Fat Man

"Fat Man" was the codename for the nuclear bomb that was detonated over the Japanese city of Nagasaki by the United States on 9 August 1945. It was the second of the only two nuclear weapons ever used in warfare, the first being Little Boy, and its detonation marked the third nuclear explosion in history. It was built by scientists and engineers at Los Alamos Laboratory using plutonium from the Hanford Site, and it was dropped from the Boeing B-29 Superfortress Bockscar piloted by Major Charles Sweeney.

The name Fat Man refers to the early design of the bomb because it had a wide, round shape; it was also known as the Mark III. Fat Man was an implosion-type nuclear weapon with a solid plutonium core. The first of that type to be detonated was the Gadget in the Trinity nuclear test less than a month earlier on 16 July at the Alamogordo Bombing and Gunnery Range in New Mexico. Two more were detonated during the Operation Crossroads nuclear tests at Bikini Atoll in 1946, and some 120 were produced between 1947 and 1949, when it was superseded by the Mark 4 nuclear bomb. The Fat Man was retired in 1950.

Fat Man
Fat man
Replica of the original Fat Man bomb
TypeNuclear weapon
Place of originUnited States
Production history
DesignerLos Alamos Laboratory
No. built120
Mass10,300 pounds (4,670 kg)
Length128 inches (3.3 m)
Diameter60 inches (1.5 m)

Filling weight14 pounds (6.4 kg)
Blast yield21 kt (88 TJ)

Early decisions

Robert Oppenheimer held conferences in Chicago in June 1942, prior to the Army taking over wartime atomic research, and in Berkeley, California, in July, at which various engineers and physicists discussed nuclear bomb design issues. They chose a gun-type design in which two sub-critical masses would be brought together by firing a "bullet" into a "target".[1] Richard C. Tolman suggested an implosion-type nuclear weapon, but the idea attracted scant consideration.[2]

The feasibility of a plutonium bomb was questioned in 1942. Wallace Akers, the director of the British "Tube Alloys" project, told James Bryant Conant on 14 November that James Chadwick had "concluded that plutonium might not be a practical fissionable material for weapons because of impurities."[3] Conant consulted Ernest Lawrence and Arthur Compton, who acknowledged that their scientists at Berkeley and Chicago respectively knew about the problem, but they could offer no ready solution. Conant informed Manhattan Project director Brigadier General Leslie R. Groves Jr., who in turn assembled a special committee consisting of Lawrence, Compton, Oppenheimer, and McMillan to examine the issue. The committee concluded that any problems could be overcome simply by requiring higher purity.[4]

Oppenheimer reviewed his options in early 1943 and gave priority to the gun-type weapon,[2] but he created the E-5 Group at the Los Alamos Laboratory under Seth Neddermeyer to investigate implosion as a hedge against the threat of pre-detonation. Implosion-type bombs were determined to be significantly more efficient in terms of explosive yield per unit mass of fissile material in the bomb, because compressed fissile materials react more rapidly and therefore more completely. Nonetheless, it was decided that the plutonium gun would receive the bulk of the research effort, since it was the project with the least amount of uncertainty involved. It was assumed that the uranium gun-type bomb could be easily adapted from it.[5]


The gun-type and implosion-type designs were codenamed "Thin Man" and "Fat Man" respectively. These code names were created by Robert Serber, a former student of Oppenheimer's who worked on the Manhattan Project. He chose them based on their design shapes; the Thin Man was a very long device, and the name came from the Dashiell Hammett detective novel The Thin Man and series of movies. The Fat Man was round and fat and was named after Sydney Greenstreet's character in The Maltese Falcon. Little Boy came last as a variation of Thin Man.[6]


Neddermeyer discarded Serber and Tolman's initial concept of implosion as assembling a series of pieces in favor of one in which a hollow sphere was imploded by an explosive shell. He was assisted in this work by Hugh Bradner, Charles Critchfield, and John Streib. L. T. E. Thompson was brought in as a consultant, and discussed the problem with Neddermeyer in June 1943. Thompson was skeptical that an implosion could be made sufficiently symmetric. Oppenheimer arranged for Neddermeyer and Edwin McMillan to visit the National Defense Research Committee's Explosives Research Laboratory near the laboratories of the Bureau of Mines in Bruceton, Pennsylvania (a Pittsburgh suburb), where they spoke to George Kistiakowsky and his team. But Neddermeyer's efforts in July and August at imploding tubes to produce cylinders tended to produce objects that resembled rocks. Neddermeyer was the only person who believed that implosion was practical, and only his enthusiasm kept the project alive.[7]

AirForceMuseum FatManReplica
Replica mockup displayed in the Wright-Patterson Air Force Museum, beside the Bockscar B-29 that dropped the original device – black liquid asphalt sealant was sprayed over the original bomb casing's seams, simulated on the mockup.

