The Yakovlev Yak-7 () was developed from the earlier Yak-1 fighter, initially as a trainer but converted into a fighter. As both a fighter and later reverting to its original training role, the Yak-7 proved to be a capable aircraft and was well liked by air crews. The Yak-7 was simpler, tougher and generally better than the Yak-1.
Design and development
In 1939, Alexander Yakovlev designed a tandem-seat advanced trainer, originally designated "I-27" and then "UTI-26", offered along with the original I-26 proposal that became the Yak-1. The "UTI" (Uchebno Trenirovochnyi Istrebitel, translated as: Training Fighter) was intended to give pilots-in-training experience on a high-performance aircraft before transitioning to a fighter. With development work started in 1940, the UTI-26 differed from its predecessor in its larger span wing being placed farther back for balance as well as having two cockpits with dual controls and a rudimentary communication system. It was armed with a single ShKAS machine gun in the cowling, mainly for use in training, but Yakovlev envisioned a multi-purpose aircraft that could also undertake courier and light transport duties at the front.
The first production aircraft known as Yak-7UTIs retained a retractable main landing gear, but beginning in the summer of 1941, a fixed landing gear variant, the Yak-7V (Vyvozoni for Familiarization) was substituted. The factory reasoned that production would be simplified and that reduced performance would not be detrimental for a trainer. Yak-7UTIs and Yak-7Vs were also equipped with skis for winter operations.
A factory team from N° 301, headed by K.A. Sinelshchikov, was detached from the Yakovlev OKB to supervise production of Yak-7UTI. One of these aircraft (serial number 04-11) was fitted with an armored backrest plate over the rear position, self-sealing fuel tanks which filled with inert gas as they emptied, three "RO" rocket launchers under each wing for as many RS-82 rockets, an axial motornaya pushka-mount ShVAK cannon firing through the propeller spinner, with 120 rounds, and two 7.62 mm ShKAS machine guns under the cowling, each with 750 rounds. The rear cockpit position was retained, allowing it to accommodate a second seat (without controls) for fast courier and transport duties or a fuel tank for extended range. The additional space could also house bombs or other gear. The engine was an M-105P and the model was designated Yak-7/M-105P.
Sinelshchikov did not inform Yakovlev about the conversion and when he learned about it, Yakovlev remained sceptical of the need for the changes. After brief factory trials, the aircraft turned out to be better than the single-seat Yak-1, thanks to the modifications already applied to the UTI as well as a revised undercarriage with bigger tires and wheels, more efficient brakes and revised elevators, among other changes. Yakovlev submitted the Yak-7 to the authorities who approved it immediately. The firing tests at the scientific trials Polygon for aircraft armament (NIPAV) were a success and the armament was found to have no effect on the flight characteristics or the general performances of the new fighter. The aircraft's stability as a firing platform was judged far better than that of the Yak-1, the Lavochkin-Gorbunov-Gudkov LaGG-3 and Mikoyan-Gurevich MiG-3.
The GKO and the NKAP issued decrees in August 1941 for the Yak-7 to be produced by Factories N° 301 and N° 153, but Factory N° 301 had to be evacuated to Novosibirsk where it merged with N° 153. So, just 62 aircraft were produced in 1941: 51 in September–October by Factory N° 301 and 11 by N° 153 in December. Test pilot A.N. Lazarev noted the good flight characteristics, how easy it was to get out of a spin, and how well it behaved when diving: characteristics that he considered safer than those of the Yak-1. But the Yak-7 showed some defects: the M-105P engine piping, the landing gear locking system, the tires and the tail wheel were identified. The Yak-7 was introduced into the production line and the first batch of 60 reached operational squadrons by the end of 1941.