Aviation of World War II
The backward view of the pre-war generation fighters was covered by a high gargrot: with it, the aerodynamic resistance was less. In the summer of 1942, the first Yaks appeared with a lowered gargrot and with an all-round view from the cockpit, and in the fall, Lavochkin introduced a similar revision, remaking one serial La-5. It was lightened by 120 kg by removing some of the equipment, the tanks in the wing consoles (the tanks in the center section were made for 350 kg of gasoline) and replacing one cannon with a BS machine gun. It was supposed to "remove" 315 kg from the next machine and bring its weight to 3 tons by partially replacing wood with metal, incl. make new wing spars from ZOHGSA steel.
On November 15, a GKO decree was issued to further improve the flight data of the La-5 and eliminate the marriage. In response, plant No. 21 performed various complexes of modifications on three machines. Common to them was the installation of the M-82 motor with an increased from 950 to 1140 mm Hg. Art. supercharged at the ground and improved exterior trim. The speed at the ground of such a La-5 # 8-53 reached 519 km / h at nominal, at the afterburner - 550 km / h (at 2700 m - 569 km / h).
The plane is gray. No. 8-71 additionally received a new oil cooler tunnel and monitoring station branch pipe. The speed on the I border of the altitude of 3200 m increased to 576 km / h, but at the ground on the afterburner it was 3 km / h less than that of the car No. 8-53.
Aircraft No. 8-50 also had external and internal hoods with improved sealing, new cooling air outlets and exhaust pipes. At an altitude of 600 m with the afterburner, the speed was 565 km / h, without it - 530 km / h, and at the I border of the altitude of 3250 m - 590 km / h.
Since December 1, 1942, on serial La-5s, they introduced bonnet sealing, improved the quality of surfaces and joints, finalized the slats, increasing their strength and making the release smoother.
By that time, a modified M-82F engine already existed, in which the afterburner control system, the oil system were improved, and a new CCP clutch was installed. The power of this variant at an altitude of 600 m was increased by 300 hp. Compared to the M-82A, the first altitude limit was reduced from 1580 to 800 m, but the power at this altitude increased from 1540 to 1760 hp. (in terms of this "combat" power, the M-82F surpassed even the M-82FN). The second altitude limit for the M-82A and F was the same - at 5410 m it was possible to develop 1330 hp. The mass of the M-82F has grown by only 20 kg. The use of this engine on the La-5 was prescribed by the order of the NKAP No. 744 of October 4.
According to the engine designation, the new modification of the fighter received the La-5F index (the internal plant code is "type 38F"). On this machine, in addition to the updated VMG, a fuselage with a lowered gargrot was introduced, and the wing, empennage, chassis, armament and systems were left the same. In preparation for the launch of this version in mass production, the strength of the aircraft was recalculated, the new design was checked in the SibNIA statistical hall and approved. Prototypes were not built, having completed the entire cycle of factory, state and military tests, as well as fine-tuning the aircraft in a short time on the head series. By lightening the design and removing some of the equipment, the takeoff weight of the La-5F "standard" was reduced by 160 kg compared to the La-5 M-82A. The speed at the ground increased by 50 km / h, and at the second altitude limit - by 20 km / h. The climb time of 5000 m was reduced by 30 s, and the steady turn at an altitude of 1000 m was obtained faster by 2-3 s. Initially, the use of the afterburner was limited, but from April 1, 1943, the restriction was lifted by order of the NKAP # 183.
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* Forcing of the engine during 10 minutes.
** On speed making 90 % from maximal.
However, control tests of the serial La-5F No. 37-18 conducted in August 1943 at the Air Force Research Institute showed a decrease in speed at the ground by 10 km / h, at the border of altitude by 5 km / h and an increase in the time to climb 5 km by 30-40 s in comparison with the machines of the head series. The decrease in altitude was due to improper adjustment of the motor control wiring, which was fixable. The excess of the temperature of the cylinder heads turned out to be worse.
The aircraft builders were required not only to create new modifications of the La-5, but also to improve the quality of serial products. The troops complained that the La-5F range was less than guaranteed due to the unstable operation of the AK-82BP carburetor, which allowed the mixture to be over-enriched in the “high-speed range” mode. Control tests for a range in the most advantageous mode at an altitude of 500-1000 m, carried out on La-5 M-82A No. 37210444 of October 1942, gave 970 km, aircraft No. 37212124, built in July 1943, - 820, and La -5F No. 37212501F, commissioned in June, - 580 km with the same refueling of 340 liters. After that, on the basis of NKAP order No. 602s dated October 29, 1943, an improved carburetor was developed and introduced into the series on the La-5.
GKO decree # 2378ss of October 7, 1942 and NKAP order # 763ss of October 10 determined the release of La-5 at plant # 381, which was evacuated from Leningrad to the Urals, to Nizhny Tagil. At the same time, an order for the IL-2 was even withdrawn from the enterprise, such importance was now attached to the new fighter. For La-5, the plant was transferred to the area of the 445th (glider) plant in Alapaevsk and an additional 4,000 workers and engineers were sent. But due to the beginning of the re-evacuation of the enterprise to Moscow, it was not possible to master the release of new products on time. And only at the end of 1943 the first La-5Fs, assembled from Gorky units, were handed over there, and then the full cycle went. By letter No. 698s dated March 23, 1943, Lavochkin and the director of plant No. 21 Agadzhanov asked for permission to produce a La-5F aircraft lighter up to 3050 kg with metal spars specifically for "hunter pilots", citing the experience of the Germans and Japanese. It was supposed to hand over 7-10% of the aircraft in this version. According to the GKO Decree No. 3101 of 03/31/1943, the plant No. 381 from May 1943 had to completely switch to the production of La-5 with metal spars. But it was not possible to do this on time, and the plan for the release of La-5 for 1943 was fulfilled by this enterprise only by 55%. Other manufacturers of La-5 exceeded the target of that year: plant No. 21 - by 9.2%, and No. 99 - by 10.2%.
In the spring of 1943, the first cases of canvas breakage were noted, which were used to paste over the wooden parts of La-5F, produced by the 21st and 99th factories. At first glance, harmless cracks in the paint ended in catastrophes, and by the beginning of June this phenomenon had become widespread. The reason was not immediately sorted out. It turned out that in the ASh-22 nitro putty, which was applied after painting the green camouflage fields with AMT-4 enamel, the lead crown was replaced with red lead iron without the consent of VIAM. This putty began to be supplied from December 1942, and while it was cold, it held on, but as soon as the sun began to bake, it began to crack, the canvas got wet and collapsed, especially on the wing and stabilizer. In the army, there were about a thousand such aircraft, which threatened various industrial leaders with reprisals. Then, mobile teams were urgently formed, which eliminated dangerous defects in 3 weeks. In the area of the Kursk salient, they completed their work literally 3 days before the start of the grandiose battle. It was not possible to find a replacement for the scarce lead crown. It was necessary to stop the production of several putties and primers that included this component, and a new camouflage scheme based on gray paints was introduced for fighters.
For 1942 - 1944 the industry produced 10003 La-5 fighters in various modifications.