AKL-201601 AviaCollection / AviaKollektsia series 01/2016: Yakovlev Yak-9 Soviet WW2 fighter. Photos, schemes, colour pictures. 32 pages, soft cover, text in Russian.

CREATING A PLANE
The history of the Yak-9 began in June 1942, when the Yak-7B fighter was lightened at Plant No. 153 in Novosibirsk by replacing the wooden wing spars with metal ones and removing one of the two UBS synchronous machine guns. A new car with an M-105PF engine and a VISH-61P propeller, designated Yak-7-DI (later they began to write Yak-7DI), had an increased fuel supply in four wing tanks, connected for uniform fuel production with a supply tank.
For factory tests, three different from each other were prepared at once sample Yak-7DI. The first retained a double-sided suction nozzle and a crutch wheel with dimensions of 300x125 mm from the serial Yak-7. The second had a one-way suction pipe (left), and the third combined the same pipe with a 255x110 mm tailwheel, improved fuselage sealing, modified water and oil cooler nacelles, enlarged exhaust outlets and ribs installed on them.
Of these, the third option was chosen during factory tests. Moreover, from the wing dismantled two gas tanks, reducing the fuel supply to 320 kg. There were other, seemingly insignificant, but important differences in operation and combat.
During the tests conducted by the pilot P.Ya.Fedrovi in October 1942 (the first flight took place on October 1) under the leadership of the leading engineer K.V. Sinelshchikov, it turned out that the fighter with a normal flight weight of 2825 kg (empty weight - 2348 kg) developed a speed of up to 593 km / h, 23 km / h more than that of the Yak-7B.
The Yak-7DI fighter successfully passed the state tests and was recommended for serial
production, subject to the elimination of identified defects. After its fine-tuning, which lasted for almost two months, an actually new aircraft appeared - the Yak-9, launched into series. Outwardly, it differed from the Yak-7B in a single cabin without a gargrot, flaps on the main landing gear were made solid. Like the Yak-7DI, the fighter had an MP-20 (ShVAK) motor-gun and a UBS synchronous machine gun with ammunition of 120 and 200 rounds, respectively, but there were no wing bomb racks. The aircraft was equipped with an RSI-4 radio station and a KPA-Zbis oxygen device.