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Rifling twist in Artillery cannons

 
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  #29  
Old 11-20-2011, 12:23 PM
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Re: Rifling twist in Artillery cannons

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Originally Posted by the gman View Post
Not exactly out of the bag as the armor is much more than just the outer shell that shows it's face to the world; lotsa stuff going on under the surface. In addition, I signed a piece of paper called 'The Official Secrets Act' which has it's roots in the early 20th century and that document applies to me until the day I die. I have no desire to be arrested should I blab and go back to the UK for a visit, even though I am now a US citizen. The Brits take their secrets pretty seriously but I also have no intention of sharing anything that may aid some scumbag terrorist somewhere in figuring out a way to penetrate the armor.

On another note, the mil is an angular measurement and is very simple to work with, if you understand metric measurements. One mil subtends 1 meter at 1000 meters with 6400 mils in a circle. So if you are calling in arty and you are 10,000 meters from the firing point, need the POI to shift 100 meters forward and 200 right, s'real easy to call that out. Compared to seconds, minutes and degrees at least!
I know what you are saying about the armor plate, but there's more to the equation than just the plate. And with that I will not go further. Lastly the turret on an M1 tank has been cracked at least twice by the Army. What with, I won't say (you probably already know).

There is a totally new MBT in the works. The drive trane will come in cheaper, and probably be better. (been finished for about six or seven years). The hull is similar in design to what we are using right now (nobody really knows what it looks like), as the parts fit all M1 series hulls and the new hull. But there's also talk about something totally different in the design pool. I will not say, but trust me it'll change the game like nothing we've ever seen before. The work on the main gun is done, and the turret concept is probably finiahed as well.

You are correct about the "circle", but they have it pegged even tighter than that with the addition of some variables to allow them to split a mill without moving the barrel. There's some new stuff in the pipe line that will allow the gun crew to split a mill in segments that will probably end up being in the quarter mill area. The stuff has been tested and the results were stunning to say the least. We saw far more range and much better shot to shot consistencey than we've ever been able to do in the entire history of artillary. The secret is so simple that it makes us look stupid! I still don't see them doing much smaller than fifteen arc seconds without a better hull design (flex has become an issue), and a better way to lock the hull into a single position. But twenty five miles is easilly in the picture if not thirty with a 155 howitzer. Then we will have to finally give the users better maps! Maps the will grid much tighter and more accurately. Right now that's a major problem, as two thirds of the maps used are suspect. What's really interesting is that with the new stuff that old 175 gun is looking far better all the time.
gary
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  #30  
Old 11-20-2011, 12:35 PM
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Re: Rifling twist in Artillery cannons

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Originally Posted by Bart B View Post
1/6400th of a circle equals 3.375 minutes of angle (trig, not shooting).That's 0.98175 of a yard (or meter) at 1000 yards (or meters). The amount's close to .001 of the range but exactly, its .00098175.

There's four different standards for a mil. It's 1/6000th, 1/6283th, 1/6300th or 1/6400th of a circle depending on whose standard you use. When in the USN and we did shore bombardment or surface target exercises, we used 1/6283 of a circle, or 0.00100003 of the range. Close enough to 1 yard at 1000. Both the observer's near the target and the ship's plotting room crew's mil spot converters were the same.
field arty uses 6400 mill circles. When shooting very close to friendlies they use a certain lot of projos and a certain lot of powder. They are called out as "contact lots." Nobody likes to drop rounds in closer than 300 yards because the atmosphere alone can cause you heart break. I have shot within 125 yards, and have brought Cofram right ontop of friendles a couple times while they were being over ran. Nobody wants to do this, and the call is always made on the recieving end. The hardest stuff to shoot are the point blank stuff. I have shot WP with one second on the time fuse with the lowest possible powder charge more than I like to remember. But with a round of WP going off between you and the neighbors; you no they ain't gonna spit in your eye. I will never forgive MacNamira for his failure to give is beehive rounds to this very day; while he had them in the states.
gary
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  #31  
Old 11-20-2011, 02:05 PM
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Re: Rifling twist in Artillery cannons

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Originally Posted by Trickymissfit View Post
Nobody likes to drop rounds in closer than 300 yards because the atmosphere alone can cause you heart break.
Battleship New Jersey's Fire Control Smooth Log had the average first shot miss distance at max range recorded as 90 meters in late 1968. That's about 2 MOA. So one could create a helo landing area with a 1900 pound high capacity round just about where ever the ground troops wanted it.
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