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 Subject: Accuracy Roman    5/25/2006 1:00:00 PM I am just wondering, what is the accuracy of modern artillery pieces (for a given range and weather conditions) assuming the use of ordinary (non-guided) projectiles?

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 Yimmy    RE:Accuracy    5/25/2006 2:05:21 PM I suppose that would be a matter of CEP, with the CEP getting slowly larger the further out you go. I doubt the CEP would be past double figures though in meters.

 Carl S    RE:Accuracy    5/26/2006 1:04:24 AM I happen to have the firng tables for the US M109 & M198 howitzers withM107 HE ammo. At 8000 meters with Charge 5Green bag the range PE is +- 27 meters & deflection PE is R/L 8 meters. At 18000 meters with chg 8W the range PE is 52 meters & deflection PE is R/L 15 meters. These are for hypothetical perfect standard conditions. At 18000 meters a tail wind of one nautical mile per hour can increase the range 22 meters; a increase of air temp by one PCT increses rgn 18 meters; a decrease in air density of one PCT increases the rgn 85 meters. We would find the actual temperture by sticking a dial & spike type cooking thermometer in a powder bag. The wind direction/speed and air density came from the battalion meterological section. I think they used a Ouiji Board to find their data. Variations in propellant powder from one manufactoring lot to another could vary the error, we also routinely used corrections for the wear on the tube, rotation of the earth, and the spin on the projectile. With the 155mm ammo anything within 50 meters could be considered a 'hit'. If there was time to burn we would try to adjust it down to 25 meters, but between the variations in wind speed, the cannon shifting, ect.. it was problematic.

 IsoT    RE:Accuracy    5/26/2006 4:59:38 AM IF recollection serves 0.3% in range and 0.3 mills in side. So in 10000m range that would do +/- 30m in range and sideways +/- 5m. But as Carl S. mentioned variables are many, and it is not really worthwhile hitting one piclebarrel. You get better effect when you have multiple impacts around the target area, so that a shelter, like a wall, only shields you from some part of the shrapnell flying. There are guided munitons like Krasnopol that can take out point tragets like tanks. But infantry is better served in trowes...

 Carl S    RE:Accuracy    5/26/2006 4:33:24 PM IsoT... what is your artillrey background? Your post has the air of experience. I served the guns over a decade in the US Marines. There are some expert gunners lurking here as well, if you have not already noticed.

 S-2    RE:Accuracy/Carl S. Reply    5/26/2006 7:01:44 PM Carl, the only addition I'd have is projo sq. wt. "we would try to adjust it down to 25 meters" For us, as I recall, only on MPI registrations. Neutralizer's comment about dispersion vs. accuracy seems reliant upon observer/target location errors, otherwise I don't understand his argument. New technology seems to mitigate strongly against these possibilities. We need an SP two-day LFX. With a few volunteers from the grunts I imagine we could man a platoon of guns, an O.P. and a MANUAL FDC. An old M102 105mm How w/ M-100 series pantel and we'd be set. 400 rounds. Don't want any M-12 pantel equipped weapons. That damn slipping guage... No beer on the gun-line, but near-very near.

 neutralizer    RE:Accuracy    5/27/2006 4:30:24 AM There is absolutely no confusion between accuracy and consistency. They are completely different things. Accuracy is the whereabout of the mpi in relation to the aimpoint (hopefully coincident with the target), consistency, which is the data given in FTs is the spread of shells around their mpi. Registration is a different thing altogether, it's an arty procedure for finding the correction of the moment for non-standard conditions and one or two other things, eg survey errors. If you want to see accuracy and consistency explained pictorially then see Figure 1 on the 'Errors & Mistakes' page of my web site at http://members.tripod.com/~nigelef/index.htm

 S-2    RE: Neutralizer Reply    5/27/2006 5:54:32 AM "There is absolutely no confusion between accuracy and consistency. They are completely different things. Accuracy is the whereabout of the mpi in relation to the aimpoint (hopefully coincident with the target), consistency, which is the data given in FTs is the spread of shells around their mpi." " Neutralizer's comment about dispersion vs. accuracy seems reliant upon observer/target location errors, otherwise I don't understand his argument." Neutralizer, I understand your point about consistency (dispersion) vs. accuracy and concur. Clearly, poorly directed fire can in fact display a consistent impact sheaf at the wrong location, for a variety of possible reasons at the observer and/or FDC locations. What I don't understand, perhaps, is your admonishment to Carl. As near as I can tell, Carl explained the essentials of accounting for non-standard conditions. The means chosen to compensate for non-standard conditions, whether METRO or registration, will provide the desired ballistic solution. It cannot resolve target location errors from the forward observer, nor errors generated in the computation of firing data. However, assuming a good target location and no firing data computational errors, those non-standard condition must still be addressed to achieve accurate fires. For myself, aside from survey, this becomes the point of departure in any discussion relating to technical fire direction. For young fire direction specialists and new artillery officers, the effect of non-standard conditions and the means to compensate are among the first hurdles to be overcome. In point of fact, I doubt there's any real misunderstanding whatsoever. Thanks for the link. Great website. I imagine I'll be over for an extended visit shortly. It looks fantastic.

 Carl S    RE:Accuracy    5/27/2006 8:22:01 AM "We need an SP two-day LFX. With a few volunteers from the grunts I imagine we could man a platoon of guns, an O.P. and a MANUAL FDC. An old M102 105mm How w/ M-100 series pantel and we'd be set. 400 rounds. Don't want any M-12 pantel equipped weapons. That damn slipping guage... No beer on the gun-line, but near-very near." My gun section will have the M101 105mm howitzer. We were still training with those in 1991 & I've heard claims they are still tucked away in the storage sheds on Lejune & Pendelton.

 Carl S    RE:Accuracy    5/27/2006 8:42:45 AM It took me a moment to figure out this "tut tut" of nuetralizer. He hid it off in a different thread. Perhaps to test our intellegence? The splitting of hairs over the concepts of consitiency & accuracy is important when sorting out the details for organizing firng tables or writing up solution programs for computers. The firing table and columns I drew my numbers from were error for non standard conditions that would deviate the MPI from the target point. The dispersion or consistency can also be affected by these but the difference between the MPI & target will be much more noticeable than the dispersion or inconsitancy around the MPI. Enough of niggling. Lets have that beer!

 S-2    RE:Carl-M101A1   5/27/2006 3:00:08 PM Carl, believe it or not, but the only btry. command I held was for an ARMY M101A1 unit. They shifted to the L118 a few years later. I've never seen beer behind the gun line, but I'm glad you're not opposed to a first time. Naturally, we'll go "cold" on the firing point before we break out the juice.