Ernő Rubik was a co-founder and the chief designer of the Aero-Ever aircraft company of Esztergom, Hungary, which was formed in 1938. He started design of the R-18 in 1944, inspired by the Fieseler Fi 156 Storch, aiming for a smaller, lighter version, which would serve both as a glider tug and a STOLutility aircraft, to carry engineers and spares to service aircraft at other airports. The aircraft has a high wing braced by V-struts, with fixed leading-edge slots and retractable camber-changing flaps. The fuselage is of mixed construction with two side-by-side seats, with an optional third seat behind them. It has a conventional braced tailplane and a taildragger undercarriage with divided axle long-stroke oleo legs for the main gear, and a fixed tailwheel.
Development
Construction started in 1946, and the first flight of the prototype, the R-18a, c/n E-524, was on 18 May 1949. It was powered by a Walter Major 4-I four-cylinder inline engine of driving a two-bladed wooden propeller. The aircraft was well received, and was used, for a time, by the Hungarian Air Force, registered 1-002, but was soon replaced and transferred to a flying club, registered HA-RUA. The second aircraft, the R-18b, c/n E-525, registered HA-RUB, had a widened rear fuselage to make the occupant of the third seat more comfortable. It flew from 1949 to 1954 when it crashed. The third and subsequent aircraft, designated R-18c, c/n E-761, registered HA-RUC, had a Walter Minor 6-IIIsix-cylinder engine of, which extended the fuselage length to. The cabin windows and doors were slightly redesigned, and the third seat was replaced by a fuel tank. Because of problems with the Walter Minor in-line engines, all surviving R-18s were converted to licence-built Shvetsov M-11D five-cylinder radial engines of, or M-11FR engines of leading to a reduced fuselage length of. The conversion work was done by the Central Experimental Plant at Alag, between 1955 and 1958. Construction of a metal version, the R-28 Metal-Kanya, was started but was not completed.
Operational history
The first three aircraft were considered prototypes, and they were followed by six production aircraft, all designated R-18c and built in 1953-54. They were registered HA-RUD to HA-RUI. One aircraft was fitted with skis for winter use. They continued in use until 1966 by which time all aircraft except two had crashed and/or been scrapped or withdrawn from use. The R-18a crashed in 1949 and was subsequently used as an instructional airframe.
