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

German German(s) may refer to: * Germany (of or related to) ** Germania (historical use) * Germans, citizens of Germany, people of German ancestry, or native speakers of the German language ** For citizens of Germany, see also German nationality law **Ge ...

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

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...

as a defence against the ever-increasing

Allied An alliance is a relationship among people, groups, or states that have joined together for mutual benefit or to achieve some common purpose, whether or not explicit agreement has been worked out among them. Members of an alliance are called ...

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-win ...

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 ...

interceptor Interceptor may refer to: Vehicles * Interceptor aircraft (or simply "interceptor"), a type of point defense fighter aircraft designed specifically to intercept and destroy enemy aircraft * Ford Crown Victoria Police Interceptor, a police car * ...

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 prototyp ...

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, usually near the front of an aircraft or spacecraft, from which a Pilot in command, pilot controls the aircraft. The cockpit of an aircraft contains flight instruments on an instrument panel, and the ...

and

tailplane A tailplane, also known as a horizontal stabiliser, is a small 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 and gyroplane ...

). 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 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 ...

. 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 ''fuselé'' "spindle-shaped") is an aircraft's main body section. It holds crew, passengers, or cargo. In single-engine aircraft, it will usually contain an engine as well, although in some amphibious aircraft t ...

. At the end of each was a

ramjet A ramjet, or athodyd (aero thermodynamic duct), is a form of airbreathing jet engine that uses the forward motion of the engine to produce thrust. Since it produces no thrust when stationary (no ram air) ramjet-powered vehicles require an ass ...

. 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 good battlefield mobility provided by tracks and a powerful engin ...

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

cruciform Cruciform is a term for physical manifestations resembling a common cross or Christian cross. The label can be extended to architectural shapes, biology, art, and design. Cruciform architectural plan Christian churches are commonly described ...

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 around ...

s that would also have functioned as combined

rudder A rudder is a primary control surface used to steer a ship, boat, submarine, hovercraft, aircraft, or other vehicle that moves through a fluid medium (generally aircraft, air or watercraft, water). On an aircraft the rudder is used primarily to ...

s and

elevator An elevator or lift is a wire rope, cable-assisted, hydraulic cylinder-assisted, or roller-track assisted machine that vertically transports people or freight between floors, levels, or deck (building), decks of a building, watercraft, ...

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 Undercarriage is the part of a moving vehicle that is underneath the main body of the vehicle. The term originally applied to this part of a horse-drawn carriage, and usage has since broadened to include: *The landing gear of an aircraft. *The ch ...

. 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 ...

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 his 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 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") was an American experimental tailsitter prototype aircraft built by Lockheed in the early 1950s to demonstrate the operation of a vertical takeoff and landing (VTOL) fighter for protect ...

, and

Convair XFY Pogo The Convair XFY Pogo was an experiment in vertical takeoff and landing (VTOL) tail-sitter. The Pogo had delta wings and three-bladed contra-rotating propellers powered by a turboprop engine. It was intended to be a high-performance fighter aircr ...

), but these were powered by conventional

turboprop A turboprop is a turbine engine that drives an aircraft propeller. A turboprop consists of an intake, reduction gearbox, compressor, combustor, turbine, and a propelling nozzle. Air enters the intake and is compressed by the compressor. Fuel ...

s, with nose-mounted

contra-rotating propellers Aircraft equipped with contra-rotating propellers, also referred to as CRP, coaxial contra-rotating propellers, or high-speed propellers, apply the maximum power of usually a single piston or turboprop engine to drive a pair of coaxial propell ...

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