DE PERE, Wis. — You probably did it with a firecracker when you were a kid.

You'd set it on rock or a stump, then you'd light the fuse, clamp your hands over your ears and run, to get out of range of the cardboard shrapnel. Or, if you set it on someone's porch, you ran so as not to get caught.

Well, that's what Mark Bentley of De Pere practiced doing in the U.S. Army, only he did it with atomic bombs: Carry one on your back, plant it somewhere, set the timer, clamp your hands over your ears and run like hell.

“We all knew it was a one-way mission, a suicide mission,” Bentley, who is now 68 and quite probably not even quick enough anymore to outrun firecracker shrapnel, told the Green Bay Press-Gazette.

You might not have realized they ever made A-bombs small enough for one man to carry, but they did. They had one called the W54 that fit into a duffel bag. It was less than a tenth as powerful as “Little Boy,” the one dropped on Hiroshima a quarter-century earlier, but without benefit of you being able to fly away in an airplane before it goes off. There was also a bigger one that fit into a 55-gallon drum, two or three times as powerful as the one you could carry on your back, Bentley recalled.

H-912 transport container for SADM is seen at the National Atomic Museum. (via Wikimedia Commons)
H-912 transport container for SADM is seen at the National Atomic Museum. (via Wikimedia Commons)


It was part of the post-WWII, Cold War era in which the Soviet Union was viewed as an expansionist threat into western Europe, said John Sharpless, newly retired professor at the University of Wisconsin-Madison, where he taught a class on the period.

"The Soviet Union had a substantially larger land army, considerably larger than NATO and the U.S.," Sharpless said. "When you consider the possibility of war in Europe, if the Russians decided to invade from the east, it would be nearly impossible to stop them. So, one strategy was to block various access routes and perhaps funnel them into an area where you could use larger weapons against them."

That was the apparent strategy with the hand-carried nukes, Bentley said — not to nuke Russians directly but rather nuke big holes in the Alps, so that all the resultant ash would fill up the valleys and prevent Soviet tanks and trucks from being able to pass, he said.

The hand-carried nukes evolved out of even smaller nuclear weapons that had been developed in the 1950s, Sharpless said. Those included the Davy Crockett nuclear warheads that could be fired from bazookas and even recoilless rifles, he said.

"The problem was, the blast range was larger than the trajectory," he said.

In other words, you couldn't shoot them far enough to keep yourself out of harm's way. That essentially was the same worry about the hand-carried nuclear mines that Bentley and his fellow soldiers were training to plant: You were unlikely to be able to get out of range yourself.

The funny thing is, Bentley put in for the duty. And no, not because he was suicidal.

The year was 1968, when the Vietnam War was still raging, and Bentley, a new high school graduate, had an alarmingly low draft number.

"It's the only lottery I ever won," said Bentley, who was holding lucky number 27.

Enrolling in college, getting married, having a son — none of it staved off the inevitable.

"The question was, do I go in as a draftee and essentially become a target for two years, or do I enlist for three and maybe get to do something I want?" he said.

He decided to enlist. His timing wasn't great; the draft was eliminated just about when he signed the dotted line. But at least the Vietnam War was coming to an end.

He eventually found himself at Fort Belvoir, Virginia, home of the Army engineers. At first, he was trained in a program to deliver acetylene and oxygen to engineers to do repairing and welding in the field. That program was finally deemed unfeasible and he was transferred to one of the Special Atomic Demolition Munition platoons. He recalled he was in one of two such platoons stationed stateside, training, while several others were stationed in central Europe.

Anyway, Bentley never got to the Alps. He kept training and practicing against the possibility of Soviet aggression in Virginia. They took turns carrying a dummy version of the bomb into the woods near the base, setting the timer and imagining the results.

"You constantly trained," he said. "You talk about something being driven through your brain — that's all you ate, slept and thought about eight hours a day."

He got to carry the duffel bag bomb once and set the timer.

"You set your timer, and it would click when it went off, or it went ding or I forget what, but you knew you were toast," he said. "Ding! Your toast is ready, and it's you."

