Lavochkin La-7

By 1943, the La-5 had become a mainstay of the Soviet Air Forces, yet both its head designer, Semyon Lavochkin, as well as the engineers at the Central Aerohydrodynamics Institute (), felt that it could be improved upon. TsAGI refined earlier studies of aerodynamic improvements to the La-5 airframe in mid-1943 and modified La-5FN c/n 39210206 to evaluate the changes. These included complete sealing of the engine cowling, rearrangement of the wing center section to accommodate the oil cooler and the relocation of the engine air intake from the top of the cowling to the bottom to improve the pilot's view. The aircraft was evaluated between December 1943 and February 1944 and proved to have exceptional performance. Using the same engine as the standard La-5FN c/n 39210206 had a top speed of at a height of , some faster than the production La-5FN. It took 5.2 minutes to climb to . It was faster at low to medium altitudes than the La-5 that used the more powerful prototype Shvetsov M-71 engine. Lavochkin had been monitoring TsAGIs improvements and began construction in January 1944 of an improved version of the La-5 that incorporated them as well as lighter, but stronger, metal wing spars to save weight. The La-5, as well as its predecessors, had been built mostly of wood to conserve strategic materials such as aircraft alloys. With Soviet strategists now confident that supplies of these alloys were unlikely to become a problem, Lavochkin was now able to replace some wooden parts with alloy components. In addition Lavochkin made a number of other changes that differed from c/n 39210206. The engine air intake was moved from the bottom of the engine cowling to the wing roots, the wing/fuselage fillets were streamlined, each engine cylinder was provided with its own exhaust pipe, the engine cowling covers were reduced in number, a rollbar was added to the cockpit, longer shock struts were fitted for the main landing gear while that for the tail wheel was shortened, an improved PB-1B(V) gunsight was installed, and a new VISh-105V-4 propeller was fitted. Three prototype Berezin B-20 autocannon were mounted in the engine cowling, firing through the propeller, arming the 1944 standard-setter (), as the modified aircraft was named. FN engine Five La-7s were built in March by Factory () Nr. 381 in Moscow and three of these were accepted by the Air Force that same month. The Moscow factory was the fastest to complete transition over to La-7 production and the last La-5FN was built there in May 1944. Zavod Nr. 21 in Gorky was considerably slower to make the change as it did not exhaust its stock of wooden La-5 wings until October. The quality of the early production aircraft was significantly less than the etalon due to issues with the engine, incomplete sealing of the cowling and fuselage, and defective propellers. One such aircraft was tested, after these problems had been fixed, by the Flight Research Institute () and proved to be only slower than the etalon at altitude. Aircraft from both factories were evaluated in September by the Air Force Scientific Test Institute () and the problems persisted as the aircraft could only reach at a height of and had a time to altitude of 5.1 minutes to . Combat trials began in mid-September 1944 and were generally very positive. However four aircraft were lost to engine failures and the engines suffered from numerous lesser problems, despite its satisfactory service in the La-5FN. One cause was the lower position of the engine air intakes in the wing roots of the La-7 which caused the engine to ingest sand and dust. One batch of flawed wings was built and caused six accidents, four of them fatal, in October which caused the fighter to be grounded until the cause was determined to be a defect in the wing spar. Production of the first aircraft fitted with three B-20 cannon began in January 1945 when 74 were delivered. These aircraft were heavier than those aircraft with the two ShVAK guns, but the level speed was slightly improved over the original aircraft. However, the time to climb to increased by two-tenths of a second over the older model. More than 2,000 aircraft were delivered before the war's end, most by Zavod Nr. 21. A total of 5,753 aircraft had been built by Zavod Nr. 21, Nr. 381, and Nr. 99 in Ulan-Ude, when production ended in early 1946. ==Operational history==

