VFW SG 1262 Schwebegestell

As part of the development of the VFW-Fokker VAK 191B vertical take-off aircraft, it was necessary to configure and test the monitoring of its flight control system. In order to minimise costs and risks during the development of the 191B the SG 1262 rig was designed and built in 1966 to simulate essential functions. Of high importance was the necessity to test the fly-by-wire flight control system, a redundant flight controller and a self-diagnosis system. A total of approximately 650 hours of simulation time, 2,000 hours of test runs on system test benches and 6,900 hours of wind tunnel tests were documented during the design phase of the project.^[2][3]

The aircraft was based on a trapezoidal frame without any skin panels. Deviating from the vectored thrust engine concept of the VAK 191B, five Rolls-Royce RB.108 turbojet lift engines with 9 kN (2,000 lbf) thrust each were mounted vertically. In addition to extensive sensor equipment, the rig used an auxiliary gas turbine for autonomous electrical power supply, it was also fitted with a Martin-Baker ejection seat.^[3]

The control commands were transmitted via an electrical control (fly-by-wire) system with mechanical feedback. The flight control system had triple redundancy and double electro-hydraulic servo units with integrated self-monitoring. The control commands for the three axes were accomplished with compressed air nozzles that were actuated by a 280 bar (4,000 psi) high-pressure hydraulic system, movement of the main engines for control purposes was deliberately omitted. A direct mechanical back up of the compressed air control system was provided for emergencies.^[3]

40 tethered flights were initially carried out using a fixed telescopic apparatus before the aircraft flew in free flight for the first time on 5 August 1966. 150 free flights were made during the 18-month test program, including a demonstration flight at the 1968 Hanover Air Show at Hanover-Langenhagen.^[3]

Despite the discontinuation of all German vertical take-off programs the findings from experiments with the SG 1262 and experience gained from the VAK 191B project were used by German engineers during the development of the Multi Role Combat Aircraft (MRCA) project which became the Panavia Tornado.^[3]

The SG 1262 is preserved and on display at the Bundeswehr Museum of German Defense Technology in Koblenz.^[4]

 

Data from Flugrevue ^[3]

General characteristics

• Crew: 1
• Gross weight: 3,900 kg (8,598 lb)
• Fuel capacity: 800 kg
• Powerplant: 5 × Rolls-Royce RB.108 turbojet engines, 9 kN (2,000 lbf) thrust each

Performance

• Maximum speed: 75 km/h (47 mph, 40 kn)
• Endurance: 12 minutes
• Service ceiling: 200 m (660 ft)
• Thrust/weight: 1.15

• NBMR-3 - A 1961 NATO requirement for V/STOL military aircraft designs

Aircraft of comparable role, configuration, and era

• Aérospatiale Ludion
• Lunar Landing Research Vehicle
• Rolls-Royce Thrust Measuring Rig - A similar but earlier (1954) VTOL research aircraft

Related lists

• List of VTOL aircraft

• Taylor, John W.R. Jane's Pocket Book of Research and Experimental Aircraft, London, Macdonald and Jane's Publishers Ltd, 1976. ISBN 0356 08409 4.
• Kuckuk, Pophanken and Schalipp. Ein Jahrhundert Luft- und Raumfahrt in Bremen, Edition Falkenberg, 2016 (German language). ISBN 395494071X

 

Wikimedia Commons has media related to VFW SG 1262.

• V/STOL Fighter Programs in Germany: 1956-1975 PDF, in flight image of SG 1262, p. 39