Oppenheimer brought John von Neumann to Los Alamos in September 1943 to take a fresh look at implosion. After reviewing Neddermeyer's studies, and discussing the matter with Edward Teller, von Neumann suggested the use of high explosives in shaped charges to implode a sphere, which he showed could not only result in a faster assembly of fissile material than was possible with the gun method, but which could greatly reduce the amount of material required, because of the resulting higher density.[8] The idea that, under such pressures, the plutonium metal itself would be compressed came from Teller, whose knowledge of how dense metals behaved under heavy pressure was influenced by his pre-war theoretical studies of the Earth's core with George Gamow.[9] The prospect of more-efficient nuclear weapons impressed Oppenheimer, Teller, and Hans Bethe, but they decided that an expert on explosives would be required. Kistiakowsky's name was immediately suggested, and Kistiakowsky was brought into the project as a consultant in October 1943.[8]

The implosion project remained a backup until April 1944, when experiments by Emilio G. Segrè and his P-5 Group at Los Alamos on the newly reactor-produced plutonium from the X-10 Graphite Reactor at Oak Ridge and the B Reactor at the Hanford site showed that it contained impurities in the form of the isotope plutonium-240. This has a far higher spontaneous fission rate and radioactivity than plutonium-239. The cyclotron-produced isotopes, on which the original measurements had been made, held much lower traces of plutonium-240. Its inclusion in reactor-bred plutonium appeared unavoidable. This meant that the spontaneous fission rate of the reactor plutonium was so high that it would be highly likely that it would predetonate and blow itself apart during the initial formation of a critical mass.[10] The distance required to accelerate the plutonium to speeds where predetonation would be less likely would need a gun barrel too long for any existing or planned bomber. The only way to use plutonium in a workable bomb was therefore implosion.[11]

Flash X-Ray images of the converging shock waves formed during a test of the high-explosive lens system.

The impracticability of a gun-type bomb using plutonium was agreed at a meeting in Los Alamos on 17 July 1944. All gun-type work in the Manhattan Project was directed at the Little Boy, enriched-uranium gun design, and the Los Alamos Laboratory was reorganized, with almost all of the research focused on the problems of implosion for the Fat Man bomb.[11] The idea of using shaped charges as three-dimensional explosive lenses came from James L. Tuck, and was developed by von Neumann.[12] To overcome the difficulty of synchronizing multiple detonations, Luis Alvarez and Lawrence Johnston invented exploding-bridgewire detonators to replace the less precise primacord detonation system.[12] Robert Christy is credited with doing the calculations that showed how a solid subcritical sphere of plutonium could be compressed to a critical state, greatly simplifying the task, since earlier efforts had attempted the more-difficult compression of a hollow spherical shell.[13] After Christy's report, the solid-plutonium core weapon was referred to as the "Christy Gadget".[14]

The task of the metallurgists was to determine how to cast plutonium into a sphere. The difficulties became apparent when attempts to measure the density of plutonium gave inconsistent results. At first contamination was believed to be the cause, but it was soon determined that there were multiple allotropes of plutonium.[15] The brittle α phase that exists at room temperature changes to the plastic β phase at higher temperatures. Attention then shifted to the even more malleable δ phase that normally exists in the 300–450 °C (570–840 °F) range. It was found that this was stable at room temperature when alloyed with aluminum, but aluminum emits neutrons when bombarded with alpha particles, which would exacerbate the pre-ignition problem. The metallurgists then hit upon a plutonium–gallium alloy, which stabilized the δ phase and could be hot pressed into the desired spherical shape. As plutonium was found to corrode readily, the sphere was coated with nickel.[16]

Fat Man test unit being raised from the pit into the bomb bay of a B-29
A pumpkin bomb (Fat Man test unit) being raised from the pit into the bomb bay of a B-29 for bombing practice during the weeks before the attack on Nagasaki.

The size of the bomb was constrained by the available aircraft. The only Allied aircraft capable of carrying the Fat Man were the British Avro Lancaster and the American Boeing B-29 Superfortress. For logistic and nationalistic reasons, the B-29 was preferred, but this constrained the bomb to a maximum length of 11 feet (3.4 m), width of 5 feet (1.5 m) and weight of 20,000 pounds (9,100 kg). Removing the bomb rails allowed a maximum width of 5.5 feet (1.7 m).[17] Drop tests began in March 1944, and resulted in modifications to the Silverplate aircraft due to the weight of the bomb.[18] High-speed photographs revealed that the tail fins folded under the pressure, resulting in an erratic descent. Various combinations of stabilizer boxes and fins were tested on the Fat Man shape to eliminate its persistent wobble until an arrangement dubbed a "California Parachute", a cubical open-rear tail box outer surface with eight radial fins inside of it, four angled at 45° and four perpendicular to the line of fall holding the outer square-fin box to the bomb's rear end, was approved.[19] In drop tests in early weeks, the Fat Man missed its target by an average of 1,857 feet (566 m), but this was halved by June as the bombardiers became more proficient with it.[20]

