SES's Position on Brit Magazine Explosions

Bullethead

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SUMMARY
After exhaustive study of the issue of Brit magazine explosions in WW1, we have come to the conclusions stated below. This is essentially a restatement of the long section on magazine explosions found in the summary chapter of Campbell's Jutland: An Analysis of the Fighting. Of all that has been written on the subject, we think this is the best argument.

Brit ships blew up due to the extremely volatile nature of their cordite, which basically would explode (as in very rapid combustion releasing vast quantities of high-pressure gas in an extremely short time) even when not contained within the breech of a gun. In effect, the pile of cordite in the magazine was analogous to the filling of a shell, and the hull of the ship was analogous to the shell's body, becoming fragments when the filling exploded. The rapid build-up of gas pressure from the burning cordite ripped the ships to pieces.

This was in sharp contrast to the German propellant, which burned slower and did not release such huge amounts of high-pressure gas in such a short time. Thus, while German propellant would burn spectacularly, it was incapable of creating the over-pressures necessary to rip a ship to pieces.

Because all British ships carried the same cordite, all of them could potentially explode this way, even DDs. However, the only ships that suffered catastrophic explosions were those that were hit somewhere on or near their main turrets/barbettes. Thus, only Brit ships with main turrets are subject to the special "advanced critical hit" (ACH) that causes magazine explosions over and above the rare regular critical hit explosion that can happen to any ship on either side. That means ALL Brit BBs, BCs, and ACs, but nothing else, are subject to the ACH.

For most of the ships that exploded, witnesses observed hits on or near the turrets. It seems reasonable to assume that these hits penetrated the armor of the turret, barbette, or associated magazine. Therefore, in the game, the to cause an ACH explosion, the shell must not only hit the turret (which includes the barbette and magazine) but also penetrate it. Only then does the 20% chance of explosion come into play.

DISCUSSION
1. Why SES Believes Cordite was the Culprit
In both WW1 and WW2, German ships had propellant fires inside their magazines yet did not explode. Brit ships did explode, apparently from propellant igniting in the magazines, but nobody survived to tell exactly what went on there. However, clearly the different outcomes strongly suggests a fundamental difference in the combustion properties of the 2 propellants.

The best data on internal Brit cordite fires comes from Lion's Q turret at Jutland. There, 8 charges between the magazine and the turret ignited from a smoldering ember some minutes after the hit. The combustion was nearly instantaneous, effectively an explosion. Just these 8 charges created enough gas over-pressure to blow big armor plates off the turret above and seriously distort the magazine bulkheads and hatches below. The flash killed everybody still in handling rooms and even some people in the surrounding area, and produced a huge mushroom cloud seen in photographs. Campare this to Seydlitz at Dogger Bank, where a much greater propellant burned, some of it inside the magazines, yet there was no damaging over-pressue.​

2. Sloppy Brit BC Ammo Handling and Flash Protection Measures
Many people claim that the Brit explosions at Jutland were the result of the BC gun crews keeping magazine doors open, having too much cordite out of the magazines, and otherwise circumventing what flash protection they then had. Further, they say that this would not have happened to the BBs in the "by the book" Grand Fleet. We, however, do not think this was a significant factor.

In Lion's Q turret, the magazine doors were close and the only the proper amount of cordite was out of the magazines. All of that cordite was also in approved positions, either cages or waiting boxes, with their flash protection in place. Yet not only did all those charges ignite anyway, but they created enough over-pressure to damage the ship's structure. In fact, this damage was enough to expose the contents of the magazine to flash, due to the distortion of the magazine bulkheads. Had not the magazine already been flooded, it seems highly probable that Lion would have blown up from this flash. Thus, even if all then-existing safety procedures been followed, it would not likely have made a difference.

Of course, the structurale distortion of the magazine bulkheads was not necessary in 1916. Apparently at that time, Brit magazine doors were only flash-proof from inside the magazine going out into the handling room, but not going in from the handling room to the magazine. Thus, the ignition of a few charges in the barbette somewhere was capable of getting flash into the magazine even if the doors were closed, and even if the bulkheads weren't distorted by over-pressure.

