The USA's forgotten bomber-the Convair B-36 Peacemaker By Willie Bodenstein For ten years between 1949 and 1959 the Convair B-36 Peacemaker was the primary nuclear weapons delivery vehicle of USA's Strategic Air Command (SAC) until in the beginning of 1955 when it was replaced by the jet-powered Boeing B-52 Stratofortress. The B-52 is still flying operationally today while the B-36 is almost forgotten. The requirement for a long distance bomber was first mooted in early 1941 when it was realised that Britain might fall to the German onslaught and the United States would have to start a long distance strategic bombing campaign from its own shores against the Nazi forces. The need grew with the campaign in the east against the Japanese and reached a pinnacle during the Cold War. A surviving B-36J on static display at the Pima Air & Space Museum. Photo © commons.wikimedia.org at A true behemoth of the skies, the B-36 is the largest mass-produced piston-engine aircraft ever built and was the first bomber in the USAF's arsenal capable of delivering any of the nuclear weapons in the U.S. arsenal from inside its four bomb bays. Capable of intercontinental flight without refuelling it had a range of 10,000 mi (16,000 km) and a maximum payload of 87,200 lb (39,600 kg) and was then the only American aircraft with the range and payload to carry such bombs from airfields on American soil to targets in the USSR. A B-29 being dwarfed by a B-36. Photo © United States Air Force Historical Research Agency commons.wikimedia.org Being piston-powered and slow, with no mid-air refuelling capability and coupled with the widespread introduction of first generation jet fighters in potential enemy air forces, the B-36 was arguably obsolete from the outset when it entered service. However, it had an ace or two up its sleeve; it could stay aloft for as long as 40 hours and its phenomenal cruising altitude of over 40,000 feet (12,000 m) made possible by its huge wing area and six 28-cylinder engines. Defensive armament consisted of six remote-controlled retractable gun turrets and fixed tail and nose turrets. Each turret was fitted with two 20 mm cannons giving its a total of 16. With its turrets and other nonessential equipment removed the B-36 could comfortably cruise at 50,000 feet (15,000 m) while flying at 423 miles per hour (681 km/h) thus putting it out of range ground-based anti-aircraft guns and most of the interceptors of the day. A B-36 showing of its six 28-cylinder Pratt & Whitney R-4360 'Wasp Major' radial engine. Photo © USAF The propulsion system of the B-36 was unique, with six 28-cylinder Pratt & Whitney R-4360 'Wasp Major' radial engines, each delivering 18,000 hp (13,000 kw), mounted in an unusual pusher configuration rather than the conventional four-engine, tractor propeller layout of other heavy bombers. This unusual configuration prevented propeller turbulence from interfering with airflow over the wing. Each engine drove a three-bladed propeller, 19 feet (5.8 m) in diameter, the second-largest diameter propeller design ever used to power a piston-engine aircraft. A B-36D with its two pods of twin jet engines in flight. Photo © United States Air Force / commons.wikimedia.org Beginning with the B-36D, Convair added a pair of General Electric J47-19 jet engines suspended near the end of each wing which were also retrofitted to all extant B-36Bs. The two pods with four turbojets and the six piston engines combined gave the B-36 a total of 40,000 hp (30,000 kW) for short periods of time. Personnel and equipment required to get and keep a B-36 aircraft in the air. Photo © USAF A complex weapons system took a crew of 15 housed in a pressurised flight deck and crew compartments as well as a rear compartment that featured six bunks and a dining galley to keep the B-36 aloft. Many more were needed to keep it flying. All compartments, turrets and the bomb bay were linked by pressurised tunnels and movement through which was by means of a rope and trolley system. USAF 03 A YRF-84F fighter in flight with its parent B-36 Peacemaker. Photo © USAF What however set the B-36 apart from any other aircraft ever made is the fact that two B-36s were modified in the early 1950s as part of the US's Aircraft Nuclear Propulsion (ANP) program by the installation of 1 MW, air-cooled nuclear reactor in the aft bomb. To protect the crew, the highly modified cockpit was encased in lead and rubber, with a 1-foot-thick (30 cm) leaded glass windshield. A number of large air intake and exhaust holes were installed in the sides and bottom of the aircraft's rear fuselage to cool the reactor in flight. The reactor was operational, but did not power the aircraft; its sole purpose was to investigate the effect of radiation on aircraft systems. Between 1955 and 1957, the NB-36H completed 47 test flights and 215 hours of flight time, during 89 of which the reactor was critical The withdrawal from service of the B-36 started in February 1956. Those were initially replaced by the B-52 were flown to Davis-Monthan AFB, Arizona where they were stored for reclamation and destruction. Defence cutbacks in 1958 compelled the stretching of the procurement process of the B-52s stretched the service life for a number of B-36s. Those remaining in service were supported with components scavenged from aircraft sent to Davis-Monthan. One of the surviving B-36Js in the National Museum of the United States Air Force. By December 1958 only 22 B-36Js were still operational and on 12 February 1959, the last B-36J built left Biggs AFB, Texas, where it had been on duty with the 95th Heavy Bombardment Wing and was flown to Amon Carter Field in Fort Worth, where it was put on display. Within two years, all B-36s, except five used for museum display had been scrapped at Davis-Monthan AFB.

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