A powered lift aircraft takes off and lands vertically under engine power but uses a

fixed wing A fixed-wing aircraft is a heavier-than-air flying machine, such as an airplane, which is capable of flight using wings that generate lift caused by the aircraft's forward airspeed and the shape of the wings. Fixed-wing aircraft are distin ...

for horizontal flight. Like

helicopter A helicopter is a type of rotorcraft in which lift and thrust are supplied by horizontally spinning rotors. This allows the helicopter to take off and land vertically, to hover, and to fly forward, backward and laterally. These attributes ...

s, these

aircraft An aircraft is a vehicle that is able to fly by gaining support from the air. It counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engine ...

do not need a long runway to take off and land, but they have a speed and performance similar to standard

fixed-wing A fixed-wing aircraft is a heavier-than-air flying machine, such as an airplane, which is capable of flight using wings that generate lift caused by the aircraft's forward airspeed and the shape of the wings. Fixed-wing aircraft are distinct ...

aircraft in combat or other situations. Some powered-lift aircraft, like the

Bell Boeing V-22 Osprey The Bell Boeing V-22 Osprey is an American multi-mission, tiltrotor military aircraft with both vertical takeoff and landing (VTOL) and short takeoff and landing (STOL) capabilities. It is designed to combine the functionality of a conventio ...

used by the

United States Marines The United States Marine Corps (USMC), also referred to as the United States Marines, is the maritime land force service branch of the United States Armed Forces responsible for conducting expeditionary and amphibious operations through com ...

, use a

tiltrotor A tiltrotor is an aircraft which generates lift and propulsion by way of one or more powered rotors (sometimes called ''proprotors'') mounted on rotating shafts or nacelles usually at the ends of a fixed wing. Almost all tiltrotors use a trans ...

tiltwing A tiltwing aircraft features a wing that is horizontal for conventional forward flight and rotates up for vertical takeoff and landing. It is similar to the tiltrotor design where only the propeller and engine rotate. Tiltwing aircraft are typical ...

. These are called a

convertiplane A convertiplane is defined by the Fédération Aéronautique Internationale (FAI or World Air Sports Federation) as an aircraft which uses rotor power for vertical takeoff and landing (VTOL) and converts to fixed-wing lift in normal flight. In the ...

. Others like the British

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 ma ...

use

thrust vectoring Thrust vectoring, also known as thrust vector control (TVC), is the ability of an aircraft, rocket, or other vehicle to manipulate the direction of the thrust from its engine(s) or motor(s) to control the attitude or angular velocity of the ve ...

or other direct thrust techniques. The first powered-lift ratings on a civilian pilot certificate were issued by the

Federal Aviation Administration The Federal Aviation Administration (FAA) is the largest transportation agency of the U.S. government and regulates all aspects of civil aviation in the country as well as over surrounding international waters. Its powers include air traffic ...

(FAA) on 21 August 1997 to pilots of

Bell Helicopter Bell Textron Inc. is an American aerospace manufacturer headquartered in Fort Worth, Texas. A subsidiary of Textron, Bell manufactures military rotorcraft at facilities in Fort Worth, and Amarillo, Texas, as well as commercial helicopters in M ...

Boeing The Boeing Company () is an American multinational corporation that designs, manufactures, and sells airplanes, rotorcraft, rockets, satellites, telecommunications equipment, and missiles worldwide. The company also provides leasing and p ...

, and the

United States Marine Corps The United States Marine Corps (USMC), also referred to as the United States Marines, is the maritime land force service branch of the United States Armed Forces responsible for conducting expeditionary and amphibious operations through combi ...

Definition

The term is an aircraft classification used by the

International Civil Aviation Organization The International Civil Aviation Organization (ICAO, ) is a specialized agency of the United Nations that coordinates the principles and techniques of international air navigation, and fosters the planning and development of international a ...

(ICAO) and the United States' FAA:

Convertiplane

uses rotor power for vertical takeoff and landing (VTOL) and converts to fixed-wing lift for normal flight. In tiltrotor and tiltwing designs such as the

, the rotor swings forward to act as a propeller in forward flight. Some designs have a

ducted fan In aeronautics, a ducted fan is a thrust-generating mechanical fan or propeller mounted within a cylindrical duct or shroud. Other terms include ducted propeller or shrouded propeller. When used in vertical takeoff and landing (VTOL) applicati ...

design, in which the propeller is surrounded by a large ring-shaped duct to reduce tip losses.

