Yakovlev Yak-1

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Yak-1
Early-model Yak-1 of Soviet Air Force
Type	Fighter
Manufacturer	Yakovlev OKB
Maiden flight	1940-01-13
Introduced	1940
Primary user	Soviet Air Force
Produced	1940-1944
Number built	8,700

The Yakovlev Yak-1 was a World War II Soviet fighter aircraft and the first among the war's many successful Yakovlev fighters.

Contents 1 Development 2 Operational history 3 Variants 4 Operators 5 Specifications (Yak-1b) 6 References 7 External links 8 Related content

[edit] Development

Although prior to World War II Yakovlev was best known for building light sports aircraft, the Yak-4 light bomber impressed the Soviet government enough to order the OKB to design a new fighter with a Klimov M-106 V-12 liquid-cooled engine. Formal specifications released on July 29, 1939, called for two prototypes - I-26-1 with a top speed of 620 km/h (385 mph) at 6,000 m (20,000 ft), combat range of 600 km (375 mi), a climb to 10,000 m (32,800 ft) of under 11 minutes, and armament of 2x 7.62 mm ShKAS machine guns and 1x 12.7 mm Berezin BS heavy machine gun, and I-26-2 with a turbocharged M-106 engine with a top speed of 650 km/h (404 mph) at 10,000 m (33,000 ft) and armament of 2x 7.62 mm ShKAS machine guns. The design took full advantage of Yakovlev OKB's experience with sports aircraft and promised agility as well as high top speed. Since M-106 was delayed, the design was changed to incorporate Klimov M-105P with a 20 mm ShVAK cannon in the "vee" of the engine block. I-26-I first flew on January 13, 1940. The prototype suffered from oil overheating problems which required 15 emergency landings during early testing and were never completely resolved. Then, on April 27, 1940, I-26-1 crashed killing its test pilot Yu.I. Piontkovskiy. The investigation of the crash found that the pilot performed two consecutive barrel rolls at low altitude which was in violation of test flight plan. It was believed that during the first roll main landing gear became unlocked, causing it to crash through the wing during the second roll. It has been hypothesized that Piontkovskiy's deviation from the flight plan was caused by frustration that his aircraft was being used for engine testing while I-26-2, built with the lessions of I-26-1 in mind, was already performing aerobatics. Poor quality of subassemblies provided by different suppliers raised I-26-2's weight 400 kg (880 lb) above projected which restricted the airframe to only 4.4 G, and oil overheating was still a problem. The many defects caused I-26-2 to fail government testing in 1940. Fortunately for Yakovlev, its competitors I-200 (future Mikoyan-Gurevich MiG-3) and I-301 (future LaGG-3) also failed testing. Requested improvements were incorporated into I-26-3 which was delivered for testing on October 13, 1940. Although it passed on December 9, 1940, the aircraft was still very much unfinished with unresolved engine problems.

Troublesome and slow testing and development must have been quite worrisome for Soviet officials considering the fact that I-26 was ordered into production under the name Yak-1 on February 19, 1940 - a mere month after I-26-1 made its maiden flight! The goal of this gamble was to reduce lag time between prototype and production aircraft. A very similar approach was used by USAF when F-101 Voodoo was ordered into production without any prototypes built. As a backup, I-200 and I-301 were also ordered into production. Although Yak-1 was slower than I-200 and less heavily armed than I-301, it enjoyed the advantage of having been started earlier which gave it a consistent lead in testing and development over its competitors. Beginning of the Great Patriotic War on June 22, 1941 made development and implementation of several other upcoming promising designs like Polikarpov I-185 unfeasible. The fact that Yakovlev was Stalin's personal favorite likely also played in Yak-1's favor.

Simultaneous manufacturing and testing of a design that required as many improvements as I-26 wreaked havoc on the production lines. Almost 8,000 changes were made to the aircraft's blueprints by 1941 with an additional 7,000 implemented the following year, and 5,000 more changes coming in 1942. Production was further slowed by shortages of engines, propellers, radiators, wheels, and cannons. Shortage of quality materials led resulted in plywood being torn off the wings on several aircraft. To make the matters worse, Factory No.292 which was the main manufacturer of Yak-1 was bombed on June 23, 1943 and burned to the ground. Amazingly, production resumed among the ruins on June 29. Due to loose tolerances, each aircraft was essentially unique with workers performing the final assembly having the unenviable task of mating what often proved to be very dissimilar components. For example, left and right main landing gear could be of different lengths and different angles relative to the aircraft which required adjusting their attachments to ensure an even stance for the completed aircraft. Parts were often non-interchangeable between aircraft. Production of Yak-1 ended in July 1944 with somewhere around 8,700 built.

[edit] Operational history

At the onset of Great Patriotic War on June 22, 1941, 425 Yak-1 were built, although many of these were en route or still disassembled. It was soon discovered that most air combat took place below 4,000 m (13,000 ft) which placed the new Soviet fighters, designed for high-altitude performance at a disadvantage. Still, Yak-1 did prove to have a significant advantage over its Soviet competitors. A full circle turn took just 17 seconds in the Yak-1M. MiG-3, which had the best high-altitude performance, did poorly at low and medium altitudes and its light armament made it unsuitable even for ground attack. LaGG-3 experienced a significant degradation in performance (as much as 100 km/h (62 mph) on some aircraft) compared to its prototypes due to manufacturers' inexperience with its special wooden construction and it suffered from warping and rotting when exposed to the elements. Yak-1's plywood covering also suffered from the weather but the steel frame kept the aircraft largely intact. The aircraft's major problem early in deployment was fuel leaks caused by disintegration of spot-welded fuel tanks from vibration. Also troublesome was the fact that the canopy could not be opened at high speeds, potentially trapping the pilot in a falling aircraft. As the result, some pilots had the sliding portion of the canopy removed altogether. The notoriously unreliable and short-ranged radio equipment was also frequently removed to save weight. Like most early carburetor-equipped engines, M-105 could not tolerate negative G forces which starved it of fuel.

