Aviation of World War II
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.
In March 1942, the AK-82BP carburetor was replaced with an NV direct injection unit on an experimental M-82NV engine, made on the basis of the M-82A. The maximum power of this engine was raised to 1850 hp. It was achieved in combat mode up to the first altitude limit (1650 m), with a boost pressure of 1200 mm Hg. Art. and revolutions of 2400 rpm. In the summer, flight tests of the M-82NV were carried out on the Il-4 and Su-2. On September 12, 1942, by order of the NKAP No. 698s, plant No. 21 was ordered to install the M-82NV on 5 serial La-5s, carry out their tests together with the LII and the Air Force Research Institute and by October 10 send them to the combat unit for military tests. But the M-82NV (M-82FN) engine required significant improvements, and the development of the "NV" units at the plant No. 296 was delayed. However, in 1943, plant number 19 was already able to deliver 1520 M-82FN, although according to the plan it was supposed to be 2483.
But the problems were not only with the motor. Lavochkin explained the failure to meet the deadlines for the La-5 M-82NV by the fact that it was difficult to conduct experimental work at a serial plant, 8 of his machines are in Moscow, and asked to allocate plant No. 241 next to the LII in Bykovo as an additional base for him. But he was refused, and all work on the La-5 M-82NV continued in the old place, and on April 2, 1943, the NKAP order No. 187ss was issued, according to which the plant No. 21 was to immediately begin production of the La-5 with a new power plant, to by the end of the month to hand over 20 vehicles, in May - 100, and in June - 150 over the previously established plan for La-5F.
Specifications for La-5 "type 39" with M-82FNV (Designation M-82FN was approved in the middle of 1943) Lavochkin approved on April 21, 1943. Finally, the following modes were set for the serial engine: take-off (short-term) power 1850 hp, power at an altitude of 600 m - 1530 hp, at the 1st border of an altitude of 1650 m - 1630 hp, at the II border of an altitude of 4650 m - 1430 hp. Compared to the La-5F, the weight of the new aircraft has increased by 55 kg due to the heavier engine.
A new modification of the fighter, which in the second half of 1943 received the designation La-5FN, began to be produced at an increasing pace. Aggregate assembly plant No. 99 in the capital of Buryatia, Ulan-Ude, was connected to the production of the machine. This was the first aircraft that this plant built in a full cycle, not everything went well at first, but the team nevertheless coped with the task.
At first, La-5s were equipped with VISH-105V propellers with wooden blades, which could not be restored in the event of a lumbago or landing on the fuselage. Repaired metal blades for VISH-105V appeared already in 1942, but at first they were enough for only a part of fighters. On July 17, 1943, GKO decree No. 375ss was issued, which required not only to dramatically increase the production of La-5, but also to increase the number of serviceable vehicles in service. It obliged to supply at least 15 of the 17 La-5s delivered per day with metal screws, while at the end of 1942 this figure did not exceed 12.
In the fall of 1943, the LII completed tests of three new propellers manufactured by plant number 467 for La-5FN. Based on their results, from the end of 1943, the VISH-105V-4 was launched into mass production. Thanks to the new speed profiles of TsAGI and the change in the twist of the blades, the aircraft's speed increased by 11 km / h, and the takeoff and takeoff distances were reduced by 30 and 75 m, respectively.
On the La-5, the engine often "cut off" after more than 3/4 of the refueling, and sometimes with a remainder of 100 liters or even more. The defect turned out to be in the drainage system, which did not ensure equal pressure in the wing and in the central tanks. In combat units, this was fought by drilling additional holes in the drain pipes that connected the tanks. In the series, they simply ceased to be installed, using individual drainage of each tank. It's simple, but this solution was implemented only in November 1943.
