The Development of the Lavochkin La-5/5F/5FN

In the fall of 1942, the German Luftwaffe encountered to the Soviet Lavochkin La-5 for the first time in the skies over the Eastern Front. At first unaware of the ability and potential of the new fighter, German pilots dubbed the aircraft the Neue Rata, comparing it to the Polykarpov I-16s that had been heavily involved in the Spanish Civil War in the 1930s and were by this time obsolete. Luftwaffe airmen, however, quickly learned that the radial-engined fighter was not only better than the I-16, but was an improvement over the VVS’ “modern” fleet of Yak-1s and LaGG-3s as well. Over the next several months, the Lavochkin Design Bureau and Shvetsov’s OKB-19 engine manufacturer would continue to make improvements to the aircraft, culminating in the La-5FN variant, which in many ways was superior to the Luftwaffe’s own Bf-109 and Fw-190 fighters. The upgraded version of the La-5 would arrive at the front in time for the Battle of Kursk, where the new fighters played a crucial role in the Soviet Union’s pivotal victory over the German military during the latter’s last major offensive on the Eastern Front.


An LaGG-3. Photo source: WW2 Planes

One of the VVS’ primary fighters at the time of the German invasion in June of 1941 was the LaGG-3. Designed by Semyon A. Lavochkin, Vladimir P. Gorbunov and Mikhail I. Gudkov in 1940, the LaGG-3 suffered from an acute lack of power with its Klimov M-105PF inline engine that produced 1,260 horsepower. Soviet pilots generally disliked the fighter. “Pilots didn’t like flying the LaGG-3 – a heavy beast with a weak … engine… They got used to it … but we had higher losses in LaGG-3s than in I-16s,” one Soviet airman, Viktor M. Sinaisky, recalled. The aircraft’s handling was also a source of concern for Soviet pilots, since the fighter had the tendency to enter a spin during steep banking turns. Nevertheless, in the early stages of the Great Patriotic War, the LaGG-3 was an improvement over the VVS’ outdated Polikarpov I-153 and I-15 biplanes, and Soviet airmen learned to accentuate the aircraft’s attributes. Indeed, in the hands of a skilled pilot, the LaGG-3 was an effective machine. For example, the top scoring LaGG-3 ace, Andrey Kulagin, shot down 22 German aircraft and 4 more in a group while flying the underpowered fighter.

Nevertheless, the aircraft’s operational performance, in general, left much to be desired, prompting Semyon Lavochkin to search for ways to increase the LaGG-3’s power. Indeed, the aircraft’s poor service record in the summer of 1941 caused Lavochkin to fall out of favor with the Soviet leadership, and in the fall, factories that had previously been assigned to LaGG-3 production were turned over to building Yakovlev Yak-1s and Yak-7s. In December, Deputy Commissar of Aviation Industry Pyotr Dementyev told Semyon Lavochkin, “the storm is coming down on you. Your days are numbered. Now you must take extraordinary steps to completely change the attitude of the military and the government toward the LaGG-3.”

Lavochkin initially sought to increase the fighter’s power by replacing the M-105PF engine with Klimov’s new M-107. Despite the fact that the new inline engine had significant teething problems of its own (unreliable and prone to overheating), Lavochkin successfully installed an M-107 on an LaGG-3. However, the experiment was decidedly unsuccessful, since all 33 test flights resulted in emergency landings. Meanwhile, an engineer at Lavochkin’s OKB, Semyon Alekseyev, suggested mating Arkadiy Shvetsov’s new M-82 air-cooled radial engine to the LaGG-3’s airframe. Lavochkin himself was convinced that his fighter’s redemption lay in the M-107, but he reluctantly agreed to let Alekseyev and “not more than two or three” other employees work on an M-82-powered LaGG-3.  Tracing its origins to a license-built version of the Wright R-1820 Cyclone radial engine (the M-25), the 14-cylinder M-82 could produce 1,700 horsepower, a significant improvement over the Klimov M-105. Alekseyev believed it would much easier to simply install the M-82 engine on the LaGG-3’s airframe than to design a new aircraft from scratch, and he and his team set about installing the large radial engine on the LaGG-3’s sleek airframe.

