CSS Hunley query

[on again]

What was it that killed the last crew of the Hunley? was it shock waves from their exploding torpedo?

 

[USS ALASKA]

Air blast injuries killed the crew of the submarine H.L. Hunley

Abstract
The submarine H.L. Hunley was the first submarine to sink an enemy ship during combat; however, the cause of its sinking has been a mystery for over 150 years. The Hunley set off a 61.2 kg (135 lb) black powder torpedo at a distance less than 5 m (16 ft) off its bow. Scaled experiments were performed that measured black powder and shock tube explosions underwater and propagation of blasts through a model ship hull. This propagation data was used in combination with archival experimental data to evaluate the risk to the crew from their own torpedo. The blast produced likely caused flexion of the ship hull to transmit the blast wave; the secondary wave transmitted inside the crew compartment was of sufficient magnitude that the calculated chances of survival were less than 16% for each crew member. The submarine drifted to its resting place after the crew died of air blast trauma within the hull.

Conclusion
This work has several limitations. The largest limitation is weak charge confinement owing to the construction of the scaled charges. This inability to achieve pressure levels comparable to the levels expected from the full-sized charge means that the experiments herein likely underestimate the actual blast transmission. However, the pressure values transmitted inside the boat demonstrated that even at these low blast levels, sufficient transmission would have occurred to cause fatal pulmonary or brain trauma to the crew.

A second major limitation is that the equations to calculate the transmission of impulse to flat surfaces assume, in the final steps of their derivation, that the surrounding medium is air. For a surface with water on one side and air on the other, the final forms of these equations must be re-derived if it is desired to calculate the exact impulse values imparted to the metal hull. Then the impulse and resultant plate motion must be combined with the laws of compressible fluid mechanics to calculate the exact pressures that would have been experienced by the crew. However, the purpose of this study was not to determine analytical equations to describe the exact pressure level for all such blasts, but rather to draw qualitative conclusions about the fate of the crew. For the purposes of this study, this limitation has therefore been addressed by fitting the form of the equations to the data and performing a sensitivity analysis. The quantitative data strongly suggest that the whole crew was instantly killed by airblast trauma, and the sensitivity analysis suggests that this conclusion is insensitive to moderate changes. All test data are available online via PLOS One in S1 File.

The Pyrrhic attack of H.L. Hunley was responsible for the deaths of 21 Confederate crewmen and 5 Union sailors. An earlier Confederate vessel that successfully used a spar torpedo, the David, was made of wood and floated much higher in the water. Additionally, earlier designs of the Hunley had the submarine towing the torpedo on the surface of the water far behind its stern, and were successfully used in trial runs in the harbor [2]. It was the combination of all the simultaneous design changes: conversion from wood to wrought iron, sinking the vessel deeper in the water, lowering the torpedo, and attaching the charge much closer at the end of a spar that ultimately led to the demise of the crew. The H.L. Hunley presents the first documented case of primary blast-induced fatality to personnel within a structure.

Full article here - https://pmc.ncbi.nlm.nih.gov/articles/PMC5568114/#abstract1

...and a rebuttal from the USN...

Black Powder Blast Effects on the Confederate Submarine Hunley
Information Paper
Prepared by the U. S. Navy
August 28, 2017

https://www.history.navy.mil/research/underwater-archaeology/sites-and-projects/ship-wrecksites/hl-hunley/black-powder-blast-effects-hunley.html

New Clues About Why the Confederate Submarine H.L. Hunley Sank

New Clues About Why the Confederate Submarine H.L. Hunley Sank

An emergency keel-block release suggests the crew did not panic, meaning they may have been incapacitated when the sub went down

www.smithsonianmag.com

HTHs,
USS ALASKA

 

[13 IL Cav & 64 GA Inf]

Air blast injuries killed the crew of the submarine H.L. Hunley

Abstract
The submarine H.L. Hunley was the first submarine to sink an enemy ship during combat; however, the cause of its sinking has been a mystery for over 150 years. The Hunley set off a 61.2 kg (135 lb) black powder torpedo at a distance less than 5 m (16 ft) off its bow. Scaled experiments were performed that measured black powder and shock tube explosions underwater and propagation of blasts through a model ship hull. This propagation data was used in combination with archival experimental data to evaluate the risk to the crew from their own torpedo. The blast produced likely caused flexion of the ship hull to transmit the blast wave; the secondary wave transmitted inside the crew compartment was of sufficient magnitude that the calculated chances of survival were less than 16% for each crew member. The submarine drifted to its resting place after the crew died of air blast trauma within the hull.

