<p>From 1948 to 1959, the B-36 formed the backbone of the US Air Force's Strategic Air Command, threatening the Soviet Union and any other nation with massive nuclear retaliation. Blessed with enormous size, power, range and presence, the B-36 remains one of the all-time 'greats' of the aviation world.
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<p>Like many of the world's greatest aircraft, the Convair B-36 was conceived for an eventuality that never materialized. Fearful of losing England as a base to strike against Nazi Germany, the US Army Air Corps on 11 April 1941 issued a requirement for a truly intercontinental bomber. The machine had to be able to span oceans in an era when inflight refueling was rare. It was expected to carry a 10,000-lb (4,536-kg) bomb load to a target 3,400 miles (5,472 km) away and return nonstop. US top brass also wanted the bomber to be capable of flying at 300 mph (482 km/h) with an operational ceiling of 35,000 ft (10,670 m). Rejecting several other proposals, the USAAC chose the Consolidated Model 37, a design with twin fins similar to those of the firm's B-24 Liberator, and with an unusual layout of six air-cooled engines in pusher configuration. Ultimately, the twin fins disappeared and various refinements went into what became the biggest bomber ever built.
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<p>The first aircraft in the series, the sole XB-36 and the only machine with a flush-type canopy (42-13570), was rolled out at Fort Worth on 8 September 1945. Nearly a year's work was needed before the mighty bomber was ready to fly. On 8 August 1946, while 7,000 Convair employees watched, the XB-36 rumbled aloft for its 36-minute first flight with test pilots Gus Green and Beryl A. Erickson at the controls. The XB-36 prototype was to remain in flying status for years and in early 1950 was used in USAF experiments with tracked landing gear, using armored vehicle-type treads instead of wheels.
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<p>Early experience revealed that pilots disliked the limited visibility afforded by the flush cabin design. Beginning with the second aircraft, designated YB-36 (42-13571), a bubble canopy was added, as was a nose-gun position, both later becoming standard for SAC machines in squadron service. This second airframe would also be a stalwart survivor, gaining a new YB-36A designation when retrofitted with the four-wheel bogie main landing gear which would later become standard, and long afterward being converted to RB-36E for the reconnaissance role. Meanwhile, the first fully operational B-36A (44-92004) flew on 28 August 1947 and was assigned to SAC's 7th Bombardment Group (Heavy), which remained a B-36 unit until February 1958. The group was stationed at Carswell AFB, on the other side of the field from the Fort Worth plant, giving the new bomber a short trip to its first destination.
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<p>After 22 B-36A aircraft (44-92004/92025) had come off the line, Convair shifted to manufacture of an improved model and turned out 73 B-36Bs (44-92026/92098). These were genuine operational bombers, fitted with the full complement of 16 20-mm cannon paired in eight turrets. In addition to nose and tail gun stations, the B-36B and later models had fully retractable, remotely controlled gun turrets in the fuselage, protected by sliding doors from the airstream and from prying eyes.
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<hi style=hdr1>Unprecedented Scale</hi>
<p>Because of the aircraft's sheer enormity (its 230-ft/70.1-m wing span exceeded the entire distance covered by the Wright Brothers on their first flight on 17 December 1903), the powerplant of the B-36 was essential to its success. The designation B-36C was assigned in 1947 to a proposed tractor version of the bomber, but this was not built. Meanwhile, the six pusher Pratt & Whitney R-4360-25 engines were refined and improved, their rating being upped from 3,000 hp (2,237 kW) to 3,500 hp (2,610 kW). it became apparent that any further increase in power would require a major change, so in March 1949 a converted B-36B was tested with a pair of jet pods slung under each wing, outboard of the piston engines. The Allison J35 turbojets initially used were soon replaced by General Electric J47s each of 5,200 lb (23.13 kN) thrust, and the radically reconfigured bomber (now with 'six turning and four burning') was redesignated B-36D, a standard to which 64 existing B-36Bs were converted while 22 more were built new. The B-36D, painted white on its underside to reflect the heat of a nuclear blast, was also identified by its faster-opening bomb bay doors and the K-3A bombing/navigation system instead of the older K-1A.