The early Y-1222 model Fat Man was assembled with some 1,500 bolts.[21][22] This was superseded by the Y-1291 design in December 1944. This redesign work was substantial, and only the Y-1222 tail design was retained.[22] Later versions included the Y-1560, which had 72 detonators; the Y-1561, which had 32; and the Y-1562, which had 132. There were also the Y-1563 and Y-1564, which were practice bombs with no detonators at all.[23] The final wartime Y-1561 design was assembled with just 90 bolts.[21]

On 16 July 1945, a Y-1561 model Fat Man, known as the Gadget, was detonated in a test explosion at a remote site in New Mexico, known as the "Trinity" test. It gave a yield of about 20 kilotonnes (84 TJ).[24] Some minor changes were made to the design as a result of the Trinity test.[25] Philip Morrison recalled that "There were some changes of importance... The fundamental thing was, of course, very much the same."[26]


The bomb was 128 inches (3,300 mm) long and 60 inches (1,500 mm) in diameter. It weighed 10,300 pounds (4,700 kg).[27]

Fat Man external schematic
  1. One of four AN 219 contact fuzes.
  2. Archie radar antenna.
  3. Plate with batteries (to detonate charge surrounding nuclear components).
  4. X-Unit, a firing set placed near the charge.
  5. Hinge fixing the two ellipsoidal parts of the bomb.
  6. Physics package (see details below).
  7. Plate with instruments (radars, baroswitches, and timers).
  8. Barotube collector.
  9. California Parachute tail assembly (0.20-inch (5.1 mm) aluminum sheet).

Fat Man internal schematic

Fat Man internal schematic


Fat Man Detonation
Fat Man's detonation method
Fat Man Assembly Tinian 1945
Fat Man's "physics package" nuclear device about to be encased
Fat Man Assembled Tinian 1945
Fat Man on its transport carriage, with liquid asphalt sealant applied over the casing's seams
Atomic Bomb Pits - Tinian - panoramio (3)
Preserved Tinian "bomb pit #2", where Fat Man was loaded aboard Bockscar

The plutonium pit[21] was 3.62-inch (92 mm) in diameter and contained an "Urchin" modulated neutron initiator that was 0.8-inch (20 mm) in diameter. The depleted uranium tamper was a 8.75-inch (222 mm) diameter sphere, surrounded by a 0.125-inch (3.2 mm) thick shell of boron-impregnated plastic. The plastic shell had a 5-inch (130 mm) diameter cylindrical hole running through it, like the hole in a cored apple, in order to allow insertion of the pit as late as possible. The missing tamper cylinder containing the pit could be slipped in through a hole in the surrounding 18.5-inch (470 mm) diameter aluminum pusher.[28] The pit was warm to touch, emitting 2.4 W/kg-Pu, about 15 W for the 6.19 kilograms (13.6 lb) core.[29]

The explosion symmetrically compressed the plutonium to twice its normal density before the "Urchin" added free neutrons to initiate a fission chain reaction.[30]

The result was the fission of about 1 kilogram (2.2 lb) of the 6.19 kilograms (13.6 lb) of plutonium in the pit, i.e. of about 16% of the fissile material present. 1 gram (0.035 oz) of matter in the bomb is converted into the active energy of heat and radiation, releasing the energy equivalent to the detonation of 21 kilotons of TNT or 88 terajoules.[36]

Bombing of Nagasaki

Mushroom cloud after Fat Man exploded over Nagasaki on 9 August 1945

The first plutonium core was transported with its polonium-beryllium modulated neutron initiator in the custody of Project Alberta courier Raemer Schreiber in a magnesium field carrying case designed for the purpose by Philip Morrison. Magnesium was chosen because it does not act as a tamper.[30] It left Kirtland Army Air Field on a C-54 transport aircraft of the 509th Composite Group's 320th Troop Carrier Squadron on 26 July and arrived at North Field on Tinian on 28 July. Three Fat Man high-explosive pre-assemblies (designated F31, F32, and F33) were picked up at Kirtland on 28 July by three B-29s: Luke the Spook and Laggin' Dragon from the 509th Composite Group's 393d Bombardment Squadron, and another from the 216th AAF Base Unit. The cores were transported to North Field, arriving on 2 August, when F31 was partly disassembled in order to check all its components. F33 was expended near Tinian during a final rehearsal on 8 August, and F31 was the bomb dropped on Nagasaki. F32 presumably would have been used for a third attack or its rehearsal.[37]

In August 1945, the Fat Man was assembled on Tinian by Project Alberta personnel, and the physics package was fully assembled and wired. It was placed inside its ellipsoidal aerodynamic bombshell and wheeled out, where it was signed by nearly 60 people, including Rear Admiral William R. Purnell, Brigadier General Thomas F. Farrell, and Captain William S. Parsons.[38] It was then wheeled to the bomb bay of the B-29 Superfortress named Bockscar after the plane's command pilot Captain Frederick C. Bock,[39] who flew The Great Artiste with his crew on the mission. Bockscar was flown by Major Charles W. Sweeney and his crew, with Commander Frederick L. Ashworth from Project Alberta as the weaponeer in charge of the bomb.[40]

