A convertiplane is defined by the
Fédération Aéronautique Internationale
The (; FAI; en, World Air Sports Federation) is the world governing body for air sports, and also stewards definitions regarding human spaceflight. It was founded on 14 October 1905, and is headquartered in Lausanne, Switzerland. It maintai ...
(FAI or World Air Sports Federation) as an aircraft which uses rotor power for vertical takeoff and landing (
VTOL
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-win ...
) and converts to
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 ...
lift in normal flight.
In the US it is further classified as a sub-type of
powered lift
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 ...
. In popular usage it sometimes includes any aircraft that converts in flight to change its method of obtaining lift.
Types of convertiplane
Most convertiplanes are of the
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 ...
type, in which the same spinning blades are used as rotor blades for vertical flight and then pivot forward to act as propeller blades in horizontal flight. Proprotor types may be of either
tilt rotor or
tilt wing configuration. Tiltwing mechanisms tends to be more complicated. As with the
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 ...
, an engine failure could be disastrous even in the case of a cross-coupled twin rotor configuration.
The stopped rotor type has a separate system for forward thrust. It takes off like a helicopter but for forward flight the rotor stops and acts as a fixed wing. The
gyrocopter
An autogyro (from Ancient Greek, Greek and , "self-turning"), also known as a ''gyroplane'', is a type of rotorcraft that uses an unpowered rotor in free autorotation to develop lift (force), lift. Forward thrust is provided independently, by an ...
is similar except that the rotor continues to spin and to generate a significant amount of lift, and so is classed as a
rotorcraft
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 Internati ...
and not a convertiplane.
Tiltrotor
The powered rotors of 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 ...
(sometimes called ''proprotor'') 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 from ...
. For vertical flight, the rotors are angled to provide thrust upwards, lifting the way a
helicopter rotor
A helicopter main rotor or rotor system is the combination of several rotary wings (rotor blades) with a control system, that generates the aerodynamic lift force that supports the weight of the helicopter, and the thrust that counteracts aerody ...
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 can ...
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
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 convention ...
has two turbine engines, each driving a three-bladed rotor. 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 while ...
(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 2017.
Tiltwing
The
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 ...
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
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 ...
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.
Stopped rotor
A
stopped rotor
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 Internati ...
rotates like a conventional lifting rotor for takeoff and landing, but stops to act as a fixed wing in forward flight. None has yet been successful. 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 st ...
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.
History
Convertiplanes have appeared only occasionally in the course of aviation history.
In 1920 Frank Vogelzang filed a patent for a convertiplane, but the design was never constructed. Between 1937 and 1939 the British designer L.E. Baynes developed a proposal for his Heliplane, a tiltrotor convertiplane having two tilting wingtip-mounted nacelles containing the engines, proprotor mounting and main undercarriage. The wheels did not retract but were partially covered and protruded from the rear of the nacelles when in forward flight. The proposed engines were of an unusual hybrid gas turbine design, in which the proprotor was driven off a gas turbine supplied in turn by a
free-piston
A free-piston engine is a linear, 'crankless' internal combustion engine, in which the piston motion is not controlled by a crankshaft but determined by the interaction of forces from the combustion chamber gases, a rebound device (e.g., a piston i ...
hot gas generator. Baynes was refused official backing and the type was never built. The basic design would not be revisited for some 20 years or so, and would eventually become the basis of the successful
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 convention ...
.
[Gunston, W. and Batchelor, J.; ''Helicopters 1900-1960: Phoebus history of the world wars special'', Phoebus, 1977.]
In 1950s the concept gained brief attention in United States as an intended improvement of helicopters, but the experimental
McDonnell XV-1
The McDonnell XV-1 is an experimental Convertiplane developed by McDonnell Aircraft for a joint research program between the United States Air Force and the United States Army to explore technologies to develop an aircraft that could take off a ...
and
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 ...
did not enter production.
[
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 convention ...
tiltrotor is thus far the only example to enter production. It entered service with the United States military in 2007. The design indirectly derives from Bell's work on the XV-3 and XV-15
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.
Development Early VTOL ...
.
See also
* Autogyro
An autogyro (from Greek and , "self-turning"), also known as a ''gyroplane'', is a type of rotorcraft that uses an unpowered rotor in free autorotation to develop lift. Forward thrust is provided independently, by an engine-driven propeller. Whi ...
* Gyrodyne
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 (aircraft), propeller or jet engines to provide forward thrust d ...
* Tailsitter
A tail-sitter, or tailsitter, is a type of VTOL aircraft that takes off and lands on its empennage, tail, then tilts horizontally for forward flight.
Originating in the 1920s with the inventor Nikola Tesla, the first aircraft to adopt a tail-sitt ...
Notes
Bibliography
* Harris, Franklin D.
An Overview of Autogyros and the McDonnell XV–1 Convertiplane
' NASA
The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research.
NASA was established in 1958, succeeding t ...
, 2003
Mirror1
Mirror2
Size: 284 pages in 13MB
* Robb, Raymond L.
Hybrid helicopters: Compounding the quest for speed
', Vertiflite. Summer 2006. American Helicopter Society
American(s) may refer to:
* American, something of, from, or related to the United States of America, commonly known as the "United States" or "America"
** Americans, citizens and nationals of the United States of America
** American ancestry, pe ...
.
External links
How the USSR combined the plane and the helicopter
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