Doak 16 VZ-4DA

The Doak Model 16 was the first vertical take off and landing aircraft to demonstrate the tilt duct concept, which Doak Aircraft Company proposed to the military in the early 1950s as a utility and observation vehicle combining the VTOL capabilities of a helicopter with the maneuverability of a higher speed fixed-wing aircraft. In 1956, the Transportation Research and Engineering Command purchased one Doak 16 and designated it VZ-4DA, and the aircraft made its first flight in February 1958. It used ducted propellers on each wing tip that rotated 90 degrees to shift from vertical take-off and hovering to horizontal flight, and it demonstrated conventional and vertical flight as well as short take-offs and landings. Although the aircraft showed some undesirable flight characteristics, only a few were considered fundamental to the tilt-duct system, and those were easily solvable. As the end product of Doak's many years of research and development in the VTOL field, the VZ-4 proved reasonably useful in exploring the military potential of non-helicopter VTOL vehicles. After three years of joint testing by the Army and NASA, the sole VZ-4, Number 56-9642, was withdrawn from Army inventory, then used solely by NASA before being turned over to the Transportation Museum in 1973.

Newport News, Virginia · United States