Bang but no boom

DAMAGE to aircraft fuel tanks doomed roughly half of the 5,000 or so American warplanes and helicopters destroyed during the Vietnam war. Some crashed or blew up after only a few bullet hits drained or ignited their fuel, says Robert Ball, the author of a textbook on the combat survivability of aircraft. But such “cheap kills” are becoming increasingly rare, says Dr Ball, a former engineering professor at the Naval Postgraduate School in Monterey, California. Thanks to clever engineering, fuel tanks in aircraft, vehicles and even storage facilities can now withstand direct hits from enemy fire or tremendous impacts without exploding.