[3] 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 (Russian: TsAGI), 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.

[7] Three prototype 20 mm (0.79 in) Berezin B-20 autocannon were mounted in the engine cowling, firing through the propeller, arming the 1944 standard-setter (etalon), as the modified aircraft was named.

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.

Aircraft from both factories were evaluated in September by the Air Force Scientific Test Institute (NII VVS) and the problems persisted as the aircraft could only reach 658 kilometers per hour (409 mph) at a height of 5,900 meters (19,357 ft) and had a time to altitude of 5.1 minutes to 5,000 m (16,000 ft).

[7] 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.

During this time the new fighters made 462 individual sorties and claimed 55 aerial victories while losing four aircraft in combat.

[10] 63rd GIAP regimental commander Colonel Yevgeny Gorbatyuk, a Hero of the Soviet Union, commented: "The La-7 exhibited unquestionable advantages over German aircraft in multiple air combats.

"[10] The twin ShVAK armament inherited from the La-5 was no longer powerful enough to bring down later, more heavily armored German fighters, especially the Focke-Wulf Fw 190, in a single burst, even when Soviet pilots opened fire at ranges of only 50–100 meters (160–330 ft).

[citation needed] 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.

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".

[Note 1] Those aircraft still in service after the end of the war were given the NATO reporting name Fin.

[20] The La-7 ended the superiority in vertical maneuverability that the Messerschmitt Bf 109G had previously enjoyed over other Soviet fighters.

[21] 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.

[15] According to VVS-KA records, only 3 La-7s were actually shot down in air combat in all of 1944 and a mere 10 fell victim to anti-aircraft fire with a further 23 due to non-combat cause.