Bockscar lifted off at 03:47 on the morning of 9 August 1945, with Kokura as the primary target and Nagasaki the secondary target. The weapon was already armed, but with the green electrical safety plugs still engaged. Ashworth changed them to red after ten minutes so that Sweeney could climb to 17,000 feet (5,200 m) in order to get above storm clouds.[41] During pre-flight inspection of Bockscar, the flight engineer notified Sweeney that an inoperative fuel transfer pump made it impossible to use 640 US gallons (2,400 l) of fuel carried in a reserve tank. This fuel would still have to be carried all the way to Japan and back, consuming still more fuel. Replacing the pump would take hours; moving the Fat Man to another aircraft might take just as long and was dangerous as well, as the bomb was live. Colonel Paul Tibbets and Sweeney therefore elected to have Bockscar continue the mission.[42]

Nagasaki 1945 - Before and after (adjusted)
Effects of the Fat Man's detonation on Nagasaki

The original target for the bomb was the city of Kokura, but it was found to be obscured by clouds and drifting smoke from fires started by a major firebombing raid by 224 B-29s on nearby Yahata the previous day. This covered 70% of the area over Kokura, obscuring the aiming point. Three bomb runs were made over the next 50 minutes, burning fuel and repeatedly exposing the aircraft to the heavy defenses of Yahata, but the bombardier was unable to drop visually. By the time of the third bomb run, Japanese anti-aircraft fire was getting close; Second Lieutenant Jacob Beser was monitoring Japanese communications, and he reported activity on the Japanese fighter direction radio bands.[43]

Sweeney then proceeded to the alternative target of Nagasaki. It was obscured by cloud, as well, and Ashworth ordered Sweeney to make a radar approach. At the last minute, however, bombardier[41] Captain Kermit K. Beahan[40] found a hole in the clouds. The Fat Man was dropped and exploded at 11:02 local time, following a 43-second free-fall at an altitude of about 1,650 feet (500 m).[41] There was poor visibility due to cloud cover and the bomb missed its intended detonation point by almost two miles, so damage was somewhat less extensive than that in Hiroshima.

An estimated 35,000–40,000 people were killed outright by the bombing at Nagasaki. A total of 60,000–80,000 fatalities resulted, including from long-term health effects, the strongest of which was leukemia with an attributable risk of 46% for bomb victims.[44] Others died later from related blast and burn injuries, and hundreds more from radiation illnesses from exposure to the bomb's initial radiation.[45] Most of the direct deaths and injuries were among munitions or industrial workers.[46] Mitsubishi's industrial production in the city was also severed by the attack; the dockyard would have produced at 80 percent of its full capacity within three to four months, the steel works would have required a year to get back to substantial production, the electric works would have resumed some production within two months and been back at capacity within six months, and the arms plant would have required 15 months to return to 60 to 70 percent of former capacity. The Mitsubishi-Urakami Ordnance Works was the factory that manufactured the type 91 torpedoes released in the attack on Pearl Harbor; it was destroyed in the blast.[46][47]

Post-war development

Casing for the first Soviet atomic bomb, RDS-1
Espionage information procured by Klaus Fuchs, Theodore Hall, and David Greenglass led to the first Soviet device "RDS–1" (above), which closely resembled Fat Man, even in its external shape.

After the war, two Y-1561 Fat Man bombs were used in the Operation "Crossroads" nuclear tests at Bikini Atoll in the Pacific. The first was known as Gilda after Rita Hayworth's character in the 1946 movie Gilda, and it was dropped by the B-29 Dave's Dream; it missed its aim point by 710 yards (650 m). The second bomb was nicknamed Helen of Bikini and was placed without its tail fin assembly in a steel caisson made from a submarine's conning tower; it was detonated 90 feet (27 m) beneath the landing craft USS LSM-60. The two weapons yielded about 23 kilotonnes (96 TJ) each.[48]

The Los Alamos Laboratory and the Army Air Forces had already commenced work on improving the design. The North American B-45 Tornado, Convair XB-46, Martin XB-48, and Boeing B-47 Stratojet bombers had bomb bays sized to carry the Grand Slam, which was much longer but not as wide as the Fat Man. The only American bombers that could carry the Fat Man were the B-29 and the Convair B-36. In November 1945, the Army Air Forces asked Los Alamos for 200 Fat Man bombs, but there were only two sets of plutonium cores and high-explosive assemblies at the time. The Army Air Forces wanted improvements to the design to make it easier to manufacture, assemble, handle, transport, and stockpile. The wartime Project W-47 was continued, and drop tests resumed in January 1946.[49]

The Mark III Mod 0 Fat Man was ordered into production in mid-1946. High explosives were manufactured by the Salt Wells Pilot Plant, which had been established by the Manhattan Project as part of Project Camel, and a new plant was established at the Iowa Army Ammunition Plant. Mechanical components were made or procured by the Rock Island Arsenal; electrical and mechanical components for about 50 bombs were stockpiled at Kirtland Army Air Field by August 1946, but only nine plutonium cores were available. Production of the Mod 0 ended in December 1948, by which time there were still only 53 cores available. It was replaced by improved versions known as Mods 1 and 2 which contained a number of minor changes, the most important of which was that they did not charge the X-Unit firing system's capacitors until released from the aircraft. The Mod 0s were withdrawn from service between March and July 1949, and by October they had all been rebuilt as Mods 1 and 2.[50] Some 120 Mark III Fat Man units were added to the stockpile between 1947 and 1949[51] when it was superseded by the Mark 4 nuclear bomb.[52] The Mark III Fat Man was retired in 1950.[51][53]

