Operation Tumbler–Snapper

There were two principal test groups at TUMBLER-SNAPPER. The Military Effects Test Group (METG) was sponsored by the Department of Defense, Test Command, Armed Forces Special Weapons Project (AFSWP). The Weapons Development Test Group (WDTG) was sponsored by the Atomic Energy Commission. The METG involved more Department of Defense (DOD) participants while the WDTG was conducted principally by the Los Alamos Scientific Laboratory with the occasional involvement of DOD personnel.

Operation TUMBLER was principally focused on weapons effects tests and included Shots ABLE, BAKER, CHARLIE, and DOG. These were airdrops intended to help explain discrepancies in the actual and estimated blast shock wave damage noted on previous detonations and to establish more accurately the optimal height of burst.

Operation SNAPPER was intended to study nuclear phenomena in order to improve nuclear weapon design. The phase included two airdrop tests which were included in Operation TUMBLER, Shots CHARLIE and DOG, and four tower detonations: Shots EASY, FOX, GEORGE, and HOW.

The military exercise Desert Rock IV, involving 7350 soldiers, took place during the test series. They trained during the Charlie, Dog, and George shots and observed shot Fox.

In the official reports on the tests, the term height refers to the distance of the detonation above ground level, while altitude denotes elevation relative to mean sea level. At the test site, Yucca Flat lies at an elevation of approximately 4,000 feet (1,200 m) above mean sea level, and Frenchman Flat at about 3,000 feet (900 m). All detonation times are given in Pacific Standard Time (PST), with corresponding Coordinated Universal Time (UTC) values.

Tests

Shot ABLE

Shot ABLE was detonated on April 1, 1952 at 09:00 Pacific Standard Time (17:00 UTC) as a 1-kiloton device released from an aircraft and burst at an altitude of approximately 793 feet over Area 5 of Frenchman Flat. The detonation was part of the TUMBLER phase of the series, which examined the effects of burst height on blast characteristics in low-yield airbursts.

Units and organisations involved

• Military Effects Test Group
• Weapons Development Test Group
• Armed Forces Special Weapons Center (AFSWC)
• Strategic Air Command (SAC), including over 150 personnel observing from B-50 aircraft
• Camp Desert Rock support personnel (limited observer presence)

Results

Approximately 30 experiments were conducted to obtain data on weapons effects. AFSWC aircraft carried out the delivery of the device and supported follow-up operations, including aerial tracking of the cloud, sampling, and survey missions. No Exercise Desert Rock IV troop maneuver or observer program was conducted for this shot. Radiological surveys conducted several hours after the detonation indicated that the 0.01 R/h radiation level extended to a distance of about 600 metres from ground zero.

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Shot BAKER

Shot BAKER was detonated on April 15, 1952 at 09:30 Pacific Standard Time (17:30 UTC) as a 1-kiloton device released from an aircraft and burst at an altitude of approximately 1,109 feet over Area 7 of Yucca Flat. The test formed part of the TUMBLER phase and contributed additional data on how burst height influenced blast overpressure and related effects.

Units and organisations involved

• Military Effects Test Group
• Weapons Development Test Group
• Armed Forces Special Weapons Center (AFSWC)
• Strategic Air Command (SAC), including personnel observing from B-50 aircraft
• Camp Desert Rock support personnel (small observer presence)

Results

Approximately 45 experiments were conducted to support weapons-effects analysis. Aircraft from AFSWC carried out the delivery of the device and subsequent aerial operations, including tracking and survey activities. No Exercise Desert Rock IV troop maneuver or observer programme accompanied this detonation. Initial radiological measurements indicated levels of about 1.2 R/h at ground zero approximately one hour after the burst, decreasing to around 0.01 R/h at a distance of about 750 meters to the south.

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Shot CHARLIE

Shot CHARLIE was detonated on April 22, 1952 at 09:30 Pacific Standard Time (17:30 UTC) as a 31-kiloton device released from an aircraft and detonated at an altitude of approximately 3,447 feet over Area 7 of Yucca Flat. The test served both the TUMBLER weapons-effects program and the SNAPPER phase objectives related to weapon development.

CHARLIE was the first major event associated with Exercise Desert Rock IV, incorporating both a troop observer program and tactical maneuvers. The observer component involved approximately 535 personnel, while the maneuvers included about 1,675 troops participating in field exercises following the detonation.

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Shot DOG

Shot DOG was originally scheduled for April 29, 1952, but was postponed due to adverse weather conditions. The detonation took place on May 1, 1952, at 08:30 Pacific Standard Time (16:30 UTC) as a 19-kiloton device released from an aircraft and burst at an altitude of approximately 1,040 feet over Area 7 of Yucca Flat.

Although Pacific Daylight Time had come into effect on April 27, 1952, official reports for the series continued to use Pacific Standard Time to maintain consistency across test documentation.

The shot formed part of Exercise Desert Rock IV activities and involved U.S. Navy and Marine Corps personnel in both observer programs and tactical maneuvers conducted in conjunction with the detonation.

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Shot EASY

Shot EASY was originally scheduled for May 6, 1952, but was conducted on May 7, 1952, at 04:15 Pacific Standard Time (12:15 UTC). The device, with a yield of approximately 12 kilotons, was detonated from a 300-foot tower in Area 1 of Yucca Flat.

No formal Exercise Desert Rock IV troop maneuver or observer program accompanied this test. However, approximately 1,000 Camp Desert Rock support personnel witnessed the detonation from the Control Point at Yucca Pass.

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Shot FOX

Shot FOX was originally scheduled for May 13, 1952, but was postponed and ultimately detonated on May 25, 1952, at 04:00 Pacific Standard Time (12:00 UTC). The device, with a yield of approximately 11 kilotons, was detonated from a 300-foot tower in Area 4 of Yucca Flat.

The shot formed part of Exercise Desert Rock IV and included troop observer activities involving U.S. Army units as well as personnel from continental Army commands and service schools. Department of Defense personnel participated in multiple test-group experiments, while aircraft from the Armed Forces Special Weapons Center (AFSWC) provided operational support. Approximately 100 Strategic Air Command (SAC) personnel observed the detonation from aircraft operating in the vicinity of the Nevada Proving Ground.

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Shot GEORGE

Shot GEORGE was originally scheduled for May 20, 1952, but was postponed until June 1, 1952. The 15-kiloton device was detonated at 03:55 Pacific Standard Time (11:55 UTC) from a 300-foot tower in Area 3 of Yucca Flat.

The shot constituted a major Exercise Desert Rock IV event, incorporating both a troop observer program and tactical maneuvers involving approximately 1,800 U.S. Army personnel. Department of Defense participants took part in roughly 25 experimental projects associated with the test. Aircraft from the Armed Forces Special Weapons Center (AFSWC) provided operational support, while 24 Strategic Air Command (SAC) observers monitored the detonation from two B-50 aircraft.

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Shot HOW

Shot HOW was the final detonation of the series. Originally scheduled for May 27, 1952, it was carried out on June 5, 1952, at 03:55 Pacific Standard Time (11:55 UTC). The device, with a yield of approximately 14 kilotons, was detonated from a 300-foot tower in Area 2 of Yucca Flat.

No Exercise Desert Rock IV troop maneuver or observer program was conducted for this shot. Department of Defense personnel participated in a number of test-group experiments, with AFSWC aircraft providing air support. Strategic Air Command (SAC) observers monitored the detonation from aircraft operating in the vicinity of the test site.