The Lublin R-X was a observation and liaison aircraft that reached the pre-production stage, and which was the basis of the later R-XIII, which was produced in large numbers.
In 1927 the Department of Aviation issued a requirement for a observation and liaison aircraft to be powered by a licence built 220hp Wright J.5 radial engine. Three designs were produced in response to this request – the P.Z.L. L.2, the P.W.S.5 and the Lublin R-X.
The R-X was a high wing parasol monoplane, with elliptical wings carried on struts above the fuselage. The wings could fold back, and it could use either wheels or skis on the main undercarriage. It had a neatly streamlined fuselage, which faired into the radial engine, while a large propeller spinner completed the streamlined appearance. The fuselage was built around a framework of steel tubes, covered with duralumin at the front and fabric at the rear. The wings had a wooden frame, a plywood leading edge and fabric covering.
Lublin received an order for two prototypes and a static test aircraft. Work began early in 1928, and the first prototype and the static test airframe were ready by December. The first prototype made its maiden flight, with the ski undercarriage, on 8 February 1929. The second prototype followed in the spring of 1929. The prototypes performed well, and an order for pre-production aircraft was placed.
The pre-production aircraft began to be delivered in the summer of 1929. All but the last one were similar to the prototype, apart from being able to carry a machine gun in the rear cockpit. They went to the existing air regiments, where they were used as liaison aircraft and VIP transports.
The last pre-production aircraft, R-Xa, was modified for long range flights. It was unarmed and had extra fuel tanks, bringing its total capacity up to 219 gallons and its endurance up to 18 hours. On 25 August 1929 the R-Xa flew directly from Poznan to Barcelona, arriving after a flight of 12hr 15minutes. It was displayed at an International Exhibition in Barcelona, before flying back to Poland on 3 September to appear at a similar Poznan International Exhibition. In September 1931 the same aircraft was used for a five day tour of Europe, visiting Warsaw, Bucharest, Istanbul, Rome, Turin and London then returning to Warsaw, a trip of 4,008 miles in six stages. It was then modified for a flight to Afghanistan, which took place in October 1932, with the aircraft flying 8,942 miles in sixteen steps at an average speed on 82.2mph.
The R-X didn’t enter production, but it became the basis of the Lublin R-XIII observation aircraft, which was still in service in 1939, and the Lublin R-XIV trainer.
Engine: Polish Skoda Works (Wright) Whirlwind J.5 nine cylinder air cooled radial engine
Span: 44ft 3.5in
Length: 27ft 4.25in
Height: 9ft 9.5in
Empty Weight: 1,768lb
Loaded Weight: 2,866lb
Maximum Speed: 111.8mph at sea level
Cruising Speed: 19,685ft
Range: 466 miles
Guns: Flexibly mounted 7.7mm Lewis Gun