Yak-1 'army series' pre-production batch (A.S.Yakovlev)

'Army Series' Yak-1 from "Soviet Combat Aircraft of the Second World War" by Yefim Gordon and Dmitri Khazanov, Vol.1
Courtesy of Thomas Heinz

Assembly of the I-26 pre-production batch (also known as a zero series, small series or army series) was launched at Moscow factory N°301. Eleven aircraft were intended for trials in the service units and for participation in the military parade. Latest goal had a large psychological importance in atmosphere of the war approaching.

Decision about series production of the Yak-1 was made on April 27, 1940. At that time the first prototype trials were on the early stages, not all defects were revealed and no necessary design improvements were signed out.

In March-April 1940 design bureau transferred the blueprints to the factory N°301. Senior Engineer K.V.Sinelnikov and team of specialists was sent from OKB to the factory to assist in the mass production arrangement. Factory received an order to launch production with 3 to 4 months...

No wonder that the 'army series' aircraft were assembled in a hurry, without all necessary equipment and well-defined technology on hands. As a result, quality of the first built aircraft was far from adequate.

First assembled Yak-1s differed from the I-26-1 only by their armament. All construction defects were inherited - no wonder, same blueprint were used! - but number of assembly glitches were piled on, caused mostly by unsettled technology. Aircraft lacked radio-equipment, electric generator, fuel meters. Takeoff weight was 2844kg.

First Yak-1 was ready on March 22, the rest of planes were assembled before June 1940. 'Army series' Yak-1 took off on June 7, 1940. After circling the airfield, aircraft was pulled back to the workshop. Structural strength of the wing was found insufficient, and leading edges were cut away and replaced by reinforced ones (advantage of wooden wing, huh!). Same was done on 10 other planes. Factory trials and refinements continued until October 1940. In October-November all 11 planes passed army trials at Kubinka airfield (11th IAP).

Trials were finished quickly, even before the first snow. 1222 flights were performed, totaling 392h. Those flights included 20 high-altitude missions, 162 group flights, two mock combats with I-15 and I-16, weapon tests - 14, night flights - 11, landing with side wind - 45. One aircraft was used to evaluate landing gear, it made 300 takeoffs/landings.

Participating pilots already studied the aircraft on the factory assembly line and had 4 to 5 flights on the Yak-7UTI.

Handling of the Yak-1 was found much better than this of the I-16. Yak-1 had very good spin performance. Easy landing allowed to use Yak-1 for night missions (this was combat-proved soon in the beginning of the war). On night November 6 group of Yak-1s was flown from Kubinka to one of Moscow airfield for participation in the October Revolution parade. Landing was performed at night without problems, despite 6 of eleven pilots had less than 8 daytime landings on the Yak-1.

On November 7 five of those Yak-1s (lead by 11IAP Col.G.A.Kogrushev) made an impressive appearance on the parade.

Army trials revealed that pilots flying I-16 may be transferred to the Yak-1 without any special training. During factory trials 19 more pilots joined the 'Yak-1 club' without any transitional practice on the Yak-7UTI.

Weapons operation was found satisfactory. Reliability was quite good even in the cold conditions and on high altitude. Engine-mounted guns proved safe from over-cooling, harmful for wing-mounted weapons. But the used chain segments from the 20mm cannon occasionally hit the water cooler, and protection grid had to be installed.

Wheels turned to be undersized, and service time of the tires was too short (specially the tailwheel). Some engine overheat was noticed during continuous climb. Lack of special equipment was a shortfall: fuel meters, radio, electric generator, landing light were still missing, harming the combat value of the plane. Total number of listed defects included 93 positions.

VVS commander Gen-lieut P.V.Rychagov approved the army trials results on January 31, 1941. On February 4 joined commetee of NKAP and VVS set up a schedule for fixing Yak-1 defects, which surfaced during 'army series' tests and parallel trials of the I-26-2 and I-26-3 prototypes. 10 major defects had to be eliminated on all production machines (including the 'army series'). 53 more had to be fixed on production factories, starting from 4th batch.

Despite first production Yak-1s were far from perfect, their assembly allowed to prepare factory personnel for mass production even before the technology was settled on the prototypes. Number of pilots were ready to teach others to operate new fighter. Large number of participating pilots also helped to produce a complete list of shortcomings to fix.

Predecessors	Modifications
I-26-1	Yak-1 M-105P/PA

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Created April 10, 2000

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