The Chinook's primary roles are troop movement, artillery placement and battlefield resupply. With a top speed of 170 knots (196 mph, 315 km/h) the helicopter is still one of the fastest helicopters in the US inventory. The Chinook was designed and initially produced by Boeing Vertol in the early 1960s; it is now produced by Boeing Rotorcraft Systems. There have been many versions including the CH-47F and CH-47G, which are currently in service today.