Airbags vs Rocket-Propelled Grenades

Airbags have saved countless lives over the years in car crashes. Now they’re set to save lives in another way: by stopping rocket propelled grenades.

The RPG has been the guerrilla’s weapon of choice for decades. It’s cheap, easy to use and readily available. Even the most basic version can blast through a foot of armor, and later models can double that. Over the years, there have been many projects to make vehicles RPG-proof.
The latest offering is the Tactical Rocket Propelled Grenade Airbag System (TRAPS) made by Textron, which has just successfully completed Phase I testing of at the Army’s Energetic Materials Research and Testing Center in Socorro, New Mexico. The system comprises a set of sensors and airbags, as well as other unspecified countermeasures. During this Phase I testing, the company says, TRAPS’ airbags successfully defeated a number of incoming RPG rounds.

The progress of TRAPS has not been as fast as one might expect. It was first unveiled at an Army trade show back in October 2006, after spending $3.5 million in Pentagon cash the previous year. Phase II testing is still to take place, and an operational system will be some way down the line. Janes notes the timing of the latest tests –- Textron is bidding to be part of the Army’s new Joint Light Tactical Vehicle (JLTV) program.

The JLTV will be a Hummer-like vehicle. But unlike the Hummer, will be designed from the start as an armored scout and combat vehicle. The heavy-armor version of the JLTV, known as “B Kit” is required to provide 360-degree protection from RPG rockets, so TRAPS could be an option. There is a lot of competition in this market. RPG defence has spawned quite an industry, ranging from field expedients knocked together by troops to anti-missile systems which resemble miniature versions of the Star Wars project.

At the simple end you can just use chicken wire; pictures from Vietnam sometimes show armoured vehicles liberally decorated with wire. George J. Mordica II, of the Center for Army Lessons Learned explains why in a report on Operations in Iraq and the RPG-7:

A serious problem with the RPG-7 round is its point initiating base detonating fuse. The impact of the round sends an electrical charge through the round that sets it off. As a result, in Vietnam fabricated chain link, chicken wire, or concertina draped over a vehicle and pushed out from the vehicle many times caused the warhead not to explode and tended to short out the fuse.

Even if it does not short out the rocket, a wire barrier may cause the RPG to explode prematurely. This greatly reduces its ability to penetrate armor. In Iraq, troops found that add-on storage boxes and rails around their vehicles also provided good protection. This has led to the familiar cage of slatted armour seen bolted on to many vehicles in active theatres of operations.

Moving up the scale of cost and complexity there are a range of active protective systems which aim to intercept the incoming rocket before it can be a threat. These include the U.S. Army’s Full Spectrum Active Protection Close-In Shield, the Israeli Trophy system, and others. These detect the incoming rocket and stop it by firing at it with a grenade, rocket or similar device (in one case, a net-carrying rocket has been proposed).

These protective systems may be effective, but tend to inflict collateral damage. Dismounted troops or civilian bystanders may become casualties if the defensive system starts spitting out explosive warheads. The possibility of insurgents deliberately setting out to cause this sort of incident is all too obvious.

So “softer ” methods of protection, like Textron’s airbags, and the British textile-based TARIAN armor system may also have a future. However, it’s also a rule in this business that an advance in defence is likely to be countered by an advance in offence. Spike-nosed RPGs to burst airbags, perhaps?