A nuclear strike would have been a formidable undertaking in the post-war 1940s due to the limitations of the Mark III Fat Man. The lead-acid batteries which powered the fuzing system remained charged for only 36 hours, after which they needed to be recharged. To do this meant disassembling the bomb, and recharging took 72 hours. The batteries had to be removed in any case after nine days or they corroded. The plutonium core could not be left in for much longer, because its heat damaged the high explosives. Replacing the core also required the bomb to be completely disassembled and reassembled. This required about 40 to 50 men and took between 56 and 72 hours, depending on the skill of the bomb assembly team, and the Armed Forces Special Weapons Project had only three teams in June 1948. The only aircraft capable of carrying the bomb were Silverplate B-29s, and the only group equipped with them was the 509th Bombardment Group at Walker Air Force Base in Roswell, New Mexico. They would first have to fly to Sandia Base to collect the bombs, and then to an overseas base from which a strike could be mounted.[54]

The Soviet Union's first nuclear weapon was based closely on Fat Man's design thanks to spies Klaus Fuchs, Theodore Hall, and David Greenglass, who provided them with secret information concerning the Manhattan Project and Fat Man. It was detonated on 29 August 1949 as part of Operation "First Lightning".[55][56]


  1. ^ Hoddeson et al. 1993, pp. 42–44.
  2. ^ a b Hoddeson et al. 1993, p. 55.
  3. ^ Nichols 1987, p. 64.
  4. ^ Nichols 1987, pp. 64–65.
  5. ^ Hoddeson et al. 1993, p. 87.
  6. ^ Serber & Crease 1998, p. 104.
  7. ^ Hoddeson et al. 1993, pp. 86–90.
  8. ^ a b Hoddeson et al. 1993, pp. 130–133.
  9. ^ Teller 2001, pp. 174–176.
  10. ^ Hoddeson et al. 1993, p. 228.
  11. ^ a b Hoddeson et al. 1993, pp. 240–244.
  12. ^ a b Hoddeson et al. 1993, p. 163.
  13. ^ Hoddeson et al. 1993, pp. 270–271.
  14. ^ Hoddeson et al. 1993, pp. 293, 307–308.
  15. ^ Hewlett & Anderson 1962, pp. 244–245.
  16. ^ Baker, Hecker & Harbur 1983, pp. 144–145.
  17. ^ Hansen 1995, pp. 119–120.
  18. ^ Campbell 2005, pp. 8–10.
  19. ^ Hoddeson et al. 1993, pp. 380–383.
  20. ^ Hansen 1995, p. 131.
  21. ^ a b c Coster-Mullen 2012, p. 52.
  22. ^ a b Hansen 1995, p. 121.
  23. ^ Hansen 1995, p. 127.
  24. ^ Jones 1985, pp. 465,514–517.
  25. ^ Hoddeson et al. 1993, p. 377.
  26. ^ Coster-Mullen 2012, p. 53.
  27. ^ Hansen 1995, p. 145.
  28. ^ a b Coster-Mullen 2012, p. 186.
  29. ^ Coster-Mullen 2012, p. 49.
  30. ^ a b c Coster-Mullen 2012, p. 45.
  31. ^ a b c Coster-Mullen 2012, p. 41.
  32. ^ a b Hansen 1995, pp. 122–123.
  33. ^ Coster-Mullen 2012, p. 48.
  34. ^ Coster-Mullen 2012, p. 57.
  35. ^ Sublette, Carey (3 July 2007). "Section 8.0 The First Nuclear Weapons". Nuclear Weapons FAQ. Retrieved 29 August 2013.
  36. ^ Malik 1985, p. 25.
  37. ^ Campbell 2005, pp. 38–40.
  38. ^ Coster-Mullen 2012, p. 67.
  39. ^ "Bockscar … The Forgotten Plane That Dropped The Atomic Bomb « A Little Touch Of History". Awesometalks.wordpress.com. Retrieved 31 August 2012.
  40. ^ a b Campbell 2005, p. 32.
  41. ^ a b c Rhodes 1986, p. 740.
  42. ^ Sweeney, Antonucci & Antonucci 1997, pp. 204–205.
  43. ^ Sweeney, Antonucci & Antonucci 1997, pp. 179, 213–215.
  44. ^ Columbia universcity center for nuclear studies: Hiroshima and Nagasaki: The Long Term Health Effects Archived 23 July 2015 at the Wayback Machine, updated 7/3/2014
  45. ^ Craven & Cate 1953, pp. 723–725.
  46. ^ a b Nuke-Rebuke: Writers & Artists Against Nuclear Energy & Weapons (The Contemporary anthology series). The Spirit That Moves Us Press. 1 May 1984. pp. 22–29.
  48. ^ Coster-Mullen 2012, pp. 84–85.
  49. ^ Hansen 1995, pp. 137–142.
  50. ^ Hansen 1995, pp. 142–145.
  51. ^ a b Coster-Mullen 2012, p. 87.
  52. ^ Hansen 1995, p. 143.
  53. ^ Hansen 1995, p. 150.
  54. ^ Hansen 1995, pp. 147–149.
  55. ^ Holloway, David (1993). "Soviet Scientists Speak Out". Bulletin of the Atomic Scientists. 49 (4): 18–19.
  56. ^ Sublette, Carey (3 July 2007). "Section 8.1.1 The Design of Gadget, Fat Man, and "Joe 1" (RDS-1)". Nuclear Weapons FAQ. Retrieved 12 August 2011.


