battleship barrel service round limit?

Guns, torpedoes, mines, bombs, missiles, ammunition, fire control, radars, and electronic warfare.
CmdrKeen
Junior Member
Posts: 16
Joined: Mon Feb 06, 2012 5:34 am

battleship barrel service round limit?

Post by CmdrKeen » Wed Apr 04, 2012 8:25 pm

Various sources give IJN Yamato's 46cm barrel life as 200 to 250 service rounds.
What would happen if they tried to run the same barrels to 400 or 500 rounds?
Is there an increasing danger that the overused barrels will suddenly rupture?
Or do they start to get increasing propellent blow-by but still fire?
Do they start to become increasingly less accurate?
Do the projectiles begin losing their 28-to-1 spin (or whatever the ratio is) and wobble more in flight?
Or what's the deal?

User avatar
tommy303
Senior Member
Posts: 1528
Joined: Mon Oct 18, 2004 4:19 pm
Location: Arizona
Contact:

Re: battleship barrel service round limit?

Post by tommy303 » Thu Apr 05, 2012 12:58 am

The most noticeable effect would be the reduction in MV and range to a point where range table data becomes meaningless. As a barrel begins to wear, the rate of wear accelerates, particularly in front of the chamber; gas begins to cut more and more, resulting in blowby, which in turn causes even more gas cutting. This in turn leads to erratic ballistics since a shell might be pushed easily up the bore to start with, but eventually reaches a point where there is less wear, causing more friction. This can cause the shell to suddenly slow or even be checked momentarily and this in turn causes unpredictable rises in pressure. At best, the shot to shot MV is difficult if not impossible to predict when wear becomes this bad; at worst, the sudden checking or slowing of the projectile can cause a burst or bulged barrel. The calculated full service charge numbers are more of a guide. Once the total has been reached, the gun is taken out of service--it is not necessarily worn out, just no longer viable as a ship's weapon. Sometimes barrels that reached their full service charge limits if they could not be relined, were shipped off to coast defence where their reduced range could be offset by greater elevations allowed on land mounts or lighter shells than normally used on ship.

Their shoulders held the sky suspended;
They stood and Earth's foundations stay;
What God abandoned these defended;
And saved the sum of things for pay.

CmdrKeen
Junior Member
Posts: 16
Joined: Mon Feb 06, 2012 5:34 am

Re: battleship barrel service round limit?

Post by CmdrKeen » Thu Apr 05, 2012 6:08 am

It sounds to me almost as if, with a stated allowance of 200 to 250 service rounds, Yamato might easily go to 300, and possibly even get away with going to 400, 500, or possibly even 600 before things start to really get bad.

alecsandros
Senior Member
Posts: 4349
Joined: Wed Oct 14, 2009 2:33 pm
Location: Bucharest, Romania

Re: battleship barrel service round limit?

Post by alecsandros » Thu Apr 05, 2012 9:02 am

I don't know about that.
The propellant weight was quite high - 360kg.
By comparison, the US 16"/L50 shells were propelled by ~300kg charges, and the British 16"/L45 by 225 kg charges.

That kind of explosion would take its toll on the gun's performance.

steffen19k
Member
Posts: 77
Joined: Fri Jun 08, 2012 5:31 pm

Re: battleship barrel service round limit?

Post by steffen19k » Mon Jun 11, 2012 6:13 am

Heres something I learned from my time on tanks.

When your guntube has fired its projected life, and you exceed that number, you risk a courtmartial for willful negligence. Any soldier/sailor/airman should have the basic common sense and pride to take care of their weapon to make sure its never in a position where it might fail for any reason other than a material defect that came from the manufacturer.

Could the guns in question go 50 or 75 rounds over their projected service life?

Perhaps, but I am thoroughly convinced that absolutely no professional military organization that would even consider thinking about the possibility of letting such a thing happen. And most certainly not without mass repercussions.
Here is everything I know about war: Someone wins, Someone loses, and nothing is ever the same again. Here is everything I know about life: The only certainties are death and taxes.
The enemy of freedom are those who proclaim only they can uphold it.

Francis Marliere
Senior Member
Posts: 261
Joined: Mon Oct 18, 2010 3:55 pm

Re: battleship barrel service round limit?

Post by Francis Marliere » Mon Jun 11, 2012 12:55 pm

Steffen,

battleships and tanks guns are not of the same size and not of the same price. Correct me if I am mistaken, but I assume that changing a WWII tank gun is cheap and easy. Changing a battleship one is very expensive and time consimung (assuming that the guns are available which may not be the case).

Best regards,

Francis Marliere

steffen19k
Member
Posts: 77
Joined: Fri Jun 08, 2012 5:31 pm

Re: battleship barrel service round limit?

Post by steffen19k » Sun Jun 17, 2012 5:35 am

Changing a battleship one is very expensive and time consimung (assuming that the guns are available which may not be the case).
Umm...if it were that expensive, they would not be putting service round limits on the gun. In fact, they wouldn't even be building the battleship. Its one of those things about "Acceptable costs" where the gov't will put forward the money to keep spare parts for the projected service life of the weapon, and the military will develop a service and maintenance plan. There is MORE than enough evidence that battleships were rebarreled on a regular basis to more than back up my claim that no self respecting military or nation would run their guns over their projected service life.
Here is everything I know about war: Someone wins, Someone loses, and nothing is ever the same again. Here is everything I know about life: The only certainties are death and taxes.
The enemy of freedom are those who proclaim only they can uphold it.

Byron Angel
Senior Member
Posts: 1134
Joined: Sun Mar 06, 2011 1:06 am

Re: battleship barrel service round limit?

