H.L. Hunley submarine crew were killed by their own weapon

The first combat submarine to sink an enemy ship also instantly killed its own eight-man crew with the powerful explosive torpedo it carried, new research has found. 

The HL Hunley fought for the confederacy in the US civil war and was sunk near North Charleston, South Carolina, in 1864.

Speculation about the crew’s deaths has included suffocation and drowning, but a new study claims that a shockwave created by their own weapon was to blame.

The first combat submarine to sink an enemy ship also instantly killed its own eight-man crew (pictured) with the powerful explosive torpedo it carried, new research has found. A new study says a shockwave created by their own weapon was to blame

WHAT KILLED THE CREW? 

The researchers suggest that the crew was killed by a blast of energy as a torpedo was released. 

The shockwave of the blast would travel about 4,920 feet (1,500 metres) per second in water, and 1,115 feet (340 m) per second in air. 

When it crossed the lungs of the crewmen, the shockwave was slowed to about 100 feet (30 m) per second.

While a normal blast shockwave travelling in air should last less than 10 milliseconds, Ms Lance calculates that the Hunley crew’s lungs were subjected to 60 milliseconds or more of trauma. 

Shear forces would have torn apart the delicate structures where the blood supply meets the air supply, filling the lungs with blood and killing the crew instantly. 

It us likely they also suffered traumatic brain injuries from being so close to such a large blast. 

Researchers from Duke University in North Carolina set blasts near a scale model of the vessel to calculate their impact.

They also shot authentic weapons at historically accurate iron plates.

They used this data to work out the mathematics behind human respiration and the transmission of blast energy.

Ms Rachel Lance, one of the researchers on the study, says the crew died instantly from the force of the explosion travelling through the soft tissues of their bodies, especially their lungs and brains.

Ms Lance calculates the likelihood of immediately fatal lung trauma to be at least 85 per cent for each member of the Hunley crew. 

She believes the crippled sub then drifted out on a falling tide and slowly took on water before sinking. 

‘This is the characteristic trauma of blast victims, they call it “blast lung”, said Ms Lance.

‘You have an instant fatality that leaves no marks on the skeletal remains. 

‘Unfortunately, the soft tissues that would show us what happened have decomposed in the past hundred years.’

Blast-lung is a phenomenon of something Ms Lance calls ‘the hot chocolate effect.’ 

The shockwave of the blast would travel about 4,920 feet (1,500 metres) per second in water, and 1,115 feet (340 m) per second in air.  

The Hunley's torpedo was not a self-propelled bomb, as we think of them now. Rather, it was a copper keg of gunpowder held ahead and slightly below the Hunley's bow on a 16-foot pole called a spar (pictured)

The Hunley’s torpedo was not a self-propelled bomb, as we think of them now. Rather, it was a copper keg of gunpowder held ahead and slightly below the Hunley’s bow on a 16-foot pole called a spar (pictured)

Ms Lance said that when it crossed the lungs of the crewmen, the shockwave was slowed to about 100 feet (30 m) per second.

While a normal blast shockwave travelling in air should last less than 10 milliseconds, Ms Lance calculates that the Hunley crew’s lungs were subjected to 60 milliseconds or more of trauma.

‘When you mix these speeds together in a frothy combination like the human lungs, or hot chocolate, it combines and it ends up making the energy go slower than it would in either one,’ Ms Lance added. 

The Hunley's successful but doomed final mission was actually its third trip. The submarine sank once while docked with its hatches open in August 1863. Only three of the eight men on board escaped and survived

The Hunley’s successful but doomed final mission was actually its third trip. The submarine sank once while docked with its hatches open in August 1863. Only three of the eight men on board escaped and survived

The Hunley's first and last combat mission occurred during the Civil War on Feb 17, 1864, when it sank a 1,200-ton Union warship, the USS Housatonic, outside Charleston Harbour

The Hunley’s first and last combat mission occurred during the Civil War on Feb 17, 1864, when it sank a 1,200-ton Union warship, the USS Housatonic, outside Charleston Harbour

THE H.L. HUNLEY’S DOOMED TRIPS

The Hunley’s successful but doomed final mission was actually its third trip. 

The submarine sank once while docked with its hatches open in August 1863. Only three of the eight men on board escaped and survived.

In October 1863, designer H.L. Hunley led another eight-man crew who planned to show how the sub operated by diving under a ship in Charleston Harbor.

They never surfaced, but the sub was found weeks later and brought back to the surface. 

That crew was interred in graves that ended up below The Citadel’s football stadium for 50 years. 

‘That creates kind of a worst case scenario for the lungs.’

Shear forces would have torn apart the delicate structures where the blood supply meets the air supply, filling the lungs with blood and killing the crew instantly. 

It us likely they also suffered traumatic brain injuries from being so close to such a large blast.  

The Hunley’s first and last combat mission occurred during the Civil War on Feb 17, 1864, when it sank a 1,200-ton Union warship, the USS Housatonic, outside Charleston Harbour.

The Hunley delivered a blast from 135 pounds (60 kg) of black powder below the waterline at the stern of the Housatonic, sinking the Union ship in less than five minutes. 

Housatonic lost five seamen, but came to rest upright in 30 feet (ten metres) of water, which allowed the remaining crew to be rescued after climbing the rigging and deploying lifeboats.

The Hunley was raised from the bottom of the ocean in 2000, and initially, the discovery of the submarine only seemed to deepen the mystery.

