The Vanguard Omniplane was an American approach to vertical operation and high cruise speed. The ducts contained vertical thrust propellers that could be closed by venetian blind shutters to form small wings in forward flight. In forward flight, covers above the rotors and louvers below sealed the wing for aerodynamic lift.
The design, apparently not registered, used a 25-ft long Ercoupe light plane fuselage and weighed 2,600 lb. The round wings each housed a 6 ft diameter three-bladed propeller that was mechanically driven for vertical flight by a 265 hp Lycoming O-540-A1A six cylinder piston engine.
Thrust was produced by a 5′ shrouded prop in the tail, elevator and rudder behind the rear fan-controlled pitch and yaw, while differential propeller blade pitch affected roll in hover.
Ground tests, starting in Aug 1959 and including tethered hover trials, were followed by NASA full-scale wind tunnel testing.
Modifications in 1961, including a 860hp Lycoming YT53-L-1 turboshaft, improved control system, and 5′ nose extension to house a third lifting prop, led to the redesignation 2D. The nose prop improved control in pitch, as well as in yaw through the use of movable exit vanes. 2D completed tethered hover tests, but was damaged by a mechanical failure and discontinued in early 1962.
Engine: Lycoming O-540-A1A, 265hp
Wingspan: 22’0″
Length: 25’6″
Useful load: 500 lb
Max speed: 190 mph
Range: 150 mi
Seats: 2