External links


Bockscar, sometimes called Bock's Car, is the name of the United States Army Air Forces B-29 bomber that dropped a Fat Man nuclear weapon over the Japanese city of Nagasaki during World War II in the second – and last – nuclear attack in history. One of 15 Silverplate B-29s used by the 509th, Bockscar was built at the Glenn L. Martin Aircraft Plant at Bellevue, Nebraska, at what is now Offutt Air Force Base, and delivered to the United States Army Air Forces on 19 March 1945. It was assigned to the 393d Bombardment Squadron, 509th Composite Group to Wendover Army Air Field, Utah in April.

Bockscar was used in 13 training and practice missions from Tinian, and three combat missions in which it dropped pumpkin bombs on industrial targets in Japan. On 9 August 1945, Bockscar, piloted by the 393d Bombardment Squadron's commander, Major Charles W. Sweeney, dropped a Fat Man nuclear bomb with a blast yield equivalent to 21 kilotons of TNT over the city of Nagasaki. About 44% of the city was destroyed; 35,000 people were killed and 60,000 injured.

After the war, Bockscar returned to the United States in November 1945. In September 1946, it was given to the National Museum of the United States Air Force at Wright-Patterson Air Force Base, Ohio. The aircraft was flown to the Museum on 26 September 1961, and its original markings were restored (nose art was added after the mission). Bockscar is now on permanent display at the National Museum of the United States Air Force, Dayton, Ohio, next to a replica of a Fat Man.

Fat Man and Little Boy

Fat Man and Little Boy (a.k.a. Shadow Makers in the UK) is a 1989 film that reenacts the Manhattan Project, the secret Allied endeavor to develop the first nuclear weapons during World War II. The film is named after the weapons "Little Boy" and "Fat Man" that were detonated over Hiroshima and Nagasaki, respectively.

The film was directed by Roland Joffé and written by Joffe and Bruce Robinson.

Fat Man and Little Boy (The Simpsons)

"Fat Man and Little Boy" is the fifth episode of the 16th season of The Simpsons. It originally aired on the Fox network in the United States on December 12, 2004.

Fatman Scoop

Isaac Freeman III (born August 6, 1971), also known as Big Colorado and better known by his stage name Fatman Scoop, is an American hype man, hip hop promoter and radio personality famed for his on-stage rough, raw loud voice.

He is known for the song "Be Faithful" which went to number one in the United Kingdom and Ireland in late 2003 and top 5 in Australia. The song had been a favorite in clubs around the world for years but it took two years to clear the samples from Jay-Z, Black Sheep, Queen Pen, The Beatnuts and Faith Evans. He has also collaborated with numerous artists, such as Lil Jon, Mariah Carey, Janet Jackson, Whitney Houston, Pitbull and Skrillex, among others.

Fats Domino

Antoine "Fats" Domino Jr. (February 26, 1928 – October 24, 2017) was an American pianist and singer-songwriter. One of the pioneers of rock and roll music, Domino sold more than 65 million records. Between 1955 and 1960, he had eleven Top 10 hits. His humility and shyness may be one reason his contribution to the genre has been overlooked.During his career, Domino had 35 records in the U.S. Billboard Top 40, and five of his pre-1955 records sold more than a million copies, being certified gold. His musical style was based on traditional rhythm and blues, accompanied by saxophones, bass, piano, electric guitar, and drums.His 1949 release "The Fat Man" is widely regarded as the first million-selling Rock 'n Roll record.

George Sanger (musician)

George Alistair Sanger (born December 14, 1957, from Austin, Texas), also known as "The Fat Man", is an American musician who has composed music for computer and video games, beginning in 1983. Some of his best-known works include The 7th Guest, Wing Commander, Hard Nova, Maniac Mansion (NES version), Loom, Tux Racer, and Zombies Ate My Neighbors. Sanger leads the band Team Fat, which also includes fellow video game music composers Dave Govett, Joe McDermott and Kevin Weston Phelan. He has also written a novel, The Fat Man on Game Audio: Tasty Morsels of Sonic Goodness, described by him as, "a book about game audio wrapped in a biography wrapped in a philosophy on life."

