The Yakovlev Yak-1 was a single-seat monoplane with a composite structure and wooden wings. It was extremely maneuverable, fast and well armed plus it was reliable and easy to maintain. The Yak-1 was truly the epitome of a World War II Soviet fighter aircraft. The Yak-1b featured a new bubble canopy with lowered rear fuselage, increased armor, ShKAS machine guns replaced with a single 12.7 mm (0.5 in) Berezin UBS, electrical and pneumatic firing of the weapons instead of the mechanical system, new control stick based on the Messerschmitt Bf 109 design, new gunsight, airtight fuselage, retractable tailwheel, improved engine cooling, and a Klimov M-105PF engine with better low-altitude performance. The "b" was an unofficial designation. After October 1942, all Yak-1s were built to this standard. The first flight (aircraft No.3560) took place in June 1942, with aircraft entering production in August. A total of 4,188 were built.