Needless to say, this was not a simple task. For one thing, the Shvetsov engine was a full 18 inches (46 centimeters) wider than the Klimov. Moreover, the M-82 was 550 pounds (250 kg) heavier than the M-105, meaning that the new engine would significantly shift the aircraft’s center of gravity forward. Nevertheless, Alekseyev’s team was able to make the necessary adjustments to the LaGG-3’s airframe to allow for the large radial engine to be installed on the narrow fuselage. In order to attach the M-82 to the airframe, Alekseyev’s team bonded plywood skirting to the outer forward fuselage, which helped ease the cumbersome radial engine’s transition onto the LaGG’s airframe. Two variable cooling flaps were installed on both sides of the fuselage, which allowed the 20 mm ShVAK cannons to be mounted above the M-82 (however, this later led to significant problems with the aircraft overheating, since the top cylinders frequently did not benefit from the cooling flaps). Work on the prototype was completed in February 1942 at Plant No. 21 in Gorky, and its inaugural flight of the new aircraft, designated the LaGG-3 M-82, was made the following month.


Gu-82. Photo source:

Interestingly, the installation of an M-82 to an LaGG-3 had already been attempted by Mikhail Gudkov, one of the LaGG-3’s original designers, in the summer of 1941. Gudkov took the nose section of a Sukhoi Su-2 light bomber, which also housed an M-82, and attached it to the airframe of an LaGG-3. The resulting aircraft, which was known as the Gu-82, made its first flight in September, and reached a top speed of 360 mph (580 km/h). Though the aircraft did have a number of issues, specifically regarding its stability, initial flight tests showed promise, and it was certainly an improvement over the LaGG-3. In October 1941, Gudkov wrote to Soviet leader Josef Stalin, “Currently, I am carrying out complex developments that give me reason to believe that I will be able to increase the speed of my machine to 600 km/h, without taking into account the elimination of defects in the mass production [of LaGG-3s]… after staying at the front, I distinctly imagine that we need to have an airplane with an air-cooled engine since the use of fighters with liquid-cooled engines in air battles and especially in ground attack against the enemy brings a great percentage of losses in pilots and material, because of the great vulnerability of the water system of the engine… proceeding from these considerations, I ask you, in order to gain time, without waiting for the end of flight testing, to allow me to introduce my aircraft with the M-82 at one of the production plants that produce the LaGG aircraft.” However, Gudkov did not immediately receive a response, and by the time he did, the LaGG-3 M-82 project was already underway, and the Gu-82 was not further pursued. While it is unclear why, exactly, the LaGG-3 M-82 project was chosen instead of the Gu-82, especially since the latter was several months ahead of the former, historians believe that it was due to Lavochkin’s close relationship with members of the Soviet leadership.

In any event, Lavochkin’s new LaGG-3 M-82 performed well during its initial test flights, with test pilot G.A. Mishchenko giving the aircraft all-around positive feedback. However, Mishchenko did mention that the engine tended to overheat, which prompted the OKB to redesign the oil cooler system and to reposition the supercharger air intake system. Though the measures helped, problems with the M-82 overheating would persist throughout the La-5’s and La-7’s production. State trials of the LaGG-3 M-82 continued through April, with the prototype reaching a top speed of 383 mph (600 km/h) at an altitude of 21,160 feet (6,450 meters), faster than any other production aircraft in the Soviet Union at the time. Pleased with the results of the state trials, the VVS NII KA recommended that the fighter be put into serial production, a proposal that was approved on May 19, 1942. Switching over production from the LaGG-3 to the new radial-engined version, now known as the LaG-5, was a slow process, but most of the conversions had been completed by late summer, and in August, 145 LaG-5s were built. The following month, the aircraft lost the G in its designation, and became known simply as the Lavochkin La-5.


Lagg-3 M-82. Photo source:

The new fighter had a top speed of 382 mph (582 km/h), an improvement over the LaGG-3, but the La-5 still retained a number of glaring deficiencies. For example, overheating of the M-82 led to the aircraft’s cockpit becoming unbearably hot, which prompted pilots to fly with the canopy open. Moreover, the tail wheel’s retraction mechanism was unreliable, and airmen frequently flew with the wheel in the down position. A combination of these and other factors would often reduce the fighter’s top speed by 25 mph (40 km/h). By the end of 1942, more than 1,000 of the upgraded fighters had been produced, and though the baseline La-5 was a significant improvement over other fighters available to the VVS at the time, it was still slower than the Bf-109 and Fw-190, and had inferior maneuverability. Consequently, the Soviet leadership ordered Shvetsov to begin producing a boosted version of the La-5’s radial engine, and ordered Lavochkin to continue work on improving the fighter.

