Ryan 92 / VZ-3 Vertiplane
Ordered by the Army in 1956, the VZ-3 or Ryan Model 92 Vertiplane makes use of the deflected slipstream principle which was first proposed in the U.S. as early as 1921 by Dr. Albert F. Zahm. The principle consists of using a conventional wing and propellers for cruising flight and having large flaps on the wing trailing edge which, when extended, deflect the propeller slipstream downward to obtain vertical lift.
The VZ-3 is basically a high-wing monoplane with a 1,000 hp Lycoming T53-L-1 turboshaft engine in the fuselage driving two 9 ft diameter slow-running propellers. The wing tips were turned down to prevent spanwise flow and power loss when the flaps were down. For control at low, speeds, engine exhaust was directed to a swivel nozzle at the end of the fuselage, giving pitch and yaw control; roll control came from differential pitch applied to the propellers.
Ryan test pilot Peter Girard made the first taxying trials of the VZ-3 (56-6941) on February 7th, 1958.
Subsequently, it spent three months in the full-scale low-speed wind tunnel at the N.A.S.A. Ames Laboratory at Moffet Field. At this stage it had a tail-down undercarriage, but a nosewheel was added, as well as a large ventral fin, before the first flight was made on January 21st, 1959, at Moffet Field.
On the thirteenth test flight, on February 13th, 1959, the VZ-3 was damaged in a landing mishap caused by a malfunction in the propeller control system. Trials were resumed later in the summer and Ryan completed a test programme in which a speed range of 110 knots to 26 knots was covered, and flights were made up to 5,500 ft. For this second series of trials the cockpit canopy was removed.
In February 1960, after being handed over to NASA, the VZ-3 was almost completely destroyed on a pilot familiarization flight. Operating outside the approved envelope for safe flight, it pitched up and completed most of a loop at 5,000 ft. The pilot ejected safely at 1,000 ft.
After a complete rebuild, the VZ-3 was returned to NASA in 1961 and pilots Fred Drinkwater and Bob Innis began a programme to investigate its low-speed handling characteristics. Several modifications were made at this time, since when the VZ-3 has been contributing valuable data for the development of other VTOL aeroplanes.