Post by Byron Angel » Sun Jun 17, 2012 2:35 pm

Francis Marliere wrote:Steffen,

battleships and tanks guns are not of the same size and not of the same price. Correct me if I am mistaken, but I assume that changing a WWII tank gun is cheap and easy. Changing a battleship one is very expensive and time consimung (assuming that the guns are available which may not be the case).

Best regards,

Francis Marliere

Dear Francis,

Steffen is correct. Replacing worn guns was a matter of standard naval "housekeeping". For example, upon her return from the Falkland Islands battle, four of HMS INVINCIBLE's eight 12-inch guns were found to be sufficiently worn as to require replacing. One of the guns to be re-tubed, the left-hand gun of A turret, had fired 109 rounds at the Falklands.

The barrel life of guns depended, among many other things I'm sure, upon size of propellant charge (MV) and the burn characteristics of the propellant itself. Early British cordite was a VERY hot burning propellant, so much so that the British 12in/50 gun was deemed (IIRC) to have a barrel life of only about 60 EFC (effective full charge) rounds at its original muzzle velocity of 3000 ft/sec; the muzzle velocity of this gun was subsequently reduced to improve barrel longevity. Cooler burning propellants provided greater barrel life, but guns were regularly being replaced and/or re-lined during wartime.

B

Francis Marliere
Senior Member
Posts: 261
Joined: Mon Oct 18, 2010 3:55 pm

Re: battleship barrel service round limit?

Post by Francis Marliere » Mon Jun 18, 2012 9:42 am

Dear Byron,

my bad, I was not clear, probably due to my poor English. I know that changing and retubing guns is part of naval maintenance. My point is that changing a big gun is not an easy task and may be problematic. Some navies were short on spare guns (the Japanese build only 27 46 cm guns - hence they had only 9 spares and could not regun both Yamato and Musashi). Some navies were short on ships. Sending a battleship to dockyard for a regunning meant having too few or no battleship at all available. IMHO, the smaller the navy the bigger the problems. I guess that US Navy had no problem to change 14" guns because there were plenty of bases, ships and spare guns. Regunning a Dunkerque class BC would be more problematic.

Best,

Francis

Byron Angel
Senior Member
Posts: 1134
Joined: Sun Mar 06, 2011 1:06 am

Re: battleship barrel service round limit?

Post by Byron Angel » Mon Jun 18, 2012 11:00 am

Francis Marliere wrote:Dear Byron,

my bad, I was not clear, probably due to my poor English. I know that changing and retubing guns is part of naval maintenance. My point is that changing a big gun is not an easy task and may be problematic. Some navies were short on spare guns (the Japanese build only 27 46 cm guns - hence they had only 9 spares and could not regun both Yamato and Musashi). Some navies were short on ships. Sending a battleship to dockyard for a regunning meant having too few or no battleship at all available. IMHO, the smaller the navy the bigger the problems. I guess that US Navy had no problem to change 14" guns because there were plenty of bases, ships and spare guns. Regunning a Dunkerque class BC would be more problematic.

Best,

Francis

..... Ah, I understand better now. I do not present myself as an expert on this subject, but I believe that most (perhaps all) large caliber naval guns were designed in such a way that the worn bore tube ofthe gun could be replaced (i.e. the gun could be "re-lined"). This would presumably need to be done at a proper arsenal or factory facility.

B

lwd
Senior Member
Posts: 3810
Joined: Sat Jun 17, 2006 2:15 am
Location: Southfield, USA

Re: battleship barrel service round limit?

Post by lwd » Tue Jun 19, 2012 11:24 pm

I think the Mississippi had her barrels relined twice during WWII but am not sure about that. On the otherhand it was problematic with Yamato's design at least according to:
http://www.navweaps.com/Weapons/WNJAP_18-45_t94.htm
These guns had an unusually complex construction, perhaps reflecting the difficulty in manufacturing such a large caliber. The A tube, designated as 2A, had the 3A tube shrunk on for somewhat over half the length from the breech end. This assembly was then wire-wound and had a layer of two tubes shrunk on for the entire length, followed by a two-part jacket at the breech end. The various tube locating shoulders were fitted with Belleville spring washers, presumably to lessen stress concentration and potential "steel choke" problems. This feature was similar to many Vickers designs which used cannelured rings. The inner A tube, known as 1A, was radially expanded into place by applying hydraulic pressure in three separate operations. The inner A tube was rifled after it was in place. There were also a short breech ring and a breech bush screwed into the 3A tube. The breech is believed to have been a Japanese version of the Asbury type with a Welin breech block.

A great disadvantage of this type of construction was that the gun could only be relined by completely boring out the inner A tube. This was so expensive a process that it was considered to be more practical to simply replace a worn out gun with a new one, ...
This may have been considered acceptable as they were designed to fight the "decisive battle" after which they theoretically wouldn't be as necessary or could be retubed at leasure or they would be sunk.

Neoconshooter
Member
Posts: 33
Joined: Sun Dec 02, 2012 7:20 pm

Re: battleship barrel service round limit?

Post by Neoconshooter » Thu Dec 06, 2012 12:13 am

CmdrKeen wrote:It sounds to me almost as if, with a stated allowance of 200 to 250 service rounds, Yamato might easily go to 300, and possibly even get away with going to 400, 500, or possibly even 600 before things start to really get bad.
I would bet that the real practical service life was closer to 200 rounds than 250. Gun wear is a subtle, but pernicious fact. Other lesser known variables are the gun construction and what it is made of, have huge implications. Very small changes can have very large results. Check the expected life of all allied 16" guns to see a 100% difference!

Post Reply