Rubik R-18 Kánya

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 STOL utility aircraft, to carry engineers and spares to service aircraft at other airports.[1]

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.[2]

Construction started in 1946, and the first flight of the prototype, the R-18a, c/n E-524, was on 18 May 1949.[3] It was powered by a Walter Major 4-I four-cylinder inline engine of 96.9 kW (129.9 hp) 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-III six-cylinder engine of 116 kW (155 hp), which extended the fuselage length to 7.7 m (25 ft). The cabin windows and doors were slightly redesigned, and the third seat was replaced by a 120 l (32 US gal; 26 imp gal) 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 93.2 kW (125.0 hp),[1] or M-11FR engines of 119 kW (160 hp)[4] leading to a reduced fuselage length of 7.5 m (25 ft).[5] The conversion work was done by the Central Experimental Plant at Alag, between 1955 and 1958.[6]

Construction of a metal version, the R-28 Metal-Kanya, was started but was not completed.

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.

HA-RUG on display restored with an inline engine.

Two aircraft survive:

• HA-RUF, c/n E-778, was withdrawn from use in 1966 but was restored to flying condition in 2012 by the Goldtimer Foundation, and is based at Budaörs Airport, Budapest.[5]
• HA-RUG, c/n E-779, was withdrawn from use in 1966, and was placed on display in the Hungarian Technical and Transportation Museum in Budapest,[7] but the building was demolished in 2016 and the current status of the aircraft is unknown.

Data from Janes All the World's Aircraft 1953-54[2]

General characteristics

• Crew: 2
• Length: 7.7 m (25 ft 3 in)
• Wingspan: 11.6 m (38 ft 1 in)
• Height: 2.08 m (6 ft 10 in)
• Wing area: 14 m² (150 sq ft)
• Empty weight: 410 kg (904 lb)
• Gross weight: 690 kg (1,521 lb)
• Powerplant: 1 × Walter Minor 4-I 4-cylinder inverted air-cooled in-line piston engine, 119 kW (160 hp)

Performance

• Maximum speed: 175 km/h (109 mph, 94 kn)
• Range: 600 km (370 mi, 320 nmi)
• Service ceiling: 6,000 m (20,000 ft)
• Rate of climb: 5 m/s (980 ft/min)