The Heinkel He 51 was a German single-seat biplane which was produced in a number of different versions. It was initially developed as a fighter, and a seaplane variant and a ground-attack version were also developed. It was a development of the earlier He 49. At least 12 of these fighters were acquired by Bulgaria.
Terrific range of different types, gekho and Jarda; the top shot shows an Fw 56 Stoesser (Goshawk) at the front of the row of He 51s.