In 1943, intensive experimental studies at TsAGI continued to further improve the aerodynamics of the La-5FN. At the same time, designers improved their aircraft. As a result, at the beginning of 1944, a new La-7 fighter was launched for testing. It was distinguished by a lightweight design (finally, metal spars appeared on La aircraft), reinforced weapons, and better aerodynamic properties. There are two ways to raise the flight data of an airplane: by reducing the weight of the airframe and improving aerodynamics. Lavochkin also managed to reduce the weight of La-5FN of the latest series by about 100 kg by replacing the wooden power set of the wing with metal, while the structural strength remained unchanged. Due to Lend-Lease deliveries and production adjustment in the depths of the USSR, the situation with aluminum was facilitated. Replacing wooden structures with metal is a large reserve of mass saving. One replacement of wooden wing spars with duralumin ones with steel shelves reduced the weight by 100 kg. I must say that by this time there was no longer any delta wood in the airframe design – due to the lack of resin, ordinary pine and birch gradually replaced it from the structure. Drawings of metal wing spars and center wing were developed in the summer of 1943 in Nizhny Tagil at plant No. 381 under the direction of chief designer P.D. Grushin – subsequently an outstanding designer of anti-aircraft missiles.
Given the number of disasters that occurred with La-5, on the “1944 standard” in the back of the lantern of the cockpit they put a more durable frame. The frame could save the life of the pilot if the plane flipped over on takeoff or landing (unfortunately, the frames did not appear on the serial machines, which killed more than one pilot, including the famous ace AF Klubov from the 9th GIAP).
Characteristics of speed and rate of climb can be assessed as “standard”, slightly superior to those of the La-5FN fighter. The maximum speed at an altitude of 6000 m was 680 km / h. Ailerons and elevator control – does not require much effort and does not need further improvements. The lantern provides excellent all-round visibility from the cab. The maneuverability and takeoff and landing characteristics of the aircraft fully satisfy the requirements. Nevertheless, the results had to pay a considerable price.
Due to the transfer of the oil cooler under the fuselage, the oil pipelines had to be drawn directly under the pilot’s feet, due to which the normal temperature in the cockpit was + 40 ° C in winter and increased to + 55 ° C in summer. Considering that exhaust gases of the engine made their way into the cabin, and condensation formed on the windshield, it is quite possible to compare the cabin of the “standard” La-7 with a sauna.
The main external difference between La-7 and La-5FN was the transfer of the oil cooler from under the engine hood to the lower part of the fuselage under the cockpit, and the carburetor and supercharger air intakes to the wing root. Part of the air entering through these intakes was taken for ventilation of the cabin. Air was supplied into the cabin through the openings under the dashboard and in the cabin floor between the rudder pedals and exited through the hole in the tail segment of the cabin lantern. However, for some time production aircraft continued to be produced with ventilation holes in the fuselage in front of the cockpit light. Tests of La-7 with an improved ventilation system were carried out from March 19 to March 23, 1945, 10 flights were completed, Colonel D. G. Pikulenko flew.
In addition to the excellent flight performance, the tests revealed several shortcomings – the hydraulics often refused, interruptions in the operation of the motor were noted. The last defect remained the real scourge of La-7 until the very end of the war; it was associated with the transfer of air intakes from the engine hood to the roots of the wing planes – places more vulnerable to dust from take-off and landing, dust and soil particles led to engine failures. In frosty weather, when the La-7 passed State tests, there was no dust at the airfields, so they could not identify the defect in time. An attempt to get rid of the defect was the installation of filters on the air intakes and the appearance of additional air intakes on the lower surface of the wing planes in front of the wells for cleaning the wheels of the main landing gear legs. State tests modified the aircraft in this way (serial number 38102663 passed from May to the end of June 1945, the test results were found to be unsatisfactory. Engine failures occurred on La-7 much more often than on La-5FN.
Airplanes of various series of production externally differed from each other in small details, such as the shape of the panels covering the joints of the wing and fuselage planes, the location of the handle for opening the cockpit lantern, etc. Often various kinds of minor improvements to the aircraft design were made by the mechanics of the airborne combat units, the most common of which were the installation of a rear-view mirror and improved cabin ventilation.
It was the most advanced fighter KB S.A. Lavochkina and one of the best combat aircraft of the Second World War
The armament consists of two or three 20-mm automatic guns equipped with a hydromechanical synchronizer that prevents shells from entering the propeller blades. Most La-7 fighters were armed with two ShVAK cannons with ammunition of 200 shells per barrel. A relatively small number of La-7s received the initially assumed standard armament of three B-20 cannons with ammunition of 170 shells per barrel. The reliability of the B-20 gun was lower than required, which was confirmed by tests of the three-point La-7 at the Air Force Research Institute.
La-7 production continued until the end of 1945, a total of 6,158 vehicles were built. The NKAP factory No. 21 in Gorky built 4,610 aircraft, the Moscow factory No. 381 -1298, and factory No. 99 in Ulan-Ude – 250 fighters.
La-7 production continued until 1945. In total, three plants (No. 21 in Gorky, No. 99 in Ulan-Ude and No. 381 in Nizhny Tagil) produced 5,905 aircraft.
- Crew 1 pers.
- Wingspan, m 9.80
- Wing Area, m² 17.56
- Aircraft Length, m 8.60
- Aircraft height, m 2,54
- Engine: ASH-82FN 18500 hp (1380 kW)
- Weights, kg: Empty 2605; Curb 3265
- Maximum take-off 3400
- The maximum speed at the ground, km / h 597
- Maximum speed at altitude, km / h 680
- Practical ceiling, m 10 750
- Practical range, km 635