While this was remedied after Jutland, however, the distortion of the bulkheads caused by even a few charges in the barbette negated this. This distortion no doubt would also have negated other Brit flash protection improvements of later years, as well. All these scuttles and better cages and such were just thin sheet metal, easily capable of being twisted open by the gas over-pressure of burning cordite. You needed something as thick as a gun breech to contain a cordite explosion without rupture or distortion.​

3. Why Brit Battleships Can Explode
This should be pretty obvious by now: BBs had the same cordite as the other Brit ships. This cordite, obviously, had exactly the same combustion properties in a BB as in a BC or AC. Also, the BBs had the same standards of flash protection as the other ships. If these safety measures would not have saved Lion, they would not have saved a BB, either. Had the Brit BBs ever come under effective fire, some of them certainly would have blown up, too.

Therefore, the only advantage Brit BBs have over BCs in terms of magazine explosions is thicker turret armor. This will reduce the number of turret penetrations they will suffer, which means they have fewer chances of having an ACH explosion. However, most Brit BBs had only 11" on their turrets (compare to 9" on the "Splendid Cats") so would do well to engage at long range.​
 

Bullethead

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And don't forget, before you get your panties in a bunch, you can always turn this feature off completely.
 

Zakalwe

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THX BH!

After having read Campbell, I think your assumptions are reasonable.

IIRC at Campbell I read that on one British ship a hit on the secondary batteries nearly caused a magazine explosion too, but the chance of this happening should of course be much higher with the main turrets.

How`s the chance of German ships blowing up? Only by a direct hit to the magazine?

Z.
 

JebUSMC

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We saw something similar with the plunging hit on Hood in WW2 except that one came through the deck.
 

TBR

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To reinforce your argument I just recommend any doubters to look at the pictures of Seydlitz after Doggerbank and Lion's Q turret in the "pictoral countdown thread.
 

Wawotsch

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THow`s the chance of German ships blowing up? Only by a direct hit to the magazine?
If there is a fundamental difference in mechanism, if ignited, between British and German cordite, then the chance should be almost zero.

But there should be a great chance that such a ship would burn like hell. Heros that open a valve to flood a magazine while burning their hands to ashes will not be present 24hx7.
 

HReardon

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How`s the chance of German ships blowing up? Only by a direct hit to the magazine?
Personally, I do not think there is any historical support for German ships exploding at all. At least not from magazine exposions. Everything I have read indicates the the German propellant was simply unable to generate the necessary overpressure. Even if there was a direct magazine penetration, the gas produced would vent safely (for the ship, not the people in the venting path!) without doing more damage than perhaps lifting the turret roofs or opening some seams.
 

Rhetor

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Personally, I do not think there is any historical support for German ships exploding at all. At least not from magazine exposions. Everything I have read indicates the the German propellant was simply unable to generate the necessary overpressure. Even if there was a direct magazine penetration, the gas produced would vent safely (for the ship, not the people in the venting path!) without doing more damage than perhaps lifting the turret roofs or opening some seams.
Germans themselves claim that "Seydlitz" was saved only by flooding the magazines. Besides, apart from propellant there were also the shells.
 

Fairweather

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Didn't Pommern blow up from a magazine explosion? I know she wasn't state of the art, but still.
 

TBR

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Germans themselves claim that "Seydlitz" was saved only by flooding the magazines. Besides, apart from propellant there were also the shells.
The point here is that magazine explosions, if caused by a "Seydlitz-like" event would not be instantaneous as the "ACH's" we are discussing here but rather the result of the explosive filler of the shells stored in the magazines heated up to ignition temperature. In German ships only the explosive filler contains enough rapidly releasable explosive energy to "blow them up". I think you overestimate the probability and underestimate the time necessary for that. Remember that the shells in the magazine are usually not yet mated to the more volatile ignitors (detonators, thanks BH), the filler is inside the (in the case of AP shells espacially) thick walled shells and thus somewhat protected. High explosive that is not stored beyond "best before" and hasn't experienced continued overtemperatures (such as 60° Celsius + over several days/weeks as in the tropics with uncooled magazines) is remarkably resistant to explosion. In fact you need a more volatile extremely high temperature (as in with some high explosives higher than the temperature at which the propellant burns) explosive, the igniter, to get it to explode at all. There is nowadays modern high explosive which you can burn in a cooking fire with no danger of explosion at all. To get the explosive filler of the majority of the stored shells to explode would neccessitate either a direct penetration of the magazine with the explosion of the penetrating shell among the stored shells or a (espcially compared to the level of danger in British ships) very hot fire whose heat is allowed to propagate to the stored shells and has time to heat them up to the ignition point of the explosive filler. Even today the biggest dangers in warship magazines are signal pyrotechnics, torpedo, rocket and cruise missile fuel and propellant.

