With two 20mm cannons, a 40mm automatic grenade launcher, five .50-cal. machine guns, and two weapon pods that could carry either 70mm rocket launchers or 7.62mm miniguns, the armored ACH-47A Chinook could fly into the teeth of enemy resistance and fly back out as the only survivor.
Operating under the call sign "Guns-A-Go-Go," these behemoths were part of an experimental program during the Vietnam war to create heavy aerial gunships to support ground troops.
This monster aircraft was the helicopter version of the AC-130 gunship www.youtube.com
Four CH-47s were turned into ACH-47As by adding 2,681 pounds of armor and improved engines to each bird.
The first three birds arrived in Vietnam in 1966, where they engaged in six months of operational testing. They were tasked with supporting the U.S. Army's 1st Cavalry Division as well as a Royal Australian task force.