The Focke-Wulf ''Triebflügel'', or ''Triebflügeljäger'', literally meaning "thrust-wing hunter", was a

German German(s) may refer to: * Germany, the country of the Germans and German things **Germania (Roman era) * Germans, citizens of Germany, people of German ancestry, or native speakers of the German language ** For citizenship in Germany, see also Ge ...

concept for an aircraft designed in 1944, during the final phase of

World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...

, as a defence against the ever-increasing Allied bombing raids on central Germany. It was a

vertical take-off and landing 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 ...

tailsitter 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 configu ...

interceptor Interceptor may refer to: Arts and entertainment Film and television * ''The Interceptor'', a British drama series on BBC One * Interceptor (game show), ''Interceptor'' (game show), a British television game show that ran during 1989 * Interc ...

design for local defense of important factories or areas which had small or no airfields. The ''Triebflügel'' had only reached wind-tunnel testing when the Allied forces reached the production facilities. No complete

prototype A prototype is an early sample, model, or release of a product built to test a concept or process. It is a term used in a variety of contexts, including semantics, design, electronics, and Software prototyping, software programming. A prototype ...

was ever built.

Design

The design was particularly unusual. It had no wings, and all lift and thrust were provided by a rotor/propeller assembly 1/3 of the way down the side of the craft (roughly halfway between the

cockpit A cockpit or flight deck is the area, on the front part of an aircraft, spacecraft, or submersible, from which a pilot controls the vehicle. The cockpit of an aircraft contains flight instruments on an instrument panel, and the controls th ...

and

tailplane A tailplane, also known as a horizontal stabilizer, is a small lift (force), lifting surface located on the tail (empennage) behind the main lifting surfaces of a fixed-wing aircraft as well as other non-fixed-wing aircraft such as helicopters ...

). When the plane was sitting on its tail in the vertical position, the rotors would have functioned similarly to a

helicopter A helicopter is a type of rotorcraft in which Lift (force), lift and thrust are supplied by horizontally spinning Helicopter rotor, rotors. This allows the helicopter to VTOL, take off and land vertically, to hover (helicopter), hover, and ...

. When flying horizontally, they would function more like a giant propeller. The three rotor blades were mounted on a ring assembly supported by bearings, allowing free rotation around the

fuselage The fuselage (; from the French language, French ''fuselé'' "spindle-shaped") is an aircraft's main body section. It holds Aircrew, crew, passengers, or cargo. In single-engine aircraft, it will usually contain an Aircraft engine, engine as wel ...

. At the end of each was a

ramjet A ramjet is a form of airbreathing jet engine that requires forward motion of the engine to provide air for combustion. Ramjets work most efficiently at supersonic speeds around and can operate up to . Ramjets can be particularly appropriat ...

. To start the rotors spinning, simple rockets would have been used. As the speed increased, the flow of air would have been sufficient for the ramjets to work and the rockets would expire. The pitch of the blades could be varied with the effect of changing the speed and the lift produced. There was no reaction torque to cause a counter rotation of the fuselage, since the rotor blades were driven at their tips by the ramjets. Fuel was carried in the fuselage

tank A tank is an armoured fighting vehicle intended as a primary offensive weapon in front-line ground combat. Tank designs are a balance of heavy firepower, strong armour, and battlefield mobility provided by tracks and a powerful engine; ...

s, and was piped through the centre support ring and along the rotors to the jets. A

cruciform A cruciform is a physical manifestation resembling a common cross or Christian cross. These include architectural shapes, biology, art, and design. Cruciform architectural plan Christian churches are commonly described as having a cruciform ...

empennage The empennage ( or ), also known as the tail or tail assembly, is a structure at the rear of an aircraft that provides stability during flight, in a way similar to the feathers on an arrow.Crane, Dale: ''Dictionary of Aeronautical Terms, third ed ...