In theory, you could set the timer to give you enough time to flee properly, but somebody would have to stay behind and secure the site, Bentley said.

"The Army is not going to set a bomb like that and run away and leave it, because they don't know if someone else would get ahold of it," he said. "They have to leave troops there to make sure it's not stolen or compromised, and that would just be collateral damage. You didn't go out with the thought that it was anything other than a one-way mission. If you're Bruce Willis, you get away, but I ain't Bruce Willis."

Mercifully, even the platoons stationed near the Alps never got a chance to set off a real one. Maybe the Army decided nukes were better off being dropped from planes, or maybe the threat of attack dwindled as the Cold War was beginning to wind down, Bentley was never sure. But he wasn't surprised.

"I banked on them never doing it," he said.

While actually having to do it would be a scary proposition, merely hanging out in a base not too far from Washington, D.C., and training for it was pretty good duty in Bentley's mind.

"It was a great place to be stationed," he said. "Being a history nut, I had battlefields to visit . . . Jefferson's home at Monticello, Madison's home a couple miles away. We went camping on weekends, at Bull Run. How many people can say they camped at Bull Run, at a national Civil War battlefield?"

Bentley got out in August 1975, a few years before the Special Atomic Demolition Munition units were entirely disbanded. For some reason, he didn't find a lot of civilian employers clamoring to hire someone trained in hand-delivering atomic bombs. His undergraduate degree was in business education, but he quickly learned teaching wasn't for him, so he got a master's degree in personnel and industrial relations and spent most of his working years dealing with union negotiations and other human resources jobs.

“The best thing I ever did was go into the Army,” Bentley said. “You won’t hear many people say that, but you were exposed to so many different ways of life, occupations, places to live, people.”

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The W54 was one of the smallest nuclear warheads deployed by the United States. It was a very compact implosion-type nuclear weapon design, designed for tactical use and had a very low yield for a nuclear weapon, in the range of 10 to 1,000 tons TNT equivalent.

Its original use was in the Davy Crockett short-range rocket, later adapted as a man-portable Special Atomic Demolition Munition (SADM), and later as the basis of nuclear-tipped air-to-air missiles. A later development was the W72, which were rebuilt W54's used with the AGM-62 Walleye guided bomb. The W72 was in service until 1979.

Development

A 1958 test of the XW-54 warhead yielded 6 kilotons[1]


The W54 was designed by Los Alamos Scientific Laboratory and built by the United States Atomic Energy Commission. Around 400 units were manufactured from 1961 until early 1962 and were deployed until at least 1971.

Pre-production testing

The earliest identified nuclear tests of devices corresponding to the W54 characteristics were the Pascal-A and Pascal-B test detonations in 1957, in the Operation Plumbbob nuclear test series. These were both intended to have very low yield, but overshot to higher yields (tens and hundreds of tons of TNT).

These were followed by tests of the XW-51 design, which evolved into the XW-54 in the Operation Hardtack I test series in 1958 (Hardtack Quince and Hardtack Fig). These were both described as fizzles, or test failures.

A number of XW-51/XW-54 tests followed in the 1958 Operation Hardtack II test series, including Hardtack II Otero, Bernalillo, Luna, Mora, Colfax, Lea, Hamilton, Dona Ana, San Juan, Socorro, Catron, De Baca, Chavez, Humboldt, and Santa Fe. By this time, the XW-51 / XW-54 design had been test-fired more times than any preceding US nuclear weapon prior to its successful introduction in service, indicating the difficulty of successfully making this small and low-yield design work reliably and safely.

Further testing followed in the 1961 Operation Nougat test series, probably including Nougat Shrew, Boomer, Ringtail, and possibly others. By this time the W-54 design was performing consistently as expected at low yields.