Jake and the Fatman

Jake and the Fatman is a television crime drama starring William Conrad as prosecutor J. L. (Jason Lochinvar) "Fatman" McCabe and Joe Penny as investigator Jake Styles. The series ran on CBS for five seasons from September 26, 1987, to May 6, 1992. Diagnosis: Murder was a spin-off of this series.

Jakko Jakszyk

Michael "Jakko" Jakszyk (born Michael Lee Curran, 8 June 1958) is an English musician, record producer, and actor. He has released several solo albums as a singer, songwriter, and multi-instrumentalist and has been the lead singer for King Crimson since 2013. His work has been variously credited to "Jakko", "Jakko Jakszyk", and "Jakko M. Jakszyk".

Before joining King Crimson, he led bands for over thirty years, including 64 Spoons, Dizrhythmia, 21st Century Schizoid Band, Jakszyk Fripp Collins, and Rapid Eye Movement. He was a member of Level 42, the Lodge, and the Tangent and has collaborated with Tom Robinson, Peter Blegvad, Danny Thompson, Gavin Harrison, Warren Harry, Pandit Dinesh, and Dave Stewart. Jakszyk has also worked as a session musician and soundtrack producer.

List of people who have walked across the United States

This is a list of people who have walked across the United States from the east coast to the west coast or vice versa. Walking or running across the United States has long been pursued as a way to bring publicity to social causes.

Mark 6 nuclear bomb

The Mark 6 nuclear bomb was an American nuclear bomb based on the earlier Mark 4 nuclear bomb and its predecessor, the Mark 3 Fat Man nuclear bomb design.

The Mark 6 was in production from 1951 to 1955 and saw service until 1962. Seven variants and versions were produced, with a total production run of all models of 1100 bombs.

The basic Mark 6 design was 61 inches (150 cm) in diameter and 128 inches (330 cm) long, the same basic dimensions as the Mark 4 and close to the Mark 3. Various models of the Mark 6 were roughly 25% lighter than either the Mark 4 or Fat Man, and weighed 7,600 to 8,500 pounds (3,400–3,900 kg).

Early models of the Mark 6 utilized the same 32-point implosion system design concept as the earlier Mark 4 and Mark 3; the Mark 6 Mod 2 and later used a different, 60-point implosion system.

Various models and pit options gave nuclear yields of 8, 26, 80, 154, and 160 kilotons for Mark 6 models.

Nuclear weapon design

Nuclear weapon designs are physical, chemical, and engineering arrangements that cause the physics package of a nuclear weapon to detonate. There are three existing basic design types:

pure fission weapons, the simplest and least technically demanding, were the first nuclear weapons built and have so far been the only type ever used in an act of war (over wartime Japan).

boosted fission weapons improve on the implosion design using small quantities of fusion fuel to enhance the fission chain reaction. Boosting can more than double the weapon's fission energy yield.

staged thermonuclear weapons are essentially arrangements of two or more "stages", most usually two. The first stage is always a boosted fission weapon as above. Its detonation causes it to shine intensely with x-radiation, which illuminates and implodes the second stage filled with a large quantity of fusion fuel. This sets in motion a sequence of events which results in a thermonuclear, or fusion, burn. This process affords potential yields up to hundreds of times those of fission weapons.A fourth type, pure fusion weapons, is a purely theoretical possibility. Such weapons would produce far less radioactive byproducts than current designs, although they would release huge numbers of neutrons.

Pure fission weapons historically have been the first type to be built by new nuclear powers. Large industrial states with well-developed nuclear arsenals have two-stage thermonuclear weapons, which are the most compact, scalable, and cost effective option once the necessary technical base and industrial infrastructure are built.

Most known innovations in nuclear weapon design originated in the United States, although some were later developed independently by other states.In early news accounts, pure fission weapons were called atomic bombs or A-bombs and weapons involving fusion were called hydrogen bombs or H-bombs. Practitioners however favor the terms nuclear and thermonuclear, respectively.

Project Alberta

Project Alberta, also known as Project A, was a section of the Manhattan Project which assisted in delivering the first nuclear weapons in the atomic bombing of Hiroshima and Nagasaki during World War II.

Project Alberta was formed in March 1945, and consisted of 51 United States Army, Navy, and civilian personnel, including one British scientist. Its mission was three-fold. It first had to design a bomb shape for delivery by air, then procure and assemble it. It supported the ballistic testing work at Wendover Army Air Field, Utah, conducted by the 216th Army Air Forces Base Unit (Project W-47), and the modification of B-29s to carry the bombs (Project Silverplate). After completion of its development and training missions, Project Alberta was attached to the 509th Composite Group at North Field, Tinian, where it prepared facilities, assembled and loaded the weapons, and participated in their use.