Considering that both the time interval and necessary heat level to get German magazines to explode are significantly higher German ships should get a "flooding check bonus" if such a check is done before the rare "non ACH" magazine explosions (such as it was done in Fighting Steel, where the German ships didn't get such a bonus). This should in no way be construed as relativising the achievment of Seydlitz XO, gunner and chief pumping mate.
 
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HReardon

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Germans themselves claim that "Seydlitz" was saved only by flooding the magazines. Besides, apart from propellant there were also the shells.
My understanding has been that unfused shells are super hard to set off. The Jutland wrecks have literally piles of unexploded shells laying around.
 

Bullethead

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IIRC at Campbell I read that on one British ship a hit on the secondary batteries nearly caused a magazine explosion too, but the chance of this happening should of course be much higher with the main turrets.
Historically, the Brits were extremely worried about 2ndary ammo leading to explosions, much moreso than they were about main turrets. This is understandable, because the main magazines were the best-protected things on the ship, while 2ndary ammo was often quite exposed. However, during the war, no ship blew up from 2ndary ammo fires while quite a few did from main turret hits. That can't be just coincidence, because there were many more hits on 2ndary batteries and CL gun decks (essentially the same thing for purposes of this discussion) than there were on main turrets, and many of these hits caused serious propellant fires. Thus, despite appearances, 2ndary/CL ammo fires must have been fundamentally less likely to blow up the ship than main ammo fires.

In most Brit capital ships, the 2ndary magazines were at the ends of the ship adjacent to the main magazines. Thus the hoists came up near the end main turrets, from whence the ammo had to be carried the length of the battery. The main guns of CLs on both sides were fed the same way. Alternatively, the magazines were still at the ends but there were multiple hoists near the guns supplied by ammo carried along below deck through the "ammunition passage", which ran the length of the battery. Either way, you had what looked like a long powder train running the length of the battery, composed of ready use cases and exposed bag charges, leading to magazines. You can thus see why the Brits worried a lot about fires anywhere in the batteries reaching the magazines.

However, that never happened, despite a lot of bad fires in batteries and CLs. In most cases, the fire didn't spread the length of the battery, but only involved 1 or a couple of guns. Thus, there often wasn't the continuous powder train the Brits feared. This was no doubt because these areas were well ventilated to the atmosphere, either by being on the open deck or by having skylights, large gun openings, and such. Thus, most of the heat and flash could go upwards (as it wanted to do) and outwards, leaving the ship, instead of being constrained to go sideways along the battery (this is the same reason firemen often cut holes in the roofs of burning buildings). This venting also prevented the build-up of ship-tearing over-pressures.

In a couple of cases, burning debris from a fire in the battery went down hoists, either into the handling room adjacent to the magazine, or into ammunition passage. However, people there were able to stamp these embers out before they ignited any charges. The fact that these people were still alive to do this indicates that no flash came down the hoists, and that no pressure came down, either. This supports the notion that the vast bulk of the conflagration in the battery vented up and away from the ship.

This is why we don't have an ACH for Brit 2ndary battery hits, or for hits on ships without main turrets. The bottom line seems to be that while the main turret armor protected the main gun ammo from incidental sparks and flash exterior to the turret, if that protection was ever breached, the huge amount of propellent in the main magazines would destroy the ship.

How`s the chance of German ships blowing up? Only by a direct hit to the magazine?
German ships can explode, but only rarely. AFAIK, they have the same chance to blow up as any ship in the RJW--a fluke hit every now and then. The Brits always have this same chance in Jutland, too, even if you turn the ACH magazine explosions off. This covers the odd German blowing up (and a few did in real life), plus a very unlucky set of circumstances in a Brit 2ndary battery :).

