The situation with the quality of the Yak-9 was changed after the war. In September 1946 Novosibirsk factory # 153 military built a series of 30 cars Yak-9 (product P) with the engine VK-107A. “Yakah” this series was needed to eliminate the defects revealed in the course of state tests of two cars in June — September 1946
20 military aircraft series did not differ from previously released. Ten other machines plywood sheathing of the wing and fuselage was replaced by a metal.
The motors are all fighters equipped with device thinning the oil with gasoline, facilitating their start in the winter time.
Armament consisted of two synchronous machine gun UBS and ShVAK cannons.
Start the engine, release and lifting of the chassis, including a tail prop, control flaps and the wheel brakes is carried out using a pneumatic system.
The canopy pilot had armoured glass front and a movable portion with the mechanism of emergency drop. On the pilot’s seat was set back and bananagrowing.
The equipment allowed the plane to operate only during the day in the presence of a visible terrestrial landmarks.
In October 1946 29 Yak-9 was transferred to military trials 246 th fighter air division to form a separate regiment.
The tests took place in February 1947 at the airport Tolmachevo (Novosibirsk), which had two concrete runways.
The maneuverability of the Yak-9 in vertical and horizontal planes is satisfactory. To the height of 6000 — 6500 m all figures (simple and complex maneuvers) in the vertical plane, you could complete the climb. The most advantageous height for air combat were considered range from 1000 to 7000 m. Snap properties were the same as other fighters of A. S. Yakovlev.
Engines during the trials worked satisfactorily. At the same time, were failures in their work and the shaking caused by the low quality of components, in particular of candles.
In conclusion, the act on the military trials it was noted that the Yak-9, built on the model of aircraft, held military trials, may be approved by the air force only after elimination of these defects.
Basic data of Yak-9U with the engine VK-107A
*Flight data is given at 3000 rpm at 3200 rpm maximum speed at an altitude of 5150 m, reached 654 km/h are Common to all modifications of the Yak-9 was: wingspan of 9.74 m, length of 8.55 m and a wing area of 17.15 m2.
After the Yak-9U to the test in NII VVS did the Yak-9UT with the engine VK-107, equipped with a gun of calibre of 37-mm N-37 and two synchronized 20 mm B-20S. The fighter was built based on serial Yak-9 Omsk aircraft plant. The largest machine on the stage of state tests was engineer G. A. Sedov and pilot A. Manucharov.
Testing ended in April, 1945, showed that the fighter, in comparison with the serial, had an almost identical top speed to the second boundary of the altitude motor. His weapons effectively destroy air and ground targets.
When firing weapons the aircraft was more stable than the Yak-9T and Yak-9K with 45mm gun due to lower recoil guns N-37. According to experts of the research Institute of the air force, the Yak-9UT was the need of the air force, and they recommended the car for serial production, but it remained in the category of experienced.
Built on the Yak-9U and Yak spark-9УВ. The exact date of its transfer to the state tests could not be found, but apparently this happened in early August since 12 September 1945 act with their results approved General Repin. The leading machine was the engineer G. A. Sedov and pilot-test L. M. Kuvshinov.
Tests showed that maximum speed double the Yak-9 decreased compared to the Yak-9M with the same engine, due to the reduction of the engine speed and deterioration of aerodynamic characteristics. At the same time, the aircraft flying qualities did not differ from Yak-9U, the load on the arm from the Aileron and Elevator slightly decreased, but still remained large.
Yak-9УВ not stood the trial, and the main reason for this was overheating of the water in almost all flight modes (except the lower) and on the taxiway. Noted and other defects. However, the time that aircraft passed, and he remained in a single copy.
The Yak-9 is possible, although rare, and today found not only on the eternal Parking in the museums and private collections. A few flying replicas of this machine under the designation YAK-9УМ equipped with motors “Merlin” was built on the Orenburg NGO “Boom” and sold to foreign customers.