Convair B-36

B-36J Peacemaker
Convair B-36
Description
Role	Long-range strategic heavy bomber
Crew	15
Dimensions
Length	162 ft 1"	49.40 m
Wingspan	230 ft	70.10 m
Height	46 ft 8"	14.22 m
Wing area	4772 sq ft	443.3 m²
Weights
Empty	171,035 lbs	77,580 kg
Loaded	266,100 lbs	120,701 kg
Maximum take-off	410,000 lbs	185,973 kg
Powerplant
Engines	6 Pratt & Whitney R-4360-53 Wasp Major 4 GE J47-GE-19 turbojets
Power	Wasp: 3,800 hp (22,800 hp total) J47: 5200 lbs (20,800 lbs total)	2461 kW (14766 kW) 2359 kg (9436 kg total)
Performance
Maximum speed	439 mph	707 km/h
Combat range	~3,400 mi	~ 5500 km
Ferry range	~8,000 mi	~ 12900 km
Service ceiling	44,000 ft	13.5 km
Rate of climb	1920 ft/min	9.75 m/s
Armament
Guns	16 20 mm M24A1 cannon, paired in 6 retractable turrets plus nose and tail turrets
Bombs	72,000 lbs (normal) 86,000 lbs (max)	32,700 kg (normal) 39,000 kg (max)

The Convair B-36 (officially named the "Peacemaker", but the name is rarely used) was an American strategic bomber aircraft, and the largest bomber ever flown by the United States. The design process began in 1941, the first prototype flew in 1945, and the first production aircraft was delivered in 1947. As the only truly long-range bomber in service, the B-36 provided the United States and the newly formed United States Air Force's Strategic Air Command with the mainstay of its nuclear deterrent until the mid 1950s when the B-52 Stratofortress became operational. The last B-36 was withdrawn from service in 1959.

Design

The B-36 concept began with Consolidated Aircraft's successful proposal to meet a 1941 USAAC intercontinental bomber requirement. If Britain fell, bombers would have to reach Europe directly in the event of the USA joining a European war. Though that never happened, the B-36 was still considered necessary to take the war to Japan, and development continued.

The B-36 took shape as a six-engined aircraft of immense proportions; a 230 ft wingspan, and 163 ft in length. The engines, six Pratt & Whitney Wasp Major 28-cylinder radials, were mounted embedded in the thick wings driving (at half engine speed, to keep the tips subsonic) immense 19 ft diameter three-bladed propellers in pusher configuration, to avoid propeller turbulence interfering with wing lift and aerodynamics. The 7.5 ft thick wing roots allowed the flight engineer to maintain the engines during flight.

As in the Boeing B-29 Superfortress, a pressurised flight deck and crew compartment was linked to the rear gunners' compartment by a pressurised tunnel equipped with a wheeled trolley to ride upon. A crew of fifteen was needed; pilot and co-pilot, radar/bombardier, navigator, flight engineer, two radiomen, and eight gunners (3 forward, 5 rear). Four bunks were provided for rest and relief, as well as a galley in the rear compartment.

Defensive armament was six remote-controlled retractable gun turrets, a tail turret and a nose mounting, each fitted with two 20mm cannon; this was the most powerful defensive armament ever carried by a bomber. The maximum bomb load was 72,000 pounds in four giant bomb bays.

The first prototype featured giant 110 inch diameter single-wheel main undercarriage, but this restricted it to only three airfields in the entire United States that were strong enough to take the load; production aircraft had four-wheel undercarriages.

Prototypes

The first prototype XB-36 flew on August 8, 1946. Its speed and range failed to meet requirements, and there were large numbers of problems, to be expected for a groundbreaking design. A second prototype, the YB-36, flew on December 4, 1947; it featured a redesigned high-visibility 'bubble' canopy, adopted for production, and was much closer to the production aircraft.

Early production

The first of 21 B-36A planes were delivered in 1948. No defensive armament was fitted (the system wasn't ready), and they were explicitly interim planes for crew training and conversion. Once newer B-36B aircraft were introduced, the B-36As were converted to RB-36E reconnaissance planes.

73 full production B-36B aircraft were delivered starting in November of 1948. The B-36B met or exceeded all the 1941 requirements but was still plagued by problems, especially with the defensive armament and engine reliability; parts supply problems left availability poor.

Even at this stage, many considered the B-36 effectively obsolete; as a piston-engined aircraft in an age of jet fighters, there were many doubts as to its effectiveness and survivability. However, the available jet bombers were still hugely limited in range, and the B-36 was the only truly intercontinental bomber available. Increasing concern about the Soviet threat kept the B-36 program alive and the aircraft in service.

Jet assistance

The B-36 suffered from long, lumbering takeoff runs and a low top speed. Convair addressed this in the new B-36D model by providing auxiliary jet engines for short-term boosts in power. Pods mounted under each outer wing contained pairs of General Electric J47-GE-19 turbojets modified to run on gasoline fuel. 26 B-36D aircraft were built new, and 64 B-36B aircraft were converted to B-36D specification.

The B-36F (34 built) improved on this by having 3,800 hp engines, up from 3,500 hp, and improved radar. The B-36H (83 built, and 73 RB-36H) followed, with improved tail turret gunlaying radar and a redesigned crew compartment. The jets had traded range for performance, and the final B-36J version added 2770 gallons of fuel in the outer wing panels.