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<p>The 'bigness' of the B-36 was almost beyond words. The volume of the bomber, at nearly 18,000 cu ft (510 m<su>2</su>), was approximately the volume of three average five-room houses. A man standing on the shoulder-mounted wing could be killed in a fall to the ground. The crew of 15, increased to 22 in the RB-36D reconnaissance version, needed several intercom channels. A tunnel almost 7 ft (2.13 m) high within the wings allowed maintenance men to walk upright from the fuselage to the outer engines. So high loomed the vertical rudder, at 46 ft 8 in (14.22 m), that B-36s were almost always hangared with the tail protruding out of doors.
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<p>Strategic Air Command eventually operated 10 wings of B-36 bombers with about 30 aircraft in each wing, including RB-designated reconnaissance variants. The RB-36E (22 machines) was converted from the YB-36A and B-36As. This model was followed by the RB-36F, with increased fuel capacity. The designation B-36G was applied to the swept-wing all-jet bomber which, had it won a 'fly-off' competition, might still be in widespread service today. First flown in April 1952 and powered by eight J57 engines in four pods, this all-jet machine was redesignated YB-60 and lost out in the contest to the Boeing B-52 Stratofortress.
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<p>B-36J machines, the heaviest bomber then built at an operational weight of 410,000 lb (185,973 kg), featured increased fuel tankage in the outer wing panels and strengthened landing gear.
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<p>Flying the B-36 was a unique experience. For the officer pilots, navigators and bombardiers, it was a rare opportunity to handle a huge and mighty aircraft while travelling in comfort and style. For the enlisted man, in the last bomber having manned gun positions, it was a chance for flight pay, adventure and, again, comfort. Aircrews aboard today's B-52 cannot stand erect or walk around and prefer not to use the cramped lavatories unless absolutely necessary. By contrast the B-36 was, as one crewman put it, "an airborne Hilton Hotel." The flight deck, with its position for aircraft commander, second pilot and rearward-facing flight engineer, was simply colossal. There were three comfortable bunks in the aft cabin. At several points along the 162-ft 1-in (49.40-m) fuselage a 6-ft (1.83-m) man could stand fully erect. There is a documented story of a B-36 returning from Okinawa with 4,000 cases of whiskey on one occasion, a Nash Rambler auto on another, conveniently stashed in the plane's spacious bomb bays. Tall tales of contraband smuggling are a small but humorous part of B-36 lore; another is that crews kept a calendar on the flight deck.
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<p>Freewheeling incursions into Soviet skies are another part. A former B-36 tail gunner claims that his crew routinely flew into the Soviet Union on exercises in the mid-1950s. In the days before SAM missiles, a B-36 aircraft commander could cruise at 50,000 ft (15,240 m) secure in the knowledge that his vast wing area (4,772 sq ft/443.32 m<su>2</su>) made him more maneuverable at that height than any fighter extant. Some kind of practice for the 'real thing' would have been logical for the period: although they often deployed abroad and were seen routinely in the UK, all B-36s were permanently based in the continental USA (and Puerto Rico) and were intended for transpolar assault on Soviet population centers.
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<hi style=hdr1>Aerial Odysseys</hi>
<p>A mission in a B-36 was no simple undertaking. The pre-flight check could take several hours. The aircraft commander would make his walk-around inspection an hour before take-off. On some missions he was obliged to make certain that crew members had dispensed with all personal identification except for a laminated Geneva Convention Card giving only name, rank and service number. Crew size varied according to the model and mission, with RB-36s flying up to 42 hours and carrying relief crews. The bomber models usually carried the commander plus two more pilots, radar bombardier, navigator, crew chief (who was also nose gunner), two engineers, two radiomen, an electronic countermeasures (ECM) operator who doubled as side gunner, and three additional gunners. Once ready to fly, these men still had hundreds of details to check before and during a mission.
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<p>Take-off was made with all 10 engines, the jet powerplants being shut down once the aircraft was at cruising altitude. Each crewman had assigned tasks and, typical of SAC, a serious mood prevailed whether or not the B-36 actually carried the massive freefall thermonuclear bomb which was its intended cargo. (The era of stand-off ordnance came after the B-36; three bombers were converted to DB-36H standard to carry the Bell GAM-63 stand-off bomb, but only in tests.) During their long patrols, B-36 crews paid special heed to their parachutes, oxygen and Arctic survival gear, for a sudden loss of pressure could cause pandemonium or worse. One crew member recalls a sudden decompression which sucked him up against a suddenly-opened puncture in the fuselage and held him there until others could pry him free. Because missions often involved climatic changes, B-36 crews were trained for survival in snow or desert, heat or cold. Surprisingly, most crew members reported that they were not fatigued touching down after a mission which, even very routinely, could last over 24 hours.
