The Fairey Delta 2 or FD2 was a British supersonic experimental aircraft produced by the Fairey Aviation Company in response to an Air Ministry specification from the UK to investigate the conditions flight and control in transonic and supersonic speeds. The first Delta 2, WG774 , was rebuilt by British Aircraft Corporation (BAC), when Fairey was absorbed in 1960, was rebuilt FD2 called BAC 221 . The main objective of 221 &#8203;&#8203;BAC test was under the aerodynamic development program Concorde supersonic passenger transport. It was equipped with new wings, modified air intakes, Vertical drift changed and enlarged undercarriage to mimic the behavior of the ground Concorde. Numerous tests conducted from 1964 to 1973, when it was decommissioned.