Pumpkin bomb
Encyclopedia
Pumpkin bombs were conventional high explosive aerial bomb
s developed by the Manhattan Project
and used by the United States Army Air Forces
against Japan
during World War II
. The name "pumpkin bomb" resulted from the large ellipsoidal shape of the munition and was the actual reference term used in official documents.
of the Ordnance Division at Los Alamos
and USAAF Colonel Paul W. Tibbets, commander of the 509th CG, on December 13, 1944, as a means of providing continued realistic training for the B-29 crews assigned to drop the atomic bomb after their deployment to the Western Pacific
. The bomb would be a close but non-nuclear replication of the Fat Man
plutonium bomb with the same ballistic
and handling characteristics. Mission parameters would be similar to those of the actual atomic bomb missions, and all targets would be located in the vicinity of the cities designated for atomic attack.
The development of the bomb was managed by the California Institute of Technology
under the direction of Dr. Charles C. Lauritsen
. Specifications for the bomb required that it be carried in the forward bomb bay
of a Silverplate
B-29 and be fuze
d to be effective against actual targets. The bomb shells were manufactured by two Los Angeles, California
, firms, Consolidated Steel Corporation
and Western Pipe and Steel Company
, while the tail assembly was produced by Centerline Company of Detroit, Michigan
. After initial development, management of the program was turned over to the U.S. Navy Bureau of Ordnance
in May 1945.
Pumpkin bombs were produced in both inert and high explosive variants, with the inert versions filled with a cement
-plaster
-sand
mixture combined with water to the density of the Composition B
used in the high explosive versions. The filler of both variants had the same weight and weight distribution as the inner sphere used in the plutonium bomb. All of the inert versions were shipped from the manufacturers directly to Wendover Army Air Field, Utah
, by rail, where they were used by the 216th Base Unit in flight testing of the bomb shape.
The bombs intended as live ordnance were shipped to the Naval Ammunition Depot, McAlester, Oklahoma
, for filling with explosives. The Composition B was poured as a slurry
, solidified in a drying facility, sealed, and shipped by railroad to the Port Chicago Naval Magazine, California
for shipment by sea to Tinian
.
A total of 486 live and inert bombs were eventually assembled.
s arranged in an equilateral triangle around the nose of the bomb while the atomic bomb had four fuse housings. The atomic bomb had its sections bolted together but most if not all of the pumpkin bombs were welded with a four-inch hole used for filling the shell. The Fat Man also had four external mounting points for radar
antennas
which the pumpkin bombs did not have.
The pumpkin bombs were twelve feet eight inches in length and five feet in maximum diameter. The most commonly-given weight for the bombs is 5.26 tons, consisting of 3,800 pounds for the shell, 425 pounds for the tail assembly, and 6,300 pounds of filler. The shells were made of .375-inch steel plate
and the tail assemblies from .200-inch aluminum plate
. Although anecdotal sources attribute the naming of the bombs to painting them a pumpkin color, photographs indicate that the units delivered to Tinian
came painted in the same Zinc Chromate primer color worn by Fat Man
, to practice dropping the Fat Man nuclear shape
from the B-29 Superfortress
. A total of 49 bombs were dropped on 14 targets. More than 400 people were estimated killed and 1,200 others injured.
In addition to the live ordnance dropped on Japan, several hundred inert bombs were used by combat crews of the 509th's 393rd Bomb Squadron to test the ballistics of the bomb shape in conjunction with Project Alberta
, and to train bombardiers in mission procedures before movement of the group overseas.
Bomb
A bomb is any of a range of explosive weapons that only rely on the exothermic reaction of an explosive material to provide an extremely sudden and violent release of energy...
s developed by the Manhattan Project
Manhattan Project
The Manhattan Project was a research and development program, led by the United States with participation from the United Kingdom and Canada, that produced the first atomic bomb during World War II. From 1942 to 1946, the project was under the direction of Major General Leslie Groves of the US Army...
and used by the United States Army Air Forces
United States Army Air Forces
The United States Army Air Forces was the military aviation arm of the United States of America during and immediately after World War II, and the direct predecessor of the United States Air Force....
against Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
during World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
. The name "pumpkin bomb" resulted from the large ellipsoidal shape of the munition and was the actual reference term used in official documents.
Development
The concept for the pumpkin bomb originated with Navy Captain William S. ParsonsWilliam Sterling Parsons
Rear Admiral William Sterling "Deak" Parsons was a naval officer who worked as an ordnance expert on the Manhattan Project during World War II...
of the Ordnance Division at Los Alamos
Los Alamos National Laboratory
Los Alamos National Laboratory is a United States Department of Energy national laboratory, managed and operated by Los Alamos National Security , located in Los Alamos, New Mexico...
and USAAF Colonel Paul W. Tibbets, commander of the 509th CG, on December 13, 1944, as a means of providing continued realistic training for the B-29 crews assigned to drop the atomic bomb after their deployment to the Western Pacific
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
. The bomb would be a close but non-nuclear replication of the Fat Man
Fat Man
"Fat Man" is the codename for the atomic bomb that was detonated over Nagasaki, Japan, by the United States on August 9, 1945. It was the second of the only two nuclear weapons to be used in warfare to date , and its detonation caused the third man-made nuclear explosion. The name also refers more...
plutonium bomb with the same ballistic
External ballistics
External ballistics is the part of the science of ballistics that deals with the behaviour of a non-powered projectile in flight. External ballistics is frequently associated with firearms, and deals with the behaviour of the bullet after it exits the barrel and before it hits the target.-Forces...
and handling characteristics. Mission parameters would be similar to those of the actual atomic bomb missions, and all targets would be located in the vicinity of the cities designated for atomic attack.
