The Lavochkin-Gorbunov-Gudkov LaGG-3 (Лавочкин-Горбунов-Гудков ЛаГГ-3) was a Soviet fighter aircraft of World War II. It was a refinement of the earlier LaGG-1 and was one of the most modern aircraft available to the Soviet Air Forces at the time of Germany's invasion in 1941. Compared to its opponents the LaGG-3 was underpowered and, despite its wooden construction, overweight. It was unpopular with Soviet pilots, but despite this, at one point in the war, on average 12 LaGG-3s were being completed daily and 6,528 had been built in total when production switched to the Yak-3 in 1944. The LaGG-3 was steadily improved, forming the basis for the more successful La-5 and La-7.
Design and development The prototype of the LaGG-3 was called the I-301 and was designed by Semyon A. Lavochkin, and . The prototype was later renamed the LaGG-1 and production aircraft were called the LaGG-3. The prototype was designed and produced by the GAZ-301 factory in Khimki to the North West of Moscow. The design was approved for production in January 1940 and in the prototype's name the I- prefix stood for istrebitel () and the number signified the design bureau responsible (which in this case was the GAZ-301 factory). The I-301 was a single-seat, low-wing monoplane, with a semi-monocoque fuselage, and skinned with birch veneer and plywood.
The I-301 airframe was partially made of "delta wood": a material composed of very thin (0.35–0.55 mm) layers of birch or pine wood veneer, and a phenol-formaldehyde resin known as VIAM-B-3, which together were baked at high temperatures and pressures. Delta wood was used for critical parts of the airframe. This novel construction material had tensile strength comparable to that of non-hardened aluminum alloys and only 30% lower than that of precipitation hardened D-1A grade duralumin. It was also incombustible and completely invulnerable to rot, with service life measured in decades in adverse conditions. During production of the prototype, it was discovered that the adhesive used in delta wood caused skin irritation and safety procedures needed to be devised for workers.
The full wooden wing (with plywood surfaces) was analogous to that of the Yak-1. The only difference was that the LaGG's wings were built from two spars. The fuselage was of similar construction to the MiG-1.
The I-301 was armed with one axial mounted MP-6 23 mm autocannon designed by Yakov Taubin which fired through a hollow propeller shaft in the "vee" between the engine cylinders and two synchronized Berezin UBS machine guns in the cowl. The MP-6 had 81 rounds of ammunition while the Berezin UBS had 230 rounds per gun. The MP-6 was abandoned after the prototype due to excessive recoil forces that damaged engine fittings. The I-301 used a Klimov M-105P engine of a licensed derivative of the Hispano-Suiza HS 12Y with a two-speed two-stage supercharger. At it was heavier than its competitors the Yak-1 and MiG-1, which meant its ceiling of was less than both. The I-301 took to the air for the first time on 30 March 1940 and by 12 June 1940 the manufacturer's tests were completed. The test pilot, A. Nikashin, reported that the fit and finish of the prototype was very good, it handled well, was maneuverable, and could be mastered by pilots of average ability.
On 14 June 1940 state acceptance trials began and it reached at sea level, at , and climbed to in 5.85 minutes. Later, the I-301 reached at with its radiator doors shut making it the fastest M-105P powered aircraft. The I-301 had a fuel capacity of carried in three self-sealing fuel tanks between the wing spars in the wing's center-section giving it a range of . During testing the state specification was increased to a maximum range of and fuel capacity was increased to . Aircraft with this fuel capacity were designated as LaGG-3's while the prototype was re-designated as the LaGG-1. The test flights revealed 114 faults that needed to be fixed but the project was given high priority so most of these faults were to be addressed in production aircraft.
Operational history On 29 June 1940 the LaGG-3 was accepted for production. The first plant to build LaGG-3's was Plant No.23 in Leningrad and was tested in December 1940. As soon they were built, the first aircraft were sent to their units in Soviet Asia. The LaGG-3 proved immensely unpopular with pilots. It was somewhat hard to control as it reacted sluggishly to stick forces. In particular, it was difficult to pull out of a dive, and if the stick was pulled too hard it tended to fall into a spin. As a consequence, sharp turns were difficult to perform. Moreover, pilots reported several imperfections: badly made hydraulic systems, broken connecting rods, oil leaks, engine overheating, rapid engine wear and loss of power. Other faults included defective landing gear, tail wheel failure, poor quality cockpit glass, poorly finished cowling panels, and poor quality delta wood panels due to rushed production as a result of the German invasion. The quality of aircraft varied widely from factory to factory.
As reports of these problems came back to Lavochkin's Experimental Design Bureau (OKB) in February 1941 no less than 2,228 modifications were ordered to be introduced into the series. Actually, despite the military's doubts, the Soviet government ordered 66 series of the Lavochkin fighter, which underwent a host of successive improvements in engines, propeller, and armament. The airframe was lightened as well. The LaGG team re-examined the design and pared down the structure as much as possible. Moreover, automatic slats were added to the wings to improve climb and maneuverability on the 35th Series and further weight was saved by installing lighter armament. The first four series were equipped with one axial Berezin machine gun firing through a hollow propeller shaft, two more synchronized cowl mounted Berezin machine guns with 200 rounds per gun and two synchronized ShKAS machine guns above and to the rear of the cowling with 325 rounds per gun; from 8th Series the axial Berezin was replaced by a ShVAK, coupled with a port Berezin in the cowling. But the improvement was slight and, thus, without an alternative powerplant, when the LaGG-3 was first committed to combat in July 1941, it was effective against bombers but it was completely outclassed by the Messerschmitt Bf 109 F.
