The aircraft, designated the Doak Model 16 by the Doak company and assigned the serial number 56-9642, was originally powered by an Lycoming YT53 turboprop engine mounted in the fuselage, later replaced by a Lycoming T53-L-1 turbine. The engine drove two wingtip-mounted fiberglass tilting ducted fan propellers through a "T" box on the engine that transmitted power to the propellers via a 4-inch (102-mm) aluminum tubular shaft and two smaller shafts. Each propeller was 48-inch (1.22-meter) in diameter and the duct outer diameter was 60-inches (1.52-meter)). The fans were positioned vertically for takeoff and landing – with a rotation speed of 4,800 rpm required for liftoff – and rotated to a horizontal orientation for horizontal flight, the first time this VTOL propulsion concept was tested successfully. The aircraft had metal wings and a metal tail. To save weight, the aircraft originally was constructed of uncovered welded steel tubing, but after it was found that the open frame interfered with forward-speed tests, molded fiberglass was installed over its nose section and thin aluminum sheeting over its aft fuselage. It accommodated a two-person crew, with a pilot and observer seated in tandem in the cockpit. The pilot used a standard stick and rudder to control the aircraft. Its landing gear were taken from a Cessna 182 Skylane, its seats from a North American P-51 Mustang, and its duct actuators from a Lockheed T-33 Shooting Star.