VFW VC 400
| VFW VC 400 | |
|---|---|
| Type: | VTOL - transport aircraft project |
| Design country: | |
| Manufacturer: | |
The VFW-Fokker VC 400 was a project for a vertical takeoff and landing transport aircraft made by the German manufacturer VFW-Fokker in the 1960s. The four rotors of the convertible aircraft should be arranged in pairs on tiltable tandem wings . In contrast to similar paper projects from this time, the VC 400 reached the stage of test bench construction. The project was abandoned in 1971 for financial reasons before the test rig was completed (construction stage A).
The VC 400 was intended to be used as a medium-weight VTOL transport aircraft on medium and short-haul routes for civil and military purposes.
history
prehistory
The origins of the VC 400 go back to a patent application by Henrich Fockes in March 1955 for a convertible aircraft with pivoting propellers. At meetings held in December 1962 at the Federal Association of the German Aerospace Industry , it turned out that VFW and Heinkel had very similar ideas about the conception of a VTOL transporter. After the merger of VFW and Heinkel in 1964, the newly formed company continued the work under the direction of Siegfried Günter and carried out the first studies for a tilt-wing aircraft. Previous studies had shown that the first generation of VTOL aircraft could not take advantage of the jet propulsion, which was attractive per se, due to the lack of suitable engines. In order to achieve an early realization of an operational V / STOL aircraft, the western aviation industry concentrated on tilt-wing aircraft with propeller drive. The recommendation of the USAF System Command, which came out in favor of a tilt-wing aircraft with propeller drive as part of the LIT ( Light-Intratheater Transport ) program , was a confirmation of this concept.
In addition to the general advantages of a tilt-wing aircraft, which, for example, does not require any additional lift engines, has helicopter-like properties when hovering and can take off and land on grass or arable land, additional advantages have been identified for the tandem wing concept. According to VFW, this is the optimal concept for the arrangement of four large-diameter propellers, VTOL stabilization is possible without tail rotor or cyclic blade adjustment , large pitch control torques can be used in the VTOL flight phase and the wing area is relatively small. For the VC 400 project, more than 2000 hours were spent on wind tunnel studies. The results formed the basis for the definition of the VC 400 at the end of 1968.
Development planning
In accordance with the planned development program, work on the “VC 400 test stand” began at the end of 1968 and was scheduled to last for around four years. The client was the Federal Ministry of Defense , which shared the financing with VFW-Fokker, the Motoren- und Turbinen-Union (MTU) and the United Aircraft International Standard Division (USA). The development of the test bench was part of the so-called "basic development VC 400". The second part, which was to be worked on in parallel at times, concerned the system development and the construction of two test aircraft that were to take off for the first flight in mid and late 1973. The construction of a pilot series of the military version was planned according to the development program from mid-1974, the civilian pilot series a year later. Military readiness for action should be achieved in 1977.
The ground test stand at VFW-Fokker in Speyer should be completed by the end of 1971 and already consist of aircraft parts. According to the plan, the completion of a hover frame was planned in order to be able to test the concept in hover flight. In development stage B, the testing should be extended to transition and high-speed flight with two test aircraft. The test aircraft V1 and V2 had the completion date in mid and late 1973.
construction
Four T64-GE-7 turboprop engines with 3980 hp each were planned for the test aircraft. The engine speed of 15,600 min −1 is reduced to the propeller speed of 745 min −1 via a two-stage planetary gear . The three-blade propellers have a diameter of 7 m and are designed in a conventional steel blade spar construction.
A shaft system is used to compensate for a possible engine failure while hovering and during the transition. The two engines of one wing are connected and a longitudinal shaft in the fuselage also connects the two wings. The tubular steel shafts can transmit a maximum of 4000 hp in the event of an engine failure.
Of the two wings, the longer one is at the rear. The four propellers with a diameter of 7 meters each are arranged in a square and can be swiveled with the wings. A free-wheeling turboprop engine is arranged behind each propeller . The propellers are mechanically coupled by two transverse and one longitudinal shaft. During a vertical take-off, they are placed upwards, while in forward flight they are oriented towards the front.
variants
An even larger model, the VC500 , was supposed to carry 7.5 tons of payload at 400 knots, but did not get beyond the design stage.
Technical classification
This construction method was rarely put into practice. So far, with the Bell X-22 and the Curtiss-Wright X-19 , which used tilt rotors and no tilt wings, only two realized examples of this design have become known. Currently (2017), however, with the Bell-Boeing Quad TiltRotor , another project is in an unspecified concept stage.
See also
literature
- Gerd Mentzel: VC 400 - a German contribution to the development of a VTOL transporter (aerospace technology) . In: Flug Revue May 1966, pp. 89-92, 101-104
- H. Räbel: Basic development VFW-Fokker VC400 (aerospace engineering) . In: Flug Revue November 1970, pp. 40–42
Web links
- [1]
- Brief description in FLIGHT of February 4, 1971
- Classification of the VC 400 in the VTOL development history of the Federal Republic of Germany
- Spiegel report in which the VC 400 is mentioned as the last remaining German VTOL aircraft
- Pictures of the VC400 on www.aviastar.org
- Pictures of the VC500 on www.aviastar.org