page_title: Convair B-36 Peacemaker
section_title: Engine fires
hierarchical_section_title: Convair B-36 Peacemaker / Operational history / Engine fires
caption_attribution_description: English: 11th Bombardment Wing Convair B-36J-5-CF Peacemaker (52-2225), 1955, showing "Six turnin', four burnin"
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: As engine fires occurred with the B-36's radial engines, some crews humorously changed the aircraft's slogan from "six turning, four burning" into "two turning, two burning, two smoking, two choking, and two more unaccounted for." This problem was exacerbated by the propellers' pusher configuration, which increased carburetor icing. The design of the R-4360 engine tacitly assumed that it would be mounted in the conventional tractor configuration—propeller/air intake/28 cylinders/carburetor—with air flowing in that order. In this configuration, the carburetor is bathed in warmed air flowing past the engine, so is unlikely to ice up. However, the R-4360 engines in the B-36 were mounted backwards, in the pusher configuration—air intake/carburetor/28 cylinders/propeller. The carburetor was now in front of the engine, so could not benefit from engine heat, and also made more traditional short-term carburetor heat systems unsuitable. Hence, when intake air was cold and humid, ice gradually obstructed the carburetor air intake, which in turn gradually increased the richness of the air/fuel mixture until the unburned fuel in the exhaust caught fire. Three engine fires of this nature led to the first loss of an American nuclear weapon when a B-36 crashed in February 1950.
caption: B36-J (serial 52-2225) of the 11th Bombardment Wing in 1955 showing "six turning, four burning"
exif: {"Image Make": "HP", "Image Model": "HP ojp7700", "Image XResolution": "300", "Image YResolution": "300", "Image ResolutionUnit": "Pixels/Inch", "Image Software": "Paint Shop Pro Photo 12.01", "Image DateTime": "2012:03:19 15:51:48", "Image YCbCrPositioning": "Co-sited", "Image ReferenceBlackWhite": "[0, 255, 128, 255, 128, 255]", "Image ExifOffset": "274", "EXIF ExifVersion": "0220", "EXIF DateTimeOriginal": "2012:03:19 15:48:31", "EXIF ComponentsConfiguration": "YCbCr", "EXIF FlashPixVersion": "0100", "EXIF ColorSpace": "sRGB", "EXIF ExifImageWidth": "1864", "EXIF ExifImageLength": "1116", "Interoperability InteroperabilityIndex": "\u0002\u0002\u0002\u0002", "Interoperability InteroperabilityVersion": "[3, 0, 0, 0]", "EXIF InteroperabilityOffset": "970", "EXIF Saturation": "Normal", "EXIF Sharpness": "Normal", "EXIF DeviceSettingDescription": "[1, 0, 19, 0, 32, 32, 32, 48, 65, 48, 32, 32, 32, 55, 65, 48, 32, 32, 32, 56, ... ]"}