The 63rd Guards Fighter Aviation Regiment (GIAP) began combat trials of the La-7 in mid-September 1944 in support of the 1st Baltic Front. Thirty aircraft were provided for the trials, which lasted one month. During this time the new fighters made 462 individual sorties and claimed 55 aerial victories while losing four aircraft in combat. Four other La-7s were lost to non-combat causes, mostly related to engine problems. A total of three pilots were killed during the trials to all causes. By 9 May 1945 this had increased to 967 aircraft, of which only 169 were unserviceable. For the invasion of Japanese Manchuria, 313 La-7s were assigned and only 28 of these were unserviceable on 9 August 1945. The La-7 was flown by the top Soviet ace of the war, Ivan Nikitovich Kozhedub and was successfully used by him to down an Me 262 jet fighter, one of the few such shoot downs of the war. Kozhedub, a three-time Hero of Soviet Union, scored his last 17 air victories in 1945 in the La-7 numbered 27, which is now preserved in the Central Air Force Museum at Monino on the outskirts of Moscow. One fighter regiment of the 1st Czechoslovak Composite Aviation Division was later equipped with the La-7 after participating in the Slovak National Uprising of August–October 1944 with La-5FN. It remained in service with the Czechoslovaks until 1950 and was designated postwar by them as the S-97. One of these aircraft survives in the Prague Aviation Museum, Kbely. Despite reports to the contrary, no La-7s were ever sold or transferred to the People's Republic of China or North Korea. Such reports arose from misidentification by Western pilots of the La-9s or La-11s that were given to those countries. The British test pilot, Eric Brown, was given the chance to fly an La-7 at the former Erprobungsstelle Tarnewitz Luftwaffe aircraft test station on the Baltic coast, shortly after the German surrender in May 1945. He described the handling and performance as "quite superb", but the armament and sights were "below par", the "wooden construction would have withstood little combat punishment" and the instrumentation was "appallingly basic". Production of the La-7 amounted to 5,753 aircraft, plus 584 La-7UTI trainers. Those aircraft still in service after the end of the war were given the NATO reporting name Fin. The follow-up model, the La-9, despite its outward similarity, was a completely new design. Tactical significance The La-7 ended the superiority in vertical maneuverability that the Messerschmitt Bf 109G had previously enjoyed over other Soviet fighters. Furthermore, it was fast enough at low altitudes to catch, albeit with some difficulties, Focke-Wulf Fw 190 fighter-bombers that attacked Soviet units on the front lines and immediately returned to German-controlled airspace at full speed. The Yakovlev Yak-3 and the Yakovlev Yak-9U with the Klimov VK-107 engine lacked a large enough margin of speed to overtake the German raiders. 115 La-7s were lost in air combat, only half the number of Yak-3s. ==Variants==

La-7TK :One aircraft used to evaluate the TK-3 turbosupercharger in July 1944 in the hopes of improving high-altitude performance. It was destroyed when the TK-3 disintegrated in flight. The rocket was rated at of thrust and its fuel ( of kerosene and of red fuming nitric acid) was expected to last between three and three and a half minutes. While the rocket was firing it increased the fighter's speed by , but the aircraft's other flying qualities deteriorated. Fifteen flights were made in the first quarter of 1945, although the rocket exploded on the ground on 12 May. The aircraft was repaired, but later had an explosion in flight although the pilot managed to land it safely. Details of any later flights are unknown, but the La-7R was displayed at the August 1946 Tushino Airshow with the rocket firing. La-7PVRD :Testbed for two underwing ramjet engines. The aircraft was expected to reach a speed of at a height of , but could not exceed due to the high drag of the ramjets. La-7/M-71 :One aircraft was fitted with the Shvetsov M-71 for trials in 1944. However the engine was not yet ready for service and the program was cancelled. ==Operators==

• Czechoslovak Air Force • Czechoslovak National Security Guard • Soviet Air Forces ==Surviving aircraft==

Czech Republic • 77 – La-7 on static display at the Prague Aviation Museum in Kbely, Prague. Russia • 27 – La-7 on static display at the Central Air Force Museum in Monino, Moscow. It was flown by Ivan Kozhedub. ==Specifications (1945 production model)==