The aircraft was designed by Ryszard Bartel in Samolot factory in Poznań, as an advanced trainer, transitory between primary trainers and bomber or reconnaissance aircraft. Bartel had worked since 1926 on his BM-3 advanced trainer design, the preliminary design for which won a military contest, but in the meantime he developed a quite successful primary trainerBartel BM-4 and then decided to model the advanced trainer upon that plane, to obtain better durability. The result was the BM 5 design. The BM 5 prototype was built in 1928 and flown on 27 July that year in Poznań. It had good handling, high stability and spin resistance, which made it a suitable trainer for larger aircraft. A distinguishing feature of all Bartels was an upper wing of a shorter span, because lower and upper wing halves were interchangeable. The first prototype was designated BM 5a and was fitted with a Austro-Daimlerinline engine. The second prototype, flown on 15 April 1929, was designated BM 5b and was fitted with a SPA-6A inline engine, then was refitted in August with a Hispano-Suiza 8FbV-engine and redesignated BM 5c. Next 20 aircraft of each type were built: BM 5a, BM 5b and BM 5c. A disadvantage of most BM 5s were old and faulty engines. From all the variants the BM 5a variant was the heaviest and had the worst performance. For that reason in 1935 one BM 5 was fitted at the PZL works with a Wright Whirlwind J-5radial engine, produced in Poland. This variant was designated the BM 5d and 20 of BM 5a and BM-5b were next converted to BM 5d.
Operational history
BM 5s were used in the Polish Air Force for training from 1930, in a central pilots' school in Dęblin. Five BM 5c's were used in Naval Air Unit in Puck, but most were written off in the second half of 1930s and replaced with the PWS-26. Some survived until the German invasion of Poland in September 1939, but none survived the war.
Wooden construction biplane. Fuselage rectangular in cross-section, plywood covered. Rectangular two-spar wings, plywood and canvas covered. Crew of two, sitting in tandem in open cockpits, with individual windshields and twin controls, instructor in rearcockpit. Fixed landing gear, with a rear skid. Engine in front, with a water radiator below fuselage nose. Two-blade woodenpropeller. Fuel tanks in upper wings and fuselage, capacity: 235-270 l.