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<hi style=hdr1>FICON</hi>
<p>SAC men had never forgotten how the war in Europe shifted in their favor once North American P-51 fighters could escort Boeing B-17s all the way to Berlin. They wanted fighters with them in the 1950s. When a 1949 'penetration' (escort) fighter, the McDonnell XF-88 Voodoo, failed to reach production, and also because the USSR's detonation of its own first atomic bomb gave fighter-interceptors priority, SAC's top brass posed a tantalizing question to the Air Research and Development Command: could a B-36 attack force enjoy fighter escort by carrying its own fighters along? Once over target, the fighter would be released from its B-36 'mother ship' still carrying a full load of fuel and able to fend off the interceptors of the USSR's defense force, the PVO. Reconnaissance missions could also be carried out by the 'parasite' fighters, it was argued.
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<p>The initial proposal, the McDonnell XF-85 Goblin, first tested on 23 August 1948, was a stubby fighter specifically designed to fit the dimensions of a B-36 bomb bay (although actually tested only aboard a Boeing B-29). The XF-85 proved too unorthodox and too difficult to handle. The sacrifice in performance which inevitably came with its intended function was too great.
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<p>SAC turned instead to a mating of B-36 bomber and a 'real' fighter, a Republic F-84, under the FICON (fighter conveyor) project. The mighty Convair bomber, now with the designation GRB-36F, was tested with the straight-wing F-84E Thunderjet, and the swept-wing F-84F Thunderstreak and RF-84K Thunderflash. Apart from their escort role, these jets were also seen as being launched from the B-36, near the target, for photo-taking or bomb-dropping tasks. Various methods, including 'towing' with wingtip attachments and carrying the fighter in the bomb bay, were tried. A little-known fact is that FICON, far from being merely an experiment, was fully operational for about a year, in 1955-56, before SAC turned instead to relying on inflight refueling to lengthen the 'legs' of its fighters. In 1959, coincidental with the end of the B-36's career, SAC got out of the fighter business altogether.
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<hi style=hdr1>Cargo Version</hi>
<p>The sole cargo aircraft based on the B-36 design, the Convair XC-99, was originally envisaged as a civilian airliner which would have been larger even than today's Boeing 747. American Airlines was interested. Only one XC-99 (43-52436) was actually built, however, and was used by the US Air Force, being based at Kelly AFB, Texas, for many years. The aircraft was essentially a B-36 without jet engines and with a larger fuselage; mid-way through its career a nose radome was added, altering its configuration. The double-deck XC-99 could transport 109,000 lb (49,442 kg) of cargo, or 410 fully-equipped combat troops, or 300 medical patients. It served as an effective cargo carrier and air show attraction until being retired in 1957 and placed on outdoor display at Kelly AFB. Like the all-jet version of the B-36 which flew in prototype form as the YB-60 but was markedly inferior to a newer machine called the B-52, the cargo aircraft never generated enough interest to be produced in numbers.
<item><hi format=bold>Powerplant:</hi> six 3,600-hp (2,685-kW) Pratt & Whitney R 4360-53 radial piston engines and four 5,400-lb (24.02-kN) thrust General Electric J47 19 turbojets
<item><hi format=bold>Performance:</hi> maximum speed 411 mph (661 km/h) at 36,400 ft (11,095 m); cruising speed 391 mph (629 km/h); service ceiling 39,900 ft (12,160 m); range 6,800 miles (10,945 km) with a 10,000-lb (4,536-kg) bomb load
<item><hi format=bold>Weights:</hi> empty 171,035 Ib (77,581 kg); maximum take-off 410,000 lb (185,976 kg)
<item><hi format=bold>Dimensions:</hi> span 230 ft (70.10 m); length 162 ft 1 in (49.40 m); height 46 ft 8 in (14.22 m); wing area 4,772 sq ft (443.32 m<su>2</su>)
<item><hi format=bold>Armament:</hi> 16 20-mm cannon in nose, tail and six fuselage turrets, plus a bomb load of up to 46,000 lb (20,866 kg) depending on distance flown; normal bomb load was 10,000 lb (4,536 kg) over a range of 6,800 miles (10,945 km)