Shvetsov’s new boosted engine, known as the M-82F, increased the supercharger’s output to 1,760 horsepower below 10,000 feet (3,048 meters). Though the increase in horsepower was not significant, the engine could run at such power with no limitations, whereas the unboosted M-82 could operate at full power for only several minutes. While Shvetsov was finalizing the upgraded radial engine, Lavochkin continued improving the La-5’s airframe, and the decision was made to lower the fuselage decking behind the cockpit and lengthen the canopy to increase the pilot’s field of vision. Similarly, the aircraft’s cowling joints were sealed and its oil cooler ducts were reshaped. The upgraded La-5, known as the La-5F, went into production in November of 1942, and was sent to frontline units in early 1943.


An La-5F in flight.

However, many of the issues that plagued the baseline La-5 persisted in the F variant. The overheating problem of the M-82 continued in the M-82F, and pilots continued to complain that the cockpit would become too warm. According to famous Soviet writer Anatoly Markushi, “the pilots were tortured by the African heat in the cabin, and the soles of the sergeants’ boots were caked and cracked after ten flights.” As was the case with the baseline La-5, pilots would frequently fly with the canopy open, which increased drag and decreased speed. Nevertheless, when the La-5F entered service in early 1943, it was a vast improvement over most other Soviet fighters at the time, and Soviet pilots were willing to tolerate a degree of discomfort if it meant flying a faster and more maneuverable aircraft. Indeed, with a top speed of 364 mph (586 km/h) at an altitude of 12,00 feet (3,658 meters), the La-5F was faster than the Luftwaffe’s new Fw-190A-4 at this altitude.

As the F variant was reaching frontline units, Shvetsov was testing the new variant of his radial engine, the M-82FN, which featured direct fuel injection. The new engine could produce 1,850 horsepower, and featured an improved NB-3U injection pump. The M-82FN-powered La-5 received the designation La-5FN, and featured a number of ostensibly minor changes in an attempt to eradicate the deficiencies of previous La-5 models. The most significant of these alterations was a tighter fitting firewall along the cowling and oil cooler insulation, which helped decrease cockpit temperature. Moreover, the engine’s cylinder ribbing was enlarged to improve cooling in flight. The first La-5FN was tested in December of 1942 using an older “highback” airframe, and in March, a second La-5FN prototype was built using the latest “lowback” fuselage. At the end of the month, the second prototype underwent state trials, during which it reached a top speed of 372 mph (599 km/h) at low altitudes, 390 mph (628 km/h) at 10,500 feet (3,200 meters), and 405 mph (652km/h)  at 20,500 feet (6,250 meters). What is more, the aircraft demonstrated greatly improved handling characteristics and maneuverability. This new variant would become the definitive version of the aircraft that would have such a tremendous impact on the war on the Eastern Front.


La-5FN. Photo source:

The La-5FN had its first major success at the Battle of Kursk in the summer of 1943. Though Kursk is well-known for being the largest tank battle in history, aircraft on both sides played significant roles, providing close air support and air coverage for ground troops. La-5FNs by this time were flown by the 3rd GIAP, 88th GIAP, 31 IAP, 131th IAP (40th GIAP), 239th IAP, 254th IAP, and 272nd IAP. While the Luftwaffe maintained air superiority during the first part of the battle, the Soviet pilots in La-5FNs were eventually able to show German airmen that the new plane not only had significant firepower, it had the speed and maneuverability to match the Messerschmitts and Focke-Wulfs. Indeed, the La-5FN’s climb rate and turning radius were superior to those of the Fw 190A-8A, and its roll rate was slightly better than the Bf-109. The new Lavochkin in the hands of a skilled Soviet pilot was as deadly as anything on the battlefield. Some exploits of Lavochkin pilots have become legendary. One A.K. Horowitz, for example, is believed to have shot down nine German planes in a single battle near Kursk, though only six were confirmed (two Ju-87s, two Ju-88s, and two FW-190s). Later that same day, Horowitz was killed in a battle against four enemy fighters. He was posthumously awarded the title Hero of the Soviet Union.

