Yak-1 (M-105P/PA) mass-production fighter, A.S.Yakovlev

Early production Yak-1s from "Soviet Combat Aircraft of the Second World War" by Yefim Gordon and Dmitri Khazanov, Vol.1 (Courtesy of Thomas Heinz)

Yak-1 was launched into mass production on three factories: N°47 (Leningrad), N°301 (Moscow), Factory N°292 (Saratov). Correspondingly, three governmental orders were issued on May 4, 16 and 29, 1940.

In 1941 Factory N°47 was evacuated to Chkalov after only 2 Yak-1 were assembled before evacuation. Factory N°301 produced 48 aircraft in 1940 and 69 in 1941, before it was switched to production of the Yak-7UTI trainers in March.

Saratov Factory N°292 became sole manufacturer of Yak-1. Documentation was received in June 1940, and first Yak-1 rolled out in September. After ground tests, it was flown by Col.P.N.Shustov in October. At the end of the year, aircraft from Factory N°292 started to arrive to the service units, with priority given to the PVO forces. PVO units were preferred mostly because generally higher personal skills.

On early stages of production design refinement had a priority over the production rate. As mentioned on the page dedicated to Yak-1 of the 'army series', 10 major design defects had to be fixed on December 20, 1940. But first aircraft with sufficient modifications was presented to NII VVS only on February 13, 1941. Delay was caused by effort of Yakovlev OKB and Factory N°301 to introduce not 10, but 43 corrections (28 - airframe, 8 - engine and propeller, 15 - special equipment). But two of ten 'most wanted' fixes were not implemented: the tailwheel turn range was insufficient and oxygen mask tubing was still unreliable.

After trials, 3/4 of these corrections were adopted. At the end of February first Yak-1 of the 4th batch was delivered to the NII VVS. As could be expected, this aircraft was more refined and suitable for army service, but... 37 of 53 defects supposed to be eliminated on the 4th series were still in place. Combined with large number of small manufacturing defects, this resulted in excessive service time, and increased risk for pilots.

Factory N°301 failed to fulfill demands of the NKAP and VVS commetee, issued after Yak-1 'army series' trials. Quality of aircraft built on this factory was sharply criticized.

On June 10, 1941 NII VVS received first aircraft from Saratov. It was practically identical to the I-26-2 prototype, except required changes. Overall refinement was much better than one of Moscow built aircraft.

But engine still suffered from oil leaks, oil and water overheated, fuel consumption from port and starboard tanks was uneven. Radiostation, radiocompass and landing light were not installed. Assembly defects included cracks on the engine air intake and exhaust stacks, frequent burning of instrument panel lights, leaks in pneumatic system, loosening of bolts and screws, cracks on the wing paint. Ammo chain was spontaneously jammed in the starboard ammo box.

Anyway, situation was much better than on the Factory N°301.

In November 1941 Yak-1 N°20-29 (aircraft 29 of 20th batch) arrived to NII VVS. All aircraft of this batch had a RSI-4 radiostation with range 80km (but only 1 of 10 had a transmitter), landing light, improved engine controls, flare gun, rails for RS-82, neutral gas filling system (engine exhaust) for fuel tanks. ShVAK ammo was increased from 110 to 120 rounds. Electric system was shielded. Unreliable tailwheel retraction mechanism was deleted.

All changes were adopted except the neutral gas system - during tests excessive pressure in tanks resulted in fuel leak.

Necessity of the war time forced production of Yak-1 to continue, with defects cured gradually. Aircraft weight was changing from batch to batch. Poor manufacturing control of early aircraft resulted in extra 140 to 300kg overweight compared to I-26-2. Installation of radio (51kg), landing light and other equipment for night landing (7kg), RS-82 rails (9kg), engine modifications (14kg), airframe reinforcement (20kg) resulted in maximum weight of series Yak-1 achieving 2950kg.

Flight characteristics of early series (1941 - 1942) were generally worser than of the I-26-2 prototype. Moreover, they varied in quite wide range. Reasons were not only in poor quality of assembly like poor sealing of access hatches, paint quality. Aircraft repairs in the field conditions and impact of the elements did not improve aircraft quality as well. And not the last, varying pilot skills alone could result in speed losses up to 50km/h. But fine aircraft handling, stability, climb were almost identical to those of the prototype.

Special weight saving effort allowed to stabilize aircraft takeoff weight at 2917kg, starting from 29th batch.

In 1941 new engine of M-105P family M-105PA was installed on Yak-1. It had new carburetor, improved boost and rate controls, new shaft bearing design. With this engine Yak-1 was faster than Bf-109(??) (1940 model) by 50km/h at altitudes up to 3000m. Bf-109F-2 which appeared during Fall 1941 was superior to Yak-1 below 3000m mostly due to better climb, but above 3000m better speed and turn capability of Yak-1 made chances even.

2947 Yak-1 with M-105P and M-105PA were built between September 1940 and May 1942.

Predecessors	Modifications
I-26-2	Yak-1 winter variant	Yak-1 with RS-82	Yak-1 fighter-bomber
Yak-1 'army' pre-production batch	Yak-1 M-105PF	Yak-1 M-105PA with improved view, armament and armor (Yak-1B)

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Created April 19, 2000

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