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Tumbler-Snapper was the third series of nuclear tests conducted at the Nevada Test Site. The series was conducted between April 1, 1952 and June 5, 1952 and involved eight nuclear detonations in two separate phases. The first phase, Tumbler, was conducted by the Department of Defense (DOD) and consisted of four weapons effects shots. The four Tumbler shots were airdropped from B-50 aircraft and detonated over Frenchman and Yucca Flats. These devices were detonated to collect data on the effect of the height of burst on overpressure. The code names of the Tumbler shots were Able, Baker, Charlie, and Dog.
The second phase, Snapper, was primarily a weapons development operation conducted by the Atomic Energy Commission (AEC) and Los Alamos Scientific Laboratory (LASL). The four Snapper shots, Easy, Fox, George, and How, were detonated atop 300 foot towers. Shots Charlie and Dog, fired during Tumbler, were also part of the Snapper phase. The primary goal of the weapons development effort during Snapper was to study nuclear phenomena and improve the design of nuclear weapons.
During Operations Sandstone (1948), Greenhouse (1951), and Buster-Jangle (1951), unexpected anomalies on blast over pressure and arrival times from airbursts were observed. Gathering further data on these anomalies was one of the primary goals of the Tumbler phase. The first two shots, Able and Baker, were 1 kiloton shots fired to develop scaling laws for future reference. All of the test devices were fired in the Mk-4 heavy bomb.
Some of the ambitious projects tested during the Snapper weapons development phase were deuterium gas fusion boosting, external initiation, and the use of beryllium neutron reflector/tampers. Smaller implosion systems and schemes for achieving high core compression were also tested. The TOM internal neutron initiator was calibrated during the Snapper phase.
10,600 DOD personnel participated in Tumbler-Snapper, 7,350 of which participated in Desert Rock IV exercises. The remaining DOD personnel were involved in assisting scientific experiments, air support activities, and administration and support activities at the Nevada Test Site. Desert Rock IV exercises involved observer programs and tactical maneuvers around an atomic detonation. The observer programs were conducted during shots Charlie, Dog, Fox, and George. The observer programs involved briefings on the effects of nuclear detonations, observation of the actual nuclear detonation, and a tour of the displays of military equipment exposed to the detonation. Radiation exposures for the personnel were limited to 3.0 rem. However, a number of personnel sustained doses higher then the limit. 48 were measured with doses of 305 rem, 9 with 5-10 rem, and 1 with excess of 10 rem.
Two test groups conducted scientific experiments during Tumbler-Snapper; the Military Effects Test Group and the Weapons Development Test Group. The Military Effects Test Group was sponsored by the Test Command and Armed Forces Special Weapons Project (AFSWP). The LASL conducted most of the Weapons Development Test Group activities. In the days and weeks before a shot, the test groups placed instruments and equipment at various distances around the intended ground zero of a nuclear detonation. After the shot, when it was determined the area was radiological safe, the test groups were allowed to retrieve data collected by the instruments.
The Air Force Special Weapons Center (AFSWC), operating out of Kirtland Air Force Base, was responsible for cloud tracking, cloud sampling, aerial surveys of the terrain, and other air support duties. The AFSWC consisted of the 4901st Support Wing, which was staged out of Indian Springs AFB.
The devices proof tested during Snapper involved weapons of a smaller physical size that might be carried externally by fighter-bomber aircraft during tactical support of ground operations. Developing small, tactical nuclear weapons became an immediate priority since the outbreak of the Korea War in 1950.
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Tumbler Phase Tests
| Code Name:
| Able |
| Time and Date: | 09:00 April 1, 1952 (local) |
| Location: | Area 5, Nevada Test Site (NTS) |
| Height: | 793 feet |
| Type: | Air Burst - Air Drop |
| Predicted Yield: | --- |
| Actual Yield: | 1 kt |
Able, detonated on April 1, 1952, was the first shot of Operation Tumbler-Snapper. The same device was tested earlier in Ranger Able, Jangle Sugar, and Jangle Uncle. The device was based on the Mk-4 and weighed 10,800 lb. The yield of the explosion was 1 kiloton. The bomb was detonated over Frenchman Flat, the only test conducted in the area during Tumbler-Snapper.
About 30 scientific and diagnostic experiments were conducted during the test by the Military Effects Test Group and Weapons Development Test Group. AFSWC activities involved cloud sampling, cloud tracking, courier service, aerial surveys, and the actual airdrop of the device. 150 personnel from the Strategic Air Command observed the shot from B-50 aircraft flying over the test area. No formal military operations were conducted during the shot, however, 15 members from the Camp Desert Rock support staff observed the shot. Onsite radiation consisted of small areas of low-level contamination surrounding ground zero.
