Command guided shells getting smaller

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Subject: Command guided shells getting smaller
doggtag 3/15/2007 2:02:10 PM

From DefenseUpdate.Com: US Army to Evaluate C-RAM Gun System The US Army is seeking countermeasures to defeat incoming enemy rocket, artillery and mortar (RAM) attacks. As part of the Extended Area Protection & Survivability (EAPS) program the Army plans to evaluate gun-based countermeasures currently under development at Alliant Techsystems (NYSE:ATK). The company received a $4.6 million contract from the U.S. Army Armament Research, Development and Engineering Center (ARDEC), to develop and demonstrate a 50mm gun and ammunition system that will be fired from a derivative of the ATK's Bushmaster cannon. The projectile will employ course-correction techniques based on commands received via data-link. ---- 50mm guided shells. SWEET. (links to follow)

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doggtag 3/16/2007 11:50:17 PM

Thanx for all your info, HIPAR/CHAS.

As for furthering this thread to be an AFV armaments discussion,

I'm well aware the C-RAM concept is, most likely, for a static system to defend fixed installations (US bases that currently are seeing their fair share of mortar barrages, for instance).

Suggesting a vehicle mount would, most likely, mean the crew will be actively moving it around, not necessarily ideal for point defense.

But I do see the possibility of ammo and gun commonalities if the system finds merit as a useful land-based CIWS: suggesting we could also see the same gun being fitted to AFVs isn't out of the question...although I would question the necessity of really needing the anti-artillery CIWS capability in an AFV which should be primarily concerned with ground targets (an airburst for anti-infantry, a general use explosive round, and a KE round).

I could see that, under certain environments, it may prove desireable to carry a few clips of anti-helicopter rounds in the AFV.

And the benefit of single-barrel guns is we can more easily rig multiple ammo feed chutes. The AFV benefits from this configuration (many current autocannon-armed AFVs use dual feed, KE and HE types), but the CIWS doesn't really need more than one kind of ammo, the programmable airburster.

In such a role, it could work against inbound artillery & mortar threats, small UAVs and missiles, aircraft, and anti-personnel (think M42 Duster in VietNam).

But if my base is coming under fire from other AFVs, I think I'd use other assets instead of my primary close-in air defense gun.

Seeing the speeds at which the processors and interceptors of the anti-ballistic missile system must function, I don't really see it would be all that much more difficult in hitting-a-bullet-with-a-bullet down into the class of mortar rounds, artillery shells, and autocannon ammo. We'll just have shorter flight times to react to, meaning engagements must happen much quicker, and the weapon system's mount's servos must function quite rapidly to bring the weapon to bear.

And having the proper detonation programming for the round shouldn't prove too impossible either: do we want it to detonate as close to the incoming round as possible to detroy it by blast shockwave (or kinetic impact), or do we want to create a dense-enough cloud of kinetic (& possibly incendiary) pellets to disrupt or tear apart the inbound threat?

I think the choice for 50mm was made on 3 main points:

1)-it would create a strong-enough close range blast radius to do damage by shockwave (although, preferrably, I still prefer to use hit-to-kill, hence the ability to steer the shell)).

2)-it can carry a large enough fragment/pellet payload to generate a reasonably-sized destruction cloud (to 5m diameter? I need a cloud large enough to guarantee at least some of my fragments are going to disrupt the round, and at least enough to do sufficient damage to destroy it outright as opposed to just knocking it off course to land somewhere else that may be inhabited).

3)-it is believed that course-correction/command guidance technology can be packaged into it, and still allow enough payload to perform #'s 1 and 2.

Other points could be that:

- with the upgrading of AC-130s to 30mm Bushmasters (same ammo as A-10's GAU-8) instead of 25mm GAU-12s and 40mm guns, the US is finally moving away from 40mm cannon ammuntion entirely, and there's little favor in choosing another 40mm program (even though the 30mm Bushmaster can upgrade to Super Forty ammo).