The development of the bomb was managed by the California Institute of Technology
California Institute of Technology
The California Institute of Technology is a private research university located in Pasadena, California, United States. Caltech has six academic divisions with strong emphases on science and engineering...
under the direction of Dr. Charles C. Lauritsen
Charles Christian Lauritsen
Charles Christian Lauritsen was a Danish-born, American physicist.-Early life and career:Lauritsen was born in Holstebro, Denmark and studied architecture at the Odense Tekniske Skole, graduating in 1911...
. Specifications for the bomb required that it be carried in the forward bomb bay
Bomb bay
The bomb bay or weapons bay on some military aircraft is a compartment to carry bombs, usually in the aircraft's fuselage, with "bomb bay doors" which open at the bottom. The bomb bay doors are opened and the bombs are dropped when over the target or at a specified launching point.Large-sized...
of a Silverplate
Silverplate
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 for the B-29 Superfortress to enable it to drop an atomic weapon, Silverplate eventually came to identify...
B-29 and be fuze
Fuse (explosives)
In an explosive, pyrotechnic device or military munition, a fuse is the part of the device that initiates function. In common usage, the word fuse is used indiscriminately...
d to be effective against actual targets. The bomb shells were manufactured by two Los Angeles, California
Los Angeles, California
Los Angeles , with a population at the 2010 United States Census of 3,792,621, is the most populous city in California, USA and the second most populous in the United States, after New York City. It has an area of , and is located in Southern California...
, firms, Consolidated Steel Corporation
Consolidated Steel Corporation
Consolidated Steel Corporation was an American steel and shipbuilding business. Consolidated built ships during World War II in two locations: Wilmington, California and Orange, Texas...
and Western Pipe and Steel Company
Western Pipe and Steel Company
The Western Pipe and Steel Company was an American manufacturing company that is best remembered today for its construction of ships for the Maritime Commission in World War II. It also built ships for the U.S...
, while the tail assembly was produced by Centerline Company of Detroit, Michigan
Detroit, Michigan
Detroit is the major city among the primary cultural, financial, and transportation centers in the Metro Detroit area, a region of 5.2 million people. As the seat of Wayne County, the city of Detroit is the largest city in the U.S. state of Michigan and serves as a major port on the Detroit River...
. After initial development, management of the program was turned over to the U.S. Navy Bureau of Ordnance
Bureau of Ordnance
The Bureau of Ordnance was the U.S. Navy's organization responsible for the procurement, storage, and deployment of all naval ordnance, between the years 1862 and 1959.-History:...
in May 1945.
Pumpkin bombs were produced in both inert and high explosive variants, with the inert versions filled with a cement
Cement
In the most general sense of the word, a cement is a binder, a substance that sets and hardens independently, and can bind other materials together. The word "cement" traces to the Romans, who used the term opus caementicium to describe masonry resembling modern concrete that was made from crushed...
-plaster
Plaster
Plaster is a building material used for coating walls and ceilings. Plaster starts as a dry powder similar to mortar or cement and like those materials it is mixed with water to form a paste which liberates heat and then hardens. Unlike mortar and cement, plaster remains quite soft after setting,...
-sand
Sand
Sand is a naturally occurring granular material composed of finely divided rock and mineral particles.The composition of sand is highly variable, depending on the local rock sources and conditions, but the most common constituent of sand in inland continental settings and non-tropical coastal...
mixture combined with water to the density of the Composition B
Composition B
Composition B, colloquially "comp B", is an explosive consisting of castable mixtures of RDX and TNT. It is used as the main explosive filling in artillery projectiles, rockets, land mines, hand grenades, sticky bombs and various other munitions...
used in the high explosive versions. The filler of both variants had the same weight and weight distribution as the inner sphere used in the plutonium bomb. All of the inert versions were shipped from the manufacturers directly to Wendover Army Air Field, Utah
Utah
Utah is a state in the Western United States. It was the 45th state to join the Union, on January 4, 1896. Approximately 80% of Utah's 2,763,885 people live along the Wasatch Front, centering on Salt Lake City. This leaves vast expanses of the state nearly uninhabited, making the population the...
, by rail, where they were used by the 216th Base Unit in flight testing of the bomb shape.
The bombs intended as live ordnance were shipped to the Naval Ammunition Depot, McAlester, Oklahoma
McAlester, Oklahoma
McAlester is a city in Pittsburg County, Oklahoma, United States. The population was 17,783 at the 2000 census. It is the county seat of Pittsburg County. It is currently the largest city in the Choctaw Nation of Oklahoma, followed by Durant....