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| Code Name: | Charlie |
| Time and Date: | 09:30 April 22, 1952 (local) |
| Location: | Area 7, Nevada Test Site (NTS) |
| Height: | 3447 feet |
| Type: | Air Burst - Air drop |
| Predicted Yield: | 40-60 kilotons |
| Actual Yield: | 31 kilotons |
Charlie was a joint Tumbler and Snapper phase experiment. It combined the proof testing of a new high-efficiency core and blast effects measurements. The Mk-4 based bomb was dropped from a B-50 aircraft over Area 7 of Yucca Flat. This was also the first test that was broadcast on live television.
Desert Rock IV activities involved 535 personnel in observer programs and 1,675 personnel in tactical troop maneuvers. The Army tactical maneuver during shot Charlie was conducted by the 2nd Battalion, 504th Airborne Infantry Regiment, 82nd Airborne Division from Fort Bragg, Carolina; Company B, 167th Infantry Regiment, 31st Infantry Division, Camp Atterbury, Indiana; Company C, 135th Infantry Regiment, 47th Infantry Division, Fort Rucker, Alabama; Tank Platoon, 11th Armored Calvary Regiment, Camp Carson, Colorado; Engineer Platoon, 369th Engineer Ambitious Support Regiment, Fort Worden, Washington; Medical Detachment (augmented), Sixth Army, numerous Sixth Army Posts. The Air Force’s 140th Fighter-Bomber Group (Provisional), 140th Fighter-Bomber Wing, Clovis Air Force Base, New Mexico also participated in Desert Rock IV exercises.
The five activities conducted during Desert Rock IV were observation of the shot, psychological testing, movement to objective, inspection of an equipment display, and airborne exercise. After observing the shot from trenches 20,480 feet from ground zero, the troops were tested by the Human Resources Research Office and the Operations Research Office to determine their reactions to the detonation. The troops then toured the display area and approached as close as 512 feet to ground zero. Army paratroopers landed in a drop zone north of ground zero after the detonation. Some of the paratroopers jumped too soon and missed the drop zone by as much as 20 miles.
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| Code Name: | Dog |
| Time and Date: | 08:30 May 1, 1952 (local) |
| Location: | Area 7, Nevada Test Site (NTS) |
| Height: | 1040 feet |
| Type: | Air Burst - Air drop |
| Predicted Yield: | 15-20 kilotons |
| Actual Yield: | 19 kilotons |
Dog was the fourth detonation of Operation Tumbler-Snapper. The 19 kiloton device was detonated at 8:30 on May 1, 1952. A B-50 dropped the modified TX-7 bomb over same ground zero location used for the Baker and Charlie shots. The device tested the usefulness of deuterium gas fusion boosting.
The Navy and Marines conducted an observer program during the shot as part of Exercise Desert Rock IV. Approximately 350 Navy and Marine personnel participated in the observer program. The detonation was observed from a position 20,480 feet south of ground zero. 1,950 Marines from the 1st Provisional Marine Battalion of Camp Pendleton and 2nd Provisional Marine Battalion of Camp Lejeune took part in tactical maneuvers during the shot. These two battalions formed the Marine Corps Provisional Atomic Exercise Unit, which consisted of both officers and enlisted men.
This was the first time the Marine Corps participated in military exercises in a nuclear combat environment. As with shot Charlie, the troops observed the shot, were tested by the Human Resources Research Office and the Operations Research Office to determine their reactions to the detonation, and toured the display areas. The Marines stopped their tour 2,624 feet from ground zero due to high radiation levels.
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Snapper Phase Tests
| Code Name: | Easy |
| Time and Date: | 04:15 May 7, 1952 (local) |
| Location: | Area 1, Nevada Test Site (NTS) |
| Height: | 300 feet |
| Type: | Tower Burst |
| Predicted Yield: | 9 kilotons |
| Actual Yield: | 12 kilotons |
Easy was the first test of the Snapper phase. The device, code named BROK-1, was a test of a prototype Mk-12 bomb, designated a TX-12. The Mk-12 was intended to be a slender and lightweight tactical nuclear bomb that could be carried externally by high-speed bomber aircraft. It had the smallest implosion system (22 inches) and weight (550 lb) of any nuclear device developed up until that time. The total device weight was 625 lb.
