Fighter La-5FN: flight performance

During the Great Patriotic War, a significant contribution to the cause of victory was made by fighter planes. Despite the fact that the German air force was equipped with such powerful combat vehicles as Messerschmitt Bf 109G and Focke-Wulf FW 190A, Soviet aviation dominated the sky. Airweights Wehrmacht significantly inferior to the product of the designers of the USSR, which was the La-5FN fighter.

What was inferior to the German aviation?

The Soviet fighter La-5FN with maneuvering on the verticals and horizontals was much better than the main German fighter "Messerschmitt" Bf 109G, because after several turns could enter the enemy in the tail and produce targeted fire. This was possible even with almost identical speed indicators, which possessed these two rival models.

The La-5FN fighter did not leave any chances at all for the victory and the German Fokke-Wulf FW 190A. This model was inferior even in speed. The fighter FW190A-8, which appeared in the armed forces of the Wehrmacht, had no advantages in maneuverability over the La-5FN, which had high speed characteristics and good maneuverability, which, combined with the pilot's experience, ensured the victory of the Soviet aircraft in an air battle. According to the instructions issued by the German flight crew, the Soviet fighter La-5FN was considered the most dangerous enemy, in the battle with which the pilots of the Wehrmacht needed exceptional attention and concentration.

Start of creation

In 1941 the designer S.A. Lavochkin was modernized aircraft LaGT-3 - fighter, which at that time had already ceased to meet all the requirements. There was an acute need for a new model capable of withstanding a modern air battle. The basis was taken by LaGG-3.

It was decided to use in the new car a screw-motor group АШ-82ФН with a capacity of 1700 hp. And synchronous twenty-millimeter ShVAK guns. At one time to equip their aircraft with this engine, tried such designers as AI. Mikoyan, S.V. Ilyushin, V.M. Petlyakov and A.S. Yakovlev. But best of all, he took root in the aircraft engine SA. Lavochkin.

Initially, the engine of the AS-82FN did not fit into the fuselage of the aircraft, since it was designed for the M-105 model. But the designers were able to equip their product with a two-row star-shaped engine, so the design, geometry and dimensions remained unchanged in the LaGG-3 glider adopted as the basis.

Thanks to the ASh-82FN engine, the La-5FN fighter received improved maneuverability and speed, which was particularly reflected in the performance of deep bends and vertical maneuvering. The presence in the Soviet La-5 twenty-millimeter cannons SHVAK enabled pilots in aerial battles with German cars to take a defensive rather than a defensive position.

Application in the construction of a new engine

The forced Shvetsov engine ASh-82F was used in such fighters as La-5F (which affected the abbreviation of the aircraft) and La-5FN. The abbreviation of the latter means that it belongs to the forced models with direct injection of fuel.

According to the legend, the equipment of this Soviet fighter with a powerful engine was caused by Stalin's dissatisfaction with the technical capabilities of the AS-82 in the afterburner mode. They were missing for a few minutes. At the behest of Stalin, one such engine was launched in this mode and worked until it failed. The marked time demonstrated a great motor-life - it exceeded 50 hours.

For combat fighters this is good performance. In the design of the La-5FN this engine produced power 1750-1850 hp. And maintained the afterburner mode for at least ten minutes. With a large fuel reserve, the period of such a regime could be extended.

Testing

The La-5FN fighter is one of the modifications of the La-5 aircraft. In the spring of 1942 in Lyubertsy they passed a comprehensive test, after which their design was approved. Testing represented an improvised air battle between La-5FN and the captured Bf 109G-2. After the battle, conclusions were drawn: the Soviet fighter is ideal for working at low and medium altitudes, which were the main ones for the aviation of the Eastern Front.

In April of this year, the State Defense Committee gave permission to start serial production, which resulted in the release of several modifications of the La-5, among which was the La-5FN fighter. The photo below represents the design features of this aircraft.

For what flights was intended?