Similarly, in July, in the skies northeast of Kursk, several La-5 pilots shot down two Fw-190s piloted by Major Reinhard Seiler and Lieutenant Hugo Hunerfield of JG 54. Both Luftwaffe pilots were seasoned aces, with Seiler having 102 victories and Hunerfield 28. Both pilots ejected. Hunerfield was captured by Soviet ground forces. Seiler was rescued by German troops and sent back to the Reich for hospital treatment, where he was declared unfit for further combat duties. Such episodes in the skies over Kursk made it clear that the Soviet Union had developed an aircraft after two years of war that could match, and in many ways exceed, the performance of German fighters.

That same summer, a new La-5FN made a forced landing on a German airfield, which provided the Luftwaffe with a chance to examine and test-fly the VVS’ new fighter, and the results were sobering. The aircraft was sent to Germany to undergo extensive testing at the Luftwaffe Research Center in Rechlin. German test pilot Hans-Werner Lerche wrote a detailed report of his experiences flying the La-5FN, explaining that the new Soviet fighter excelled at altitudes below 3,000 meters, and its performance at this altitude was comparable to Luftwaffe fighters. He also noted that the new Lavochkin possessed superior maneuverability in some regards. Both German fighters, however, outperformed the La-5FN at higher altitudes, though given the fact that the majority of the air war over the Eastern Front was fought below 10,00 feet (3,000 meters), this was often not a problem.


Captured La-5FN. Photo source:

Lerche also discovered numerous problems with the new Lavochkin, though these defects would be eradicated by Soviet engineers in what would become the La-5’s successor, the La-7. For example, all engine controls in the La-5FN’s cockpit had separate control levers, meaning the pilot had to make constant adjustments during the flight. In contrast, contemporary German fighters had integrated controls, so only one lever was needed to control throttle, mixture, propeller pitch, radiator and cowl flaps. In addition, the German test pilot noted that the aircraft suffered from a short flight time- only about 40 minutes at cruise engine power. Despite these shortcoming, however, Lerche acknowledged that the La-5FN was a significant improvement over the Soviet fighters that had gone up against Luftwaffe pilots earlier in the war.

Following the successful development of the La-5, the Soviet industrial machine, which had recently recovered after being moved eastward away from the German advance in 1941 and 1942, produced a total of 5,048 La-5s of all variants in 1943, the majority of which were manufactured at the Sokol Aircraft-Building Plant in Nizhny Novgorod. A further 3,826 were built in 1944, though the number decreased when the upgraded La-7 began being produced in April. Production switched completely to the La-7 in November of that year.

Up against the German Luftwaffe, the La-5FN was as deadly as any other aircraft on the Eastern Front. The Soviet Union’s top ace, Ivan Kozhedub, scored the majority of his 64 victories flying his La-5FN. Following their introduction, the Lavochkins made a significant contribution to the VVS gaining air superiority over the Eastern Front. From Kursk all the way to Berlin, the La-5 played a crucial role in the last two years of the war. The Lavochkin La-5, as much as anything, is symbol of the Soviet Union’s industrial and military recovery in 1943. The momentum would take the Red Army and VVS all the way to Berlin in 1945.

-Patrick Kinville


  1. Khazanov, Dmitriy & Medved, Aleksander. La-5/7 vs Fw-190: Eastern Front 1942-1945. Osprey Publishing, 2011.
  2. Moore, Jason. Lavochkin Fighters of the Second World War. Fonthill Media, 2016.
  3. Yakubovich, Nikolai. Istrebitel La-5: Koshmarnii Son, Bubnovikh Tuzov. Yauza, Eksmo, 2008.
  4. Yakubovich, Nikolai. Neizvestnii Lavochkin. Yauza, Eksmo, 2012.
  5. Baevskii, Georgii. Stalinskie Sokoli Provit Asov Luftvaffe.
  6. Kylobovskii, A. & Blashchuk, V. La-5FN s Tochki Zreniya Luftvaffe. Aerokhobbi, Vol. 1, 1993.
  7. Khazanov, Dmitriy. Air War Over Kursk: Turning Point in the East. SAM Publications, 2010.

5 thoughts on “The Development of the Lavochkin La-5/5F/5FN

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