The Martin XB-51 was a three engine jet ground attack aircraft that reached the prototype stage but didn’t enter production.
The Martin Model 234 was designed in response to an USAAF requirement for a close support bomber, and was originally given the designation of XA-45. The Air Force then abandoned the ‘Attack’ designation, and the aircraft became the XB-51.
The XB-51 had a long narrow fuselage, with short swept back wings mounted quite far forward (with tips about half way back along the fuselage). It had a ‘T’ tail, with the horizontal surfaces mounted at the top of quite a tall tail. The thin wings couldn’t take normal landing gear, and so the ‘bicycle’ system used on the XB-48 was adopted. This saw two sets of main wheels installed at the front and back of the fuselage, with smaller balance wheels at the wing tips.
The most unusual feature of the aircraft was the layout of its three GE J47 turbojets. Two were carried in pods that were carried below the forward fuselage, one on each side. The third was carried at the rear of the fuselage, with its air intake above the fuselage and the jet pipe in the tail.
The aircraft carried a crew of two - pilot and radio operator - in a pressurised cabin close to the nose. The angle of incidence of the wings could be altered to improve the aircraft’s characteristics when landing and taking off.
The first prototype made its maiden flight on 28 October 1949. It performed well, and was considered to be reliable and have good handling, but despite this no order was placed, partly because of its poor endurance and less impressive manoeuvrability. The B-51 lost out to the English Electric Canberra, which became the first foreign designed aircraft to see service with the USAF after the Second World War. However Martin didn’t entirely lose out, as they were given the contract to produce the American Canberras, under the designation B-57.
Engine: Three General Electric J47-GE-7 or -13 turbojets
Span: 53ft 1in
Length: 85ft 1in
Height: 17ft 4in
Empty Weight: 29,584lb
Gross Weight: 55,932lb
Maximum Speed: 645mph
Cruising Speed: 532mph
Climb rate: 6,980 ft/ min
Range: 1,600 miles