Variants

There were four distinct models of the basic W54 design used, each with different yield, but the same basic design. These were:

  • Mk-54 (Davy Crockett) – 10 or 20 tons yield, Davy Crockett artillery warhead
  • Mk-54 (SADM) – approximate yield from 10 tons to 1 kiloton, Special Atomic Demolition Munition device
  • W-54 – 250-ton yield, warhead for AIM-26 Falcon air-to-air missile
  • W72 – 600-ton yield, rebuilt W-54 (Falcon warhead) for AGM-62 Walleye


Specifications

All four variants share the same basic core: a nuclear system which is 10.75 inches (273 mm) diameter, about 15.7 inches (400 mm) long, and weighs around or slightly over 50 pounds (23 kg).[2]

Known and theoretical uses

The W54 would have fit into the Special Atomic Demolition Munition("Backpack Nuke") casings

These small-size devices were first intended for use by United States Army ground soldiers in battle and were in theory small enough to be delivered by a bazooka-style firing mechanism. Early known versions could destroy a two-block area, with an estimated yield comparable to approximately 10 tons TNT equivalent. Larger versions were later developed with a selectable yield of between 10 and 250 tons. The yield of 10 tons TNT equivalent was just below the largest yield for any conventional bomb built until the 1950s, T-12 Cloudmaker (designed in 1944), at a mass of close to 20 metric tons yielding a blast of 11 tons TNT equivalent. The W54 is small enough to be deployed as a SADM (Special Atomic Demolition Munition), or so-called "Backpack Nuke". It was the closest thing the U.S. is known to have developed to a so-called "suitcase bomb".

The W54 style warhead was known to be used on the M-388 Davy Crockett, a tactical nuclear recoilless rifle projectile that was deployed by the United States in 1961 and decommissioned in 1971.

The W54 was tested for use in a U.S. Navy SEAL project that was demonstrated as feasible in the mid-to-late 1960s, designed to attack a harbor or other strategic location that could be accessed from the sea. The SEAL version would be delivered into water by parachute along with a two-man team, then floated to the target, set in place and armed by hand.

The United States Air Force also developed a project using the W54, the Hughes Electronics AIM-26 Falcon. This was a larger, more powerful version of the AIM-4 Falcon air-to-air missile. It is notable for being the only known production U.S. guided air-to-air weapon with a nuclear warhead. It was intended to destroy formations of Soviet bombers at a time when guided missiles were not accurate enough to produce high-probability kills with small conventional warheads.

W72

After the AIM-26 Falcon was retired, 300 units were rebuilt into an improved configuration with a higher yield and redesignated the W72. These warheads were then used to produce a number of nuclear versions of the AGM-62 Walleye television-guided glide bomb system. The W72 variant had a yield of around 600 tons of TNT.

The 300 W72 units were produced between 1970 and 1972 and were in service until 1979.

Documented testing

Stockpiled W54 warheads were test-fired at the Nevada Test Site on July 7 and July 17, 1962. In Little Feller II (July 7), the warhead was suspended 3 feet above the ground and had a yield equivalent to 22 tons of TNT. In Little Feller I (July 17), the warhead was launched as a Davy Crockett device from a stationary 155-millimeter launcher and set to detonate between 20 and 40 feet above the ground around 1.7 miles from the launch point, with a yield of 18 tons. This test was the last atmospheric test at Nevada Test Site and was performed in conjunction with Operation Ivy Flats, a simulated military environment. It was observed by Attorney General Robert F. Kennedy and presidential advisor General Maxwell D. Taylor. Ivy Flats Film Report[3] was declassified by the United States Department of Energy on December 22, 1997. Limited operational details of early SADM projects were published prior to this declassification.

See also

  • List of nuclear weapons

References

  1. Socorro (22 October 1958 13:30 PST) United States Nuclear Tests: July 1945 through September 1992 (PDF) (DOE/NV-209 REV15), Las Vegas, NV: Department of Energy, Nevada Operations Office, 2000-12-01, archived from the original (PDF) on 2006-10-12, retrieved 2013-12-18
  2. Data from 1st Battalion, 33rd Armor: https://web.archive.org/web/20...-33rdar.org/M388.jpg
  3. Declassified U.S. Nuclear Test Film #32
  • List of all US Nuclear Weapons at Nuclear Weapon Archive
  • W54 at GlobalSecurity.org
  • The Davy Crockett at the Brookings Institution