Lublin R-XIII

At Podlasie Aircraft Factory in Biała Podlaska, Engr. Aleksander Grzędzielski and technician Augustyn Bobek (who later changed his second name to Zdaniewski) designed a wooden biplane PWS-7 that soon received a new designation, PWS-5. The first prototype of PWS-5 flew for the first time on December 28, 1928, whereas the second one, a little improved PWS-5a, was flown in February 1929. In spring 1929, the planes were sent to the Institute of Aviation Technical Research (Polish: Instytut Badań Technicznych Lotnictwa, IBTL) in Warsaw for testing. Simultaneously, they started pilot production of five PWS-5t2 planes modified according to conclusions about their prototypes testing. In autumn 1929, the factory delivered five PWS-5t2 planes to the Air Force. PWS-5 aircraft had military numbers type 51 as well as serial numbers from 51-1 to 51-7. At IBTL, the PWS-5 aircraft received negative evaluation as its takeoff distance was long, it had a low rate of climb and its landing was long so it could not be used on unprepared airfields.
Using the experience of testing his trainer biplane PWS-12, the designer of PWS-5 quickly created the improved project, PWS-6, at the beginning of 1930. The prototype equipped with slats was built in 1930 but it could not compete with other aircraft because of the worse handling qualities.
State Aviation Works in Warsaw had privileges. In the second half of 1928, Jerzy Dąbrowski who had already gained the experience of designing the R-X in Lublin joined the factory’s construction office. Being consulted by Władysław Zalewski, he and Franciszek Kott were commissioned by PZL to design the PZL.2 liaison aircraft (later designated PZL Ł.2) intended for entering the contest in 1927. As a state manufacturer, the factory had big chances of receiving orders on a priority basis. The PZL Ł.2 had the all-metal construction: its fuselage was welded from steel pipes, its wings and empennage had a duralumin skeleton and were covered with canvas. A PZL Ł.2 prototype with the military number 55-1 (that later received a registration SP-ADN) rose into the air at the end of 1929, after both competitive aircrafts had been tested at IBTL. That enabled fixing some drawbacks of the PZL Ł.2 found in the aircraft mentioned by making changes in the course of construction. The aircraft passed tests at IBTL at the beginning of 1930. The comparison of the aircraft revealed that the PZL Ł.2 had considerably better performance indicators. The PZL Ł.2 took first place in the contest, the R-X came in second and the PWS-5 was disqualified. The factory received an order for 35 PZL Ł.2. In 1930, they completed 10 aircraft, among which the example no 55-10 was made as a civil sport variant and received a registration SP-AFA. Flying Captain Stanisław Skarżyński and eng. Andrzej Markiewicz flew it around Africa (February 1-May 31, 1931), a total distance of 25,000 km. In 1931, another 25 PZL Ł.2a were completed. Yet the exploitation showed that the aircraft could move well at low speed but it also entered a spin, which led to two accidents. As the factory was commissioned the PZL P.7 fighter aircraft, the manufacturing of the PZL Ł.2 stopped soon and they were written off fairly quickly.

