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.

Operationally, it was intended to have been armed with nuclear weapons as a deterrent against aggression from the Soviet Union and, in the event of a major war breaking out, to survive the first wave of attacks by deploying to dispersed locations, rather than conventional airfields, and to retaliate against targets behind enemy lines.

[2] 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.

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.

[7] The VAK 191B was similar in concept to the British Harrier jump jet, but was designed for a supersonic dash capability (Mach number 1.2–1.4) at medium to high altitudes.

By contrast, the Harrier possessed a significantly higher thrust-to-weight ratio, it was effective as a dogfighter, and had larger wings which were put to good use when performing rolling short takeoffs.

[1] The slow progression can be viewed as a natural result of specification changes, such as a revised operational requirement that called for the aircraft to possess greater manoeuvrability issued during 1965.

At one stage, the prototypes were used for testing some of the concepts that were then being considered for the European MRCA programme (which led to the Panavia Tornado strike fighter), including the use of fly-by-wire technology.