Doak VZ-4
The Doak VZ- 4DA ( manufacturer's designation: Model 16, DA stood for Doak ) was an experimental VTOL aircraft transformation of the U.S. manufacturer Doak Aircraft Company from the late 1950s. There was only one copy built, the USAF / Army serial number 56-6942 was wearing. The VZ- 4 used as the first airplane ever, the concept of the tiltable propeller for vertical take off and landing.
History
The contract to build a prototype received Doak on April 10, 1956 by U.S. Army Transportation Research and Engineering Command. Soil tests began in February 1958 on the Torrance Airport near Los Angeles and included 32 hours in a test rig, as well as 18 hours of handcuffed Hovers and rolling tests. After the completion of testing in June 1958, the machine was dismantled, subject to a thorough inspection and then transferred in October to Edwards Air Force Base. Here, the aircraft completed another 50 hour flight that included also complete transitions from hover to horizontal flight in up to 1830 m altitude. The U.S. Army took the Doak 16 then and brought them to the station NASA Langley. She stayed there until 1972 before it was permanently exhibited in the Transportation Command Museum of the U.S. Army at Fort Eustis ( Virginia).
Construction
In the two-seat cockpit, the two crew members sat behind each other in tandem. The mid-wing aircraft had a conventional tail and a fixed tricycle landing gear. The fuselage was a welded mesh ear design, which was disguised from the cockpit to the nose cone with fiber glass moldings. The special feature of the design were the two ducted propeller on the wing tips. The rear fuselage area was planked with thin aluminum, while the cantilever support and tail surfaces were an all-metal construction. To keep development costs to a minimum, many parts already proven patterns were used, for example, the chassis came from a Cessna 182, the seats of an F -51 Mustang, and the adjustment of the propeller came over flap motors Lockheed T -33.
The propeller coat consisted of an aluminum alloy with a leading edge of the inlet from GRP. The eight blades of the propeller were not adjustable and ran at a maximum speed of 4800 rpm. In the front part of the inlet guide vanes adjustable to 14 were also made of fiberglass, which were by the possibility of thrust control in hover state responsible for the control about the roll axis.
The pivoting range of the propeller ranged from the horizontal adjustment of up to 2 ° backwards to compensate for the resulting thrust from the turbine exhaust gases. The drive of the propeller was ran through a shaft by the support surface in about 1 /4 of the tread depth. The Lycoming T53 - shaft turbine (initially was a Vorserienausführung YT -53 built ) was housed in the fuselage below the wing root and worked first on a single aluminum shaft with a diameter of 10 cm and then a transfer case on two 3.8 cm thick steel shafts. The smaller waves ran in about a quarter of the tread depth by the wings and transferred their power to the two propellers. There was no additional control devices and also no automatic position control.