page_title: Convair B-36 Peacemaker
section_title: Weaponry
hierarchical_section_title: Convair B-36 Peacemaker / Design / Weaponry
caption_attribution_description: English: Dismounted B-36_Peacemaker gun turret at the National Museum of the United States Air Force, Dayton, Ohio
context_page_description: The Convair B-36 "Peacemaker" is a strategic bomber built by Convair and operated by the United States Air Force from 1949 to 1959. The B-36 is the largest mass-produced piston-engined aircraft ever built. It had the longest wingspan of any combat aircraft ever built, at 230 ft. The B-36 was the first bomber capable of delivering any of the nuclear weapons in the U.S. arsenal from inside its four bomb bays without aircraft modifications. With a range of 10,000 mi and a maximum payload of 87,200 lb, the B-36 was capable of intercontinental flight without refuelling.
  Entering service in 1948, the B-36 was the primary nuclear weapons delivery vehicle of Strategic Air Command until it was replaced by the jet-powered Boeing B-52 Stratofortress beginning in 1955. All but four aircraft have been scrapped.
context_section_description: The four bomb bays could carry up to 87,200 pounds (39,600 kg) of bombs, more than 10 times the load carried by the World War II workhorse, the Boeing B-17 Flying Fortress, and substantially more than the entire B-17's gross weight. The B-36 was not designed with nuclear weaponry in mind, because the mere existence of such weapons was top secret during the period when the B-36 was conceived and designed (1941–46). Nevertheless, the B-36 stepped into its nuclear delivery role immediately upon becoming operational. In all respects except speed, the B-36 could match what was arguably its approximate Soviet counterpart, the turboprop-powered Tu-95, which began production in January 1956 and was still in active service as of September 2019. Until the B-52 became operational, the B-36 was the only means of delivering the first generation Mark-17 hydrogen bomb, 25 ft (7.6 m) long, 5 ft (1.5 m) in diameter, and weighing 42,000 lb (19,000 kg), the heaviest and bulkiest American aerial nuclear bomb ever. Carrying this massive weapon required merging two adjacent bomb bays.
  The 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, for a total of 16. Recoil vibration from gunnery practice often caused the aircraft's electrical wiring to jar loose or the vacuum tube electronics to malfunction, leading to failure of the aircraft controls and navigation equipment; this contributed to the crash of B-36B 44-92035 on 22 November 1950.
  The Convair B-36 was the only aircraft designed to carry the T-12 Cloudmaker, a gravity bomb weighing 43,600 lb (19,800 kg) and designed to produce an earthquake bomb effect. Part of the testing process involved dropping two of the bombs on a single flight mission, one from 30,000 ft (9,100 m) and the second from 40,000 ft (12,000 m), for a total bomb load of 87,200 lb (39,600 kg).
  The first prototype XB-36 flew on 8 August 1946. The speed and range of the prototype failed to meet the standards set out by the USAAC in 1941. This was expected, as the Pratt & Whitney R-4360 engines required were not yet available, and the qualified workers and materials needed to install them were lacking.
  A second aircraft, the YB-36, flew on 4 December 1947. It had a redesigned, high-visibility, yet still "greenhouse-like" bubble canopy, heavily framed due to its substantial size, which was later adopted for production, and the engines used on the YB-36 were more powerful and more efficient. Altogether, the YB-36 was much closer to the production aircraft.
  The first few of 21 B-36As were delivered in 1948. They were interim airframes, intended for crew training and later conversion. No defensive armament was fitted, since none was ready. Once later models were available, all B-36As were converted to RB-36E reconnaissance models. The first B-36 variant meant for normal operation was the B-36B, delivered beginning in November 1948. This aircraft met all the 1941 requirements, but had serious problems with engine reliability and maintenance (changing the 336 spark plugs was a task dreaded by ground crews) and with the availability of armaments and spare parts. Later models featured more powerful variants of the R-4360 engine, improved radar, and redesigned crew compartments.
  The four jet engines increased fuel consumption and reduced range. The advent of air-to-air missiles then rendered conventional gun turrets obsolete. In February 1954, the USAF awarded Convair a contract for a new "Featherweight" design program, which significantly reduced weight and crew size. The three configurations were:
  Featherweight I removed defensive hardware, including the six gun turrets.
  Featherweight II removed the rear compartment crew comfort features, and all hardware accommodating the McDonnell XF-85 Goblin parasite fighter.
  Featherweight III incorporated both configurations I and II.
  The six turrets eliminated by Featherweight I reduced the aircraft's crew from 15 to 9. Featherweight III had a longer range and an operating ceiling of at 
caption: B-36 upper or lower gun turret with two M-24A1 20-mm cannon
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