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Hiller X-18 tilting its wing X-18 tilting its wing bw.jpg
Hiller X-18 tilting its wing

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 typically fully capable of VTOL operations. [1]


VTOL disc loading lift efficiency VTOL DiscLoad-LiftEfficiency.svg
VTOL disc loading lift efficiency

The tiltwing design offers certain advantages in vertical flight relative to a tiltrotor. Because the slipstream from the rotor strikes the wing on its smallest dimension, the tiltwing is able to apply more of its engine power to lifting the aircraft. For comparison, the V-22 Osprey tiltrotor loses about 10% of its thrust to interference from the wings. [2]

Another advantage of tiltwing aircraft is the ease of transition between VTOL and horizontal flight modes. A tiltrotor must first fly forwards like a helicopter, building airspeed until wing lift is sufficient to allow the nacelles to begin tilting down. As a note, the MV-22 Osprey's stall speed in airplane mode is 110 knots (204 km/h; 127 mph). Conversely, a tiltwing aircraft can begin the transition from helicopter to airplane at zero forward airspeed. Because of this, the Canadair CL-84 Dynavert was able to take off vertically, then accelerate from zero airspeed to 100 knots (185 km/h; 115 mph) in 8 seconds. [3]

However, the fixed wing of a tiltrotor aircraft offers a superior angle of attack—thus more lift and a shorter takeoff roll—when performing STOL/STOVL operations.[ citation needed ]

The main drawbacks of tiltwing aircraft are susceptibility to wind gusts in VTOL mode and lower hover efficiency. The wing tilted vertically represents a large surface area for crosswinds to push against. [1] Tiltrotors generally have better hover efficiency than tiltwings, but less than helicopters. [4] This is due to the difference in rotor disk loading.

As of 2014, NASA is testing a diesel-electric hybrid 10-foot 10-rotor tiltwing called the GL-10 Greased Lightning, with most propellers folding during horizontal flight. [5]

List of tiltwing aircraft

Tiltwing designs with rocket, jet, or propeller propulsion

See also

Related Research Articles

A vertical take-off and landing (VTOL) aircraft is one that can take off and land vertically without relying on a runway. This classification can include a variety of types of aircraft including helicopters as well as thrust-vectoring fixed-wing aircraft and other hybrid aircraft with powered rotors such as cyclogyros/cyclocopters and gyrodynes.

<span class="mw-page-title-main">Tiltrotor</span> Aircraft type

A tiltrotor is an aircraft that generates lift and propulsion by way of one or more powered rotors mounted on rotating shafts or nacelles usually at the ends of a fixed wing. Almost all tiltrotors use a transverse rotor design, with a few exceptions that use other multirotor layouts.

<span class="mw-page-title-main">Takeoff</span> Phase of flight in which a vehicle leaves the land or water surface

Takeoff is the phase of flight in which an aerospace vehicle leaves the ground and becomes airborne. For aircraft traveling vertically, this is known as liftoff.

<span class="mw-page-title-main">V/STOL</span> Aircraft takeoff and landing class

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 aeroplanes, 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.

<span class="mw-page-title-main">Bell XV-15</span> American experimental tiltrotor aircraft

The Bell XV-15 is an American tiltrotor VTOL aircraft. It was the second successful experimental tiltrotor aircraft and the first to demonstrate the concept's high speed performance relative to conventional helicopters.

<span class="mw-page-title-main">Tail-sitter</span> Type of VTOL aircraft

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.

<span class="mw-page-title-main">Hiller X-18</span> Experimental cargo transport aircraft

The Hiller X-18 was an experimental cargo transport aircraft designed to be the first testbed for tiltwing and V/STOL technology.

<span class="mw-page-title-main">Curtiss-Wright X-19</span> Experimental VTOL tiltrotor quadcopter airplane

The Curtiss-Wright X-19, company designation Model 200, was an American experimental tiltrotor aircraft of the early 1960s. It was noteworthy for being the last aircraft of any kind manufactured by Curtiss-Wright.

<span class="mw-page-title-main">Canadair CL-84 Dynavert</span> Canadian experimental tiltwing VSTOL aircraft

The Canadair CL-84 "Dynavert", designated by the Canadian Forces as the CX-131, was a V/STOL turbine tiltwing monoplane designed and manufactured by Canadair between 1964 and 1972. Only four of these experimental aircraft were built with three entering flight testing. Two of the CL-84s crashed due to mechanical failures, with no fatalities occurring in either of the accidents. Despite the CL-84 being successful in the experimental and operational trials carried out between 1972 and 1974, none of the prospective customers placed any orders for the type.

