How the guns work?

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José M. Rico
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How the guns work?

Post by José M. Rico »

This topic has been moved here from the old forum. Feel free to continue the discussion.
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02 Sep 2004 04:52:35 - Billy

Can anyone tell me the step by step process of firing the big guns? Or name a website or book that might go into detail about this? Thanks.

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02 Sep 2004 21:27:15 - Tankerace

Well, this is how my grandfather described it to me. He was abaord the battleship USS Mississippi BB-41 from 1943-45. He was a Gun Captain, and commanded one of the three rifles in turret 2, USS Mississippi.

This applies to the US 14"/50 Mk 7 rifle, but probably is very similar.

Process.

1. Open Breech
2. Lower loading tray.
3. Ram 14" Shell into Breech via the loading tray
4. Ram 2 bags powder into the breech.
5. Ram 2 more bags powder.
6. Remove loading tray.
7. Close and lock breech.
8. All gun crew stand in back of the turret, approx 6.5 feet from breech of gun.
9. The guys in the dirctor fire the gun. Gun recoils 6 feet into turret.
10. Wait 5 to 10 seconds, to make sure all remnants of powder bags are forced out of the muzzle by air pressure.
11. "Break the breech", unlocking it.
12. Repeat steps 1-11 to load and fire the next shell.

He said on the turret explosion (which happened in his turret) of 1943 on the Mississippi, the gunnery officer of one of the guns forgot to do srep 10, and when he broke the breech, smoldering ashes were still in the gun, and these ignighted the powder for the next shell, causing the explosion. Around 60 men were killed.

So, that is basically how to load and fire the gun, but not get the shell and powder to the gun.

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03 Sep 2004 01:33:24 - Jack B.

Go to this web site: http://www.usstexasbb35.com/14_naval_gun.htm
They have a great animation on the workings of a 14" gun

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03 Sep 2004 04:42:44 - Tankerace

That particular model is the 14"/45 cal Mk 8 Rifle. Shouldn't be too different from the Mk 7 Rifle I described.

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03 Sep 2004 00:43:11 - Billy

Thank you for that info. It helps a lot. In addition, though, does anyone know the step-by-step process of targeting another ship and feeding that information into the individual turrets?

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03 Sep 2004 01:51:05 - thomas fuller

In the German system:

1. Into the A component (essentially a rate of change predictor) the following values are input by hand--averaged ranges from radars and optical rangefinders; enemy course and speed estimates from gunnery officer; target bearing from director; corrections for previous fall of shot observations.

2 Automatic input into A component of the fire control system are own course and speed from ship's mechanical log and true north from gyro compass.

These values are used to establish a predictable set of real time values for the B component or ballistic computer. This then takes these and produces true gun range modified for such variables as shell drift from the rifling twist, wind velocity, wind direction, barrel wear, and barometric pressure.

The true gun range is then taken up by the spherical angle convertor and the output is the fire solution in angles of azimuth and elevation. These can be either transmitted directly to the guns by means of follow the pointer dials which require the gun layers and turret trainers to match the pointers on their order receiving dials, or through remote power control via the power amplification room. In some German ships remote control was for elevation only, while in others for train only.

When the system was set to Zentral--firing was done through the stabilized spherical angle convertor's firing circuit and the time interval gear fitted to the guns. Alternately, firing could be done at the director in which case the director layer fired the guns. The former tended to be used for initial ranging, while the latter was preferred once the target was aquired as lesser lag time permitted potentially more rapid salvos.
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Post by Bgile »

Can someone explain the mechanics of salvo firing? I understand that Bismarck fired A & B turrets together and then C & D together, whereas British ships fired half the guns in each turret together. I have no idea what US practice was, or where to find out.

How often were the salvos fired? My understanding is that time of flight at 18K meters is about 30 seconds, which coincides with designed loading cycle for US guns. Was Bismarck the same way?

Did they wait for fall of shot before firing another salvo, or was it routine to have a salvo in the air already when the previous one impacted the target area?