-the US Army seems content, for now, to have chosen the 30mm gun also for the IFV variant of FCS, the USMC for the EFV, USN for San Antonios (all with capability to fire the new airburst rounds). But 50mm guns could offer the 2 AFVs considerable firepower improvement in the future (although San Antonios and other larger naval vessels are less likely to adopt a 50mm CIWS gun, even if it adopted a tri-role CIWS, anti-air & anti-surface capability, not when 57mm is already chosen for LCS & DDG1000 and SeaRAM-type anti-missile missiles are becoming more prominent as CIWS for other vessels, superceding the Phalanx).

-50mm Bushmaster offers a more compact round (SuperShot) overall than 57mm naval, and the Bushmaster series can be equipped with muzzle-mounted induction programmers with minimal modification as compared to 57mm naval (I'm pretty sure the 3P fuzes need to be programmed before firing, and with said 3P fuze, why would we need another programmable round dependent on a muzzle-mounted primer?).

-the lower rate of fire of the Bushmaster gun (currently 200 rpm for 35/50mm) offers minimal dispers

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Jeff_F_F oops! 3/17/2007 12:38:50 AM

I'd completely missed that this was a point defense system. For some reason (because I've been thinking about armored warfare a lot lately) I jumped to the conclusion this was a form of ADS for armored vehicles. The Russians seem quite fond of systems that are based on individual vehicles for shooting down incomming missiles and such, but the US Army seems resistant to such systems, presumably due to considerable concerns over collateral damage to neary infantry. I've heard that FCS is inteded to include such a system, but haven't heard a lot about it, so I assumed this was it.

You know what they say about assumptions.

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Jeff_F_F oops again! 3/17/2007 12:41:56 AM

I mean "...a form of APS..."

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reefdiver 3/17/2007 4:17:18 PM

I'm more intrigued by the impilications of using this system for ground attack rather than for counter RAM. With (auto?) tracking of the laser targeting system you no longer have to lead moving targets with rounds. I would think this would mean you can use a lot less ammunition. You might have 1 shot 1 kill unless its a harder target. Overall accuracy is radically improved. You might not even need as high a rate of fire. It could extend gun life and lower maintenance.

Do you fire tracers in a 50mm? If so, with the laser guidance, I'd think you'd be able to eliminate the tracer rounds as you know where the round is going to hit. You're then carrying more live ammo and your position would be less vulnerable.

I wonder how small this might end up going - might we someday see a 20mm guided round?

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doggtag 3/17/2007 10:31:45 PM

A benefit this could give us is, faster slew rates.
We no longer would have to traverse the whole turret to engage a (moving) target: we could create a modified hunter/killer sight system that carries the command guidance link, so effectively after firing a couple rounds off, the turret could slew to aim towards another target while the roof-mounted system, much smaller in size, keeps those first rounds correcting into their targets.

It also might offer an off-boresight capability in an air defense role (or even against ground targets), when the main turret can't train onto the target fast enough (or its line-of-sight is obstructed). The rounds are fired in the general direction, and the command guidance module on top of the turret actually takes the rounds precisely into the target.

Almost seems like the line between gun shell and guided missile will be starting to blur over the next couple decades.

(Is it so difficult to believe that one day we'll no longer fire any unguided ammunition from any cannon-caliber weapons?)

As for guided rounds down to 20mm size? Like I mentioned, they'd make for ideal long range sniping (routinely >2000m), providing you have the magnified optics that allow you to see that far, and adjust the round accordingly.

Depending on the target (personnel or equipment), we might not even need a warhead.

The other option that we get is, a heavy sniper team armed with a big weapon like the Barrett 25mm payload rifle could become dedicated anti-armor assets: if I suddenly gain the ability to snipe at a tank over 2000m away, with the ability to pinpoit its optics, or put a round into the turret ring and destroy the traversing ability, or better yet puch a hole cleanly thru its barrel, I can render it ineffective without needing a $100,000 ATGM. If I know where the weaker points are along a vehicle's armor protection, I can exploit that by guiding my micromissiles to impact those points.

That could actually cut down on heavy loads the ground units have to carry, and I would no longer need lightweight, thinly armored vehicles to carry anti-armor systems.

