the ground on a runway. For balloons, helicopters and some specialized fixed-wing aircraft (VTOL aircraft such as the Harrier), no runway is needed. Takeoff is the opposite of landing.Takeoff and landing
Aircraft can have different ways to take off and land. Conventional airplanes accelerate along the ground until sufficient lift is generated for takeoff, and reverse the process to land. Some airplanes can take off at low speed, this being a short takeoff. Some aircraft such as helicopters and Harrier Jump Jets can take off and land vertically. Rockets also usually take off vertically, but some designs can land horizontally.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 all. Generally, a V/STOL aircraft needs to be able to hover. Helicopters are not considered under the V/STOL classification as the classification is only used for airplanes, aircraft that achieve lift (force) in forward flight by planing the air, thereby achieving speed and fuel efficiency that is typically greater than the capability of helicopters.
Most V/STOL aircraft types were experiments or outright failures from the 1950s to 1970s. V/STOL aircraft types that have been produced in large numbers include the Harrier, Yak-38 Forger and V-22 Osprey.
A rolling takeoff, sometimes with a ramp (ski-jump), reduces the amount of thrust required to lift an aircraft from the ground (compared with vertical takeoff), and hence increases the payload and range that can be achieved for a given thrust. For instance, the Harrier is incapable of taking off vertically with full weapons and fuel load. Hence V/STOL aircraft generally use a runway if it is available. I.e. short takeoff and vertical landing (STOVL) or conventional takeoff and landing (CTOL) operation is preferred to VTOL operation.
V/STOL was developed to allow fast jets to be operated from clearings in forests, from very short runways, and from small aircraft carriers that would previously only have been able to carry helicopters.
The main advantage of V/STOL aircraft is closer basing to the enemy, which reduces response time and tanker support requirements. In the case of the Falklands War, it also permitted high-performance fighter air cover and ground attack without a large aircraft carrier equipped with aircraft catapult.Yakovlev Yak-38
The Yakovlev Yak-38 (Russian: Яковлев Як-38; NATO reporting name: "Forger") was the Soviet Naval Aviation's only operational VTOL strike fighter aircraft in addition to being its first operational carrier-based fixed-wing aircraft. It was developed specifically for, and served almost exclusively on, the Kiev-class aircraft carriers (heavy aviation cruiser in Russian classification).