Battleship powder ram question?

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petsan
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Battleship powder ram question?

Postby petsan » Wed Sep 30, 2015 4:24 am

Battleship powder ram question?
The rammer operator rams the projectile until it is seated, the rotating band must be forced into the rifling so that the projectile will not move to the rear when the gun is elevated. The rammer-man rams 6 powder bags, the rearmost bag not more than 4" from the mushroom when the breech is closed (a +4" gap between the last bag and the primer might prevent the powder from igniting, causing a misfire) When using reduced numbers of bags or 55 lb reduced service bags this step is a little tricky, the reduced service bags are smaller in diameter as well as shorter, If they are pushed too far into the breech, elevating the gun barrel will cause the bags to flop back against the mushroom head, this will result in the red patch of black powder igniter to slump out of position where the primer charge cannot get to it. On April 16, 1989 there was an explosion in a gun turret on the U.S.S. Iowa, the experiment being done on the center gun required the loading of only 5 bags of powder. There were two basic kinds of shells, a 2,700 pound armor piercing shell and a 1,900 lbs. high explosive shell. The lower weight shell required more powerful powder, called D-846. The D-846 bags could not be used with the 2,700 pound shells, and were actually stenciled with "WARNING: Do Not Use with 2,700-pound projectile". The experiments involved placing 5 bags of D-846 propellent behind a 2,700 pound shell.

OK now to my question, and PLEASE PLEASE this is not for a discussion on what caused the IOWA turret explosion....

1- When the guns are raised how do the 6x standard powder bags not drop back on the primer 4" under it?
2- How could the Rammer-man push 5x D-846 powder bags in....the right distance into the breech while leaving the required 4"?
3- Does the increased space between the 5x D-846 powder bags and the base of the 16" projectile change any ballistics?
(see photo below)
4- And finally.....If a hypothetical ultra-modern layered propellant, with split stick powder was developed for a hypothetical
BB 16" gun with only 3 powder bags necessary for a full charge, how would one ram it.......hypothetically speaking?

Image

Bill Jurens
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Re: Battleship powder ram question?

Postby Bill Jurens » Thu Nov 05, 2015 6:32 am

I just noticed your question now. Very quickly, and in somewhat general terms, the answers are as follows:

1- When the guns are raised how do the 6x standard powder bags not drop back on the primer 4" under it?

A) If the angle of departure was high enough, they did. Usually the angle of elevation of the gun was low enough that this did not happen, i.e. the bags remained in place due to friction. At some angles of elevation this caused problems in accuracy because some bags would slip back where others would not. This led to some erratic variations in initial velocity.

2- How could the Rammer-man push 5x D-846 powder bags in....the right distance into the breech while leaving the required 4"?

A) He was usually guided by with hand signals from the gun captain.

3- Does the increased space between the 5x D-846 powder bags and the base of the 16" projectile change any ballistics?
(see photo below)

A) Yes. Whether or not the effects might have been considered significant is a somewhat debatable point. It's my recollection that there was a feeling that the 5 bag load, which was completely safe regarding pressures, etc, would have resulted in more repeatable ballistics.

4- And finally.....If a hypothetical ultra-modern layered propellant, with split stick powder was developed for a hypothetical
BB 16" gun with only 3 powder bags necessary for a full charge, how would one ram it.......hypothetically speaking?

A) A good question. It might have taken some experimentation and computation to determine exactly what arrangement and positioning of bags would provide the most repeatable initial velocities.

Bill Jurens

XR4ever
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Re: Battleship powder ram question?

