Hanriot HD.19
The Hanriot HD.19 was a military trainer aircraft produced in France in the 1920s. Design and development. Part of the family of designs that began with the HD.14, the HD.19 was a two-bay biplane with unstaggered wings of equal span. The pilot and instructor sat in tandem, open cockpits. While the HD.14 and most of its derivatives were powered by rotary or radial engines, the HD.19 had a Hispano-Suiza Vee-8. The aircraft was Hanriot's submission in a 1923 competition by the "Aéronautique Militaire" to select a new intermediate training aircraft, was found suitable by the  military authorities, and was ordered into production. Some 50 examples saw service as the HD.19 ET.2 ("École de Transition"). Poland bought six aircraft HD.19bis in 1925 and a licence to produce the type for the Polish Air Force. Production was located in the WWS Samolot factory in Poznań, which built 80 examples between 1925 and 1928, designated Hanriot H-19. The final 30 were an improved variant H-19a, with the water radiator placed underneath the engine, as opposed of the original position above the engine. A total of 86 aircraft were used by the Polish Air Force until their withdrawal in  1935. Single examples were also built by Hanriot for export to Japan and Czechoslovakia. The aircraft was disliked by Polish pilots, as too difficult to fly for a trainer, among other difficulties demanding a precision landing. In addition, the water radiator was originally placed above the engine, which obstructed the view from the cockpit.