VFW VAK 191B - Design and Development

Design and Development

The VAK 191B was produced by the German company Vereinigte Flugtechnische Werke (VFW). Initially, Fiat of Italy was also involved but dropped out in 1967, though it remained as a major sub-contractor. VAK was the abbreviation for Vertikalstartendes Aufklärungs- und Kampfflugzeug (V/STOL Reconnaissance and Strike Aircraft).

Propulsion was provided by a Rolls-Royce/MAN Turbo RB.193-12 vectored thrust engine for both lift and cruise which was augmented by two vertical lift engines.

The program was begun in 1962 to replace the Fiat G.91 ground attack fighter with a VTOL aircraft but NATO requirements changed and it became a technology demonstrator. Three VAK 191B aircraft were flown in the flight test program between 1970-1975 making 91 flights. The first hovering flight was made in Bremen on 20 September 1971. The first transition from vertical flight to horizontal and vice versa was achieved on 26 October 1972 in Munich. The prototypes were used to test some of the concepts in what was to become the Panavia Tornado programme, including 'fly-by-wire' technology.

The VAK 191B was similar in concept to the British Harrier, but was designed for a supersonic dash capability (Mach 1.2-1.4) at medium to high altitudes. It was judged that having a single engine would create too much drag, but the two lift engines were dead weight in cruise, and the small cruise engine gave a poor thrust to weight ratio. It also had very small highly loaded wings. By contrast, the Harrier had a much higher thrust to weight ratio, it was effective as a dogfighter, and had larger wings which were put to good use in rolling short takeoffs.