In combat, the main advantage of the LaGG-3 was the strength of its airframe and the fact that it did not easily catch fire, despite the extensive use of wood. However, the laminated wooden panels did tend to shatter when hit by high explosive rounds and Soviet pilots nicknamed the plane Lakirovanny Garantirovanny Grob (Russian: Лакированный Гарантированный Гроб), or "guaranteed varnished coffin".
On the whole, pilots disliked the type. Pilot Viktor M. Sinaisky recalled:
Later in 1941, the LaGG-3 appeared with an internally balanced rudder, retractable ski landing gear for the winter, retractable tailwheel and plumbed for drop tanks. The result was still not good enough. Even with the lighter airframe and revised supercharged engine, the LaGG-3 was underpowered. However, despite its limitations, some Soviet pilots managed to reach the status of ace flying the LaGG-3. G. I. Grigor'yev, from 178th IAP, was credited of at least 11 air victories plus two shared. But pictures of his LaGG-3 "Yellow 6", in November–December 1941, show 15 "stars", so his score was probably higher. Experiments with fitting a Shvetsov M-82 radial engine to the LaGG-3 airframe finally solved the power problem and led to the Lavochkin La-5 and La-7.
Variants Series production 1st SeriesProduction of the 1st Series progressed slowly and there were teething problems with the aircraft due to an untrained workforce with no aircraft manufacturing experience, unfamiliarity with the delta wood structure, incomplete technical drawings, a lack of jigs, and some factories hadn't fully converted from producing the Polikarpov I-16 and I-153 to the LaGG-3. Production LaGG-3's differed from the prototype by having strengthened landing gear, seat armor, enlarged carburetor air intake, and were armed with three Berezin UBS and two ShKAS machine guns. The 1st Series also had a 5-channel RSI-3 transmitter/receiver and antenna which was normally fitted to only flight leader aircraft while other aircraft in the flight only had receivers or no radio. Mass balance weights were added above and below the rudder to eliminate control surface flutter. In addition to three self-sealing fuel tanks the LaGG-3 had a unique fire suppression system which collected exhaust via a tube on the port side of the exhaust manifold that ran to a condenser where the gasses were cooled and pumped into the empty fuel tanks. The 1st Series used the Klimov M-105P engine of with a centrifugal two-speed two-stage supercharger. Due to the addition of equipment the 1st Series was heavier than the prototype which negatively affected wing loading, rate of climb, ceiling, and maneuverability. As a result, the LaGG-3 was slow: its top speed was just at which was slower than the prototype's while climb to that altitude was 8.6 minutes instead of 5.85 for the prototype. Its rate of climb at ground level was as slow as . The take-off run was at least , compared to for the prototype because flaps could not be used due to the propeller speed governor which could not exceed 2,400 rpm instead of the engine's rated 2,700 rpm. Neither of the LaGG-3's competitors experienced as dramatic a performance decrease between prototype and production aircraft.
AircraftPrototypeProductionI-200/MiG-3I-26/Yak-1I-301/LaGG-3
4th SeriesThe 4th Series of fighters incorporated several changes such as replacing the Berezin machine gun firing through the propeller hub with a ShVAK 20 mm with 120 rounds, deletion of the starboard cowl mounted Berezin machine gun, taller antenna mast, enlarged wing root intakes, and enlarged oil cooler intake. The 4th Series used a Klimov M-105PA engine of During 1941 2,463 LaGG-3's were produced with 2,141 being built after their factories were relocated to the East. The counterweight at the bottom of the rudder from the 1st Series was deleted of the 4th Series. In an effort to improve performance the fuel capacity was reduced from to and range was reduced to . 8th SeriesThe 8th Series reduced the armament of the LaGG-3 by removing the two cowl mounted ShKAS machine guns and standardizing on the axially mounted ShVAK and one Berezin machine gun. The ShKAS machine guns were removed because they were believed to be dead weight because the 7.62 mm only caused minor damage to control surfaces, oil coolers, and radiators of enemy aircraft. A few had a VYa-23 cannon in place of a ShVAK depending on availability. 11th SeriesThe 11th Series was similar to the 8th Series except it was modified as a ground attack aircraft. The conversion included adding two wing-mounted D3-40 bomb racks and six RO-82 launch rails for RS-82 or RS-132 rockets. The D3-40 bomb racks could carry bombs such as the FAB-50 or drop tanks. The racks could also be used for chemical weapon dispensers or napalm dispensers. The LaGG-3 could also be modified to use ski landing gear and when combined with external stores this caused further performance degradation. 23rd SeriesThe rudder of the 23rd series could be differentiated from earlier aircraft because it now had an aerodynamic horn balance in front of the hinge line at the top of the rudder while the previous rudder was aerodynamically unbalanced with no protrusion in front of the hinge line [straight]. During the production of the 23rd Series, some factories switched to producing the more effective Yakovlev Yak-1 and Yak-7.