Conclusion
This work has several limitations. The largest limitation is weak charge confinement owing to the construction of the scaled charges. This inability to achieve pressure levels comparable to the levels expected from the full-sized charge means that the experiments herein likely underestimate the actual blast transmission. However, the pressure values transmitted inside the boat demonstrated that even at these low blast levels, sufficient transmission would have occurred to cause fatal pulmonary or brain trauma to the crew.

A second major limitation is that the equations to calculate the transmission of impulse to flat surfaces assume, in the final steps of their derivation, that the surrounding medium is air. For a surface with water on one side and air on the other, the final forms of these equations must be re-derived if it is desired to calculate the exact impulse values imparted to the metal hull. Then the impulse and resultant plate motion must be combined with the laws of compressible fluid mechanics to calculate the exact pressures that would have been experienced by the crew. However, the purpose of this study was not to determine analytical equations to describe the exact pressure level for all such blasts, but rather to draw qualitative conclusions about the fate of the crew. For the purposes of this study, this limitation has therefore been addressed by fitting the form of the equations to the data and performing a sensitivity analysis. The quantitative data strongly suggest that the whole crew was instantly killed by airblast trauma, and the sensitivity analysis suggests that this conclusion is insensitive to moderate changes. All test data are available online via PLOS One in S1 File.

The Pyrrhic attack of H.L. Hunley was responsible for the deaths of 21 Confederate crewmen and 5 Union sailors. An earlier Confederate vessel that successfully used a spar torpedo, the David, was made of wood and floated much higher in the water. Additionally, earlier designs of the Hunley had the submarine towing the torpedo on the surface of the water far behind its stern, and were successfully used in trial runs in the harbor [2]. It was the combination of all the simultaneous design changes: conversion from wood to wrought iron, sinking the vessel deeper in the water, lowering the torpedo, and attaching the charge much closer at the end of a spar that ultimately led to the demise of the crew. The H.L. Hunley presents the first documented case of primary blast-induced fatality to personnel within a structure.

Full article here - https://pmc.ncbi.nlm.nih.gov/articles/PMC5568114/#abstract1

...and a rebuttal from the USN...

Black Powder Blast Effects on the Confederate Submarine Hunley
Information Paper
Prepared by the U. S. Navy
August 28, 2017

https://www.history.navy.mil/research/underwater-archaeology/sites-and-projects/ship-wrecksites/hl-hunley/black-powder-blast-effects-hunley.html

New Clues About Why the Confederate Submarine H.L. Hunley Sank

New Clues About Why the Confederate Submarine H.L. Hunley Sank

An emergency keel-block release suggests the crew did not panic, meaning they may have been incapacitated when the sub went down

www.smithsonianmag.com

HTHs,
USS ALASKA

Superior reply, @USS ALASKA.

 

[on again]

RIP...Those who died RIP

 

[bdtex]

What was it that killed the last crew of the Hunley? was it shock waves from their exploding torpedo?

I saw this article today. Shock wave from the explosion killed them.

When the Navy Found This Sunken Submarine, the Crew Was Dead. Why Were They Just Sitting There?

The H.S. Hunley crew corpses didn’t show any signs of a struggle or panic, which stumped scientists for 17 years. Researchers just figured out why.

www.popularmechanics.com

 

[bankerpapaw]

What was it that killed the last crew of the Hunley? was it shock waves from their exploding torpedo?

Very nice Hunley museum in Charleston.

 

[Wadersmith]

The shockwave killing the crew wouldn't make sense given the timeline. The crew is reported to have signaled one of the batteries the blue light after sinking the Housatonic, basically saying mission complete heading back. It also wouldn't account for the ballast tanks being open when the Hunley was found.