Examine individual changes

'{{Short description|VTOL capable fixed-wing aircraft}} [[File:MV-22 mcas Miramar 2014.JPG|thumb|[[Bell Boeing V-22 Osprey]] flown by the U.S. Marines]] [[File:Spanish EAV-8B Harrier II+ "Cobra" (27448607244) (cropped).jpg|thumb|A Spanish [[McDonnell Douglas AV-8B Harrier II|EAV-8B Harrier II+]]]] A '''powered lift''' aircraft [[VTOL|takes off and lands vertically]] under engine power but uses a [[fixed-wing aircraft|fixed wing]] for horizontal flight. Like [[helicopter]]s, these [[aircraft]] do not need a long runway to take off and land, but they have a speed and performance similar to standard [[fixed-wing]] aircraft in combat or other situations. Some powered-lift aircraft, like the [[Bell Boeing V-22 Osprey]] used by the [[United States Marines]], use a [[tiltrotor]] or [[tiltwing]]. These are called a [[convertiplane]]. Others like the British [[Harrier jump jet]] use [[thrust vectoring]] or other direct thrust techniques. The first powered-lift ratings on a [[Pilot certification in the United States|civilian pilot certificate]] were issued by the [[Federal Aviation Administration]] (FAA) on 21 August 1997 to pilots of [[Bell Helicopter]], [[Boeing]], and the [[United States Marine Corps]].<ref>[http://www.boeing.com/news/releases/1997/news_release_970821a.html "Osprey Pilots Receive First FAA Powered Lift Ratings"], www.boeing.com, 21 August 1997. [https://web.archive.org/web/19990220043218/http://www.boeing.com/news/releases/1997/news_release_970821a.html 1999 Archive]</ref> In 2024 FAA established a special class of powered-lift aircraft to certificate them under § 21.17(b) of FAR Part 21 to address certain unique features without applying special conditions or exemptions. The final rule allows for flight training in single control eVTOL aircraft and for issue by the FAA certain deviations in cases of future technological advancements.<ref>{{Cite web |date=2024-10-31 |title=FAA creates America's first new aircraft category since the 1940s |url=https://www.militaryaerospace.com/home/article/55239460/faa-creates-americas-first-new-aircraft-category-since-the-1940s?utm_term=8921DD2D-7985-449E-940E-59E8F298FAB0&lrh=01640d504ea22e63adbe11de1276735f7baf8ded2b17e6459ffe192d108353a9&utm_campaign=337624C8-7BB5-4B82-B90E-C7A6E26E4D65&utm_medium=email&utm_content=2F4C2364-DE38-40B9-9EFF-6ECD5C98EF2B&utm_source=SmartBrief |access-date=2024-11-05 |website=Military Aerospace |language=en}}</ref> ==Definition== [[Image:LiftThrust1.PNG|thumb|Powered lift and thrust forces of various aircraft]] The term is an aircraft classification used by the [[International Civil Aviation Organization]] (ICAO) and the United States' FAA: {{Blockquote|Powered-lift. A heavier-than-air aircraft capable of vertical take-off, vertical landing, and low-speed flight, which depends principally on engine-driven lift devices or engine thrust for the lift during these flight regimes and on non-rotating aerofoil(s) for lift during horizontal flight.|ICAO Annex I, Chapter 1.1 Definitions|source=}} ==Convertiplane== {{main|convertiplane}} A [[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 [[Bell Boeing V-22 Osprey]], the rotor swings forward to act as a [[propeller (aircraft)|propeller]] in forward flight. Some designs have a [[ducted fan]] design, in which the propeller is surrounded by a large ring-shaped duct to reduce tip losses. === Tiltrotor === [[Image:CV-22 Osprey in flight.jpg|thumb|An USAF CV-22 in flight]] [[File:Bell X-22 ducted fan.jpg|thumb|The Bell X-22 with four tilting ducted fans]] The powered rotors of a [[tiltrotor]] (sometimes called ''[[proprotor]]'') are mounted on rotating shafts or nacelles at the end of a fixed wing, and used for both lift and [[thrust|propulsion]]. 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]] 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. An important early tiltrotor in the 1950s, was the [[Bell XV-3]], which was one of the first aircraft designs to go from vertical takeoff to horizontal successfully. The Osprey by [[Bell Helicopter]] and [[Boeing]] is a twin-engine [[tiltrotor]] 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]] (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=== [[File:Ling-Temco-Vought XC-142A.jpg|thumb|left|The LTV XC-142A had 4-engines articulated on a tilt''wing'']] The [[tiltwing]] 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]] was a research aircraft developed in the late 1950s. Unlike other [[tiltwing]] aircraft, Vertol designed the VZ-2 using rotors in place of propellers.