at the rear of the fuselage comprised four tailplanes, fitted with moving

aileron An aileron (French for "little wing" or "fin") is a hinged flight control surface usually forming part of the trailing edge of each wing of a fixed-wing aircraft. Ailerons are used in pairs to control the aircraft in roll (or movement aroun ...

s that would also have functioned as combined

rudder A rudder is a primary control surface used to steer a ship, boat, submarine, hovercraft, airship, or other vehicle that moves through a fluid medium (usually air or water). On an airplane, the rudder is used primarily to counter adverse yaw ...

s and

elevator An elevator (American English) or lift (Commonwealth English) is a machine that vertically transports people or freight between levels. They are typically powered by electric motors that drive traction cables and counterweight systems suc ...

s. The tailplane would have provided a means for the pilot to control a tendency of the fuselage to rotate in the same direction as the rotor, caused by the friction of the rotor ring, as well as controlling flight in pitch, roll and yaw. A single large and sprung wheel in the extreme end of the fuselage provided the main undercarriage. Four small castoring wheels on extensible struts were placed at the end of each tailplane to steady the aircraft on the ground and allow it to be moved. The main and outrigger wheels were covered by streamlined clamshell doors when in flight. When taking off, the rotors would be angled to give lift in a similar manner to a

. Once the aircraft had attained sufficient altitude the pilot would tilt it over into level flight. The rotors continued spinning in level flight, maintaining 220 rpm at the aircraft's maximum forward speed.Sharp, D.; ''Luftwaffe: Secret Jets of the Third Reich'', Mortons, 2015, Pages 98–101. Forward flight required a slight nose-up pitch to provide some upward lift as well as primarily forward thrust. Consequently, the four

cannon A cannon is a large-caliber gun classified as a type of artillery, which usually launches a projectile using explosive chemical propellant. Gunpowder ("black powder") was the primary propellant before the invention of smokeless powder during th ...

in the forward fuselage would have been angled slightly downward in relation to the centreline of the fuselage. To land, the craft had to slow its speed and pitch the fuselage until the craft was vertical. Power could then be reduced and it would descend until the landing gear rested on the ground. This would have been a tricky and probably dangerous maneuver, given that the pilot would be seated facing upward and the ground would be behind their head at this stage. Unlike some other tailsitter aircraft, the pilot's seat was fixed in the direction for forward flight. The spinning rotor would also obscure rear vision.

Comparable aircraft designs

This design was unique among 20th-century VTOL craft, and other German concept craft. However, some early design studies for the

Rotary Rocket Rotary Rocket Company was a rocketry company that developed the Roton concept in the late 1990s as a fully reusable single-stage-to-orbit (SSTO) crewed spacecraft. The design was initially conceived by Bevin McKinney, who shared it with Gary Hud ...

Roton spacecraft in the 1990s showed a free-spinning rotor with tip-driven rotors providing lift. In the 1950s, the US built prototype

aircraft (the

Lockheed XFV The Lockheed XFV (sometimes referred to as the "Salmon") is an American Experimental aircraft, experimental tailsitter prototype aircraft built by Lockheed Corporation, Lockheed in the early 1950s to demonstrate the operation of a VTOL, vertic ...

, and Convair XFY Pogo), but these were powered by conventional

turboprop A turboprop is a Gas turbine, gas turbine engine that drives an aircraft Propeller (aeronautics), propeller. A turboprop consists of an intake, reduction drive, reduction gearbox, gas compressor, compressor, combustor, turbine, and a propellin ...

s, with nose-mounted

contra-rotating propellers Aircraft equipped with contra-rotating propellers (CRP) coaxial contra-rotating propellers, or high-speed propellers, apply the maximum power of usually a single engine piston powered or turboprop engine to drive a pair of coaxial propellers i ...

to counter torque. They also used conventional wings for lift, though their cruciform tails with integral landing gear were broadly comparable to the ''Triebflügel''.

Notable appearances in media

Specifications

References

External links