At the risk of getting off-topic (this thread is supposed to be about Brits), here's our take on German magazine explosions....

The German ships that exploded seem to have done so for the same reason that modern AFVs explode: the explosive in their shells detonated. German propellant simply did not generate the huge over-pressures necessary to rip ships apart.

Most high explosives (except for things like picric acid) are difficult to make explode. This is why shell fuzes have detonators in them, and why unfuzed shells are pretty safe even in fires. But if you have a stack of shells, the explosion of one of them can act as a detonator to the rest. Thus, to blow up a shell magazine, the easiest way is to trigger the fuze of 1 shell. And that's a LOT easier to do than cook off unfuzed HE. So, if there's sufficient shock, some shell fuzes can become armed, and then bounce around until they're triggered, and then KABOOM. There are, of course, safety features that try to prevent this, so it doesn't happen that often. However, this is apparently what happened to Pommern, and it nearly happened to Konig. While cleaning up the mess in a 2ndary magazine after Jutland, wrecked by an underwater shell hit, the Germans found a shell with an armed fuze under the debris.

FWIW, I've see dozens of AFVs have magazine problems, and have caused a few of those problems myself :laugh:. Most of the time, the propellant burns in a big POOF that makes a quick fireball. This leaves all the flammable material like insulation, clothing, seat cushions, etc., burning, as well as sometimes the fuel tanks. But the tank is usually structurally intact, although the turret might be lifted a little. But every so often, the HE shells explode, too. This is what makes the turret pop off and sometimes breaks the hull up as well.
 
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TBR

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Whoa! this is the second time this evening I experience cross-posting, the discussion is truly heating up!
 

PepsiCan

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Further to that, I believe the Japanese used cordite that was based on the British formula. BB Mikasa blew up and sank shortly after the end of the RJW because of a short fire which led to a magazine explosion.

This further illustrates that British cordite was very volatile.

Also, this is what Wikipedia has to say about British naval cordite:

"Cordite RDB

During World War I acetone was in short supply in Great Britain and a new experimental form was developed.[2] This was Cordite RDB (= Research Department formula B); which was 52% collodion, 42% nitroglycerine and 6% vaseline (Petroleum jelly). It was produced at HM Factory, Gretna;[2] and the Royal Navy Cordite Factory, Holton Heath.

Cordite RDB, unfortunately, tended to become unstable if stored too long. Once acetone production increased, by the use of fermentation (see Chaim Weizmann), the older form of Cordite, Cordite MD, was brought back for use by the Royal Navy."
 

Von der Tann

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I am pleased by the arguments cited here, they should suffice to make the given position plausible. Only one little thing to add, perhaps: German propellant charges were encased in metal, while the British kept theirs in silken bags - makes a much quicker fire.
 

Zakalwe

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THX again, for all your answers, very interesting.

One short question, slightly OT:

So I have learned British propellant burns faster than the German one.

Is it also more "powerfull", as in my understanding, it should through burning faster producing more gas in a given period of time. So did a German gun of a given calibre need more propellant than a British counterpart to reach the same range? Or are the circumstances in a gun totally different?

:shy:

Z.
 

HReardon

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I watched a Discovery Channel documentary on Jutland where among other things, they measured crudely the rate of propogation of cordite flash. Now I do not remember if they had WWI cordite. As I remember they came up with a burn rate of 600ft/sec in a tube. That seems awfully fast to me in comparison to black powder which burns at 560-2000 ft/sec when confined.
 
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HReardon

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Or are the circumstances in a gun totally different?
The burn rates of propellants vary greatly between the confined and unconfined condition. As I understand it, smokeless powders only burn briefly at their maximum propagation rate and then slow as the projectile proceeds down the barrel.
 

Atago

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Question - will a ship like HMS Agincourt with 7 twin turrets be more likely to suffer a turret hit (and hence the following KABOOM if it penetrates) than a ship with fewer turrets? Assume armor is the same. I've often thought Agincourt was a multiple magazine explosion just waiting to happen.
 
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