Entering service in 1948, the B-36 was the primary nuclear weapons delivery vehicle of Strategic Air Command (SAC) until it was replaced by the jet-powered Boeing B-52 Stratofortress beginning in 1955.

[2] The United States would need a new bomber to reach Europe and return to bases in North America,[3] necessitating a combat range of at least 5,700 mi (9,200 km), the length of a Gander, Newfoundland–Berlin round trip.

[6] These requirements were too demanding and far exceeded the technology of the day,[4] so on 19 August 1941, they were reduced, to a maximum range of 10,000 mi (16,000 km), an effective combat radius of 4,000 mi (6,400 km) with a 10,000 lb (4,500 kg) bomb-load, a cruising speed between 240 and 300 mph (390 and 480 km/h), and a service ceiling of 40,000 ft (12,000 m)[3] The ceiling in both cases was chosen to exceed the maximum effective altitude of most of Nazi Germany's anti-aircraft guns.

[2][10] The Boeing B-47 Stratojet, its jet engined counterpart, did not become fully operational until 1953, and lacked the range to attack the Soviet Union from North America without aerial refueling and could not carry the huge Mark 16 hydrogen bomb.

[2] Moreover, the B-36 was believed to have "an ace up its sleeve": a phenomenal cruising altitude for a piston-driven aircraft, made possible by its huge wing area and six engines, putting it out of range of most interceptors, as well as ground-based anti-aircraft guns.

The wings of the B-36 were large even when compared with present-day aircraft, exceeding, for example, those of the C-5 Galaxy, and enabled the B-36 to carry enough fuel to fly the intended long missions without refueling.

[18] The propulsion system of the B-36 was unique, with six 28-cylinder Pratt & Whitney R-4360 Wasp Major radial engines mounted in an unusual pusher configuration, rather than the conventional tractor propeller layout of other heavy bombers.

The large, slow-turning propellers interacted with the high-pressure airflow behind the wings to produce an easily recognizable very-low-frequency pulse at ground level that betrayed approaching flights.

Deliveries began in November 1948 of the combat-capable B-36B, which finally met the 1941 requirements, but had serious engine reliability and maintenance problems (changing the 336 spark plugs was a task dreaded by ground crews) and with the availability of weapons and spares.

The B-36J-III configuration (the last 14 made) had a single radar-aimed tail turret, extra fuel tanks in the outer wings, and landing gear allowing the maximum gross weight to be increased to 410,000 lb (190,000 kg).

[34] In particular, the United States Navy saw it as a costly bungle, diverting congressional funding and interest from naval aviation and aircraft carriers in general, and carrier–based nuclear bombers in particular.

To this end, the Navy designed USS United States, a "supercarrier" capable of launching huge fleets of tactical aircraft or nuclear bombers.

Several high-level Navy officials questioned the government's decision in cancelling the United States to fund the B-36, alleging a conflict of interest because Johnson had once served on Convair's board of directors.

[35]: 42 The congressional and media furor over the firing of Admiral Denfeld, as well as the significant use of aircraft carriers in the Korean War, resulted in the Truman administration subsequently ousting both Johnson and Matthews, and procuring Forrestal-class supercarriers, which were similar in size to United States, but geared towards multirole use with air wings of fighter, attack, reconnaissance, electronic warfare, early warning and antisubmarine-warfare aircraft.

[citation needed] Normal maintenance consisted of tedious measures, such as changing the 56 spark plugs on each of the six engines which were often fouled by the lead in the 145 octane antiknock fuel required.

Since even an aircraft with the range of the B-36 needed to be stationed as close to enemy targets as possible, this meant the plane was largely based in the extreme weather locations of the northern continental United States, Alaska, and the Arctic.

[38] In 1950, Consolidated-Vultee developed streamlined pods that looked like large drop tanks that mounted on each side of the fuselage to carry spare engines between bases.

Veteran crews recall feeling confident in their ability to fly the missions, but not to survive weapon delivery, as the aircraft were not fast enough to escape the blast.

[citation needed] Other experiments involved providing the B-36 with its own fighter defense in the form of parasite aircraft carried partially or wholly in a bomb bay.

[49] One of the essential criteria of the early postwar reconnaissance aircraft was the ability to cruise above 40,000 ft (12,000 m), a level partly determined by knowledge of the capability of Soviet air-defense radar.

The main Soviet air-defense radar in the 1950s was the American-supplied SCR-270, or locally made copies, which were only effective up to 40,000 ft (12,000 m) – in theory, and an aircraft cruising above this level likely would remain undetected.

RB-36 aircraft operating from RAF Sculthorpe in England made a number of overflights of Soviet Arctic bases, particularly the new nuclear weapons test complex at Novaya Zemlya.

RB-36s performed a number of rarely acknowledged reconnaissance missions and are believed to have frequently penetrated Chinese (and Soviet) airspace under the direction of General Curtis LeMay.

[citation needed] Two major factors contributing to the obsolescence of the B-36 and its phaseout were a lack of aerial refueling capability and its low speed which made it vulnerable to interceptors and severely decreased its ability to reach Soviet targets.

52-2827, 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.

[63] On Labor Day, Monday, 1 September 1952, a tornado hit Carswell Air Force Base, Fort Worth, damaging aircraft of the 7th and 11th Bomber Wings' complement of B-36s.

[67] On 4 November 2016, however, an object similar to the bomb was reported to have been located by a diver near the Haida Gwaii archipelago , 50 mi (80 km) off the coast of British Columbia.

On 22 May 1957, a B-36 accidentally dropped a Mark 17 thermonuclear bomb 4.5 mi (7.2 km) away from the control tower while landing at Kirtland Air Force Base in Albuquerque, New Mexico.

The weapon had come loose from its mounts and fell through the bomb bay doors, and sending the aircraft into an uncontrollable climb due to the sudden and unexpected weight shift.

[61][70] Data from National Museum of the U.S. Air Force[71]General characteristics Performance Armament In 1949, the B-36 was featured in the documentary film, Target: Peace, about the operations of the 7th Bombardment Wing at Carswell AFB.