Aviation of World War II
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The La-5 fighter appeared under circumstances that were not quite ordinary, if not dramatic, for the design team headed by S.A. Lavochkin. Fighter LaGG-3. for the release and improvement of which this design bureau was responsible, due to insufficient efficiency, they were removed from production. And the very existence of the design bureau was now in question. Of course, the designers perfectly understood the nature of the LaGG's shortcomings and had already carried out design work on its radical modification. Along with the need for a sharp improvement in flight data, the main thing in this matter was the efficiency and the requirement for the continuity of the LaGG-3 design and its new modification. Only if these conditions were met could the plant be transferred to the production of a new aircraft before the Yak fighter appeared on the assembly line (as planned). And the design bureau of S.A. Lavochkin coped with this task successfully.
Carrying out the modification of LaGG, the designers focused on the new promising air-cooled motor M-82 A.D. Shvetsova. Due to its significantly higher power in comparison with the M-105P, the LaGG-5 fighter acquired the qualities that it lacked so much: the speed and climb rate increased significantly, and the vertical maneuverability improved. The new aircraft was created in the spring of 1942, the State Defense Committee issued a Decree on August 6, and 2 days later, NKAP order No. 683, according to which the new fighter was renamed La-5 - "Lavochkin-5" and after testing it, under the brand name La-5, immediately put into production.
Along with increasing reliability, the most important direction for improving the La-5 was weight reduction. Replacing the electric start of the motor with an air one gave a saving of 20 kg, an improvement in the quality of gluing - another 20, the removal of the load in the tail - 15 kg, then the pipelines and control wiring were cleaned up. As a result, the takeoff weight was reduced from 3370 kg for the prototype to 3200 kg in the series.
Progressive technical processes were introduced, which made it possible to increase the rate of La-5 production. For example, at first the La-5 hoods had to be “knocked out” by hand, but on July 1, 1942, the first dies were delivered, which ensured the daily production of parts for 2 aircraft, and by the end of the month a new section was organized with a daily capacity of 6 sets. The same thing happened with casting and hot stamping. Throughout the glider, work was underway to replace the delta wood with conventional wood. In the end, only power frames, tail spars and skin in especially loaded areas were made from the "delta". Without loss of strength, it was possible to reduce the weight of the aircraft and its cost.
Engine. The plant guaranteed the operating time of the M-82A before repairs of 100 hours, but in reality the resource was less. Due to the deterioration of the fit of the piston pairs and rings, oil accumulated in the combustion chambers of the lower cylinders, the engine smoked and filled up the entire fuselage. But if not all of the accumulated oil was thrown out through the exhaust pipes, a hard blow occurred during the compression stroke and, as a result, a connecting rod break or a cylinder head destruction. The VG-12 candles used on the M-82 were kept for 5 hours, and during the period of intense battles, one La-5 required 14 candles per day. The problem lay in the unfortunate shape of the cylinder heads: the candles were constantly in oil, from which they smoked, and lead from leaded gasoline settled on the soot.
Initially, the Flight Operations Manual of the La-5 M-82A aircraft allowed to keep the takeoff mode (1700 hp) at the ground for 5 minutes. The prototype aircraft in this mode accelerated to 600 km / h, and at the nominal (1400 hp) only up to 515 km / h. But if the pilot got carried away and did not turn off the afterburner on time, the new engine stalled in 10 minutes, and the worked one did not pull out even the permitted 5 minutes. Combat pilots constantly reported that any La-5 of their group did not return from departure due to engine failure in battle. The tests carried out at the LII confirmed the objectivity of the claims, and the use of the afterburner in battle was prohibited. Without it, the speed at the ground dropped to 505-510 km / h, from 600 to 580 km / h, the speed at the 2nd altitude limit decreased, and the time to climb 5000 m increased from 5.2 minutes for the prototype to 6.0.
The first La-5s, like the LaGG-3s, did not have slats and had a tendency to stall on the wing. GKO decree No. 1895ss of June 7, 1942 obliged to introduce mechanization of the leading edge of the wing on LaGG-3 and La-5 from July 1, but by the end of the first decade of July it was possible to do this only on 7 LaGG-3 and 8 La-5. Only by August, all aircraft began to be produced with slats.
In the summer of 1942, the La-5 carried out work to improve the fit of the hatches and landing gear sashes. We ensured the synchronization of the release of the right and left slats, they were better adjusted and lightened. Provided for the release of flaps on a bend, reducing its radius and execution time. Based on the results of TsAGI's research, the design and installation of the Pitot tube was changed. Modified the electrical system.
On July 24, an order of the NKAP and Air Force No. 559a / s / 032 was issued on the use of armor on fighters. First, an armored back was installed on the La-5, and tank protection was also introduced. Then, in accordance with the GKO decree No. 2359ss of October 1, 1942, a frontal armored glass was introduced. In addition, the same document determined the use on the La and Yak fighters of the red illumination of the sight reticle, the push-button electropneumatic release of the Me-109 type guns instead of the tight mechanical triggers.
Order No. 605s of August 8, starting from August 10, it was required to install an RSI-4 radio receiver on each La-5, and a transmitter, as well as an RPK-10 radio compass, on every third. Although it was not possible to meet the deadlines (for 2 days!), The matter nevertheless moved forward, and Soviet fighters began to receive radio navigation and communications equipment.
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GKO - Gosudarstvennyy komitet oborony - State Defense Committee
NKAP - Narodnyy komissariat aviatsionnoy promyshlennosti - People's Commissariat of Aviation Industry
RPK - Radiopolukompas - Radio compass
LII - Letnyy issledovatel'skiy institut - Flight Research Institute
TsAGI - Tsentral'nyy aero gidrodinamicheskiy institut - Central Aerohydrodynamic Institute
* Forcing of the engine during 10 minutes.
** On speed making 90 % from maximal.
By the end of 1942, in Gorky, the La-5 began to be produced with a significantly modified nose: the double skin finally disappeared, the fuselage became lighter, and labor intensity decreased. By that time, on the recommendation of TsAGI, a drain was installed on the rear frame of the sliding part of the canopy, smoothing the step between the cab and the gargrot. The kinematics of the tail support was also changed, now its wheel was pulled higher, and the flaps did not protrude beyond the bypass of the tail section.
In December 1942, the production of La-5 began at plant number 31 in Tbilisi, where production of the LaGG-3 continued. By the end of the year, this plant had built 22 new fighters and commissioned 5 more at the beginning of the next. However, the 1943 plan for this enterprise provided for an increase in the production of LaGGs by 1.5 times while improving their performance characteristics. In addition, Yakovlev strove for the transition of the Tbilisi plant to the production of a new Yak-3 fighter. In this situation, the director of the 31st Pivovarov managed to insist on the withdrawal of the order for the La-5 and the continuation of the production of LaGGs, which, although they became better, still could not compete with the Bf 109G and FW 190A.
The first air regiments armed with this fighter appeared at the front in the fall of 1942 near Stalingrad.
La-5 quickly gained recognition. The pilots liked not only its high performance and powerful armament (two ShVAK cannons), but also the air-cooled motor, which had greater survivability than the liquid-cooled motor, and at the same time served as protection against enemy fire from the front hemisphere.
The production of the first serial version of the La-5 with the M-82A engine was stopped in the summer of 1943.