, for filling with explosives. The Composition B was poured as a slurry
Slurry
A slurry is, in general, a thick suspension of solids in a liquid.-Examples of slurries:Examples of slurries include:* Lahars* A mixture of water and cement to form concrete* A mixture of water, gelling agent, and oxidizers used as an explosive...
, solidified in a drying facility, sealed, and shipped by railroad to the Port Chicago Naval Magazine, California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
for shipment by sea to Tinian
Tinian
Tinian is one of the three principal islands of the Commonwealth of the Northern Mariana Islands.-Geography:Tinian is about 5 miles southwest of its sister island, Saipan, from which it is separated by the Saipan Channel. It has a land area of 39 sq.mi....
.
A total of 486 live and inert bombs were eventually assembled.
Description
The pumpkin bombs were externally similar to the Fat Man bomb in size and shape, and both had the same 52-inch square tail assembly and single-point attachment lug. The pumpkin bomb had three contact fuseContact fuse
A contact fuze, percussion fuze or direct-action fuze is the fuze that is placed in the nose of a bomb or shell so that it will detonate on contact with a hard surface....
s arranged in an equilateral triangle around the nose of the bomb while the atomic bomb had four fuse housings. The atomic bomb had its sections bolted together but most if not all of the pumpkin bombs were welded with a four-inch hole used for filling the shell. The Fat Man also had four external mounting points for radar
Radar
Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...
antennas
Antenna (radio)
An antenna is an electrical device which converts electric currents into radio waves, and vice versa. It is usually used with a radio transmitter or radio receiver...
which the pumpkin bombs did not have.
The pumpkin bombs were twelve feet eight inches in length and five feet in maximum diameter. The most commonly-given weight for the bombs is 5.26 tons, consisting of 3,800 pounds for the shell, 425 pounds for the tail assembly, and 6,300 pounds of filler. The shells were made of .375-inch steel plate
Structural steel
Structural steel is steel construction material, a profile, formed with a specific shape or cross section and certain standards of chemical composition and mechanical properties...
and the tail assemblies from .200-inch aluminum plate
Sheet metal
Sheet metal is simply metal formed into thin and flat pieces. It is one of the fundamental forms used in metalworking, and can be cut and bent into a variety of different shapes. Countless everyday objects are constructed of the material...
. Although anecdotal sources attribute the naming of the bombs to painting them a pumpkin color, photographs indicate that the units delivered to Tinian
Tinian
Tinian is one of the three principal islands of the Commonwealth of the Northern Mariana Islands.-Geography:Tinian is about 5 miles southwest of its sister island, Saipan, from which it is separated by the Saipan Channel. It has a land area of 39 sq.mi....
came painted in the same Zinc Chromate primer color worn by Fat Man
Use
Twelve combat missions were flown between July 20 and July 29, 1945, using the bombs against targets in Japanese cities by the 509th Composite Group509th Composite Group
The 509th Composite Group was a United States Army Air Forces unit created during World War II, and tasked with operational deployment of nuclear weapons...
, to practice dropping the Fat Man nuclear shape
Fat Man
"Fat Man" is the codename for the atomic bomb that was detonated over Nagasaki, Japan, by the United States on August 9, 1945. It was the second of the only two nuclear weapons to be used in warfare to date , and its detonation caused the third man-made nuclear explosion. The name also refers more...
from the B-29 Superfortress
B-29 Superfortress
The B-29 Superfortress is a four-engine propeller-driven heavy bomber designed by Boeing that was flown primarily by the United States Air Forces in late-World War II and through the Korean War. The B-29 was one of the largest aircraft to see service during World War II...
. A total of 49 bombs were dropped on 14 targets. More than 400 people were estimated killed and 1,200 others injured.
In addition to the live ordnance dropped on Japan, several hundred inert bombs were used by combat crews of the 509th's 393rd Bomb Squadron to test the ballistics of the bomb shape in conjunction with Project Alberta
Project Alberta
Project Alberta was a section of the Manhattan Project which developed the means of delivering the first atomic bombs, used by the United States Army Air Forces against the Empire of Japan during World War II...
, and to train bombardiers in mission procedures before movement of the group overseas.
See also
- Claude EatherlyClaude EatherlyClaude Robert Eatherly was an officer in the U.S. Army Air Forces during World War II, and the pilot of a weather reconnaissance aircraft Straight Flush that supported the dropping of the atomic bomb on Hiroshima, Japan, August 6, 1945.-The bombing of Hiroshima:The Straight Flush was one of seven...
- Straight Flush (B-29)
- Atomic bombings of Hiroshima and NagasakiAtomic bombings of Hiroshima and NagasakiDuring the final stages of World War II in 1945, the United States conducted two atomic bombings against the cities of Hiroshima and Nagasaki in Japan, the first on August 6, 1945, and the second on August 9, 1945. These two events are the only use of nuclear weapons in war to date.For six months...