FOCKE-WULF TRIEBFLÜGEL
(1944-1945)
By Rob Arndt
Muck’s concept
The origin of the Focke-Wulf Triebflügel started in 1938 with a patent application by Siemens engineer Otto Muck who proposed a VTO (Vertical Take-Off) aircraft. Intrigued by Muck’s concept, aerodynamicist Professor Kurt Tank of the Focke-Wulf Flugzeugbau decided to develop the idea further with a coleopter designed by Focke-Wulf’s Dr. Ing. Heinz von Halem in September 1944 submitted as Focke-Wulf’s fighter/interceptor proposal.
This tail-sitting coleopter was considered ideal for point defense operations, needing nothing more than a clear area for take-off, even from dense urban centers.
VTO was achieved through the use of three un-tapered wing-rotors that held three Pabst ramjets at their tips. Since ramjets don’t operate at low speed it was intended to install a Walter liquid-fuelled rocket unit in each ramjet core or as an alternative fit jettisonable Walter 109-501 RATO units to the fuselage for launch.
To achieve this VTO, the wing-rotors were tilted to the +3 degrees angle.
The wing-rotors were located roughly a third of the way down from the nose and caused no torque problems with the fuselage.
Once 300 km/hr was achieved the ramjets ran on their own and the pilot, sitting in the cockpit near the nose, gradually tilted the wing-rotors through to 90 degrees transitioning from vertical flight to horizontal flight using the vertical launch thrust for lifting thrust. Increases in rpms and tilting of the wings were to be used for increased maneuverability at speed.
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Control was achieved by use of control surfaces at the trailing edges of the tail fins.
Once in combat the Triebflügel was armed with two 30mm MK-103 cannon with 100 rounds each and two 20mm MG-151 cannon with 250 rounds each- all located beneath the pilot.
The most hazardous part of the Triebflügel’s mission wasn’t combat. It was transitional flight with the return vertical descent being of most danger since the pilot’s vision was obstructed by the spinning wing-rotors and the exhaust halo surrounding the craft. The landing gear consisted of four retractable tail fin pods and one fuselage pod that contained the wheels for VTOL.
 Triebflügel podded gear arrangement |
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The Triebflügel held promise but unfortunately the project was cancelled along with all other design projects that could not produce an emergency aircraft within 60 days. Only the Bachem Ba-349 Natter (Viper) VTO point defense interceptor made the cut but never made it into action.
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Pabst ramjet and Triebflügel wing being wind tunnel tested |
A scale model of the Triebflügel was tested in an aerodynamic wind tunnel and reached Mach 0.9.
Postwar, the victorious Allies made use of the tail-sitter interceptor with the Convair XFY-1 Pogo and Lockheed XFV-1 Salmon X-planes.
Technical Data:
Crew: Pilot only
Powerplants: 3x Pabst ramjets, each of 2,000 lb thrust augmented by three undetermined Walter liquid fuel rocket motors or two standard German Walter 109-501 RATO units of 3,306 lb thrust each
Wing-Rotor diameter: 38 ft
Overall Length: 30 ft
Weight loaded: 5,200 lb
Max. Speed: 621 mph est.
Armament: 2x 30mm MK-103 + 2x 20mm MG-151
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Fw Triebflügel in VTO
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