Air battles at low altitude are considered the main task for which the La-5FN fighter was designed, the device and controllability of which made it the best model in the Soviet aviation of those times. Aileron efficiency and climb rate La-5FN outperformed the German FW 190A-8, which was significantly heavier and had low overclocking characteristics. But the enemy fighter had the ability during maneuvers with dives at high speeds to make a combat turn for attacks on the La-5FN fighter.

The controllability of the Soviet car provided that, by diving at high speeds, it evaded the attacks and itself switched to a position for attack in a shallow climb. This was possible, since the La-5FN had a better climb rate compared to the FW 190A-8, which allowed a German fighter to overtake a steep slope. Among the recommendations that were given to pilots instructors in flight schools in the event of a collision in the sky with FW 190A-8, was a ban on long maneuvering and slowing down. In addition, the pilots should remember that to perform a long afterburner the aircraft is not designed, since the engine's power is calculated less than forty minutes.

Permissible speed

The aircraft could develop speed at cruising power and afterburner. They had different permissible parameters and differed for ground and sea levels.

• The La-5FN fighter on the afterburner could reach speeds of up to 520 km / h.
• At cruising power of this level, the speed was 409 km / h.
• Above the ground level, afterburners were permitted at a kilometer distance. The speed was 540 km / h. It was permissible for cruising capacity, but at an altitude of 2,400 meters.
• For a distance of 5 thousand meters, the cruising power increased to 560 km / h.

The design of the engine, which was equipped with La-5FN fighter, was not adapted for afterburner at a distance exceeding two kilometers. This is due to the peculiarities of the air channel of the throttle, the cross-section of which did not provide the maximum power of the motor.

Fighter La-5 FN. Characteristics

The aircraft was highly appreciated by both Soviet and German, and by British airmen. The La-5FN fighter was considered the best among all the analogues of the Eastern Front.

• The cockpit was designed for only one pilot;
• The weight of the fighter was 3290 kg;
• Dimensions (length and size of the wing) - 8.67 x 9.8 meters;
• The wing area is 17.5 square meters. M;
• The load per wing per square meter was 191 kg;
• The design was equipped with a single engine M-82FN with a capacity of 1750 hp;
• At an altitude of 6250 meters the car developed a speed of flight up to 634 km / h;
• Practical ceiling (maximum height) for a fighter - 10,750 meters;
• The average rate of climb is 16.6 m / s;
• Tanks are designed for 460 liters;
• Weight of oil - 46 kg;
• Two twenty-millimeter SHVAK cannons were available in equipping the La-5FN;
• The fighter is capable of withstanding a bomb load of up to 100 kg;
• The aircraft was intended for distances not exceeding 930 km.

Fighter La-5FN. Device

• The design of this aircraft is characterized by the direct injection of fuel into the cylinders.
• Instead of exhaust manifolds in the aircraft, individual nozzles were used, which were seven in each side.

• The top of the bonnet contained a special air intake.
• The gargroft of the fuselage was lowered, and the shape of the lantern was also changed (they were designed by Yakovlev AS Yak-9 aircraft).
• The use of the instrument panel made it possible to carry out sorties at night and under bad meteorological conditions.
• A number of improvements were made that touched the internal sealing and thermal insulation of the La-5FN cab. The fighter received an improvement in overall aerodynamics.
• To improve the view, the aircraft was equipped with a new lantern, which was added to the emergency situation by an easily removable sliding part.
• The design was completed with a tail wheel. It could be removed during the flight, and with the taxiway self-orientated.
• The twin-wings had plywood lining and contained automatic duralumin slats that could be deflected by 60 degrees with the help of landing flaps if necessary.
• In the production of the fuselage and keel, birch veneer was used. It was made of several layers, which were covered with linen.
• For the installation of a two-row star-shaped engine ASh-82FN, a welded motor halide made of steel pipes was intended. The engine itself was located in a container, which was constructed of lightweight duralumin panels. This provided free access to the motor during its repair or maintenance.

What was the plane covered with?

