Why Silk?

ManyBeers

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Aug 30, 2004
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..silk is used to bag propellant charges for large naval guns? I was reading an article about the USS Iowa's 16 inch guns and how the powder charge bags are made of silk. I have tried wikipedia articles on silk naval weaponry etc. I can't find the answer.
 

LikeLinus

Lifer
Jul 25, 2001
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Is it spider silk? :)

Spider silk is extremely strong -- it is about five times stronger than steel and twice as strong as Kevlar of the same weight. Spider silk also has the ability to stretch about 30-percent longer than its original length without breaking, which makes it very resilient.
 

ManyBeers

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Aug 30, 2004
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I found the answer here

The material used for powder bags is silk, because only this fabric will completely burn away when combustion of the charge takes place, leaving no smoldering residue to cause the premature explosion of the next charge loaded. Each bag is roughly cylindrical in shape. One end consists of an ignition pad containing black powder quilted into the fabric so as to keep the black powder evenly spread throughout the pad. Light-weight cloth, dyed red, is used for the ignition pad. A heavier weight of fabric is used for the rest of the bag. Bags are fitted with handling straps and lacings, which can be used to take up any slack in the bag.

It was driving me nuts trying to find the reason. I was sure it was some kind of safety reason and initially thought it might have to do with static electricity. But whatever
 

jagec

Lifer
Apr 30, 2004
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I'm not positive, BUT

1)It's strong stuff
2)It's thin and light
3)It's a tight weave which is pretty waterproof.
4)It's not cheap, but it doesn't cost an exorbitant amount.

Basically they need something disposable, and silk beats plastic for this use.
 

FoBoT

No Lifer
Apr 30, 2001
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fobot.com
Bag Ammunition - Ammunition in which silk or rayon bags are used to hold the propellant and the projectile is handled separately. Propellant bags were manufactured from a special coarse silk known as "shallon" or "cartridge cloth." This burned without leaving any smoldering residue in the barrel which would present a safety hazard when loading the subsequent round. Rayon bags replaced silk ones in the USN after a serious propellant fire aboard USS South Dakota BB-57 in 1945 was traced to a spark generated when a bag was removed from its metallic container.
http://www.navweaps.com/Weapons/Gun_Data_p2.htm
 

FoBoT

No Lifer
Apr 30, 2001
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fobot.com
Originally posted by: ManyBeers
...initially thought it might have to do with static electricity. But whatever

silk is actually an electrical insulator, so yes, you can get a static charge from rubbing a silk bag
 

ManyBeers

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Aug 30, 2004
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One other interesting fact i discovered while reading about the 16 inch guns is the turret assembly (all 5 stories) is not attached to the ship in any way. It rides on rollers. If the ship were to capsize the turrets would fall out.
 

ManyBeers

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Originally posted by: FoBoT
Bag Ammunition - Ammunition in which silk or rayon bags are used to hold the propellant and the projectile is handled separately. Propellant bags were manufactured from a special coarse silk known as "shallon" or "cartridge cloth." This burned without leaving any smoldering residue in the barrel which would present a safety hazard when loading the subsequent round. Rayon bags replaced silk ones in the USN after a serious propellant fire aboard USS South Dakota BB-57 in 1945 was traced to a spark generated when a bag was removed from its metallic container.
http://www.navweaps.com/Weapons/Gun_Data_p2.htm

Thanks I actually found the same article upon further digging.
 

ManyBeers

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Originally posted by: LikeLinus
Is it spider silk? :)

Spider silk is extremely strong -- it is about five times stronger than steel and twice as strong as Kevlar of the same weight. Spider silk also has the ability to stretch about 30-percent longer than its original length without breaking, which makes it very resilient.

No ,it is silk from silkworms.
 

ManyBeers

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This is interseting:
As modernized in the 1980s, each turret carried a DR-810 radar that measured the muzzle velocity of each gun, which made it easier to predict the velocity of succeeding shots. Together with the Mark 160 FCS and better propellant consistency, these improvements made these weapons into the most accurate battleship-caliber guns ever made. For example, during test shoots off Crete in 1987, fifteen shells were fired from 34,000 yards (31,900 m), five from the right gun of each turret. The pattern size was 220 yards (200 m), 0.64% of the total range. 14 out of the 15 landed within 250 yards (230 m) of the center of the pattern and 8 were within 150 yards (140 m). Shell-to-shell dispersion was 123 yards (112 m), 0.36% of total range.

That is like shooting an 11 foot group at 1,ooo yards.

The Armor Piercing (AP) shell fired by these guns is capable of penetrating nearly 30 feet (9 m) of concrete, depending upon the range and obliquity of impact. The High Capacity (HC) shell can create a crater 50 feet wide and 20 feet deep (15 x 6 m). During her deployment off Vietnam, USS New Jersey (BB-62) occasionally fired a single HC round into the jungle and so created a helicopter landing zone 200 yards (180 m) in diameter and defoliated trees for 300 yards (270 m) beyond that.