The Lublin R-XIII was the main observation aircraft in Polish service at the start of the Second World War, but only because its replacements had failed to enter service when planned.
The R-XIII was developed from the Lublin R-X, a high wing parasol monoplane aircraft with elliptical wings that could fold back against the fuselage. Development on it began in 1927 and the first prototype made its maiden flight on 8 February 1929. A number of pre-production aircraft were also produced, and the Lublin team began to work on further developments of the aircraft
Work on these new designs began late in 1928. Two versions were developed – the R-XIV trainer and the R-XV armed reconnaissance and liaison aircraft. The two aircraft were both parasol winged monoplanes with elliptical wings, although the R-XV would have been slightly smaller in all dimensions, but was expected to be slower, probably due to the weight of the 7.7mm machine gun in the observer’s cockpit.
Lublin submitted a tender to produce 15 R-XIVs and 15 R-XVs, but the Polish Department of Aeronautics decided against producing two similar but not quite identical designs, and preferred to take the R-XIV as the trainer, and an armed version of the R-XIV for the laison role. An order was placed for fifteen aircraft, 14 to be completed as R-XIVs and one as the development aircraft for the armed observation aircraft.
In December 1929 the modified design was selected as the standard equipment of the Polish air force’s observation units. The trainer was also ordered into production, and the first R-XIVs began to enter service during 1930.
The last of the fifteen R-XIVs was completed on 1 July 1931 as the prototype for the new laiason aircraft. It was armed with a 7.7mm Lewis gun on a detachable mounting in the observers cockpit, and carried observation and liaison equipment. It began its service evaluation trials later in the month, where it performed well. However on one test part of the control stick actually broke off, and the test pilot, Col Jerzy Kossowski, bailed out. Remarkable the aircraft then managed to make an un-manned landing in a field, before suffering damage when it crashed into a ditch!
By this point the Department of Aviation had already requested a number of changes, including the use of a Scarff ring to carry the gun. The modified aircraft had a slightly longer fuselage but a smaller tail. The modified aircraft was given the designation Lublin R-XIII, and a single prototype was ordered, making its first flight in the summer of 1931. This aircraft became the R-XIIIA.
On 21 July 1931 an order was placed for fifty slightly modified aircraft, which became the R-XIIIB. Work on these aircraft began on 17 September 1931, and the first was accepted by the Polish air force on 7 June 1931. Production of the fifty aircraft took almost two years, and the final one wasn’t delivered until 15 May 1933 (as a civilian aircraft without the Scarff ring).
The aircraft began to enter service in the second half of 1932 when three aircraft flights were attacked to the Polish air force wings (known as Dyons, and containing two or three squadrons).
The R-XIIIC was an improved version of the R-XIIIB, powered by a 220hp Wright/ Skoda engine, and with a better message pick-up hook under the fuselage and a better electrical system. 48 were ordered on 19 September 1932 as part of a contract for 120 more R-XIIIs, and they were all delivered by December 1933.
The R-XIIID was a cleaned up version of the aircraft. The engine was enclosed in a narrow-chord ring, with a low drag head plate with cooling louvers, a fairing over the oil cooler, a modified fuselage cover, a modified exhaust system and faired undercarriage legs. 70 were ordered on 19 September 1932 as part of a contract for 120 more aircraft. The first R-XIIID was delivered for its evaluation trials on 28 February 1933,
In February 1934 another 50 aircraft were ordered, including 25 R-XIIIDs and 25 R-XIIIFs. This brought the total of R-XIIIDs up to 95, the last of which was delivered on 2 March 1935.
The R-XIIIE was a prototype for a version of the aircraft to be powered by a 360hp Gnome-Rhone 7K Titan Major radial, ordered in the September 1932 batch. Work began July 1933 and the aircraft was completed on 24 January 1934. However by this point the R-XIIIF was already seen as the more promising design, so late in 1934 the R-XIIIE was delivered to P.W.S. to be used on experiments with a moveable virtual tail surface that could be lowered to give a better field of fire for the flexibly mounted gun.
The R-XIIIF was a prototype for a version of the aircraft to be powered by a Polish designed 340hp Polish Skoda Works G.1620 Mors radial engine, ordered in the September 1932 batch. Both of these experimental versions used the standard R-XIIID fuselage, but with some strengthened parts to cope with the heavier, more powerful engines. Work began in July 1933, and the aircraft was completed on 3 November 1933.