For Soviet aircraft of that period, oil was thrown out through a prompter - a device that served to lower the pressure in the oil tank in order to prevent it from bursting with rise to a height. On the La-5, they fought with this, limiting the oil refueling from 40 to 35 liters. In the fall of 1943, having studied the FW 190, TsIAM developed and recommended for implementation on the La-5 an oil tank, which did not emit oil up to an altitude of 8000 m.However, apparently, this innovation did not go into production.
June 15, 1943 Shakhurin reported to Stalin about the tests of the La-5 with metal spars, the shelves of which were made of duralumin. The aircraft was lightened by 120 kg. But it was possible to introduce into production such a wing for the La-5FN only by the end of 1943.
They tried to improve the speed and range of the La-5 by using a wing without slats. Such an aircraft was tested at the LII in the fall of 1943, but its corkscrew characteristics deteriorated, and work on this topic was resumed only on the La-9.
From July-August 1943, some of the La-5 aircraft in service began to be equipped with ultraviolet cockpit lighting lamps, which was caused by the intensification of enemy actions at night.
In October 1943, a new instrument panel, developed for La-5 and LaGG-3 in OKB-21, together with LII, received a recommendation for production. It was more ergonomic, with no indirect light screen obscuring part of the panel, with a hinged or detachable middle part for easy access to the equipment behind it.
In the fall of 1943, according to test data at the LII, the charging of shock absorbers of the main landing gear struts was changed: the pressure in the air chamber was reduced from 40 to 25 atm., the amount of fluid in each rack was increased from 550 to 800 ml. This gave an increase in stem travel to 220 mm, providing smoother ground travel and shock absorption during a rough landing.
Although the German cockpit emergency release systems were already known, on domestic aircraft such a possibility was absent for a long time. La-5 only in 1943 received an emergency discharge of the sliding part of the glazing. Repair kits for combat units were made by the 381st plant.
The very low quality of the serial Lavochkins remained a serious problem. In 1943, military tests of the latest modifications of the Lavochkin were carried out, the reason for which was the reports to Moscow by the commanders of units and formations about the shortcomings of the aircraft. La-5F was tested from 14 to 20 August. Used! 9 aircraft, of which 4 were lost during intense air battles, and only one pilot returned to the unit, 4 aircraft were out of order due to damage received, 1 crashed due to engine oil starvation. According to a report from the lead test engineer, the Bf 109F was the most common enemy. Most of the damage occurred in the tail section. The military trials of the La-5FN were much more successful. On 14 aircraft in 25 air battles, 3 Bf 109G, 21 FW 190, 3 He 111H, 1 Ju 87 and 5 Ju 88 were shot down at the cost of losing four of their aircraft.
Control tests of La-5FN No. 39213047F, produced by plant No. 21 in the summer of 1943, showed that the speed at the ground dropped by almost 40 km / h. This was caused by the absence of sealing washers between the cannon barrels and the bonnet, the inability to close the inner bonnet DZUS locks under the exhaust manifold and the poor fit of the bonnet front tie strap (“step” of 10 mm). On the II border of the altitude, the monitoring station failed, and the plane was only able to accelerate to 600 km / h instead of the prescribed 640. The director of the plant was strictly pointed out the shortcomings. But it was not possible to get rid of the marriage. On September 18, Shakhurin appointed a commission for a detailed examination of the quality of the products of this enterprise, which revealed many shortcomings. A debriefing took place, after which the situation began to improve. On the next control tests La-5FN ser. Nos. 0531 and 0540, produced by this plant in October 1943, showed the speed at the ground 572 and 570 km / h, and at the II border of altitude 625 and 636 km / h, which was within the 3% tolerance. The characteristic defects of these machines were the loss of the tail wheel after harvesting and still burning and premature failure of the VG-12 spark plugs.
A lot of criticism was caused by the operation of the centrifugal and pendulum air separation systems on the NB-ZU direct fuel injection pump. In the fall of 1943, the LII conducted tests of the M-82FN motor only with a centrifugal air separator, according to the results of which it was recommended to remove the pendulum system.