How long does it take to adjust fire? For example, if a salvo is "over", how many seconds will it take to correct the next salvo, change gun elevation, and fire the next one. Does the director officer have a firing key?

Did Bismarck always fire 4-gun salvoes, or did she sometimes fire all guns together?

Last question (for now) is:

Do any of the regulars here even look at posts about old topics? <grin>
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Post by Dave Saxton »

Von Mullenheim was gunnery officer on Bismarck and Scharnhorst., so he probably had a very good understanding:

"..Either the main battery or the secondary battery could be controlled from any one of three stations, whose directers were brought to bear on target by two petty officers under the direction of the gunnery officer who observed the fall of shot. In each station there was a 'lock ready shoot' indicator whose three-colored lights showed the readiness of the battery, the salvo, and any possible malfunctions with the guns. When the battery was ready, the petty officer on the right side of the director would fire by pressing a button, or blowing into a mouthpiece. It was also possible to acuate the firing system from any of the computor rooms.

The gunnery officer could order a test shoot, to find the range or he could order a series of full or partial salvoes. Rather than waiting to spot each splash between salvos of a test shoot, he could use a bracket to find the target(range). A bracketing group consisted of three salvoes seperated by a unifiorm range, usually 400 meters, and fired so rapidily, that they were all in the air at the same time. On Bismarck, it was customary to fire bracketing groups, and with aid of our high resolution optical range finders, we usually succeeded in boxing or staddling the target on the first fall of shot. The gunnery officer was aided in spotting the fall of shot by one of the gunnery computor rooms, which signaled him by a buzzer when the calculated time of projectile flight had expired.

Once the range and bearing had been found, the gunnery officer in controll would order, "good rapid!". He could choose to fire full salvos of all eight guns, or partial, four gun salvos fore and aft. In either case the firing for effect was as rapid as possible."(Mullenheim pg. 39-40)

In the GkDOS 100 document, it was reccomended to fire as soon as possible(and at long range), and at the highest rate possible.

Paul Schmalenbach was a gunnery officer on Prinz Eugene and has wrote extensively on German naval gunnery practices. He has reviewed the loading and firing practices inside the turrets, and the control procedures of the cental control systems. According to Schmalenbach, the turrets contained a high degree of mechanization for the time period(although nothing like now-a days). The Germans used metal cartride charges, and a bagged fore charge. Large German naval guns also had sliding "quick fire" type breaches, not interruped screw type breaches. The breach was automaticly opened, and the metal cartridge ejected into a catch cage as the gun was being lowered, immediantly after firing. The metal cartridges were automatically ejected outside the turret. The entire reloading operation was mostly automatic (assuming no problems), with the gun crew mostly monitoring the operations, and pushing buttons. Once fired, the gun had to be brought to a reloading angle. Once it was reloaded, the gun captian would determine if all was well and push a button, then the gun would go automatically to the firing angle, as determined by the solutions of the fire control systems. IIRC, the gun captian also had to activate the ready to shoot light. In PG, the whole cycle could be completed in as little as 13 seconds. In Bismarck this could be done in as little as 18 seconds. In GkDOS 100 the nominal rate of fire was under-rated slightly, at one round in 30 seconds, per gun.
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Post by Bgile »

Thank you, sir!

I know ALL battleships seldom achieved their possible rate of fire for extended periods. Do you know whether Bismarck's entire mechanism for transferring ammunition from magazine to gun was able to match that 18 second cycle (mechanically). I know human crews probably wouldn't be able to achieve that for very long, so I'm talking theoretically.

It's extraordinary to me that they used sliding block breeches. Other navies obviously didn't consider them strong enough.

The mechanization of loading is also interesting. For example, I know that on US Battleships there was some manual manipulation of propellant bags. To my knowledge the largest US gun to use cartridge cases was the fully automatic 8" gun on the Salem class CA's.

Are you aware of any english language translations of Schmalenbach's work? I will google it, but at first attempt I didn't see any.
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Post by Dave Saxton »

As far as I know, Schmalenbach's writings are not currently in print. The best place to find this stuff is the research library of a large university. Most of his writings are in German only. I have seen some materials were the captions, and some text feature English translations.