In February 1934 another 50 aircraft were ordered, including 25 R-XIIIDs and 25 R-XIIIFs. The production version of the R-XIIIF was to include some features from the R-XXI, a failed attempt to produce a replacement for the R-XIII.
Work on the first R-XIIIF began on 5 September 1934 and it was accepted on 22 July 1935. Seven of the 25 aircraft had been delivered by the autumn of 1935 and they were tested in the Polish Army’s manoeuvres in August and September. At this point the Department of Aviation declared the type to be ‘unsuitable’ because of some fairly minor problems. The last 18 machines were already in an advantage stage of construction, and the decision forced the company into bankruptcy. The Lublin factory was immediately taken over by the Polish government, and reformed as L.W.S. The ‘new’ company was then ordered to complete the production of the R-XIIIF and probably built the remaining 18 aircraft already under construction and seven more from spare parts.
At the same time Lublin was hoping to get a contract to produce a floatplane for the Polish Navy. In 1930 they submitted a design for a float plane version of the R-XV, but the Navy also preferred to modify the existing aircraft, and ordered a twin-float version of the R-XIII. One of the existing R-XIIIs was given two flat bottomed wooden floats and delivered to the Polish Navy at Puck in the summer of 1931, as the R-XIIIbis. After successful trials the Navy ordered three R-XIIIbis floatplanes and three sets of land undercarriages that could use wheels or skis. These aircraft were ordered in the autumn of 1932.
In 1932 one of the three R-XIIIbis seaplance were given a Townen ring, which improved its performance.
Early in 1933 the Polish Navy produced a specification for a new twin float version of the aircraft, the R-XIIIter/ hydro. This used the new engine cowlings from the R-XIIID, all metal sea-type Short floats that could be swapped for the river type wooden floats of the R-XIIIbis, and a chassis. An order for ten of these new R-XIIIter/ hydro aircraft was placed on 5 May 1933. Deliveries of these aircraft began early in 1934.
On 23 May 1934 the Navy ordered six R-XIIIG/ hydro seaplanes. These used the normal 220hp Wright/ Skoda engine, and metal Short floats, These aircraft brought the total number of R-XIII floatplanes in Polish Naval service up to 20.
The R-XXI was a design for a much improved version of the aircraft produced by Jerzy Rudlicki to take advantage of the extra power promised by the Gnome-Rhone and Mors engines of the R-XIIIE and R-XIIIF. This design was submitted to the design contest to find a replacement for the R-XIII, but wasn’t accepted.
By 1936 a total of 99 R-XIIICs and R-XIIIDs were in service, split between 33 first line observation/ liaison platoons. The observation force was then reorganised, to produce 12 squadrons each with seven aircraft. Although the R-XIIIF was accepted by the Air Force, it appears that they were all used as operational trainers.
At the outbreak of war in September 1939 the Polish Air Force had 225 R-XIIIs on its inventory, although many of these were with training units. Seven front line combat observation squadrons were equipped with the type, which was used to try and pass messages between isolated Polish units. During the German invasion the R-XIII suffered very heavy losses, with around 70% of them probably caused by friendly fire as the low flying slow aircraft were an easy target for ground troops.
The Navy had sixteen aircraft still on strength in September 1936, ten with the naval co-operation squadron, one with a liaison platoon and five with the training squadron. Their role in the fighting is unclear.
Span: 43ft 6in
Length: 26ft 11in
Height: 9ft 0.75in
Empty Weight: 1,964lb
Normal loaded Weight: 2,844lb
Maximum Speed: 110mph at sea level
Climb rate: 9,842ft in 22min 35sec
Range: 373 miles
Span: 43ft 4in
Length: 29ft 11.75in
Height: 10ft 1.5in
Empty Weight: 2,273lb
Normal loaded Weight: 3,141lb
Maximum Speed: 108.7mph at sea level
Climb rate: 9,842ft in 24 min
Span: 43ft 4in
Length: 27ft 9.25in
Height: 9ft 0.75in
Empty Weight: 1,956l
Normal loaded Weight: 2,932lb
Maximum Speed: 121.1mph at sea level
Climb rate: 9,842ft in 15min 50sec