Initial production version. Yak-1b – ("b" was an unofficial designation; after October 1942, all Yak-1s were built to this standard). New bubble canopy with lowered rear fuselage, increased armor, ShKAS machine guns replaced with a single 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, Klimov M-105PF engine with better low-altitude performance. The first flight (aircraft No.3560) took place in June 1942, with aircraft entering production in August. A total of 4,188 were built. Yak-1M – Yak-3 prototype with a smaller wing, revised cooling intakes, reduced overall weight and upgraded engine. Two were built. Yak-7UTI – Initial production version of the UTI-26. Yak-7 – Conversions of Yak-7UTI and new production of fighter version of Yak-7UTI. Several other Yak-1 variants did not receive special designations. These include prototypes with Klimov VK-106 and Klimov VK-107 engines, production aircraft capable of carrying external fuel tanks, production aircraft with the ability to carry 6 × RS-82 rockets or 2 × bombs, and lightened versions for air defense. Operators Free French Air Force Normandie-Niemen Fighter Squadron Air Force of the Polish Army 1st Polish Fighter Regiment "Warsaw" Soviet Air Force SFR Yugoslav Air Force – 103 aircraft in 1944–1950 111th Fighter Aviation Regiment (1944–1948) 113th Fighter Aviation Regiment (1944–1948) 112th Fighter Aviation Regiment (1944–1945) 2nd Training Aviation Regiment (1946–1948) 101st Fighter-Training Aviation Regiment (1948–1950) 104th Training Aviation Regiment (1948–1950) Specifications (Yak-1b) See also References Notes Bibliography Angelucci, Enzo and Paolo Matricardi. World Aircraft: World War II, Volume II (Sampson Low Guides). Maidenhead, UK: Sampson Low, 1978. . Bergström, Christer. Bagration to Berlin: The Final Air Battles in the East, 1944–1945. Hersham, UK: Classic Publications, 2008. . Bock, Robert, and Wojtek Matusiak. Yak-1, Yak-3. Gdansk: AJ-Press, 1998. Donald, David and Jon Lake, eds. Encyclopedia of World Military Aircraft. London: AIRtime Publishing, 1996. . Reprinted from World Air Power Journal. Drabkin, Artem. The Red Air Force at War: Barbarossa and The Retreat to Moscow, Recollections of Fighter Pilots on the Eastern Front. Barnsley, South Yorkshire, UK: Pen & Sword Military, 2007. . Ethell, Jeffrey L. Aircraft of World War II: Glasgow, Harper Collins Publisher, 1995. . Gordon, Yefim and Dmitri Khazanov. Soviet Combat Aircraft of the Second World War, Volume One: Single-Engined Fighters. Earl Shilton, Leicester, UK: Midland Publishing Ltd., 1998. . Gordon,