ARMORED WARFARE: RPGs Stopped by Air Bags and Electricity

Strategy Page ^ | November 8, 2004

[John Jorsett]

Rocket propelled grenades (RPGs) are the typical weapons of choice when insurgents decide to attack trucks and armored vehicles. RPGs are cheap, simple to operate, and if used properly can inflict significant damage on Stryker and Bradley armored vehicles. Unarmed and armored Hummers are especially vulnerable, since the various armor kits for the Hummer are designed to protect occupants from small arms and machine gun fire, not anti-tank grenades.

One quick fix to protect the Hummer is a unique airbag system developed by a small California company that deploys a "curtain" down outside the side of the vehicle being attacked. Four bags are needed to protect all quadrants and are held in place with simple Velcro straps. A small radar detects the incoming RPG or RPGs and inflates the airbag with a carbon dioxide gas cartridge. The RPG is literally "caught" by the airbag like a pillow and slowed enough so the nose-mounted fuse doesn't detonate the warhead. Instead, the RPG ends up collapsing upon itself, shredding the secondary self-destruct fuse and looking like a stomped-on beer can. Currently, the airbag and cartridge have to be replaced after one use, but the designers are working on a reusable airbag that can simply be rolled up and put back into place.

Cost for the system is expected to run between $5,000 to $7,000 dollars and weighs around 50 pounds. The Army is in the process of awarding a contract with the goal of getting systems to Iraq within 6 months, at a initial product rate of 25 systems per month. Other systems are being refined for use on canvass-topped vehicles and the Stryker. The system has the potential to replace both the current Stryker "RPG" fence standoff metal framework as well as reactive armor systems and has the twin advantages of being lighter and less expensive than reactive armor. It's also safer around infantry than reactive armor. Multiple tests of the airbag system have been run using RPGs, with one test managing slow down an RPG enough to stop it relatively intact – forcing a stop to the tests until range safety could come out and blow it up in place.

Over the longer term, the Army is looking towards electronically "charged" armor protection. The protection scheme would be composed of an outside armored plate, a spaced gap, and an inner charged plate. Shaped charges are essentially hot streams of metal traveling at (very) rapid speed to penetrate armor. A shaped charge from an RPG or other antitank weapon would detonate, penetrate the outer armor plate, and the hot metal stream would make contact with the charged inner plate, forming an electrical circuit that ends up splattering the metal across the inner plate rather than breaking through into the hull of the vehicle.

Charged armor is a better solution than reactive armor, as it is both lighter than reactive and also non-threatening to nearby infantry. At least two manufacturers have successfully demonstrated charged armor solutions, one retrofitting a Bradley AFV with a large capacitor to charge the inner hull plate. One manufacturer has demonstrated that the Bradley charged armor can take multiple RPG hits onto the same section of the hull without penetration and was willing to show a short demonstration film to those of the proper security clearance. In theory, charged armor should work equally well against weapons with larger shaped charge warheads, but the manufacturer would not comment on any tests done in that area. Ideally, charged armor would be an integrated solution as a part of a hybrid-electric vehicle. Power would be available from the vehicle to charge the armor for protection and installing the equipment would not require an expensive rebuild from the ground up. – Doug Mohney

[Flyer]

Every PG-7 I've taken apart. . .

Where else but FR do I read stuff like that. . . and believe it!

[ApesForEvolution]

...good answer...

[patton]

Errr, I may have goofed.

[mikegi]

Is there any way we could exploit the wiring as an antenna? What I'd like is for our eggheads to electromagnetically characterize the RPGs. Figure out some way to remotely detonate the damn things by arcing between contacts, etc. Something ... anything.

[Squantos]

Understand......Raketniy Protivotankoviy Granatomet-7 was my bread and butter fer a while. Ya scared me as I really respect yer knowledge of all things behind the fence !

[patton]

hey, cut me some slack - I last fired a few cases in mummmble mummmmble

[JimC214]

actually from what I've read they use a fence so when the RPG goes thru it the fence breaks off the tail fins and it goes off course

[patton]

errr, no.

