Martin-Baker performed in-house studies of aircraft projects beyond that of the M.B.5 fighter of 1945. These were not to any official British specification but rather to test out different ideas concerning both high-speed flight and the development of aircraft escape systems- especially ejection seats. In late 1945 a high-speed interceptor concept was contemplated with the intention of mounting a mammoth 32 cylinder ultimate project Rolls-Royce RR-Guinevere "X-engine" of 4,400 hp driving a 6-blade superprop. The "X-engine" concept was envisioned as four banks of eight cylinders each with twin exhaust ports on either side of the long bullet-shaped forward fuselage. This configuration of engine had already been suggested for a British super heavy tank program but ruled out as too exotic with only one quarter of the hp output. Estimated maximum speed for the long nose machine would be well over 550 mph! The aircraft was to be covered in a black aerosheen gloss finish giving the concept aircraft the nickname "Black Bess". Small flight models were made but the concept was abandoned in 1947 with the further development of both British jet aircraft and Rolls-Royce centrifugal jet engines. The "Black Bess" name was attributed not only to the black aerosheen gloss coating for speed and tremendous hp of the engine but due to the fact that the engineers scoffed at the estimates that this aircraft could attain 550 mph in level flight and easily Mach 1 in a "short dive"- which was said to be just as "impossible" as highwayman robber Dick Turpin's "legendary" ride with his horse Black Bess! In almost all of Martin-Baker's historical references both the earlier M.B.6 WW2 jet aircraft project with an odd spring-loaded swing-arm ejection seat and the fantastic M.B.7 concept are omitted because they had little chance of success and were just novelties. Martin-Baker is known for the incredible performance aircraft M.B.5 (Britain's Mustang) and for developing zero/zero ejection seats.

No illustrations of the M.B.7 and even M.B.6 is rare; however, there are plenty of pics of the 1945 M.B.5 below with the last being a drawing of the claimed M.B.6. M.B.7 would have been more bullet shaped than M.B.5 with a massive X-engine and 6-plade prop! http://www.airplanesandrockets.com/airplanes/images/martin-maker-mb5-may-1971-aam-0.jpg http://roys-rc-tv.webs.com/MB+5.jpg http://www.ww2aircraft.net/forum/attachments/aircraft-requests/38405d1299770035t-british-possible-battle-britain-fighters-never-made-mb-6.jpg