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How accurate are Precision guided munitions?

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posted on Jul, 26 2006 @ 12:25 PM
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This comes up often in discussions here. Just how accurate of precision guided munitions?

We only ever see video of successful strikes on targets. I am assuming the military has done enough analysis to see how accurate they are. Do they hit their intended target 90%, 95% or 80%? I think we are led to believe they always hit their target because of the videos we see when they work. What about the videos we don't see? I am aware it also involves the proper "lighting up" of a target by either a munitions officer or feet on the ground, so I am sure there is some margin of inaccuracy when it comes to them.

Just curious, and I know some here have the answers at their fingertips.




posted on Jul, 26 2006 @ 07:22 PM
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LGB's are quite accurate, depending on wind and other weather conditions. A sudden strong gust will put any bomb off course.

Satelite guided JDAM's are also quite accurate however the coordinates must be precise.



posted on Jul, 26 2006 @ 08:07 PM
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Thanks for the reply. However I am looking for some percentages of hits, there must be some kind of analysis done by the military in it's damage assesment to give a figure. No doubt they are much more accurate than "dumb" munitions.

We never see any failures, which I am sure is intentional, to give the impression they are almost 100% accurate. I just wonder if they are actually close to that 100% accuracy that we see in videos released.



posted on Jul, 26 2006 @ 09:12 PM
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Weapons accuracy is measured by "Circle of Equal Probability" (CEP), which is the radius of a circle that half your shots will land in. Most GPS-guided weapons are described as having a CEP of ~10 meters. So 50% of the bombs will strike within 10m of the target and apparently (because guided weapons don't seem to follow normal distributions like unguided weapons would) the rest will strike within another 10m.

A 2,000lb bomb creates a crater 15m wide and will kill (blast fragments) anyone within 350 m.... a 10m CEP is going to land you close enough to gauruntee a hit.

By comparison in WW II we figured ~1 in 3 bombs was hitting within 8km of the target. Which is probably why we simply bombed out whole cities... it was the smallest target level-flight bombers could be reasonably expect to hit.

Laser guided/Infra-red guided weapons seem to be more accurate... while I can't find numbers, a paveway bomb can hit a moving vehicle. Officially the SLAM-ER (Harpoon cruise missile variant) is the most accurate weapon the US has....

www.boeing.com...

And if you want more detail on CEP, Wiki has a good article: en.wikipedia.org...

Hope that helps!

(Edited for spelling correction)

[edit on 26-7-2006 by RedMatt]



posted on Jul, 26 2006 @ 09:39 PM
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Just a minor amendment to your post Matt, CEP is Circular Error Probable. Your description is good though. The hit (kill) itself comes down to what is called weaponeering, which involves fusing, delivery angle, air density, topography, armour, target movement, frag pattern etc. I've seen GBU-12s smack into revetted tanks well within a couple of metres of the tank, detonate, and the tanks not be affected at all. There are a few different tools used to predict Pk (probability of kill) which is more important than CEP for precision guided munitions (most will land in the bucket these days bar failure). CEP is more from the days of dumb bombs. LGBs, if there is no failure, will land very close to where the laser is pointing. GPS munitions are less accurate, but with recent upgrades are getting better, close enough to increase the Pk anyway.

Historically, I'd expect somewhere in the order of 85 - 90% of launched PGMs to hit where they are supposed (hit, not necessarily kill as described above). Failures are usually due pilot incompetance, targeting pod failure, or aborted attacks due to collateral concerns post launch. And you are right, you only ever see the hits. Misses aren't the message most militaries want to send!



posted on Jul, 26 2006 @ 09:43 PM
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There are several conditions that can set up a miss for an LGB. Turning the laser on too early or too late will cause it to hit the ground short. Smoke/snow/rain, etc can cause the laser to blur and be harder for the LGB to see.



posted on Jul, 26 2006 @ 11:14 PM
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LGB's are dropped from the aircraft (F-16 in this example) using dumb bomb modes. For example, an LGB launched from an F-16 will be dropped using CCRP mode, and that in itself would get the bomb pretty close to the target without further guidance, however the laser makes it much more precise.



posted on Jul, 27 2006 @ 12:56 AM
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I've been led to believe that the hardest part of destroying a point target like a entrenched tank is to find it and accurately locate it?

10m CEP sounds like a lot when artillery can do a 50m CEP from 30km away with dumb 155mm rounds...



posted on Jul, 27 2006 @ 01:03 AM
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That's because 10m isn't the accurate CEP for it. LGBs generally have a CEP of less than 10 FEET.

Paveway II GBU-12 3.6ft with 99 deliveries, 8 second lasing, 10 knot random wind.

The unguided version has a CEP of 310ft.



posted on Jul, 27 2006 @ 01:55 AM
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As I indicated before, CEP simply isn't useful for precision guided munitions because you don't get the statistical spread that you do with dumb munitions.

Entrenched tanks are relatively simple to find given a half decent target pod and decent intel. The problem is the angle of arrival of the LGB compared to the wall of the revetment. The fuse is triggered by the wall, not the tank, so unless you have a prgramable delay fuse, the tank has a chance of surviving as the effect is soaked up by the dirt. And the 500lb bang isn't that great, and you're not going to go tank plinking with 2000lb munitions. There's more effective ways of dealing with tanks than attriting them one by one anyway.



posted on Jul, 27 2006 @ 04:06 AM
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Originally posted by northwolf
10m CEP sounds like a lot when artillery can do a 50m CEP from 30km away with dumb 155mm rounds...