[Squantos]

It's the simplicity of the system, not electronics. Certain crystalline materials (like quartz, Rochelle salt and some ceramics) have piezoelectric behavior. When you apply pressure to them, you get a charge separation within the crystal and a voltage across the crystal that is sometimes extremely high. It turns out one of your household appliances uses similar technology: In a grill starter, the popping noise you hear is a little spring-loaded hammer hitting a crystal and generating thousands of volts across the faces of the crystal. A voltage this high is identical to the voltage that drives a spark plug in a gasoline engine. The crystal's voltage generates a spark large enough to light the gas in the grill. This same kind of technology can be used to detonate grenades and warheads.

Its a PIBD system (Point Impact Base Detonating)...... The screens will break up and not allow the shape charge jet to properly form and thus reduce it's ability to punch a level of armor "as well"......

Just my two cents.....Stay safe !

[Squantos]

LOL.....My grey matter is getting blacker too ....that's why I pinged ya'll to check my work !!

[archy]

The RPG series has a small metal cup over the piezoelectric crush switch that send a signal to a "detonator" at the base of the shape charge via a flat wire. That cup is left on the PG if the user will fire it through heavy rain or tall grass........it is that sensitive in most cases. Based on my experience with the PG-2 and 7 series I'm skeptical as to the airbag thingie. As we see on the strykers currently the mesh grid that trashes the warhead before it can reach the armor works just like we used chainlink fence in static / fixed fighting positions to disrupt or break up so it wouldn't function as designed per se.....the stryker "fence" is a valid standoff form of protection from the side, front or rear shot.I'm gonna have to see this airbag work before I believe it. I'm thinking it will deonate the RPG at a greater standoff so the shape charge doesn't get optimum jet formation to punch the lighter armor of the "utility" vehicle forced fed into an APC wannabe.

Just my opinion ......

The PG-7 also uses the external body of the warhead as one side of the firing circuit, and the metal liner cone of the shaped charge as the other. Dent a PG-7 warhead enough that the outside body comes in contact with the liner, and the firing circuit will short-circuit, resulting in a dud round.

That was the rationale behond the chainlink RPG screens successfully used in Vietnam: when night defensive perimeters were set up the screens were unfolded and set up a couple of meters in front of the vehicle's position; come daybreak they'd be rolled up and carried on the sides or top of the vehicle, adding at least some RPK standoff or the chance of keeping an RPG fired from an angle from detonating.

But RPGs properly used are not fired singly, but by multiple gunners firing simultaneously, which is one reason the Russians in Chechnya have been moving away from external reactive armor [also hard on accompanying Infantry support when it performs its function] and instead using bundles of metal or plastic tubing slung alongside some of their vehicles. And handily in a desert enviornment, some of those metal tubes can be filled with water, both providing additional water on board and providing some fire suppression in the event a round does detonate/penetrate. And Ivan has a long history of having had his own [and Chinese] RPGs being fired at his tracked and wheeled light vehicles in Afghanistan.

[going hot]

IIRC, Da vinci was asked to design a fortification to protect the sides of the castle from the marauders. He recommended hanging mattresses over the walls to soften the blow of the cannon balls. It worked.

[Squantos]

Anti-tank teams operated w/ 4 PG-7 gunners, 2 RPD's and 2 FPK's or SVD's as I saw em around early 80's. The volley fire attack as you state was impressive and very effective.

That's why I ping ya.......Stay safe !

[archy]

Every PG-7 I've taken apart has a Piezio point switch with the flat wire running to the base det of the shape charge. It don't detonate at the point. Please splain again what yer talking about....?

Components #17 and 18 in the drawing, leading back to 19 [the cone liner] and 35 [the blasting cap body]:

[Squantos]

Bad pic ...give up one attaboy and replace with an Awwww shit !

[Lurker]

Try that again will ya?

TIA.

L

[R. Scott]

…25 a month seems like someone doesn't believe it will work.......

What happens if the attack is with multiple RPGs, or is accompanied by AK fire? I haven’t heard of many attacks consisting of a single RPG round being fired at a vehicle. Doctrine calls for multiple launches because of their lack of pinpoint accuracy.
As a side note, I know the official designation is “Rocket Propelled Grenade”, but the charge is far larger than a grenade. It seems a bit misleading to me.

[archy]

Try that again will ya?

Boje moy! Try here....

http://www.geocities.com/peru_defensa_nacional/images/rpg7_images/rpg7diag.gif

[archy]

Bad pic ...give up one attaboy and replace with an Awwww shit !

Try later:

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[Ernest_at_the_Beach]

Yahoo!

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