Bombing a forest fire?

I hadn’t heard of aircraft bombing a forest fire to stop it spreading and help put it out, but the tactic was used in Sweden this week, apparently with some success.

… on Jul. 25, a Gripen dropped a 500-lb GBU-12 Laser Guided Bomb from 3.000 meters in an attempt to cut fire affecting Älvdalen’s shooting range, a military range where unexploded ammunition and difficult terrain made conventional extinguishing methods not sufficient. The Swedish pilot dropped the GBU-12 so that the bomb would cut the fire at a certain distance from the impact point: a fire requires oxygen, heat and fuel. The explosion burns oxygen that is no longer available to the fire.

The first test had “a very good effect“, that is, the bomb broke out the fire. Even on other fires that were 50, 100 and 150 meters from the target, the effect was assessed according to the Swedish press.

According to the preliminary report, this unusual firefighting technique has been successful.

There’s more at the link.

Here’s a brief video clip of a Swedish Air Force Saab JAS 39 Gripen fighter dropping a guided bomb on the fire.

I wonder if that might be worth trying in US states where wildfires pose a major hazard to firefighters?  I suppose insurance companies would carry on about the danger to life and property involved in using high explosives, but it can’t be any worse than the danger posed by fire, can it?

Peter

6 comments

  1. IIRC an accepted way to extinguish an oil well fire is to maneuver an explosive charge close to the well head, see the movie Hellfighters.

    Using a bomb to blow out the fire and remove fuel from the area at the same time isn’t that outlandish.

  2. I imagine using a conventional bomb to suppress a wildfire, while an unconventional technique, could be quite effective. I suspect, however, that its process is addressed to another of the legs of the fire triad (fuel, oxygen, heat). If the GBU-12 were a version of a fuel-air explosive, it would indeed consume oxygen from the air in the environment thus reducing the availability of same to the fire. A GBU-12; however, uses a high explosive which contains its own oxidizer, thus it needs no oxygen from its surroundings to work. It will, though, be quite effective at scattering the fuel sources available to sustain combustion.

  3. The problem with conventional weaponry, like this GBU-12 is that it only suppresses the fire within a relatively small blast radius. It had an effect on fires up to 150 meters from the impact point, so at most a 300m swath could be suppressed. The effective radius is much smaller. For fires with natural chokepoints, such as the mouth of a canyon, that might be sufficient. A fire with a broad front can merely burn around.

    The other drawback is cost: a GBU-12 runs about $20K; the unguided iron bomb it was derived from runs $2K.

    PS – The BLU-118/B thermobaric bomb has been mentioned. Unfortunately, it has the side effect of setting fires in some circumstances. It superheats and consumes oxygen at the impact point, but then the superheated gases expand outward, and at sufficient distance, start fires.

  4. Probably the biggest problem in the US would be the environmental paperwork. Might kill Bambi, or damage a watercourse.

    True story, I was working at Hanford when they had a range fire. Parts of the old WWII Hanford site have been designated as a nature preserve. The firefighters couldn’t drive trucks on the designated areas and were forced to use water bombers, or let it burn.

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