Three or four heavy sniper teams (gunner and spotter) could successfully wipe out an entire armored column quite covertly.

It makes for an interesting ambush potential.

Maybe not part of the Army 5-10 years from now.

But as we advance in our knowledge and applications of micromechanics and nanotech devices, the capability will eventually be here.

50 years ago when PGMs were still in their infancy, few would've accepted we could one day achieve the capabilities we have today in such small rounds like the Viper Strike, Spike, and Starstreak.

We're already seeing palm-sized UAVs (with smaller, insect-mimicking prototypes being studied) that carry miniature (but still useful) digital optics.

It wouldn't surprise me at all if the systems and vehicles that will eventually be designed to replace the FCS family and all its UAVs and UGVs will not even fire any unguided ammo at all other than small arms, and a precision-steerable long range heavy sniping weapon will be part of that equipment.

Look all the longer it took us to develop a 10,000 pound atomic bomb into something that could be fired from artillery shells: 11" (Atomic Annie fired a 15 kiloton shell) , 8" (M422 could yield from 5-40 kilotons) , even 6" (M454 could yield just under 1/4 kiloton) {source: http://www.designation-systems.net/usmilav/nuke.html&nbs

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reefdiver Dogtag 3/19/2007 12:33:44 AM

You brought up the idea of simply disabling a tank by destroying its barrel. You could probably design a small UAV that would have a small explosive, but when guided (via laser GPS positioning) to say a tank, could use visual recognition to precisely target the barrel or any other site on the tank. It could even fly down the gun barrel of a tank. This would not necessarily be all that impossible or improbable.

You could perhaps do likewise with a small missile. It wouldn't need a warhead to penetrate armor - just disable the gun or otherwise vulnerable sites. It could again seek the gun barrel. Use a laser to guide it to the target, and imaging for final course correction to the barrel. Speed of image processing however becomes something of a problem in this case.

Or does the barrel need more kinetic energy to damage it than a small explosive can provide?

The point of this is that in the future, smart weapons may get much smarter - instead of just hitting a target, hitting a specific site on a target - perhaps selected from a database of potential targets and sites on those targets.

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doggtag 3/19/2007 10:47:37 AM

....Or does the barrel need more kinetic energy to damage it than a small explosive can provide?

I've seen several AFV hulks sitting downrange at a few gunnery ranges.
One that particularly comes to mind is an old M48 (pretty sure its barrel was still the 90mm, with its T muzzle brake),

and it was used quite often by Bradleys, whose 25mm shells left considerable holes all over the hull, including the barrel pierced countless times (most likely this was AP and not HE).

Over on Tank-Net several threads/weeks ago, someone posted up some pics of various hulls littered about a European range. One Leapoard showed its barrel looking like swiss cheese from all the autocannon strikes.

And for an MBT whose gun relies on maintaining high pressure, one "pinhole" from even a 25mm APFSDS round would be all it takes to fully incapacitate the gun, rendering the MBT mostly useless.

Even a 25-30mm HEAT or HEDP shaped charge would suffice (30x113 used in Apache's M230 can bore thru about 15cm of aluminum armor, so a 30-50mm thick steel barrel should prove little difficulty), and actually might be more favorable if we're aiming at optics (an incendiary mix to the explosive could ignite anything flammable nearby, to include the protective sheathing on wiring).

I don't know that I'd use the 50mm mentioned at the beginning of this thread, to perform sniping (although it would certainly work).

But if we can get the tech packed into the 50mm, and prove it works at a reasonable price per round, that could give us the ability to create an even smaller, thinner-walled low velocity round like for an M203 or similar grenade launchedr, that can be lobbed over targets and precisely guided. That could give each soldier his own equivalent of having an ODAM-capable mortar, albeit with less range. But the outcome is the same: you don't have to call for CAS or artillery support if you have a small precision weapon you can lob and fly down into a hatch (much thinner armor than the turret roof) or engine decking.

I think mini-UAV, and I think something re-usable. But I'm talking more along the lines of a microlite kamikaze drone.

