26 inch armor plate from Japanese shipyard

Andy FitzGibbon · Sep 8, 2007

Here are some photos of a piece of 26 inch armor plate on display at rhe Washington Navy Yard that were sent to me by locoguy. Our forces found it in a Japanese naval yard at the end of WWII. It was brought to the Dahlgrinn test range, and shot-through with one of our 16 inch naval guns.

Andy

L Vanice · Sep 8, 2007

Probably the test range was named for John A. Dahlgren, a famous name in Civil War cannon. I'm glad the Navy remembered him with an appropriate site. Dahlgren biography

Larry

johnoder · Sep 8, 2007

I once calculated the muzzle engergy of one of these 2200 lb shells leaving at 2600 FPS, but I have forgotten what that number was. Maybe 15,000,000 pounds feet? The steel plate had no chance. It was all over before it even had time to deform much. I expect on this occasion it was an AP made up special , lighter, and going faster.

The rifle in view thru the hole is a Parrott.

John

railfancwb · Sep 8, 2007

Steel doesn't appear to have rusted much for having been outdoors 50+ years...

Mic addict · Sep 8, 2007

Wow cool pics.
Are you sure it was 26 inches though ?
The thickest Japanese armor i heard of were the turret face plates of battleships Yamato and Musashi at 25 inches. As was standard practice at the time they designed the ships to withstand their own main guns ( 18 inch ) at watever range most fighting took place.. The thinking was if it would withstand 18 inch guns then U.S. 16 inchers could be resisted too. Japan was not unique in that way of thinking. I'm pretty sure it was standard for battleship designers.
Mid way through the war, after being tested in battle (not against battleships though) it was decided that the plates performed well enough that plates for the 3rd Yamato class battleship then under construction the Shinano could be made a bit thinner without much loss of performance. Her plates were made up but soon after it was decided that an aircraft carrier was needed more so she was converted to a carrier and the plates never used. It was these plates that U.S. occupation personnel came upon after the war and tested. They fired several rounds at different ranges. Some penetrated some did not.
Anyway, awsome pictures!!
Thanks for posting .

RickWGMkII · Sep 8, 2007

There was a program on some time back about the Bismark. At one point there were filiming at the yard where it was built & found a huge chunk of belt armor laying in the weeds... as far as I know it's still laying there...

carla · Sep 8, 2007

John.....another way to play with numbers is to remember that the 2600 feet per second is approximately the same velocity as common 30-06 M2 ball ammunition.

Comparing the 2200 lb. Naval projectile to the 150gr bullet of the M2 round, you get a 'scale', so to speak, of slightly over 'ten thousand to one'.

Now, I haven't the vaguest idea as to how 'linear' such a performance scale would work out in practise, but think of punching holes in steel plate with an '06...and then imagine ten thousand times that kinetic energy.....I can't really even visualise it myself, but, oh, my, think of all those poor sailors on Hood and Bismarck, all those years ago.

cheers

Carla

Andy FitzGibbon · Sep 8, 2007

Mic addict, I don't know... 26 inches was what locoguy told me. He'll probably post here eventually and can clarify.
Andy

johnoder · Sep 8, 2007

all those poor sailors on Hood and Bismarck

Yep - the hole is fairly benign looking. The horrible part is all the steel shards and chunks flying around at a zillion miles an hour as what used to be there before the hole does its level best to get the hell out of the way of all that energy.

There is a book of fiction, later maybe made into a mini series, that has a passage in vivid detail about was becomes of steel that is blown up. This book related to the long military career of a Army General Officer gent, but I cannot bring the title to mind.

John

On Edit: The "hard drive" up there did cough that up. Title is possibly Once An Eagle

Robert Campbell Jr. · Sep 8, 2007

Carla, yes the comparison would be linear. When the FPS differs, then "by the square of the velocity" comes into play.

Hey Carla, now that you are taking it a little easier, maybe you'll grace us with more keyboard time?

Bob

johnoder · Sep 8, 2007

'ten thousand to one'.

Actually:

7000/150= 46.67

46.67 X 2200 = 102,667 the "multiplication factor"

Both are going 2600 FPS

Lets assume the 30-06 puts up 3000 pounds feet.

so - doing the math, the 16" rifle launching a 2200 lb shell at 2600FPS is in the "fairly high" muzzle energy range of three hundred and eight million pounds feet

:eek:

John

locoguy · Sep 8, 2007

I am pretty sure that the sign by the armor plate said 26 inches, and checked it with my trusty tape to confirm. Give or take an inch or so, it is still a damn impressive chunk, including the hole.

In the background of one of the shots is a 16 inch barrel on shop trucks. 200,000 plus pounds of finely machined steel. This barel was off one of the battle wagons scrapped in the 1920's due to a treaty reducing the fleets of the naval pours of the world at the time. The big guns of these sacraficed ships were converted to shore mounts for harbor defense purposes.

Breechman · Sep 8, 2007

Really impressive pictures, reminds me the damage found on Fort Drum at Manila Bay in WWII.

chevy43 · Sep 8, 2007

I wonder how much of the plate became molten?

beckley23 · Sep 8, 2007

A few statistics on the 16" 50 cal, Mk 7, fitted to the Iowa class BB's. Source is "Battleships", by Dulin & Garzke, Naval Institute Press, 1976.
Shell weight 2700 lbs,muzzle vel 2500'/sec, range @ 45* 42,345 yds, @ 30* 36,700 yds, @ 10* 17,650 yds; shell penetration at 0 yds 32.62" side, 0 deck, at 30,000 yds 14.97" side, 6.65" deck, at 42345 yds 9.51" side 14.05" deck; gun weight 267,904 lbs, chamber vol 27,000 cu.in., muzzle energy is not available, max pres 18.5 tons/sq.in.
Side penetration at 10,000 yds is 26.16".
Harry

kenh · Sep 9, 2007

Yes, we quietly introduced the 2700lb AP round without telling anyone.
That is the major reason the Navy did not go to an 18" gun.
It is impossible to armor against the 16/2700 round.
At some ranges, (the dead zone) it would not penetrate the Yamato.
This zone is between the last of "point blank" rang and the steeper angles of "plunging fire"
The Yamato had a greater range, but their fire control
was not up to the task.

G Dean · Sep 9, 2007

Impressive damage. At close range, a 16"/50 can shoot through any practical armor. Battleship armor is indeed rated in terms of its own guns, however, armor is heavy. A fully protected ship wouldn't float, so compromises are made to balance armor weight and other factors, within the available displacement. This results in an a band of range known as the "immune zone", within which the ships armor will resist its own guns. At closer range, the armor belt can be penetrated; beyond the immune zone, shells fall at steeper angles, and can penetrate the lighter deck armor.
Substantial parts of a battleship have no heavy armor at all, and are vulnerable to to the fire of nearly any gun.

Mic addict · Sep 9, 2007

I just checked the book Beckly 23 mentioned and it lists Yamatos turrets as the most heavily armored part of the ship with 25.59" face plates. Close enough I guess. Maybe the thinner plates were for the torpedo belt or something.
Not sure where I read about the plates being tested or the specifics but I guess it doesnt matter anyway. As is mentioned above a 16" projectile cant be stopped at all ranges.

RickWGMkII · Sep 9, 2007

Imperial War Museum London. Front entrance:

I know one of the guns is from HMS Ramilles, I think the other is from the Warspite...?
or the Resolution? Hell, I haven't stood next to those guns since I was about 12...

26 inch armor plate from Japanese shipyard

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kenh

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