When you blow out a candle, you stop the fire by separating the flame from its fuel source.
A boffin in Australia likes that idea so much he's tested explosives as a means of creating a huge puff of air to keep bushfires away from the foliage on which they feast.
The video below shows the experiment in action.
At right is a metal tube wherein resides “det cord”, essentially a hose filled with Pentaerythritol tetranitrate, the stuff used to make Semtex and other explosives. At left is a metre-high flame made by a propane burner.
The vid was shot using the “shadowgraph” technique that captures action in transparent media like air. This technique was chosen by Dr Graham Doig from the University of New South Wales' School of Mechanical and Manufacturing Engineering because it allows him to watch the shockwave produced by the explosion.
Let's roll tape …
Doig has declared the test a success, saying it shows that “As soon as the flame doesn't have access to fuel anymore, it stops burning.”
Just how to deploy the explosives is Doig's next conundrum. He wonders if helicopters could lower a fire-extinguishing canon to the top of a forest canopy and not only extinguish fire but knock loose any fuel. Such an approach would work well in Australia, where fires often move through the crowns of oil-rich eucalyptus trees.
There's obviously lots more work to do on this idea, as it has massive “what could possibly go wrong with that?” potential. On the upside, fighting fire with fire often does the trick. ®