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Spin stabilization in rifled artillery shells - Weapons of the Civil War - Civil War Talk - Civil War Interactive Discussion Board
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 Posted: Thu Jul 21st, 2011 02:50 am
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Hellcat
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I've recently been looking at artillery shells and some of them have raise a question for me. Were any shells designed for spin stabilization. I'm looking at shells and seeing what I'd say looks like it was mean to cause further stabilizing spin once the shell left the gun. But then I try to find out for certain if it's the shell and all I can find really is talk about the sabot and stabilization. So am I looking at pictures of the shells themselves or of the shells with the sabots in place.

The shells in question that have lead to this are the following:

http://www.civilwarartillery.com/projectiles/rifled/FAOIIIa126.htm 

http://www.civilwarartillery.com/projectiles/rifled/IIIA75.htm

http://www.civilwarartillery.com/projectiles/rifled/IIIA76.htm

http://www.civilwarartillery.com/projectiles/rifled/images/FAOiiia100.jpg

http://www.civilwarartillery.com/projectiles/rifled/FAOIIIa99.htm

Now on the James shells I've been assuming the deal with missing in parentheses(?) means the sabot is missing, though for all I know it means the sleave for the sabot is missing



 Posted: Thu Jul 21st, 2011 12:13 pm
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Mark
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I think you are pretty much correct Hellcat. According to the Timelife Echos of Glory series the James shells had a lead sabot: "When the shell was fired gases entered the projectiles base, passed through its ribs, and expanded a lead sabot into the barrel's rifling, which made the shell rotate." I doubt that the sabot was meant to separate after firing. If I remember right, I think the sabot looked like little fins that popped out of the ribs. However, the same book has a picture of a Schenkl Shell which apparently had a paper mache' sabot that burned up as the shell left the gun. Of course, this shell was particularly sensitive to water damage and thus not terribly useful, but it seems to be an interesting experiment to me.

Mark



 Posted: Fri Jul 22nd, 2011 12:09 am
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Hellcat
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The Civil War Artillery page (http://www.civilwarartillery.com/mainpage.htm) does mention what type of sabot was used with each projectile type, if any. The second sub-patern Blakely (http://www.civilwarartillery.com/hap/page61.htm), used in heavy rifled guns, lists no sabot was was used, possibly because of the flanges on the side of the shell. But then the Pattison projectile (http://www.civilwarartillery.com/projectiles/rifled/FAOIIIa126.htm), used in field rifles, also has the flanges on the shell but it states that the sabot was a leather sleeve. Now for the definition of a flange the site's glossary says:

FLANGE: A projecting rim or ridge on the body of a projectile. The flange would guide the projectile through the grooves of the bore and cause it to rotate.

 

Make sense, especially when you look at the shell links above. After all the flanges look slanted so they could certainly impart a corckscrew spin coming out of the rifled barrle. But then you have another Blakely shell with straight flanges (http://www.civilwarartillery.com/hap/page64.htm), looking at this one I have to wonder how the flanges are meant to guide through the grooves of a rifled barrel and cause rotation. This looks more like the grooves in the barrel should run straight and just be a grooved smoothbore rather than a smoothbore converted into a rifled barrel.

And then there's the definition of sabot on the site.

SABOT: The sabot served as the driving band for the projectile, and was made of wood, brass, copper, lead, papier-mâché, leather, rope, or wrought iron. The sabot for a rifled projectile was attached directly onto the projectile. When the weapon was fired, the gases from the propellant charge caused the sabot to expand into the rifling grooves. This, in turn, caused a rotation motion of the projectile which extended its range and improved stability. In the case of a smoothbore projectile a wooden sabot, made of poplar, basswood, linden, or other close grained wood, was used to hold the projectile with its fuze forward and in the center of the bore. Solid shot had the sabot attached with two crossed tin straps. If the wooden sabot was tied to a cartridge bag, the entire round was then referred to as fixed ammunition.

 

Ok, so the third and fourth sentences there basically say the sabot does the same thing as flanges. So why would the Pattison need both a sabot and flanges? Also, did the sabot fall away from the projectile then like it does today?

Then you look at various James shells. On the canister and grape shot shell section of the field shells I found a James base (http://www.civilwarartillery.com/projectiles/canister/IIIA27.htm) which states that the holes were used to help attach the sabot to the ribs of the base. I'm guessing the ribs being those sections of metal in between the large holes. If so, then whats the purpose of some James shells having slanted ribs (http://www.civilwarartillery.com/projectiles/rifled/IIIA75.htm, http://www.civilwarartillery.com/projectiles/rifled/IIIA73.htm) while others appear to have had straight ribs?



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