The twin gun turrets(and this may have been one rational for returning to twins) had central mechanized shell and cartridge feeds that could supply the left hand and right hand guns. Each turret side also had "emergency use ready ammo" on hand. Enough to fire a few rounds per gun. These emergency use rounds had to be loaded manually. Each turret side had an overhead rail mounted chain fall to assist. There was also an emergency manual hoist system. The left and right sides of the turrets were seperated by an armoured bulkhead with the primary feeds in the middle. I don't know the time required to get a shell or cartridge from the magazines. Krupp listed the 18 second cadence as "theoretical." A sustained min reload cycle time would vary from 20-26 sec, according to Krupp data found by Breyer. Some battleships could sometimes meet the theoretical min time in the short term. The Denmark St. film indicates that Bismarck did at times. South Dakota may have done so at Guadalcanal a few times as well.

Krupp was the only supplier of large battleship caliber guns in Germany. All of their designs from both WWI and WWII featured the sliding wedge breach design, and used metal cartridge, rather than bagged ammo, although the small fore-charge was bagged. With a cartridge charge, the metal expands when fired essentially sealing the breach during the moment of firing the gun. It seemed to work quite well. The sliding breach required a longer overall barrel length (52 calibers), and therefore a heavier gun(111 tons) compared to a screw breach 15" gun. The WWII German 15" gun was also relatively longer than normal internally, essentially a ~50 caliber gun. The inner bore length from breach block to muzzle was 48.5 calibers. The internal distance travelled by the projectile to the muzzle, was, IIRC, ~43.5 calibers, or about the same as the USN 16"/50. The muzzle energy was 27,400 tons/meters

The projectiles used three driving bands. The APC projectile was called the L4.4, indicating it's length in calibers. I seem to recall reading somewhere that the windscreen was 10crh. All projectiles, be they APC, SAP, or HE, were 800 kg. The overall length of the nose fused projectiles were longer than the AP projectiles with base fuzes.
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Post by Bgile »

Thanks Dave! This has been very informative, and I really appreciate what I've learned here.

Steve Crandell
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Post by Bgile »

I've been reading Antonio's very detailed description of the Denmark Strait battle, and he lists all the salvos fired. From his description, both sides heavy ships seem to have fired only one salvo per minute, which is substantially less than their their theoretical capability. Anyone have an explanation for this?
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Post by Dave Saxton »

Hi Steve,

I usually try to avoid re-fighting the Denmark St. battle as it's virtually impossible to draw firm conclusions and it's very argument indusive. Bismarck fired only 93- 38cm shells during this combat. If we use the most accepted time line, Bismarck fired it's first salvo at about 0555, and it's last at about 0609. This means that Bismarck got off the eqivilency of about 11 1/2 full broadsides in 13-14 minutes of combat, or less than one broadside per minute. Of course, as you know, Bismarck was firing 4 gun 1/2 broadsides, with the fore turrets firing, followed by the aft turrets. On average, this probably works out to be at least one salvo per minute for the 14 minutes of combat. Actually it breaks down to about 23 four gun salvos. However, there's segments of that 14 minute time span, when Bismarck was firing very deliberately, segements when it wasn't firing much, and segments when she was firing rather quickly to give us the average.

I based my previous comments in this thread, about Bismarck achieving it's theoretical rate of fire (periodicaly), on a short segment of film I took notes on several years ago. I was able to find these notes. The film had a time indicater in minutes and seconds, and it only captures a few minutes of the battle. I took detailed notes of the combat events per the timer. The combat segment begins with the Bismarck already in action, having just fired the aft turrets some seconds before the combat footage starts, at 5 min/08 secs. I'll list only the times that Bismarck's main battery fired during the film segment, according to my notes.

