VEF I-15
The VEF I-15 was a Latvian advanced trainer aircraft of the 1930s. Two examples of the I-15, a small, single-engined monoplane were built by the VEF to the designs of Kārlis Irbītis and were used by the Latvian Air Force Development and design. In 1938, the Latvian aircraft designer Kārlis Irbītis, working at the Valsts Elektrotehniskā Fabrika (VEF) at Riga commenced design of a single-seat advanced trainer as a follow on to his earlier, similar VEF I-14 aircraft. The I-15 was a low-winged monoplane of all-wooden construction, powered by a single de Havilland Gipsy  Six air-cooled engine, and fitted with a fixed tailwheel undercarriage. In April 1939, the first prototype, the I-15a, powered by a 200 hp (149 kW) Gypsy Six I driving a two-bladed fixed-pitch wooden propeller, made its maiden flight, while a second prototype, the I-15b, was powered by a 220 hp (167 kW) Gypsy Six II engine driving a variable-pitch propeller, and armed with a single synchronised machine gun followed, this demonstrating improved performance. The two I-15 prototypes were transferred to the Latvian Air Force for use as advanced trainers, while a further two aircraft, to be  designated I-15bis and powered by Hispano-Suiza 6 Mb engines were ordered by the Air Force, but on 17 June 1940, the Soviet Union occupied Latvia, ordering all aviation related work to be stopped.