In Afghanistan, the Mujahideen often modified RPGs for use against Soviet helicopters by adding a curved pipe to the rear of the launcher tube, which diverted the backblast, allowing the RPG to be fired upward at aircraft from a prone position. This made the operator less visible prior to firing and decreased the risk of injury from hot exhaust gases. The Mujahideen also utilized the 4.5-second timer on RPG rounds to make the weapon function as part of a flak battery, using multiple launchers to increase hit probabilities. At the time, Soviet helicopters countered the threat from RPGs at landing zones by first clearing them with anti-personnel saturation fire. The Soviets also varied the number of accompanying helicopters (two or three) in an effort to upset Afghan force estimations and preparation. In response, the Mujahideen prepared dug-in firing positions with top cover, and again, Soviet forces altered their tactics by using air-dropped thermobaric fuel-air bombs on such landing zones. As the U.S.-supplied Stinger surface-to-air missiles became available to them, the Afghans abandoned RPG attacks as the smart missiles proved especially efficient in the destruction of unarmed Soviet transport helicopters, such as Mil Mi-17. In Somalia, both of the UH-60 Black Hawk helicopters lost by U.S. forces during the Battle of Mogadishu in 1993 were downed by RPG-7s. See also Bazooka Grenade launcher MANPATS Panzerfaust 3 Rifle grenade Shoulder-fired missile Rocket-assisted projectile References External links Most Valuable Weapon: the RPG, Gary Brecher on the history and use of the RPG Anti-tank rockets Soviet inventions Modern thermobaric weapons of Russia Modern incendiary weapons of Russia Explosive weapons Rocket weapons Cold War weapons of the Soviet Union