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11th of October 2011

William Whiteside (from Windsor Ca. USA) set an (unofficial) speed record for piston-engined aircraft in the under 3000 kg (6615 lbs) category. Over a 3 kilometre (1.863 miles) course, he flew his Yak-3U at a speed of 361.77 knots (416 mph / 670 kph).

Yak-3U in flight


The Yak-3U is the 11th version of the successful Yak-3 fighter.


The Yak-3 was a robust single-engine, single-seat fighter. It was a small and lightweight fighter with a high power to weight ratio. Some pilots even stated that it was superior to the P51D Mustang and Supermarine Spitfire. The origin of the Yak03 goes back to 1941 when its prototype was presented. It was powered by a Klimov M-105P engine and has an all-metal construction. It was armed with a cannon firing through the hollow driveshaft of the spinner and also had machine guns in each wing.


The history of the Yak-3 is not straightforward, mainly because of World War 2 raging through and over Russia in the early '40s of the last century.

The first prototype had a wing with slats to improve low-speed handling and short-field operations. To simplify production and to save aluminium the second prototype had a wooden wing without slats. For reasons unknown the 2nd prototype crashed during a test flight and was subsequently written off. Late in 1941, the program was temporarily abandoned under pressure of the invasion of Russia and the lack of aluminium.

Three view drawings of the Yak-3 powered by the VK108 engine

In the era 1942-1943 Yakovlev built the Yak-1M another prototype that would lead to the Yak-3. The final design of the Yak-3 as we know it now was designed by a group of Yakovlev designers under the supervision of Alexander Sergeyevich Yakovlev. It became an easy to fly aircraft, robust and easy to maintain with a great success rate in dogfights, flying low over the battlefield (mainly below 13.000ft (4000 meters). Different versions of the Yak-3 were developed and put into active service, with a total of 4848 airframes being built, an overview;

  • Yak-3 (VK-107A) Powered by the 1649 hp Klimov VK-107A engine. although excellent performance was achieved (over 390 knots at 18.860 feet - 720 kph at 5750 meters). As the engine suffered from overheating problems, which were eventually resolved, it was decided to re-engine the Yak-3 and use the VK-107A engine for the Yak-9

  • Yak-3 (VK-108A) Re-engined version with an 1851 hp Klimov VK-108 engine. Also with this engine there were overheating issues, during testing. Performance was even better than its predecessor, It reached 402 knots at 20.636 feet (745 kph at 6290 meters)

  • Yak-3K Bult for use with a 45m canon, but not a success

  • Yak-3P Post World War 2 production version, with different armament than the war era versions

  • Yak-3PD Powered by Klimov VK-105PF engine, designed as high altitude interceptor. During the test flights, it reached an altitude of 43.635 feet (13.300 meters). Did not go into production due to the engine reliability issues.

  • Yak-3RD Experimental aircraft with an auxiliary liquid-fuel rocket in the tail. In May 1945 reached an altitude of 25.600 feet and a speed of 486 knots (7800 meters - 782 kph)

  • Yak-3T Tan destroyer version with a heavy cannon in the nose. To keep the Weight & Balance within limits the cockpit was moved back 16" (0.4 meters). Also, this version suffered from engine overheating and never made it past the prototype stage.

  • Yak-3T-57 One specially modified Yak-3T with a 2.2. inch (57 mm cannon.

  • Yak-3TK Turbocharged version Yak-3

  • Yak-3U Fitted with a Shvetsov ASh-82FN radial engine providing 1851 hp it was a version to overcome the overheating VK-107 and VK-108 engines. Some airframes were modified with P&W R-1830 radial engines. (Yak-3UPW)

  • Yak-3UTI Two-seat trainer variant powered by Shvetsov ASh-21 radial engine. It became the prototype for the Yak-11


A Yak-3UPW


Finally a look at the specifications of the Yak-3PD;


General characteristics

  • Crew: 1

  • Length: 8.5 m (27 ft 11 in)

  • Wingspan: 9.2 m (30 ft 2 in)

  • Empty weight: 2,105 kg (4,641 lb)

  • Max takeoff weight: 2,697 kg (5,946 lb)

  • Powerplant: 1 × Klimov VK-105PF2 V-12 liquid-cooled piston engine, 960 kW (1,290 hp)

  • Propellers: 3-bladed constant-speed propeller

Performance

  • Maximum speed: 646 km/h (401 mph, 349 kn) at 4,100 m (13,451 ft)

  • Combat range: 550 km (340 mi, 300 nmi)

  • Service ceiling: 10,400 m (34,100 ft)

  • Time to altitude: 5,000 m (16,404 ft) in 4 minutes 30 seconds

  • Power/mass: 0.35 kW/kg (0.21 hp/lb)

  • Take-off run: 345 m (1,132 ft)

  • Landing run: 580 m (1,903 ft)

  • 360° turn: 17 seconds

Armament

  • Guns: ** 1 × 20 mm ShVAK cannon, with 150 rounds

  • 2 × 12.7 mm Berezin UBS machine guns with 170 rpg

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