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Air Weapons: Micro-JDAM
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January 6, 2009: U.S. firm General Dynamics has successfully tested its RCFC (Roll Controlled Fixed Canard) flight control and guidance system with 81mm mortars dropped from  aircraft. The RCFC is like the guidance kit attached to aircraft bombs to give them GPS accuracy, and turn them into JDAM (Joint Direct Attack Munition). The RCFC screws into the front of the mortar shell, in place of the fuze. Dropped from the air, it will land within  5-10 meters of the GPS coordinates it was programmed for. An 81mm mortar shell weighs about eight pounds, with up to half that being explosives. It causes casualties within 20 meters of impact point. Thus GPS is accurate enough to make a micro-JDAM based on 81mm mortar shells effective. The mortar shell, with the RCFC, would weigh about fifteen pounds. A more powerful weapon would be a 120mm mortar shell. Normally, these weigh about 35 pounds, with up to fifteen pounds of explosives. An RCFC version of this would weigh about 45 pounds.

Such weapons would be expensive. While the mortar shells themselves cost $50-100 each, the RCFC for each would cost over $20,000. These would be competing with the many precision weapons the troops on the ground already have. For example, there is the 26 pound Javelin, with its nine pound warhead, and the larger (fifty pound) TOW with a 13 pound warhead. These two missiles are expensive, with TOW costing $25,000 each, and Javelin $75,000. But even that can be too much bang for the infantry. That's why the AT4 rocket launcher, and its four pound warhead is so popular. It's not laser guided, and you have to be pretty close to use it. But at the normal ranges its used (a hundred meters or so), it's very accurate, and it's cheap ($2,700). The LAW is similar, smaller (2.2 pound warhead) and cheaper ($2,000). What these smaller JDAMs are handy for are smaller UAVs out on patrol, and in need of a small weapon for targets of opportunity (like a few guys trying to set up a roadside bomb.)

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esmoore5       1/6/2009 12:13:41 PM
60mm guided mortars are also possible: http://www.spacedaily.com/news/gps-05za.html . . There's even been talk of guided bullets: http://blog.wired.com/defense/2007/11/pentagon-wants.html . . How small can guided weapons get?
 
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doggtag    beaten to death...   1/6/2009 3:46:01 PM
...on the 60mm ODAM project.
Hit that one more times than I can remember.
 
Here's one from a while back : CTGP pdf
Note the dates: preliminary studies in 1999-2000 timeframe.
8 years later, surely we're capable of much more than is being mentioned in the public sector,
although I doubt we're nearly even close to the point of the guided (homing) micro shells like were depicted in the Tom Selleck movie Runaway...
 
If we're dropping munitions, they needn't necessarily have an onboard propulsion system: JDAMs and other unpowered guided bombs get to their targets by careful adjustment of their glide slope.
 
I am wondering exactly the lay-out and operation of this Roll Controlled Fixed Canard system,
as to how similar is it to, perhaps,
the "twist and steer" lay out used in a handful of MANPADS designs,
or even that used in the RAM naval anti-missile system...
 
Not needing onboard propulsion also means that the electronics are not subject to high G forces, therefore can be made cheaper than something that must withstand thousands-of-G's gun-launch forces or the high acceleration of a rocket motor.
In theory, even the servos of COTS R/C aircraft would suffice to manipulate the control surfaces of these flyweight PGMs.
A small windmill electric generator in the nose or tail could provide all the electric power necessary to work the micro-bomb's actuators and datalinks, even a nose-mounted optical imager.
Or even, the troops could just plug a couple of 9V batteries into the damn things before launch!
Dropping from several-hundred to a few-thousand feet towards a ground target, these micro-PGMs aren't going to be wasting a lot of kinematic energy in chasing their targets like AAMs do, so unpowered "glide" attacks will work fine.
 
The game could really get interesting if some enterprising weapons design firm comes out with environment-mimicking outer shells that look like the local area's flying birds: imagine a miniature SDB that has bird-wing-shaped flip-out wings to allow it to glide innocently towards a target.
 
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esmoore5       1/6/2009 4:16:44 PM
What makes the air dropped mortar any better than the already-existing Viper Strike?: http://www.irconnect.com/noc/press/pages/news_releases.html?d=79978
 
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warpig       1/6/2009 5:29:31 PM
It's a lot smaller and lighter.  Maybe it's cheaper, too, but I have no idea about the cost of a Viper Strike munition, so maybe it's not.
 
 
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WarNerd       1/6/2009 6:23:11 PM
When comparing the costs of different weapon systems you really need to look at the cost of the entire logistics chain. The purpose built Viper Strike is possibly more cost effective if you only look at the manufacturers costs.  But you have to build up a stockpile, distribute, and maintain it as well.  You also have to do the same with mortar ammunition.
 
So the question becomes which is more cost effective to supply to the troops in, lets say, Afghanistan.
1000 rds mortar + 100 Viper Strikes
or
1100 rds mortar + 100 guidance kits
Given the success of strap-on bomb guidance kits I think we can make a guess at the answer.
 
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newjarheadean       1/6/2009 9:14:02 PM
AHOY, esmoore5 the mortar could be deployed in more ways i.e. form the tube, by hand or dropped from aircraft. Maybe you already new that and where looking for something more intelligent but just sharing ideas. How small can we go? IMO the nano bots are already deployed, using some kind of genetic engeeneered chemical secresion to desolve the gigantic dust particles blocking there paths, i got an itch on my left ear just awhile ago, lol. G-day!
 
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