 The Hunley was raised from the bottom of the ocean in 2000. The 75,000-gallon tank of water and chemicals that houses the vessel (pictured) is drained three times a week for several hours to allow restoration work to take place

 The Hunley was raised from the bottom of the ocean in 2000. The 75,000-gallon tank of water and chemicals that houses the vessel (pictured) is drained three times a week for several hours to allow restoration work to take place

Pictured is the submarine

The Hunley's successful but doomed final mission was actually its third trip

When the submarine was raised in 2000, the crewmen’s skeletons were found still at their stations along a hand-crank that drove the cigar-shaped craft. They suffered no broken bones, the bilge pumps hadn’t been used and the air hatches were closed

The crewmen’s skeletons were found still at their stations along a hand-crank that drove the cigar-shaped craft. 

They suffered no broken bones, the bilge pumps hadn’t been used and the air hatches were closed. 

Except for a hole in one conning tower and a small window that may have been broken, the sub was remarkably intact. 

The eight crew members were buried in an elaborate ceremony at a Confederate cemetery in Charleston in 2004.

HOW THE HUNLEY SUBMARINE MOVED 

Researchers announced in June that they had finally cracked how the submarine was propelled through the water.

Hidden underneath the rock-hard stuff scientists call ‘concretion’ was a sophisticated set of gears and teeth on the crank in the water tube that ran the length of the 40-foot sub.

These gears enabled the crew rotating the crank to propel the sub faster by moving water more quickly through the tube, conservator and collections manager Johanna Rivera-Diaz said.

The biggest surprise for Rivera-Diaz? Discovering that some of the men wrapped the crank handle in thin metal tubes covered with cloth to try to prevent blisters.

‘You get really concentrated on a specific area working every day. I was finishing the crank system. One day, when I was through, I just stepped back and “Wow, this looks amazing”,’ she said. 

They were the sub’s commander, Lt George Dixon of Alabama, James A Wicks, a North Carolina native living in Florida, Frank Collins of Virginia, Joseph Ridgaway of Maryland and four foreign-born men about whom less is known.  

One is still only known as ‘Miller.’

The Hunley’s successful but doomed final mission was actually its third trip. 

This graphic reveals the Hunley submarine's final moments as it drove its spar-based torpedo into the hull of a Union blockade ship

This graphic reveals the Hunley submarine’s final moments as it drove its spar-based torpedo into the hull of a Union blockade ship

The submarine sank once while docked with its hatches open in August 1863, and only three of the eight men on board escaped and survived

The submarine sank once while docked with its hatches open in August 1863, and only three of the eight men on board escaped and survived

The submarine sank once while docked with its hatches open in August 1863, and only three of the eight men on board escaped and survived.

In October 1863, designer HL Hunley led another eight-man crew who planned to show how the sub operated by diving under a ship in Charleston Harbor.

They never surfaced, but the sub was found weeks later and brought back to the surface. 

That crew was interred in graves that ended up below The Citadel’s football stadium for 50 years.   

The HL Hunley (artist's impression) fought for the confederacy in the US civil war and was sunk near North Charleston, South Carolina, in 1864 by its own torpedo

The HL Hunley (artist’s impression) fought for the confederacy in the US civil war and was sunk near North Charleston, South Carolina, in 1864 by its own torpedo

Two scientists have spent the past 17 years collecting the crew's remains and restoring the vessel as part of a painstaking cleanup operation

Two scientists have spent the past 17 years collecting the crew’s remains and restoring the vessel as part of a painstaking cleanup operation

Two scientists have spent the past 17 years collecting the crew’s remains and restoring the vessel as part of a painstaking cleanup operation.

They patiently removed a century and a half of sand, sediment and corrosion from the historic submarine.

Their goal is to get it looking as close as it appeared on its mission as possible by removing gunk using a mixture of sodium hydroxide and a mild electrical current.

This gradually softens the concrete-hard buildup of sand, mud and shells that built up inside the vessel during the 140 years it was buried off Sullivan’s Island, so that the debris can be removed later.

Two scientists have spent the past 17 years collecting the crew's remains and restoring the vessel as part of a painstaking cleanup operation (pictured)

Two scientists have spent the past 17 years collecting the crew’s remains and restoring the vessel as part of a painstaking cleanup operation (pictured)

Pictured is the Hunley as it was removed from the ocean floor in 2000. Scientists have since spent 17 years restoring the vessel

Pictured is the Hunley as it was removed from the ocean floor in 2000. Scientists have since spent 17 years restoring the vessel

Since the submarine was found and removed from the ocean (pictured), the researchers' goal has been to get it looking as close as it appeared on its mission as possible by removing gunk using a mixture of sodium hydroxide and a mild electrical current

Since the submarine was found and removed from the ocean (pictured), the researchers’ goal has been to get it looking as close as it appeared on its mission as possible by removing gunk using a mixture of sodium hydroxide and a mild electrical current

They drain the 75,000-gallon tank of water and chemicals that houses the vessel three times a week for several hours, at the Confederate sub’s home in North Charleston, South Carolina.

Then, they go to work in full protective gear, bent around nooks and crannies, gingerly chipping the grime off the HL Hunley.

It took one year to remove all the crud from its hull, and nearly two more to clean out the much smaller crew compartment.

The sub itself is only four feet in diameter. Eight schoolchildren can barely cram themselves into a replica nearby at the Warren Lasch Conservation Centre.

The Hunley submarine was raised from the bottom of the ocean off the coast of North Charleston, South Carolina, in 2000

The Hunley submarine was raised from the bottom of the ocean off the coast of North Charleston, South Carolina, in 2000

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