5min/10 secs-Anton and Bruno fire.
5min/16 secs-Ceaser & Dora fire.
5min/32 secs-Anton & Bruno fire (this is 22 secs from the last time they fired).
5min/34 sec-Ceaser & Dora fire (this is 18 secs from the last time these turrets fired).
6min/00 secs Anton and Bruno have just fired ( receding shell splashes near PG have obscured the exact moment they fired).
6min/03 sec Ceaser & Dora fire. (this is 28 secs from firing previously)

At 6min/10 sec the camera is suddenly turned away to capture Hood blowing up. POW is passing Hood's wreckage and firing a salvo. The camera is turned off for an undetermined time period at about 6min/17 sec. When the camara was re-started, Bismarck had just fired a salvo, and Bismarck is close right behind PG passing toward PG's portside. Both PG and Bismarck are travelling fast, as the camera is panned to show PG's huge bow wave. Bismarck is also making a huge bow wave with a thin vapor jet streaming from her stack.
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Post by Bgile »

Thanks Dave! That's the kind of info I was looking for!

I'm also wondering if they quit firing while changing course? Do you have any indication of that?
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Post by Dave Saxton »

Probably so. Some secondary battle accounts indicate this. The ships comand may have limited the use of rapid firing of full salvos to periods only where it could be most effective, to conserve armour piercing amunition. Bismarck was embarked on a raiding cruise, and may have been stocked with greater percentages of SAP and HE shells, with a limited number of AP 38cm rounds.

The Prince Of Wales had it own set of problems, with it's gun turrets malfunctioning periodicaly ( the well known "teething problems"), and it's known that spray was fouling the range finders too. Hood probably only got off 4 gun salvoes from turrets A and B prior to her destruction. She may have been dealing with spray too, as she was on the same course and speed as POW. Nonetheless, Hood was probably using radar, as Holland denied permission to POW the use of her radar fire control set, probably thinking this may mess up Hood's radar returns. Prince Of Wales did use a different AA radar set to check range during the battle.
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Post by bbisforbattleboat »

Some great postings here from Mr. Saxton. :clap: He has very well explained a number of things and clarified them, such as the breaches and cartridges used, the bag charge in front. This guy has done a lot of homework!
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Post by Ulrich Rudofsky »

Dave Saxton wrote: "Bismarck was embarked on a raiding cruise, and may have been stocked with greater percentages of SAP and HE shells, with a limited number of AP 38cm rounds."

The ammunition overview of 1 Jan. 1941: To be placed onboard: 353 Psgr. L/4.4 (armor piercing), 338 Spgr. L/4.5 Bdz (high explosive with base fuze), 313 Spgr. L/4.6 Kz (high explosive with noze fuze). I don't know if this was revised. Had the mission been determined by that time?

Image

Staueinrichtungen sind vorhanden für: = stowage facilities are available for:

Kriegssoll = combat quota
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Post by Tiornu »

Ulrich, what document is this? Can you tell us more about what it shows? Are those the individual compartments where the shells are stowed?
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Post by Ulrich Rudofsky »

The list is entitled: Schlachtschiff "Bismarck", Artillerie-Munitions-Übersicht
Battleship "Bismarck" artillery ammunition synopsis. Stamped "Hamburg 1.2.1941, Construction Supervision of the High Command of the Kriegsmarine, Blohm & Voß, Hamburg 1, [signature illegible], for the chief naval constructor. This summary includes 38 cm, 15 cm, 10.5 cm, 3.7 cm, 2 cm, signal and saluting shells, rifle ammo, bombs, depth charges, and mine-clearing charges, and all powder charges, detonator fuzes etc. As shown on the above example:

Top line: Designation and location of ammunition chambers; type of 38 cm shell; fuzes in zinc cases; in cases. Bottom and nose fuzes are in sets of 10 ea, the small and large ignitors are in sets of 40 ea. [I don't know what Zdl stands for = Zündladung? ignitor?]
Second line: sheet no.; flooding compartment i.d.; deck; frame station [m=mittleres = center? amidships?, Stb=starboard, Bb=portside]; followed by the different types of shells and fuzes.
Last edited by Ulrich Rudofsky on Tue May 31, 2005 7:23 pm, edited 2 times in total.
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Post by Tiornu »

Thanks for the details.
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