In the same year, a neutral gas system was introduced, but at first its effectiveness was insufficient. The reason lay in the safety hole of the receiver, which served to cool the exhaust gases and separate the condensate. In November, holes were welded on all delivered La-5s, and the survivability of the fighters increased.
For a long time it was not possible to complete the epic with the simplified control of the M-82FN engine. Back in 1942, one La-5 was equipped with an experimental M-82A engine with an 82-VG hydraulic unit for combined propeller pitch and gas control, which replaced 2 levers. The old control was not only inconvenient, but also led to excessive fuel consumption - even an experienced pilot could not always clearly correlate the optimal positions of the "gas" and the propeller pitch. Ground testing of joint management at plant No. 21 was delayed due to the lack of specialists, and the car was transferred to the LII. Flights on it began only in the summer of 1943. The unit had many shortcomings, but all of them were removable. It was more difficult to link the 82-VG and the R-7 speed controller. For this, it was necessary to improve not only the control, but also the motor itself. The reference M-82F with "82-VG" began to be tested in August 1943, and at the beginning of the next year the experienced M-82FN was re-equipped for joint control, with which La-5 No. 392116161 passed State tests in July. Since August 1944, the 82-VG unit was introduced into the series.
On August 28, 1944, tests began on the La-5 with cannon electric synchronizers developed by KB-140 NKAP (chief designer Yengibaryan), which made it possible to increase the rate of fire and the reliability of the weapon. But it was not possible to achieve a positive effect, due to the lack of an electric trigger and projectiles with an electric shock capsule in the cannons.
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* Forcing of the engine during 10 minutes.
** On speed making 90 % from maximal.
By the middle of 1943, the enemy began to use the well-armored Hs 129 and FW 190F, for the fight against which two La-5 guns were no longer enough. The designers tried to strengthen the armament by preparing a project for the installation of three ShVAK cannons or two ShVAK and one UB-12.7 machine gun, but the routine of planning tasks did not allow them to tackle this closely. However, the military insisted on increasing the firepower of the fighter. For example, the Chief Engineer of the Air Force, General Repin, on October 8, 1943, sent a letter No. 615576s to the NKAP, demanding an urgent test of the "three-point" La-5. Finally, on October 13, they prepared a draft order for the NKAP to re-equip two La-5FNs under 3 ShVAK with a total ammunition of 450 rounds (on the serial - 340). By that time, the Berezin Design Bureau proposed a new UB-20 cannon, which, with the same rate of fire, projectile and initial velocity, weighed 25 kg, and ShVAK - 42. Lavochkin decided to urgently remake the project for a new weapon. Trials of the La-5FNA were planned to begin on November 15, 1944, but due to a delay in the delivery of guns, the plane was prepared only in January of the following year, and firing in the air began on February 15. After 4 days, the car was taken to the Air Force Research Institute, where the pilots A.G. Kubyshkin and GA. Modestov started State tests. The act on their results was signed in the first decade of March. GKO decree # 5404c on the "three-point" La-5 was issued on March 15, when there was no longer any need for it. With three B-20s, only La-7s were mass-produced, and even then not all of them.
La-5FN was one of the most easily controllable fighters, it kept excellent in deep bends and possessed not only high speed and rate of climb, but also extremely good maneuverability.
La-5FN got to the front in the summer of 1943 and took part in the battle at the Kursk Bulge. Air battles showed the superiority of the La-5FN over the best modifications of German fighters. In terms of its combat effectiveness, the La-5FN in 1943 became the strongest air combat fighter on the Soviet-German front.
The most productive Soviet ace I.N. Kozhedub, who won 45 victories on La-5.
Of the shortcomings, it should be noted that the aircraft remained overweight due to the use of wooden parts.
The temperature in the aircraft cockpit remained high despite attempts to improve sealing. The gaps between the pipes and holes in the firewall remained large, as a result of which air and gases from the engine penetrated into the cockpit,
For 1942 - 1944 the industry produced 10003 La-5 fighters in various modifications.