Nonetheless, Yak-1 was well-liked by its pilots. 24 of these aircraft were sent to the elite all-female 586 IAP whose pilots included the world's only female aces with 11 (Katya Budanova) and 12 (Lydia Litvyak) victories. Yak-1 were also the first aircraft of the 1 IAP "Varshava" (Warsaw) with Polish pilots and Normandie-Niemen with French pilots.

[edit] Variants

• Yak-1b - ("b" was an unofficial designation, after October 1942 all Yak-1 were built to this standard). New bubble canopy with lowered rear fuselage, increased armor, ShKAS machine guns replaced with a single 12.7 mm Berezin UBS, electrical and pneumatic firing of the weapons instead of the mechanical system, new control stick based on the Messerschmitt Me 109 design, new gunsight, airtight fuselage, retractable tailwheel, improved engine cooling, Klimov M-105PF engine with better low-altitude performance. First flight (aircraft No.3560) took place in June 1942, with aircraft entering production in August. 4,188 built.
• Yak-1M - Yak-3 prototype with a smaller wing, revised cooling intakes, reduced overall weight, upgraded engine, two built.
• Several other Yak-1 variants did not receive special designations. These include prototypes with Klimov VK-106 and Klimov VK-107 engines, production aircraft capable of carrying external fuel tanks, production aircraft with the ability to carry 6x RS-82 rockets or 2x 100 kg (220 lb) bombs, and lightened versions for air defense.
• I-28 (Yak-5) - High-altitude interceptor prototype with Klimov M-105PD engine developed from I-26-2. Differed from I-26 in having an all-metal fuselage and tail and automatic leading-edge slats on slightly smaller and reshaped wings. One aircraft built, first flying on December 1, 1940. Did not enter production due to many deficiencies of the engine but served as the basis for high-altitude versions of Yak-7 and Yak-9.
• I-30 (Yak-3) - Development of I-26 with an all-metal wing with leading-edge slats, weight and space savings were utilized for additional armament and greater fuel capacity. Two prototypes built - I-30-1 armed with 3x 20 mm ShVAK cannons and 2x 7.62 mm ShKAS machine guns, and I-30-2 with two additional ShKAS. Did not enter production. The name Yak-3 was reused for a different fighter. See Yakovlev Yak-3.

[edit] Operators

•  France: Normandie-Niemen squadron
•  Poland: Polish Air Force
•  Soviet Union: Soviet Air Force

[edit] Specifications (Yak-1b)

General characteristics

• Crew: One
• Length: 8.5 m (27 ft 11 in)
• Wingspan: 10.0 m (32 ft 10 in)
• Height: m (ft)
• Wing area: 17.2 m² (185.1 ft²)
• Empty weight: 2,394 kg (5,267 lb)
• Loaded weight: 2,883 kg (6,343 lb)
• Max takeoff weight: kg (lb)
• Powerplant: 1× Klimov M-105PF V-12 liquid-cooled engine, 880 kW (1,180 hp)

Performance

• Maximum speed: 592 km/h at altitude (368 mph)
• Range: 700 km (435 miles)
• Service ceiling: 10,050 m (33,000 ft)
• Rate of climb: 15.4 m/s (3,038 ft/min)
• Wing loading: 168 kg/m² (34 lb/ft²)
• Power/mass: 0.31 kW/kg (0.19 hp/lb)

Armament

• 1x 20 mm ShVAK cannon, 1x 12.7 mm Berezin UBS machine gun. One-second salvo weight of fire 2 kg (4.4 lb) with both the cannon and the machine gun using high-explosive ammunition.

[edit] References

• Kopenhagen, W (ed.) (1987) Das groβe Flugzeug-Typenbuch. Transpress. ISBN 3-344-00162-0
• Donald D., Lake J. (eds.) (1996) Encyclopedia of world military aircraft. AIRtime Publishing. ISBN 1-880588-24-2
• Шавров В.Б. (1994) История конструкций самолетов в СССР 1938-1950 гг. (3 изд.) Машиностроение (Shavrov V.B. (1994) Istoriia konstruktskii samoletov v SSSR, 1938-1950 gg. (3rd ed.) Mashinostroenie. ISBN 5-217-00477-0) (History of aircraf design in USSR: 1938-1950)
• Степанец А.Т.(1992) Истребители ЯК периода Великой Отечественной войны Машиностроение (Stepanets A.T. (1992) Istrebiteli Yak perioda Velikoi Otechestvennoi voiny Mashinostroenie. ISBN 5-217-01192-0) (Yak fighters of the Great Patriotic war)

[edit] External links

• http://www.aviation.ru/Yak/#1
• http://www.wio.ru/tacftr/yak.htm

[edit] Related content

Related development

• Yakovlev Yak-7
• Yakovlev Yak-9
• Yakovlev Yak-3

Comparable aircraft

• Curtiss P-40
• Messerschmitt Me 109
• Supermarine Spitfire

Designation sequence

• Yak-1 - Yak-2 - Yak-3 - Yak-4

 

See also