naval cannon blast pressure

[moses]

this may be common knowledge among you all, who knows, but when i read this, i was quite impressed, and i felt the need to share

this little blurb of text describes the blast pressure from the muzzles of the guns on board the japanese Yamato battleship

if i'm reading this correctly, everyone within 50 meters or so of the muzzles of a three-gun (one turret) salvo would be knocked unconscious


i've read that the in the later days of the Yamato, AA cannons and other smaller battlestations near the main turrets were vacated when firing the main guns

[ChristopherPerrien]

I believe it,

When I drove a tank in the Army M60, M1. I would sometimes open my drivers hatch and stick my head out .Which puts you about 8 feet behind and under the gun - 105mm, 4-inch. When the gun fired, I could feel the heat, it would not singe hair, and I could feel my clothes get pulled like someone grabbing them. My Comm helmut protected my ears from possible concussion.

Pretty blast out the barrell. 30 foot fireball.

Cool badass gung-ho stuff there

[ruma]

check this out...


http://broadsides2.tripod.com/photogallery.html

find a picture where an Iowa class fires a broadside...


second from the left and sixth from up

[admfisher]

No crew men were allowed in the open while the main guns fired. The AA had to have enclosed positions to protect the gunners from the overpressure. Also the airplanes carried were stowed under the rear deck to keep them from the blast as well.

There was a test using live animals in cages on the deck when the main guns were fired. In the tests many animals were killed.

But when fire 3200 lbs shells one must expect huge overpressure burst from the guns firing.

admfisher

[Takao]

I have seen pictures similar to this one where some uninformed media type had written a caption along the lines of "The force of the big guns firing moved the battleship 50 feet sideways."

I can only imagine the blast pressure of the 20 inch guns that were to have been placed on an enlarged Yamato hull.

[gabriel pagliarani]

But Yamato was much more massive than Iowa: I don't believe that Yamato moved 50ft =37 mt sideway each blast as Iowa, but some meter less.

[moses]

well the iowa class was longer (887ft vs 862ft yamato) but the yamato was wider and a lot heavier (45,000 ton vs 65,000 ton)

which seems odd to me, seems like one of them would have very poor movement characteristics, with that kind of major difference in dimensions between them

but then i'm not a sailor or an engineer

[varjag]

Gabriel - u are quite right! If there had been a sideways movement of such magnitude - the ship would have capsized. Of course there is some sideways movement - but it's must be miniscule,perhaps 100-200 mm, the rest is taken up by a gentle roll away from the blasts. Also 'salvoes' in battleships were somewhat staggered - i.o.w., all the guns did not fire quite simultaneously- to minimise chock-damage on the ship and turret mounts. Which could be bad enough even so. As for blast damage to deck equipment - battleship students have long expressed great concern for the Re 2000 fighters on the Impero/Roma class of your country, that perhaps would have been early casualties on their catapults - if the Triple 15-inchers had had to engage a pursuing enemy......

[Takao]

Gentlemen, before this devolves into a technical discussion, I feel I must clarify my previous post. I said the photo had been captioned by some "uninformed media type"(ie. a reporter who doesn't know a battleship from a barge and therefore doesn't know what his is talking about). As varjag said the drift was miniscule, the disturbance of the water was caused by the concussion of the guns and not from the ship's movement.

The list of damage and injury from the concussions of a ship's guns is very long and varied, running the gamut from tragic to humorous. Most easily damaged components were electrical(radar, radio, fuses, switch boxes, etc.) and objects stowed in the vicinity of the guns(lifeboats, aircraft, etc.). This blast damage was not limited to the big guns either, the secondary guns were more notorious for causing injury.

[Witch-King of Angmar]

Gentlemen, before this devolves into a technical discussion, I feel I must clarify my previous post. I said the photo had been captioned by some "uninformed media type"(ie. a reporter who doesn't know a battleship from a barge and therefore doesn't know what his is talking about). As varjag said the drift was miniscule, the disturbance of the water was caused by the concussion of the guns and not from the ship's movement.

The "uniformed media type" is so ignorant that he/she's laughable.

According to this source:

http://www.warships1.com/index_tech/tech-022.htm

and to sheer common sense, it's practically impossible for any sort of gun to move sideways a battleship. The recoil of a 15-inch or 16-inch gun is in the 50-ton range; this makes about 450 tons for all 9 guns. Or, the ship weighes 58,000 tons.... the difference is so huge that a full broadside can't move the ship even one millimeter.

~The Witch King of Angmar

[Christian Ankerstjerne]

Have a look at this photograph
http://broadsides2.tripod.com/gallery/22.jpg

(If you can't see it through the link, go to http://broadsides2.tripod.com/photogallery.html (row 6, column 2)

A blast like that would probably kill anyone near the gun, plus I guess that if the person was close enough, the sound alone would kill him...

Christian

[Caldric]

50 feet


Hehe well Takao/Varjag took care of that myth. Hell you could not fire very often push yourself out of range.

[stormjar]

To reawaken an old post, I am, with many thanks, searching for any information on Naval Cannon (of any era) blast/shockwave from the perspective of muzzle/barrel, breach block, loading positions in the upper gun house, loading positions below in the loading rails/tracks, and the immediate surrounding vicinity - including from inside the gun house in general, on deck within the restriction zones and shockwave at any distance relative to gunfire. Accounts of medical injury, general body shock, clothing interactions, scientific reports, eye witness accounts.

There are of course different rounds and cartridges - HE/Incendiary, AP, Shaprel/Directed Fragmention AA rounds, Star Burst/illumination rounds, Air Burst to name a few, all wound by hand by the CPO or PO in charge of the firing exercise, pretty dodgy stuff when you are in the guts loading by hand as an inexperienced Able Seaman, but they knew what they were doing - so "all good" as they say lol.

The main focus here, of my sought info, is the MK IV or Mark V 4.5 inch dual turret Naval Cannon, the OTO Melara 76mm Super Rapid, and the Bofor 40/60mm Anti Aircraft gun. These Cannons were mostly found on HMS Destroyers, HMAS Destroyers, a couple on HMNZ Frigates, HMAS Patrol boats and any other that you can think of. Most, MK V's, today are museum pieces but I do know that the West head Gunnery range in southern Victoria, Australia has a working Gun. Which I worked on for a couple of years when I was an active member of the Gunnery range.

In conclusion. Any info on blastwaves shockwaves, overpressure. Reports on these. Statistics. Medical information eg. Effects of waves on body parts and Traumatic Brain Injury sustained during live firings.

Cheers!! Please feel free to get back to me with any info even just your own experiences or stories.