Lublin zdj7

On account of good results demonstrated in 1929 by a sport aircraft RWD-2 designed by Stanisław Rogalski, Stanisław Wigura and Jerzy Drzewiecki, the Polish Air Force requested its liaison variant with folding wings, which received the designation RWD-3. Its prototype performed the first flight in April 1930. However, this construction turned out to be heavier than expected. Using the engine of the power of 59 kW (80 hp), its payload was too small. The aircraft was not qualified for comparison tests.
Lublin R-X
In December 1927, at the Lublin factory, Jerzy Rudlicki started designing the Lublin R-X two-seater liaison aircraft that would eventually be able to function as a mail plane. In 1928, an airframe example for static tests as well as a prototype were made. Only upon their introduction, the Aviation Department of the Ministry of Military Affairs commissioned the plane. The static tests took place in December 1928 and January 1929. The prototype number 52-1 was flown (with a wheeled chassis and skis) on February 1, 1929 at the Lublin aerodrome. The aircraft had military markings.
On both sides of the fuselage, the prototype had exhaust pipes with silencers reducing the engine noise very effectively. In spring 1929, the aircraft passed the tests which proved its ability to manoeuvre. Its performance and weight were distinctly worse than designated: the empty weight constituted 900 kg instead of 650 kg expected, its maximum speed was 160 km/h instead of 180 km/h and its service ceiling was 3400 m instead of 6000 m.
In spring and summer 1929, the Plage & Laśkiewicz factory completed a pilot series of five R-Xa ordered by the Air Force; those received numbers from 52-2 to 52-6.
Those aircraft had a rotary machine gun in the rear cockpit. Initially equipped with wooden propellers and, later, with a Townend ring protecting its engine and a metal propeller, the R-X was being tested at IBTL from summer 1929 until November 14, 1929.
In June 1929, one R-X was introduced at the Universal National Exhibition in Poznań. In spring 1929, the last R-Xa with the serial number 52-7 was built, that was a sport variant which received a registration SP-ABW; it was equipped with a fuel tank for 15 hours of flying. Its distinctive feature were individual exhaust pipes for each cylinder. On September 25, 1929, an engineer and pilot W. Makovski along with a flight engineer B. Wieman flew that plane non-stop from Poznań to Barcelona (1800 km) via Czechoslovakia, Switzerland and France carrying greetings from the Universal National Exhibition to the Iberian-American Exhibition in Barcelona. The return trip with landings in Paris and Poznań ended on September 3, 1929, in Warsaw.

Lublin zdj8

In September 1929, lieutenant S. Massalski piloting an R-X military variant took tenth in Kraków in the Tour of Southwestern Poland (Polish: Lot Południowo-Zachodniej Polski). Upon completion of the flight tests in the Air Regiments nos 2, 4 and 6, R-Xa were used in units, among other things, in the 2nd Air Regiment in Kraków and at the Aviation Training Centre in Dęblin in 1930-1932.
At the end of 1929, after completing comparison testing between the R-X, PZL Ł.2 and PWS-5 and concluding that the R-X had demonstrated the best short takeoff and landing, very good stability and controllability at low speeds and satisfactory performance, the Polish Air Force chose the latter.
However, the R-Xa did not go into series production as the designer created a refined model designated R-XIV; production of a better-performing development of it, the R-XIII, was approved.
In 1931, they rebuilt rear cockpits, removed rotary machine guns and installed comfortable seats on three R-Xa. Those functioned as staff planes, or liaison aircraft for commanders.
In the same year, flying captain S. Karpiński, who was planning a trip to Australia, chose the R-X for training races. On July 3, 1931, he flew 1,650 km around Poland; the plane had a registration SP-ABW. On September 23 – October 7, 1931, S. Karpiński and Engr. J. Suchodolski made a journey around Europe on the route Warsaw – Bucharest – Constantinople – Rome – Turin – London – Warsaw, a total length of 6,450 km.
In 1932, the aircraft was modified at the factory by adding a Townend ring, a metal propeller and spatted wheels. It received fuel tanks for 18 hours of flying. That model was designated R-Xa bis. On October 2-24, 1932, the crew comprising S. Karpiński and W. Rogalski took a trip on it to Africa and Asia on the route Warsaw – Sliven – Istanbul – Aleppo – Baghdad – Tehran – Herat – Kabul – Tehran – Baghdad – Cairo – Jerusalem – Aleppo – Istanbul – Lublin – Warsaw, a total length of 14,390 km and duration of 108 h 50 min.
Then the plane was sent to the 34th Combat Escadrille in Poznań as the business aircraft of S. Karpiński. It crashed on October 26, 1934 and was written off. Seven R-Xs were built.

Lublin zdj9

The wingspan of the R-X was 13,5 m. Its length was 8,33 m, its height was 2,98 m and its bearing surface was 25,96 m2. Its empty weight constituted 900 kg, the operating weight was 466 kg and gross weight was 1,366 kg. The plane’s maximum speed was 161 km/h, the cruising speed was 140 km/h and minimum speed was 65 km/h. Its rate of climb was 2,4 m/s, its service ceiling was 3,400 m, its range was 670 km. It required the 40m takeoff distance and the 80m ground run. A sport variant had the operating weight of 700 kg and gross weight of 1,750 kg; its maximum speed was 176 km/h and its range was 2,500 km.


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Mo71 Lublin-ang

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