<span class="mw-page-title-main">Gyrodyne</span>

A gyrodyne is a type of VTOL aircraft with a helicopter rotor-like system that is driven by its engine for takeoff and landing only, and includes one or more conventional propeller or jet engines to provide forward thrust during cruising flight. During forward flight the rotor is unpowered and free-spinning, like an autogyro, and lift is provided by a combination of the rotor and conventional wings. The gyrodyne is one of a number of similar concepts which attempt to combine helicopter-like low-speed performance with conventional fixed-wing high-speeds, including tiltrotors and tiltwings.

<span class="mw-page-title-main">Rotorcraft</span> Heavier-than-air aircraft which generates lift over rotating wings

A rotorcraft or rotary-wing aircraft is a heavier-than-air aircraft with rotary wings or rotor blades, which generate lift by rotating around a vertical mast. Several rotor blades mounted on a single mast are referred to as a rotor. The International Civil Aviation Organization (ICAO) defines a rotorcraft as "supported in flight by the reactions of the air on one or more rotors".

A convertiplane is defined by the Fédération Aéronautique Internationale as an aircraft which uses rotor power for vertical takeoff and landing (VTOL) and converts to fixed-wing lift in normal flight. In the US it is further classified as a sub-type of powered lift. In popular usage it sometimes includes any aircraft that converts in flight to change its method of obtaining lift.

<span class="mw-page-title-main">LTV XC-142</span> Experimental military tilt-wing aircraft

The Ling-Temco-Vought (LTV) XC-142 was a tri-service tiltwing experimental aircraft designed to investigate the operational suitability of vertical/short takeoff and landing (V/STOL) transports. An XC-142A first flew conventionally on 29 September 1964, and on 11 January 1965, it completed its first transitional flight by taking off vertically, changing to forward flight and finally landing vertically. Its service sponsors pulled out of the program one by one, and it eventually ended due to a lack of interest after demonstrating its capabilities successfully.

<span class="mw-page-title-main">Bell Boeing Quad TiltRotor</span> Proposed four-rotor derivative of the V-22 Osprey

The Bell Boeing Quad TiltRotor (QTR) is a proposed four-rotor derivative of the Bell Boeing V-22 Osprey developed jointly by Bell Helicopter and Boeing. The concept is a contender in the U.S. Army's Joint Heavy Lift program. It would have a cargo capacity roughly equivalent to the C-130 Hercules, cruise at 250 knots, and land at unimproved sites vertically like a helicopter.

<span class="mw-page-title-main">Powered lift</span> VTOL capable fixed-wing aircraft

A powered lift aircraft takes off and lands vertically under engine power but uses a fixed wing for horizontal flight. Like helicopters, 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.

<span class="mw-page-title-main">Proprotor</span>

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 between flying akin to both helicopters and fixed-wing aircraft. Accordingly this type of airfoil has been predominantly applied to vertical takeoff and landing (VTOL) aircraft.

<span class="mw-page-title-main">VTOL X-Plane</span> American experimental aircraft

The Vertical Take-Off and Landing Experimental Aircraft program is an American research project sponsored by the Defense Advanced Research Projects Agency (DARPA). The goal of the program is to demonstrate a VTOL aircraft design that can take off vertically and efficiently hover, while flying faster than conventional rotorcraft. There have been many previous attempts, most of them unsuccessful.

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 lifting rotors and several variations have been flown on full-size aircraft, although only the vertical-axis rotary wing has become widespread on rotorcraft such as the helicopter.

<span class="mw-page-title-main">NASA GL-10 Greased Lightning</span> American unmanned aircraft

The GL-10 Greased Lightning is a hybrid diesel-electric tiltwing unmanned aircraft.


  1. 1 2 Markman, Steve and Bill Holder. "Tilt-Wing VTOL Systems". Straight Up: A History of Vertical Flight. Schiffer Publishing, 2000. ISBN   0-7643-1204-9.
  2. Boeing looks ahead to a 'V-23' Osprey
  3. Tilting at Targets
  4. Warwick, Graham. "Tilting at targets" page 44 Flight International , February 1992. Accessed: 4 January 2014.
  5. Warwick, Graham. "Distributed power" Aviation Week & Space Technology page 31, 25 August 2014. Accessed: 26 August 2014.