Postby XR4ever » Wed Nov 25, 2015 1:18 am

I have read your question again and again and I get confused every time I try to get to the very point of the problem. I've used to think myself having quite "good" understanding about the basic principals of operating of large caliber naval gun. But your question left all my "understanding" so messed up... as neither I could make even a guess answer to it nor felt myself 'knowing" anymore... With some of a suspect if you did the whole description correct...
So I've decided to wait for reply from someone and try to see if I am wrong and where...
But then I've got confused even more :stubborn:
For all first 3 parts of your question I have faced myself with subsequent:
>
1. if there is (quote) "the rearmost bag not more than 4" from the mushroom when the breech is closed (a +4" gap between the last bag and the primer might prevent the powder from igniting, causing a misfire)"
Q.:Will it be a problem if a gap is less than 4"? I thought that it is the only problem if the gap exceeds ... Subsequently, would the problem with bags position occur with raising the gun or when depressed? Would it have occur with 6 bags of full charge?
2. As far as I know a full charge was performed with two strokes of rammer loading 3 bags with each. When loading reduced charge, if I am correct, first two bags gun captain pushed by hand one by one and the last 3 were rammer operated under careful supervision by gun captain. This I remember from watching video somewhat "Iowa's last salvo" as it looked so strange to see a man pushing the powder bag as deep to the breach as he could reach and then doing the same with second bag...
Q.: It seems now gun captain has to worry about last bag positioning no more than 4" away from the mushroom plate... (and I still doubt if the distance could not be less...) And what happens if the gun is depressed?
3.When the primer is triggered it bursts the last powder bag... and it takes a designed with purpose delay until the next bag will get burst...
Q.: Would the burst of the last bag does not push all the next bags with a tremendous pressure all the way forward before they burst? Or, rephrasing, how far the rest 4 bags can move forward before they get burn? And if they even can move an inch or the supersonic wave from the last bag burning just rips them apart?
4. Including all from 1, 2 and 3, wouldn't it be just as final phase of the 5-bags loading? And again, do they worry about the last bag being placed less than 4" from the mushroom plate?

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Rick Rather
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Re: Battleship powder ram question?

Postby Rick Rather » Mon Dec 14, 2015 5:15 am

XR4ever wrote:Q.:Will it be a problem if a gap is less than 4"? I thought that it is the only problem if the gap exceeds ... Subsequently, would the problem with bags position occur with raising the gun or when depressed? Would it have occur with 6 bags of full charge?


Less than 4" is OK. You obsess over this several times in your post. The spec (which you highlighted yourself) is "not greater than 4 inches". Less than 4" is FINE.

2. As far as I know a full charge was performed with two strokes of rammer loading 3 bags with each.


This is incorrect. The bags were delivered to the loading tray in groups of 3, but the first bags were pushed (by hand) towards the breech to get them out of the way of the 2nd group, not to position them. Once the 2nd group was on the tray, the rammer was then used (once) to push the 6 bags into position inside the breech.

Here is a 16" gun training film: https://www.youtube.com/watch?v=0OmOQs0ziSU

Projectile loading is at 6:00 minutes. Powder loading is at 6:30. Note that there is a skip in the film at 6:55 where the section on priming is missing.

When loading reduced charge, if I am correct, first two bags gun captain pushed by hand one by one and the last 3 were rammer operated...


Incorrect. see above. Note that whether loading six bags or just one, the ram is stopped in the same place: <4" from the mushroom.

Q.: It seems now gun captain has to worry about last bag positioning no more than 4" away from the mushroom plate...


There are several things to note in the training film: The ramming is done at low speed. The Ram Operator has an excellent view of the loading tray and breech. The Gun Captain has an up-close view of the position, and is on the other side of the tray so he doesn't block the Ram Operator's view. Under these conditions, and with training, the gun crew should get the powder correctly positioned within the 4" spec every time.

That said, I find it interesting that - apparently - the only control of the speed of the rammer is the position of the operator's lever. This calls for skill and good training on the part of the operator. Iirc, when Sandia Labs replicated the Iowa explosion, ramming the bags too fast was one of the factors in the accidental ignition.
I am hypothesizing here, but if the Iowa gun crew did load the reduced charge with a double-ram procedure to place the first bag near or against the shell (they violated a large number of administrative, procedural and safety protocols - the result was less accidental than it was inevitable :evil: ), then neither the Gun Captain nor the Ram Operator would have had any way of clearly gauging the position of the bags way up in the dark chamber. All it took was ramming a little too hard, a little too far to generate enough heat... :(

And what happens if the gun is depressed?


Based on personal experience, I recommend Prozac and gaming with friends around a tabletop. :D

Seriously, I don't think the guns can depress far enough for the bags to overcome friction in the barrel and slide forward.

I hope this helps.
Just because it's stupid, futile and doomed to failure, that doesn't mean some officer won't try it.
-- R. Rather


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