Tiltrotor

The powered rotors of a

(sometimes called ''

proprotor A proprotor is a spinning airfoil that function as both an airplane-style propeller and a helicopter-style rotor. Several proprotor-equipped convertiplanes, such as the Bell Boeing V-22 Osprey tiltrotor, are capable of switching back and forth betw ...

'') are mounted on rotating shafts or nacelles at the end of a fixed wing, and used for both lift and

propulsion Propulsion is the generation of force by any combination of pushing or pulling to modify the translational motion of an object, which is typically a rigid body (or an articulated rigid body) but may also concern a fluid. The term is derived f ...

. For vertical flight, the rotors are angled to provide thrust upwards, lifting the way a helicopter rotor does. As the aircraft gains speed, the rotors progressively rotate or ''tilt'' forward, with the rotors eventually becoming

perpendicular In elementary geometry, two geometric objects are perpendicular if they intersect at a right angle (90 degrees or π/2 radians). The condition of perpendicularity may be represented graphically using the ''perpendicular symbol'', ⟂. It ca ...

to the fuselage of the aircraft, similar to a propeller. In this mode, the wing provides the lift and the rotor provides thrust. The wing's greater efficiency helps the tiltrotor achieve higher speeds than helicopters. The Osprey by

and

is a twin-engine

design that has two turbine engines each driving three-blade rotors. The rotors function similar to a helicopter in vertical flight, and similar to an airplane in forward flight. It first flew on 19 March 1989. The

AgustaWestland AW609 The AgustaWestland (now Leonardo) AW609, formerly the Bell/Agusta BA609, is a twin-engined tiltrotor VTOL aircraft with a configuration similar to that of the Bell Boeing V-22 Osprey. It is capable of landing vertically like a helicopter whil ...

(formerly Bell/Agusta BA609) tiltrotor is civilian aircraft based on the V-22 Osprey. The aircraft can take off and land vertically with 2 crew and 9 passengers. The aircraft is expected to be certified in the mid 2020s.

Tiltwing

The

is similar to the tiltrotor, except that the rotor mountings are fixed to the wing and the whole assembly tilts between vertical and horizontal positions. The

Vertol VZ-2 The Vertol VZ-2 (or Model 76) was a research aircraft built in the United States in 1957 to investigate the tiltwing approach to vertical take-off and landing. Design and development The aircraft had a fuselage of tubular framework (originally ...

was a research aircraft developed in the late 1950s. Unlike other

aircraft, Vertol designed the VZ-2 using rotors in place of propellers. On 23 July 1958, the aircraft made its first full transition from vertical flight to horizontal flight. By the time the aircraft was retired in 1965, the VZ-2 had accomplished 450 flights, including 34 full transitions.

Rotor wing

rotor wing A rotor wing is a lifting rotor or wing which spins to provide aerodynamic lift. In general, a rotor may spin about an axis which is aligned substantially either vertically or side-to-side (spanwise). All three classes have been studied for use as ...

aircraft has been attempted but is not in wide use. The

Boeing X-50 Dragonfly The Boeing X-50A Dragonfly, formerly known as the Canard Rotor/Wing Demonstrator, was a VTOL rotor wing experimental unmanned aerial vehicle that was developed by Boeing and DARPA to demonstrate the principle that a helicopter's rotor could be s ...

had a two-bladed rotor driven by the engine for takeoff. In horizontal flight the rotor stopped to act like a wing. Fixed canard and tail surfaces provided lift during transition, and also stability and control in forward flight. Both examples of this aircraft were destroyed in crashes. The Sikorsky X-Wing had a four-bladed rotor utilizing compressed air to control lift over the surfaces while operating as a helicopter. At higher forward speeds, the rotor would be stopped to continue providing lift as

tandem wing QAC Quickie Q2 A tandem wing is a wing configuration in which a flying craft or animal has two or more sets of wings set one behind another. All the wings contribute to lift. The tandem wing is distinct from the biplane in which the wings are ...

s in an ''X'' configuration. The program was canceled before the aircraft had attempted any flights with the rotor system.