Most variants of combat aircraft of the La-5 model had a fully wooden design, which was constantly improved. Despite the fact that the tree had fire resistance, the strength of this material was not enough. In the model La-5FN, the developers paid special attention to the protection of the pilot and engine. The tree was replaced by duralumin and iron, which provided uninterrupted and reliable operation of the motor even with splintering hits. The fuel tanks were not armored, and this made them very vulnerable in the event of an attack. The wooden wing spar was replaced by a metal one. For the safety of the pilot and fuel tanks, the fighter began to use armored glass, the thickness of which for the frontal part of the cabin was 57 mm. From this material was made armored head (68 mm). The armored pina was made of 0.7 cm thick steel.

Arrangement of the cockpit

The upper half-sphere of the cab provided good visibility and a circular view. The front visibility was limited. This is due to a low pilot landing. The work of the engine left behind the plane a large train of exhaust gases. The pilot used a high-altitude oxygen system, which was a diaphragm ram-up economizer (the idea was taken from the German economizer system).

If before the pitch of the screw, radiators, blinds, trim tabs and other things were controlled by various hand levers - levers, which was a drawback, because during the battle to accelerate the pilot was distracted when moving the rods, then in La-5FN it was all automated. The pilot could easily control all the aggregates of the propeller group, conduct fire and monitor the operation of the guns, without detaching himself from the combat. Controlled levers only power plant, everything else was done by automatics.

How does takeoff take place?

During the fighter launch, permissible power fluctuations are observed in its engine. A small distance is provided for the take-off of the aircraft. At take-off, the tail of the fighter slowly rises. Piloting is currently difficult, since the clearance from the machine's screw to the ground is small.

Causes of stalling

Any aircraft engine has its own peculiarities and disadvantages when flying. One of the last is stalling. The La-5FN fighter is also not deprived of this shortcoming. Characteristics of stalling by experts are analyzed and taken into account when creating the next, more advanced generations of aircraft. Causes of stalling:

• Decreased speed. When retracting the chassis and flap slats are produced at a speed of 200-210 km / h. As the speed decreases, the efficiency of the ailerons decreases. Slipping the fighter or its braking at 180 km / h leads to its fall on the wing, because at such a speed it is difficult for the pilot to damp the roll. Stalling can occur with the chassis and flaps released, if the pilot continues to pull the lever toward him, as the fighter jumps out to the maximum possible angles for it.
• Performing steep turns. With the rapid deployment of La-5FN, air flows on the wing collapse. With increasing speed, the aileron efficiency decreases brighter. When the fighter accelerates to 320 km / h and reaches an altitude of 2400 meters, which completes a full turn for 30 seconds, the machine's design receives an overload of 2.6G. If it becomes necessary to perform sharp movements by the ailerons, then it is natural to leave the handle in the cockpit of the aircraft in the direction of rotation.

To prevent the aircraft from crashing, there are appropriate instructions on how long it takes to complete a turn at a certain altitude. So, for 2400 meters there are 28 seconds, and at a kilometer altitude, the turn must be performed in 25 seconds.

Flight stability

The fighter is characterized by high stability at any position of the chassis, flaps and during climbing height. Efforts on the handle are insignificant. They increase as the aircraft performs a deep bend. The direction of the rudder is considered satisfactory, but it can decrease - as a result of the low speed with which the La-5FN fighter moves. The controllability of guns in such conditions is not difficult. When the rudder deflects, the nose of the aircraft is raised or lowered. These oscillations, which are also called the Dutch step, are corrected with the help of the steering wheel movements.

Completion of flight

A value of 200 km / h was considered optimal for the speed at which the La-5FN fighter dropped. Landing was carried out on three points. Its implementation was uncomplicated on a flat surface. Otherwise, it was difficult to hold the car on the run. The cause of the difficulties was the uneven braking of the wheels. Very often the fighter planted a nosed nose when landing, as a result of which the screw could be damaged, since this aircraft machine had a limited distance between it and the ground. Significantly complicate the retention of the pilot fighter and strong gusts of the side wind. In such situations, it was impossible to manage using only the steering wheel alone. Therefore, when landing, often resorted to wheel braking.

Despite the existing design problems, the La-5FN fighter was one of the best models of Soviet aircraft technology, which, along with its analogues, provided domestic aircraft with a dominant position in the sky of wartime and made a significant contribution to the victory.