Developing guidance and control technologies that will operate from within the confines of a 50mm autocannon shell will only speed along the development of other flyweight PGMs (estimating a shell wall thickness of 5-10mm, the internal electronics & mechanical components would therefore be contained within a 40-30mm diameter space.

We're already getting a microfuze inside the programmable 25mm airburst round for the ACSW machine gun.

Remember that in WW2 the smallest gun that could effectively fit a radar proximity fuze was 3inch.

These newest programmable airburst shells are, in their entirety, even smaller than the prox fuze fitted into those 3" shells.

Now compare that to how a Starstreak dart is barely half the diameter and length of a MANPADS SAM, yet still contains enough guidance-correction capability and steering mechanisms to engage targets, and physically hit them, at >Mach3 launch velocities.

I'm actually more interested in the approach that will be taken to steer the 50mm guided round:

will they opt for twist-and-steer canards like the Starstreak dart, a miniature reaction control system using microjet bursts from very small concentric rocket motors (little more than solid-propellant-filled electronically-fired caps), flip-out multi-fin layout, a gimballed ring like some LGBs use (may prove difficult at gun-launched velocities), or what.

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reefdiver 3/19/2007 12:24:30 PM

I'm actually more interested in the approach that will be taken to steer the 50mm guided round:

I've wondered if could have small air intake ports on the front of the round with controlled exit divert valves on the rear and perimeter that would act like thrusters. It seems however that it might slow it down to much.

Another idea might be extremely small hydrogen peroxide steering thrusters. They auto-ignite in contact with silver catalyst, and you could port them out the rear or sides. You only need micro valves for the thrusters. I think you'd want some sort of short fins or grooves for stabilization - perhaps a sabot design could be useful. You might ignite the thrusters only at a certain point in the projectiles travel or have them available on demand.

Perhaps small pop-up obstructions rather than steerable fins - they would normally be flush but push out a few millimeters to change air-flow on one side or the other. At the velocities its travelling you might not have enought power in such a small shell to control full size fins.

Of course they've probably designed something far more clever.

I've also been thinking (dangerous - I know) about MAV's as tank disablers. After GPS or other guidance to a tank, and visually seeking out the barrel, it might just drop a small specially designed thermite charge down the barrel to weld a chunk of metal in the barrel. I can't imagine they'd want a shell to strike it. An electric MAV, doing this at night would be extremely difficult to detect.

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Jeff_F_F Firepower kill 3/19/2007 6:07:17 PM

1 M1 put out of action in GW1 was due to a DPICM bomblet that penetrated the barrel. That's just under 40mm HEAT.

An additional advantage of small rounds is you can use a lot to take down enemy APS systems that might be able to effectively counter a few larger PGMs. You could also use a specialized round to target APS, perhaps with a light SEFOP that would detonate at a distance to fire hypervelocity slugs into the APS launcher. Then other rounds could be used to take the tank out of action.

The first weapon systems that may fit this bill are precision guided 60mm mortar munitions. Light launch system, relatively large caliber round so plenty of room for electronics. Plus the larger caliber gives better HEAT or EFP penetration. Also a wide variety of launch profiles--high angle, low angle.

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reefdiver 3/20/2007 11:18:26 AM

1 M1 put out of action in GW1 was due to a DPICM bomblet that penetrated the barrel. That's just under 40mm HEAT.

I really agree that the mortars are one of the most practical places to put lots of different electronic packages - small to large calibers, as you mentioned - space, and lower velocity making electronics a bit easier. Warheads can even use small parachutes to slow descent providing more targeting time as with the skeet warhead being put into some designs - I just want to make the skeet even smarter. With such capability, I could see the possiblitly of detailed image processing and extremely precise targeting in the future like attacking the tank barrel, entering an open hatch, or other vulnerable areas - based on the specific vehicle or weapon type recognized. I believe there is huge potential in smart automatic image processing for final terminal guidance, instead of just "simple" IR and laser targeting. Detailed image processing has the potential to make many weapons more precise and perhaps less dependent on possibly degraded GPS. I think its the next targeting evolution.

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