Yak-9U equiped with Klimov VK-107A engine (1650 hp) was definitive Yak-9 variant. It was armed with the 20 mm ShVAK cannon firing through proppeller spinner and two 12,7 mm USB machine guns. The prototype's top speed of 700 km/h (435 mph) at 5,600 m (18,370 ft) was faster than any other production fighter aircraft in the world at the time, other than the P-51B that could reach up to 441 mph on military power. However, engine VK-107A was problematic, prone to overheating, oil leaks, loss of engine pressure during climbs etc., so the first production batches of Yak-9U starting in April 1944 were powered by the reliable M-105 PF-3 engine. The next drawback of the VK-107A engine was its small engine life - only 25 hours. In practice it was forbidden to use combat regime, since then the engines would have to be changed after two or three sorties.

Only Yak-9U planes produced in the spring and summer of 1945 had flight characteristics that practically coincided with those obtained during the tests – the top speed 672 km/h at an altitude of 5000 m. This was the result of increased production quality and improved aerodynamics. Serial version with the engine VK-107A was produced between April 1944 and August 1945 and in total 3921 Yak-9U planes were produced.

The 151st Guards Fighter Aviation Red Banner Regiment was for the its distinction in the battle during the liberation of the city of Vienna awarded the honorary name “Venskij” e.g. "Viennese" in May 7, 1945.

Yak-9U, 151 giap, Bulgaria, June 1945

The plane is camouflaged according to the NKAP 1943 order with blue grey AMT-11 and dark grey AMT-12 on the upper surfaces with light blue AMT-7 on the bottom surfaces. Propeller spinner is light blue.
This Yak-9U had Guard emblem inscription “Venskij” painted on the nose. Two Red Banner Orders and Order of the Patriotic War were painted on the rear fuselage.
The profile in the full resolution should be published in the book Soviet Fighters of the Second World War by Jason Nicholas Moore.

Pilots from 151 giap in front of Yak-9U, June 1945, Yambol, Bulgaria:

N.F. Kizim poses on the wing of the Yak-9U from 151 giap, June 1945, Yambol, Bulgaria:

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