Both Heinkel (based on Heinkel He 231) and Messerschmitt (Messerschmitt Me X1-21) had developed designs to meet the requirements of VTOL flight and by 1959, the two companies, along with Bölkow, had created a joint venture company, called EWR, to develop and manufacture an envisioned supersonic fighter aircraft, designated as the "VJ 101 D". As conceived, the production VJ 101 D aircraft was to be powered by the Rolls-Royce/MAN Turbo RB153 engine, which was to be equipped with thrust deflection apparatus. During late 1960, EWR presented their VJ 101 D concept to the BMVg. After performing a review of the proposal, the BMVg decided to issue an order for two experimental aircraft with a view to evaluating their ability towards fulfilling the standing interceptor requirement.