Lavočkin LaG-5

History of the creation

The Lavochkin LaGG-3 was still "overweight" despite the best efforts of the designers, and the Klimov inline engine VK-105PF, could not provide the speed and climb performance this aircraft needed. The LaGG designers had hoped for the necessary performance increase from the new VK-107 engine just tested, but this engine was at the very beginning of its development and could not yet be used in combat conditions. The problem with underpowered LaGGs was becoming critical and was finally solved by the half-forgotten engine of the designer Svecov, whose engine was designated M-82. Approximately 1,000 of these engines were in storage after the not-so-successful Sukhoi Su-2 fighter.


The first to realize this was the designer Gudkov, who designed the Gu-82, which was a substantially modified LaGG-3 with a twin-star M-82 engine. In total, two Gu-82s were built and tested in the autumn of 1941


S. A. Lavochkin and his OKB at Gorky also tried installing the larger and heavier M-82 engine in the fuselage of the LaGG-3, which was designed for an inline engine that was almost ½ meter smaller in diameter. Lavochkin resisted the installation, relying on Klimov's VK-107 engine. However, Yakovlev was also interested in this engine and literally stole the engine intended for Lavochkin's OKB. Yakovlev did not hesitate to use intrigue and deception to get his way at the expense of Lavochkin's design team.

Technical solution

Lavochkin finally agreed to the M-82 engine, which was not at all easy. The aerodynamic transitions between the fuselage and the engine cowling were made of plywood, this was the material used to build the LaGG-3, the problem was with the engine overheating. The engineers installed deflectors under the engine cowling to ensure effective cooling of the cylinders at the second radial, the oil was also overheating, the original oil cooler was not enough. The firewall behind the engine was moved backwards, towards the cockpit, causing hot superheated air to flow into the cockpit.


The first test flights showed further poor flight characteristics, the rudder balance was poor and the view from the cockpit deteriorated rapidly due to the larger engine diameter, especially during take-off and landing. However, the installation of the new engine resulted in a slight increase in speed and climb rate, thus improving the handling of the aircraft. However, the new engine had the potential for further performance gains. In April 1942, after modifications, the prototype was ready for state tests, which it passed successfully, and in July 1942 serial production could begin.


For the first production run, already built airframes of the LaGG-3 were used, thus the new LaG-5 also inherited all the vices of the LaGG-3, including the high demands on piloting skill. The poor workmanship and little technological discipline in production persisted with the new machine. Thus, many of the new aircraft suffered from massive vibrations that sometimes led to the pilot being unable to keep the enemy aircraft in sight. On the other hand, the new aircraft had more powerful firepower and a larger ammunition supply. Two twenty millimeter SVAKs were installed above the engine with a supply of two hundred rounds per barrel.


The designers and engineers tried to continuously troubleshoot the aircraft, focusing their efforts on the still criticized poor view from the cockpit; from September the aircraft was produced as La-5 (Gorbunov[/i] left Lavochkin's team). This version had already brought visible changes, the cockpits protruded slightly above the lowered fuselage and thus finally improved the view from the aircraft, managed to reduce vibrations and gradually slightly more powerful versions of the AS-82 engine were used. By the end of the year, 1129 aircraft of this type had been produced.

Sources used:
Václav Němeček, Vojenská letadla III,. 3. modified and supplemented edition,. Prague, Naše vojsko, 1992. ISBN 80-206-0117-1.
Zbyněk Válka. Stíhací letadla 1939/45, Olomouc, Votobia, 1999 ISBN 80-7198-396-9
http://www.airwar.ru/enc/fww2/la5.html
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