Pumpkin bomb

Pumpkin bombs were conventional aerial bombs developed by the Manhattan Project and used by the United States Army Air Forces against Japan during World War II. It was a close replication of the Fat Man plutonium bomb with the same ballistic and handling characteristics, but it used non-nuclear conventional high explosives. It was mainly used for testing and training purposes, which included combat missions flown with pumpkin bombs by the 509th Composite Group. The name "pumpkin bomb" was the actual reference term used in official documents from the large, fat ellipsoidal shape of the munition casing instead of the more usual cylindrical shape of other bombs, intended to enclose the Fat Man's spherical "physics package" (the plutonium implosion nuclear weapon core).


Silverplate was the code reference for the United States Army Air Forces' participation in the Manhattan Project during World War II. Originally the name for the aircraft modification project which enabled a B-29 Superfortress bomber to drop an atomic weapon, "Silverplate" eventually came to identify the training and operational aspects of the program as well. The original directive for the project had as its subject line "Silver Plated Project" but continued usage of the term shortened it to "Silverplate".

Testing began with scale models at the Naval Proving Ground in Dahlgren, Virginia, in August 1943. Modifications began on a prototype Silverplate B-29 known as the "Pullman" in November 1943, and it was used for bomb flight testing at Muroc Army Air Field in California commencing in March 1944. The testing resulted in further modifications to both the bombs and the aircraft.

Seventeen production Silverplate aircraft were ordered in August 1944 to allow the 509th Composite Group to train with the type of aircraft they would have to fly in combat, and for the 216th Army Air Forces Base Unit to test bomb configurations. These were followed by 28 more aircraft that were ordered in February 1945 for operational use by the 509th Composite Group. This batch included the aircraft which were used in the atomic bombings of Hiroshima and Nagasaki in August 1945. Including the Pullman B-29, 46 Silverplate B-29s were produced during and after World War II. An additional 19 Silverplate B-29s were ordered in July 1945, which were delivered between the end of the war and the end of 1947. Thus, 65 Silverplate B-29s were made.

The use of the Silverplate codename was discontinued after the war, but modifications continued under a new codename, Saddletree. Another 80 aircraft were modified under this program. The last group of B-29s was modified in 1953, but never saw further service.

Stand Up (Jethro Tull album)

Stand Up is the second studio album by the British rock band Jethro Tull, released in 1969. Before recordings for the album began, the band's original guitarist Mick Abrahams resigned because of musical differences with Ian Anderson; Abrahams wanted to stay with the blues rock sound of their 1968 debut, This Was, while Anderson wished to add other musical influences such as folk rock. He was replaced by guitarist Martin Barre, who appeared on every Jethro Tull album from this point onwards.Stand Up represents the first album project on which Anderson was in full control of the music and lyrics. The result was an eclectic album with various styles appearing in its songs, yet an album which remained somewhat in the blues rock mould, which would be the last such album from Jethro Tull.

The album quickly went to No. 1 on the UK charts, while the non-album single "Living in the Past" peaked at No. 3.

The Fat Man (film)

The Fat Man is a 1951 crime film noir directed by William Castle. It is based on a radio drama of the same name, with J. Scott Smart reprising his role as Runyan, a detective.

The cast includes Rock Hudson and Julie London. Originally released by Universal Pictures, the film is now in the public domain.

The Fat Man (song)

"The Fat Man" is a song by American rhythm and blues recording artist Fats Domino. It was written by Domino and Dave Bartholomew, and recorded on December 10, 1949. It is often cited as one of the first rock and roll records.

Verb phrase

In linguistics, a verb phrase (VP) is a syntactic unit composed of at least one verb and its dependents—objects, complements and other modifiers—but not always including the subject. Thus in the sentence A fat man put the money quickly in the box, the words put the money quickly in the box are a verb phrase; it consists of the verb put and its dependents, but not the subject a fat man. A verb phrase is similar to what is considered a predicate in more traditional grammars.

Verb phrases generally are divided among two types: finite, of which the head of the phrase is a finite verb; and nonfinite, where the head is a nonfinite verb, such as an infinitive, participle or gerund. Phrase structure grammars acknowledge both types, but dependency grammars treat the subject as just another verbal dependent, and they do not recognize the finite verbal phrase constituent. Understanding verb phrase analysis depends on knowing which theory applies in context.

Wackiki Wabbit

Wackiki Wabbit is a 1943 Warner Bros. Merrie Melodies cartoon, starring Bugs Bunny. It was written by Tedd Pierce and directed by Chuck Jones. Voices were provided by Mel Blanc (Bugs), Tedd Pierce (the tall, thin man), and Michael Maltese (the short, fat man - the two men's appearances are rough caricatures of the actual men). The musical score was conducted by Carl Stalling.

Wackiki Wabbit contains an experimental use of strongly graphic, nearly abstract backgrounds. The title is a double play on words, with "Wackiki" suggesting both the island setting (as in "Waikiki") as well as suggesting "wacky" (crazy) along with the usual Elmer Fudd speech pronunciation of "rabbit", although Elmer does not appear in this picture.

This cartoon has fallen to the public domain after United Artists (successor to Associated Artists Productions) failed to renew the copyright on time. The cartoon can be found, restored, on Disc 1 of the Looney Tunes Golden Collection: Volume 3.

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