Featherweights

Heavy defensive armament was falling out of favor by this time. Air-to-air missiles' range made hand-aimed guns obsolete; in addition, the B-36's remote power turrets were heavy, complex and unreliable. The final fourteen aircraft were therefore delivered as featherweights - all guns except for the radar-aimed tail turret were deleted, the observation blisters were replaced by flat windows, and the crew was reduced to 13. This enabled the aircraft to climb to 50,000 feet or more, and fly longer and farther. Some other B-36 aircraft were modified to featherweight configuration, including many reconnaissance versions, where range and endurance were especially valuable.

Reconnaissance versions

The B-36 was especially suited for reconnaissance missions; its giant size enabled it to carry large amounts of equipment, including huge, high resolution cameras; its high cruising altitude made it hard to intercept; and its long range and great endurance enabled very long distance missions. The first recon version was the RB-36D, of which 17 were built and 7 converted from B-36Bs. The aft bomb bay was converted into extra fuel tanks to give a maximum 50-hour endurance. All of the B-36A aircraft were converted into the very similar RB-36E.

24 new planes were built in 1951, designated RB-36F and equivalent to the B-36F, while 73 RB-36H versions were acquired during late 1952 and 1953.

More than a third of all B-36 models were reconnaissance models, and before the advent of the Lockheed U-2 in the late 1950s, the RB-36 was the mainstay of US photo-reconnaissance over hostile territory. They definitely flew over China, where Russian-supplied MiGs could not reach them; it is believed that missions approaching or even overflying the Soviet Union were also undertaken. The later RB-36 models, it is said, could reach almost 60,000 feet of altitude, and stay aloft for 50 hours.

Withdrawal from service

As the B-52 Stratofortress entered service, the B-36 fleet was scaled back. However, defense cutbacks of the late 1950s slowed the delivery of B-52s, keeping some B-36 aircraft in service through 1958, the aircraft retained being the latest B-36J models. The last aircraft in service, the final B-36J built, was withdrawn from service and donated to the city of Fort Worth, Texas on February 12, 1959.

Experiments

Some B-36s were used for a variety of experiments. The most bizarre was the NB-36H flying nuclear reactor testbed. An operational nuclear reactor was fitted in the aft bomb-bay of the aircraft; a 4-ton lead shield was fitted in front of the bomb bay, and the crew was encased in a lead and rubber capsule with a tiny, foot-thick leaded glass windshield. The nuclear reactor, though operational, performed no useful work; in preperation for planned nuclear powered aircraft, experiments were to be performed to see if the radiation would damage aircraft systems. The aircraft first flew in this configuration in 1955; following the abandonment of the nuclear aircraft program, it was scrapped in 1957, the radioactive parts being buried.

Other experiments included the carriage of jet fighters by the B-36 for defensive purposes. One plan was a tiny 'parasite' jet fighter, the McDonnell XF-85 Goblin, which could be carried in a B-36 bomb bay. The concept was tested successfully, but docking with the 'mothership' proved difficult for even experienced test pilots, budgets were short, and the XF-85 was feared no match for Soviet fighters in any case; the project was cancelled.

Another project, FICON, involved modifying F-84 Thunderjet fighters so that they could be carried by specially modified B-36 aircraft. This was more successful, with ten B-36D bombers being modified into GRB-36D hosts to carry the 25 modified RF-84K reconnaissance Thunderjets ordered. These saw active service until 1959 when they were quietly withdrawn as newer reconnaissance planes were introduced.

Summary

The B-36, although giant, lumbering and somewhat outdated, was the linchpin of the United States' nuclear deterrent until faster jet bombers with sufficient range could be introduced. The B-36 was never tested in combat and it is impossible to say how well they would have fared. The SAC argument was that few fighters could reach the B-36 at its maximum altitude, and those that could were so lacking in maneuverability at that height that the B-36 could easily evade them. Others challenge this statement.

While its role in the strategic deterrent gained all the publicity, it is possible that its unsung role in reconnaissance was just as valuable. It is believed that RB-36 aircraft were involved in numerous penetrations of Soviet and Chinese airspace, and the giant cameras carried could produce photographs of incredible clarity (pictures of a golf course taken at 40,000 feet on test showed recognisable golf balls).

Surviving examples

Four B-36 aircraft survive, one a B-36H and the other 3 being B-36J models. B-36H serial 51-13730 is on display at the Castle AFB museum. Of the three B-36J models, serial number 52-2217 is on display at the SAC Museum at Offutt AFB, 52-2220 is on display at the WPAFB Museum, and serial number 52-2827, the last B-36 built, is on display at its home town of Fort Worth, Texas. It is unlikely any will every fly again; the B-36 was a challenge to keep running even when new.

Derived aircraft

The B-36 was replaced in service by the Boeing B-52 Stratofortress; Convair's challenger, a jet-powered, swept-wing development of the B-36, was awarded a contract for two prototype Convair YB-60 airplanes, one of which flew. It was an inferior aircraft to the B-52 and the second prototype was not completed.

A transport version of the B-36, the Convair XC-99, was developed and one prototype flew, but the aircraft never went into production.

External links

Smithsonian's Air and Space Magazine article from 1996: http://www.airspacemag.com/ASM/Mag/Index/1996/AM/bacr.html

A group of B-36 veterans have a site dedicated to information about this plane: http://www.cowtown.net/proweb/B36_Home.htm

Specifications and history: http://www.csd.uwo.ca/~pettypi/elevon/baugher_us/b036i.html

Referenced By