The air cushioned vehicle (ACV) was developed by Bell Aerosystems in the late 1950s. The ability to move quickly over land and water using a cushion of air left other vehicles and watercraft behind, and caught the attention of the Army and Navy.
Bell first developed the US Navy's Patrol Air Cushion Vehicle (PACV “Swift Boat”) based on a modified British design SR-N5. The Navy's PACV first arrived in Vietnam as a unit in 1966.
The Army worked with Bell to develop it's own version of the ACV in February 1968. It was wider, longer and carried more weapons than the Navy PACV. It also had stronger side decks and the front door of the cabin was widened to accommodate soldiers with gear.
It had a turbine-powered, turbo shaft GE engine, a Hamilton 3-bladed, variable pitch, fully reversible propeller, and a centrifugal, 7 foot diameter, 12-bladed blower fan.