Tail-sitter

Tail-sitter A tail-sitter, or tailsitter, is a type of VTOL aircraft that takes off and lands on its tail, then tilts horizontally for forward flight. Originating in the 1920s with the inventor Nikola Tesla, the first aircraft to adopt a tail-sitter configur ...

is an aircraft that rests on the ground pointing vertically upwards, so that it rests on its tail. It takes off and lands vertically, tail down. The whole aircraft then tilts forward horizontally for normal flight. No type has ever gone into production, although a number of experimental variants have been flown, using both proprotor and jet thrust. Some have achieved successful transition between flight modes, as the turboprop-powered Convair XFY Pogo did in November 1954."Convair XFY."
''Flight'', 12 November 1954, p. 696. The

coleopter A coleopter is a type of VTOL aircraft design that uses a ducted fan as the primary fuselage of the entire aircraft. Generally they appear to be a large barrel-like extension at the rear, with a small cockpit area suspended above it. Coleopters ...

type has an

annular wing A closed wing is a wing that effectively has two main planes which merge at their ends so that there are no conventional wing tips. Closed wing designs include the annular wing (commonly known as the cylindrical or ring wing), the joined wing, ...

forming a duct around a lift rotor. The transition to forward flight has never been achieved, although the

SNECMA Coléoptère The SNECMA C.450 Coléoptère (meaning "beetle" in French, descended from Greek for "sheathed wing") was a vertical take-off and landing (VTOL) aircraft that was designed by the French company SNECMA and manufactured by Nord Aviation. While w ...

took off, hovered and landed vertically, solely on pure jet thrust. The German Focke-Wulf Fw Triebflügel was a design studied during the Second World War. It used pulse jets to power a rotor that rotated about the fuselage axis behind the cockpit. Similar to a

fixed-wing aircraft, the Triebflügel was intended to take off and land on its tail, rotating on the pitch axis after takeoff and acceleration for forward flight. The design was never built beyond model wind tunnel testing.

Direct thrust

Vectored thrust

The Harrier family of military VSTOL jet aircraft uses

. These aircraft are capable of vertical/short takeoff and landing (V/STOL). They are the only truly successful design of this type from the many that arose in the 1960s. These aircraft are capable of operating from small spaces, such as fields, roads, and aviation-capable ships. The Lockheed F-35B ''Lightning II'' is proposed as the next military VSTOL/

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 ...

design, to replace the Harrier.

Lift jets

lift jet {{Unreferenced, date=July 2009 A lift jet is a jet engine angled to provide an aircraft with ''aerostatic'' (i.e. not requiring the movement of air over an airfoil) lift, instead of (or in addition to) thrust. On a fixed-wing aircraft, lift jets ...

is a lightweight jet engine used to provide vertical thrust for VTOL operation, and is then shut down in forward flight. Some VTOL designs have used both vectored thrust from the main engine together with auxiliary lift jets.

Lift fans

lift fan 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 ...

configuration is where the 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 more convention fixed-wing forward flight. Several experimental craft have been flown, but only the

F-35 Lightning II The Lockheed Martin F-35 Lightning II is an American family of single-seat, single-engine, all-weather stealth multirole combat aircraft that is intended to perform both air superiority and strike missions. It is also able to provide elect ...

entered into production.

Additional examples

Bell XV-3 The Bell XV-3 (Bell 200) is an American tiltrotor aircraft developed by Bell Helicopter for a joint research program between the United States Air Force and the United States Army in order to explore convertiplane technologies. The XV-3 featured ...

* Bell XV-15 *

Bell Eagle Eye The Bell Helicopter Eagle Eye, Model 918, was an American tiltrotor unmanned aerial vehicle that was offered as one of the competitors in the United States Navy's VT-UAV (Vertical Takeoff - Unmanned Aerial Vehicle) program. Development The Eagl ...

* Canadair CL-84 Dynavert * LTV XC-142 *

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 RB.108 turbojets, four of which were used for vertical ...

Notes

{{reflist

References

"Addressing the future challenges of the operation of powered lift category/tiltrotor class aircraft in international air navigation"
report by "Assembly – 35 Session Executive Committee", www.faa.gov

Testimony of

William Wallace Sir William Wallace ( gd, Uilleam Uallas, ; Norman French: ; 23 August 1305) was a Scottish knight who became one of the main leaders during the First War of Scottish Independence. Along with Andrew Moray, Wallace defeated an English army ...

, the National Resource Specialist for Rotorcraft Operations of the

, before the Subcommittee on Space and Aeronautics, 9 May 2001, http://testimony.ost.dot.gov VTOL aircraft Aircraft categories