The device was fired at 4:15 on May 7, 1952 with a yield of 12 kilotons. It was postponed one day due to unfavorable weather conditions. The cloud reached an altitude of 34,000 feet. DOD personnel were involved in approximately 30 of the test group experiments. No formal military exercises were conducted with the shot, however, 1,000 personnel from Camp Desert Rock observed the shot from the Control Point at Yucca Pass. The radiological survey team was unable to complete the survey of on shot-day due to heavy contamination north of ground zero.
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| Code Name: | Fox |
| Time and Date: | 04:00 May 25, 1952 (local) |
| Location: | Area 4, Nevada Test Site (NTS) |
| Height: | 300 feet |
| Type: | Tower Burst |
| Predicted Yield: | 15-18 kilotons |
| Actual Yield: | 11 kilotons |
The LASL device, code named XR1, used an Mk-5 bomb assembly. The test calibrated the TOM polonium-beryllium internal neutron initiator. The device had a diameter of 40 inches and a weight of 2700 lb. The device misfired on its first attempt and had to be further postponed due to unfavorable weather conditions. It was successfully detonated at 4:00 on May 25, 1952. The cloud reached an altitude of 41,000 feet and drifted north into Utah.
1,450 military personnel observed the shot as part of Exercise Desert Rock IV. These observers consisted of 950 soldiers from the 701st Armored Infantry Battalion, 1st Armored Division, from Fort Hood, Texas and an additional 500 participants from the continental armies and service schools. No tactical maneuvers were conducted with the shot.
One B-29, four T-33s, and six F-84s collected particulate and gaseous samples from the Fox cloud. The sampler aircraft flew at altitudes ranging from 30,000 to 40,000 feet and made a total of 35 penetrations. All the aircraft returned to Indian Springs AFB after the shot.
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| Code Name: | George |
| Time and Date: | 03:55 June 1, 1952 (local) |
| Location: | Area 3, Nevada Test Site (NTS) |
| Height: | 300 feet |
| Type: | Tower Burst |
| Predicted Yield: | 30 kilotons |
| Actual Yield: | 15 kilotons |
The George device, code named XR2, used a Mk-5 bomb assembly. A device called a betatron, which is a circular electron accelerator, was used as an external initiator for the shot. The device generated high energy X-rays that induced photo-fission in the core to initiate the chain reaction. The device had a diameter of 40 inches and weighed 2700 lb.
The shot was originally scheduled for May 20 but was postponed due to unfavorable weather conditions. Originally, George was supposed to be fired at Area 2 of the Nevada Test Site, but radioactive residue left over from shots Easy and Fox delayed operations. As a result of the delays, the test location was moved to Area 3. The next shot, How, would be fired in Area 2. Consequently, Desert Rock IV exercises originally scheduled for How were moved to shot George.
George was successfully detonated on June 1, 1952. The cloud generated by the 15 kiloton explosion reached an altitude of 37,000 feet. 1,300 troops participate in military maneuvers during the shot and 500 troops participated in observer programs. The units that performed the Desert Rock IV maneuvers were the 23rd and 31st Transportation Truck Companies and elements of the 369th Engineer Amphibious Support Regiment.
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| Code Name: | How |
| Time and Date: | 03:55 June 5, 1952 (local) |
| Location: | Area 2, Nevada Test Site (NTS) |
| Height: | 300 feet |
| Type: | Tower Burst |
| Predicted Yield: | 11 kilotons |
| Actual Yield: | 14 kilotons |
How as the last test of Operation Tumbler-Snapper. The device, code named Scorpion, was designed in part by Ted Taylor. The How device was the first to use a beryllium neutron reflector/tamper. This component would become standard an later nuclear weapons. How was originally scheduled to be fired on May 27 but was postponed due to unfavorable weather conditions.
How was successfully fired at 03:55 on June 5, 1952 with a yield of 14 kilotons. The cloud reached an altitude of 41,800 feet. The cloud dispersed in several directions. The lower portion moved in a northwestern direction while the upper portion moved to the northeast.
No Desert Rock activities were conducted during How, a result of being rescheduled for the George shot. One B-29, four T-33s, and six F-84s collected particulate and gaseous samples from the cloud.
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Declassified Operation Tumbler-Snapper films at the Atomic Forum Films Archive
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Military Participation on Tumbler-Snapper - 1952
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Operation Tumbler - A Photographic Study of Thermal and Blast Effect - 1952
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