vfw vak 191b the first VTOL fighter in the world

The VFW VAK 191B is an experimental German vertical take-off and landing (VTOL) strike fighter of the early 1970s. VAK was the abbreviation for Vertikalstartendes Aufklärungs- und Kampfflugzeug (Vertical Take-off Reconnaissance and Strike Aircraft). Designed and built by the Vereinigte Flugtechnische Werke (VFW), it was developed with the purpose of eventually serving as a replacement for the Italian Fiat G.91 then in service with the German Air Force. 

The VAK 191B suffered from a protracted development cycle, spanning ten years between inception and flight, On 10 September 1971, the first prototype conducted the type's maiden flight. A total of 91 flights were performed prior to the retirement of all three prototypes in 1975. These aircraft have been preserved and two of which are now on public display in museums.

During the 1950s, rapid advances in the field of jet propulsion, particularly in terms of increased thrust and compact engine units, had contributed to an increased belief in the technical viability of vertical takeoff/landing (VTOL) aircraft, particularly within Western Europe and the United States. During 1950s and 1960s, multiple programmes in Britain, France, and the United States were initiated; likewise, aviation companies inside West Germany were keen not to be left out of this emerging technology. Shortly after 1957, the year in which the post-Second World War ban upon West Germany operating and developing combat aircraft was lifted, German aviation firms Dornier Flugzeugwerke, Heinkel, and Messerschmitt, having also been allowed to resume their own activities that same year, received an official request from the German Federal Government that urged them to perform investigative work on the topic of VTOL aircraft and to produce concept designs.

As such, multiple companies commenced work on their own conceptual designs for VTOL-capable interceptor aircraft; in order for these designs to be operationally relevant and viable, it was recognised that it would be necessary for the flight performance to equal that of conventional interceptors of the era, such as the contemporary Lockheed F-104G Starfighter. Over time, two separate and distinct requirements emerged, one calling for a VTOL-capable successor to the F-104G interceptor while the other sought a VTOL successor to the Italian Fiat G.91 ground-attack fighter. According to aerospace publication Flight International, this call for a Fiat G.91 replacement, which came under a NATO requirement, known as NBMR-3, was a crucial trigger and greatly influenced the development programme that would lead to the VAK 191B.

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