10m accuracy vs. 50m accuracy has a huge impact, because the explosives needed increases exponentially (insert inverse square law here) relative to distance from the target. At five times the range you'd need 5^2 = 25 times the explosives power: you'd need either 25 500lb bombs or a single 12,500lb bomb at 50 meters to match a single 500lb hit at 10 meters.

When you factor in the collatoral damage you didn't want to cause, and the logistics of getting that many more bombs to the target, even an apparently small increase in accuracy is going to have a big impact.



posted on Jul, 27 2006 @ 04:31 AM
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Ok, i got the point...

btw 25 rounds is pretty normal artillery strike... and even with 50m cep, it tends to be enough to take most of the targets out.

Does the US army field guided 155mm or 120mm (Mortar) rounds?

[edit on 27-7-2006 by northwolf]



posted on Jul, 27 2006 @ 05:15 AM
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Originally posted by northwolf
Ok, i got the point...

btw 25 rounds is pretty normal artillery strike... and even with 50m cep, it tends to be enough to take most of the targets out.

Does the US army field guided 155mm or 120mm (Mortar) rounds?

[edit on 27-7-2006 by northwolf]


The army is working on a "course correcting fuze" (www.gizmag.com...) which will fit 155mm and 105mm artillery shells and is ~3 times more accurate.

There's also "excaliber," which is a GPS-guided 155mm shell which can "glide" to extend it's range to 50km. However I'm not really impressed by it, as Denels V-LAP ("dumb") 155mm rounds are reaching 60km with L52 guns, and Excalibur rounds are so much more expensive than regular artillery rounds ($50,000 per shot vs. $300 for a basic 155mm round) that the exercise doesn't seem (to me) worthwhile.


As for 120mm rounds, ATK is working on a simple but effective laser guided round: Link

I like ATK's arrangement the best: no moving parts (very simple, so probably cheap) but also very accurate (they say < 1 meter). I'd be curious about combining ATK's control system with Denel's long-range 155mm rounds... this strikes me as an ideal solution.

P.S. keep in mind I'm a buisiness student minoring in statistics... and thats the limit to the facts I can offer, everything else is well-intended opinion from someone with no military experiance at all.


[edit on 27-7-2006 by RedMatt]



posted on Jul, 27 2006 @ 05:24 AM
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Swedes have the IR homing Strix round for their 120mm mortars www.defense-update.com...
With a direct top hit AT cabability... this combined with Finnish Twin 120mm Automatic AMOS Mortar system could really unleash a hell upon armoured troops... And coupled with TV/Laser guidance to all other targets too
AMOS



posted on Jul, 27 2006 @ 12:11 PM
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Finding the target in real war is the hard part. Most of the targets struck in Gulf war were decoys as was the case in the Balkans, hitting the target is less of a problem...Hell in WW-II the Germans had guided munitions that could be placed within 15m of aim point.

[edit on 27-7-2006 by psteel]



posted on Jul, 27 2006 @ 01:48 PM
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I hear LGB"s are accurate within inches wehn launched in optimum weather conditions,as conditions worsen the accuracy worsens. SO another seeker option is MMW radar which is affected less in weather while retaining high accuracy and truly offering fire and forget.



posted on Jul, 27 2006 @ 03:54 PM
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precision guided munitions work very well but things normally only work that way on training and proving grounds. Weapons ARE getting smarter and more accurate but you can not not very long destroy mud villages with million dollar cruise missiles ( even if there were unlimited production runs) in your alleged terrorist hunting campaigns.

www.sfgate.com.../c/a/2003/03/22/MN102951.DTL

Stellar



posted on Jul, 27 2006 @ 05:22 PM
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Whenever you drop a bomb, fire a missile, or basically do anything that will kill people, there is a targeting process that you have to go through, part of which examines military necessity, proportionality, and a raft of other considerations. But the simple fact is, precision munitions still don't discriminate between combatants and non-combatants. Things are certainly better than what they used to be, but you cannot fight a war without killing civilians. It is going to happen, and people who think otherwise are kidding themselves. Easiest way to avoid civilian casualties is not to go to war. Sadly, this is never going to happen.

There are other initiatives in train to try to reduce collateral damage. Selectable fusing, selectable effects, non-lethal suppression agents, cluster munitions that de-arm themselves at a given time or when a signal is sent, direct energy weapons etc. But precision will still not equal zero civilian deaths.



posted on Jul, 28 2006 @ 10:28 PM
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Thanks for all the posts, I am learning alot.

What is the blast radius of a 500 lb. bomb. The one reference I have found states a 400 meter blast radius, is that accurate? I am assuming there are different levels/rings of blast radius as well, could anyone point me to a description.

Thank you.



posted on Jul, 29 2006 @ 12:46 AM
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It depends on a few different things, delivery profile, air pressure, fusing etc, but the rough figures IIRC are about 2500 feet in diameter, and 2000 feet in altitude for the Mk-82 series munitions. Remembering that the frag pattern isn't a perfect circle, but more a maple leaf shape (sides of the bomb, then front, with little frag to the rear). This becomes important when determining attack direction if there are collateral concerns in mission planning. Hope this helps.



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