<ref>[http://www.flightglobal.com/pdfarchive/view/1957/1957%20-%201517.html "VTOL Design Problems."] ''Flight''. periodical. 18 October 1957. Retrieved on 22 October 2009.</ref> 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. The [[LTV XC-142A]] was another VTOL design that used the tiltwing concept. It was developed into a working prototype but did not enter mass production. ===Rotor wing=== A [[rotor wing]] aircraft has been attempted but is not in wide use. The [[Boeing X-50 Dragonfly]] had a two-bladed rotor driven by the engine for takeoff. In horizontal flight the rotor stopped to act like a wing. Fixed [[canard (aeronautics)|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 S-72#The X-Wing|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]]s in an ''X'' configuration. The program was canceled before the aircraft had attempted any flights with the rotor system. ==Tail-sitter== [[File:Convair XFY-1 taking off at NAAF Brown Field 1954.jpeg|thumb|Convair XFY-1 takes off, 1954]] A [[Tail-sitter]] 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.<ref>[http://www.flightglobal.com/pdfarchive/view/1954/1954%20-%203043.html "Convair XFY."] ''Flight'', 12 November 1954, p. 696.</ref> The [[coleopter]] type has an [[annular wing]] forming a duct around a lift rotor. The transition to forward flight has never been achieved, although the [[SNECMA Coléoptère]] 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 [[coleopter]] fixed-wing aircraft, the Triebflügel was intended to take off and land on its tail, rotating on the [[Roll, pitch, and yaw|pitch]] axis after takeoff and acceleration for forward flight. The design was never built beyond model wind tunnel testing. ==Direct thrust== [[File:Harrier vectored thrust vents (14172284986).jpg|thumb|Harrier jet vents for vectoring thrust]] ===Vectored thrust=== The [[Harrier jump jet|Harrier]] family of military VSTOL [[jet aircraft]] uses [[thrust vectoring]]. These aircraft are capable of [[V/STOL|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 [[F-35 Lightning II#F-35B|Lockheed F-35B ''Lightning II'']] is proposed as the next military VSTOL/[[STOVL]] design, to replace the Harrier. ===Lift jets=== [[File:F-35B Lighting II training flights 170203-M-ON157-0432.jpg|thumb|The F-35B uses both a lift-fan and vectors engine thrust down.]] A [[lift jet]] 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. The [[Dassault Mirage IIIV]] was VTOl fighter made for the NATO VTOL strike fighter requirement in the 1960s. Several other designs also resulted from this design specification. ===Lift fans=== A [[lift fan]] 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]] entered into production. ==Additional examples== [[File:Bell V-280 Valor hover demo, 2019 Alliance Air Show.jpg|thumb|Bell V-280 Valor]] * [[AgustaWestland AW609]] * [[Bell XV-3]] * [[Bell XV-15]] * [[Bell Eagle Eye]] * [[Canadair CL-84 Dynavert]] * [[LTV XC-142]] * [[Short SC.1]] * [[Bell V-280 Valor]] {{further|List of VTOL aircraft}} ==See also== {{commons|VTOL aircraft}} *[[Ducted fan]] *[[FanWing]] *[[Cyclogyro]] *[[Gyrodyne]] ==Notes== {{reflist}} ==References== *[https://www.icao.int/Meetings/AMC/MA/Assembly%2035th%20Session/wp103_en.pdf "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 *[http://testimony.ost.dot.gov/test/pasttest/01test/Wallace1.htm "Vertical flight technology in the national airspace system"], Testimony of [[William Wallace]], the National Resource Specialist for Rotorcraft Operations of the [[Federal Aviation Administration]], before the [[United States House Science Subcommittee on Space and Aeronautics|Subcommittee on Space and Aeronautics]], 9 May 2001, http://testimony.ost.dot.gov [[Category:VTOL aircraft]] [[Category:Aircraft categories]]'