Category Archives: Fighter

Fighter

Yakovlev Yak-3 (Heller)

TYPE: Fighter aircraft

ACCOMMODATION: Pilot only

POWER PLANT: One Klimov M-105PF2 liquid-cooled piston engine, rated at 1,290 hp

PERFORMANCE: 401 mph at 13,451 ft

COMMENT: The Yakovlev Yak-3 was a single-engine single-seat WW II Soviet front line fighter aircraft. Robust and easy to maintain, it was much liked by pilots and ground crew alike. It was one of the smallest and lightest major combat fighters fielded by any combatant during the war. Its high power-to-weight ratio gave it excellent performance. It proved a formidable dogfighter.
The origins of the Yak-3 went back to 1941 when the I-30 prototype was offered along with Yakovlev I-26 (Yak-1) as an alternative design. The I-30, powered by a Klimov M-105P engine, was of all-metal construction, using a wing with dihedral on the outer panels. Like the early Yak-1, it had a 20 mm ShVAK cannon firing through the hollow-driveshaft nose spinner and twin 7.62 mm synchronized ShKAS machine guns in cowl mounts ahead of the cockpit on the fuselage, but was also fitted with a ShVAK cannon in each wing. The first of two prototypes was fitted with a slatted wing to improve handling and short-field performance while the second prototype had a wooden wing without slats, in order to simplify production. The second prototype crashed during flight tests and was written off. Although there were plans to put the Yak-3 into production, the scarcity of aviation aluminum and the pressure of the German invasion led to work on the first Yak-3 being abandoned in late fall 1941.
In 1943, Yakovlev designed the Yak-1M which was a lighter version of the Yak-1. It incorporated a wing of similar design, but with smaller surface area and had further aerodynamic refinements, like the new placement of the oil radiator, from the chin to the wing roots (one of the visual differences with the Yak-1, -7, -9). A second Yak-1M prototype was constructed later that year, differing from the first aircraft in that it had plywood instead of fabric covering of the rear fuselage, mastless radio antenna, reflector gunsight and improved armor and engine cooling. The chief test pilot for the project P. M. Stefanovsiy was so impressed with the new aircraft that he recommended that it should completely replace the Yak-1 and Yak-7 with only the Yak-9 retained in production for further work with the Klimov VK-107 engine. The new fighter designated the Yak-3 entered service in 1944, later than the Ya-9 in spite of the lower designation number.
The first 197 Yak-3 were lightly armed with a engine-mount 20 mm ShVAK cannon and one 12.7 mm UBS- synchronized machine gun, with subsequent aircraft receiving a second UBS for a weight of fire of 2.72 kg per second using high-explosive ammunition. All armament was installed close to the axis of the aircraft (cannon mounted in the engine “vee”, and firing through the propeller boss; and synchronized machine guns in the fuselage above the engine), adding to the accuracy and leaving wings unloaded.
Production accelerated rapidly, so that by mid-1946, 4,848 had been built. Before the end of the war it was also flown by Polish Air Forces (of the Polish People’s Army formed in USSR) and after the war ended, it was flown by the Yugoslav Air Force (Ref.: 24).

Lavochkin La-7 (Italeri)

TYPE: Fighter aircraft

ACCOMMODATION: Pilot only

POWER PLANT: One Shvetsov Ash-82FN air-cooled radial engine, rated at 1,850 hp

PERFORMANCE: 411 mph at 19,685 ft

COMMENT: The Lavochkin La-7 was a piston-engine single-seat Soviet fighter aircraft developed during WW II by the Lavochkin Design Bureau. It was a development and refinement of the Lavochkin La-5, and the last in a family of aircraft that had begun with the Lavochkin-Gorbunov-Gudkov LaGG-3 in 1938. Its first flight was in early 1944 and it entered service with the Soviet Air Forces later in the year. The La-7 was felt by its pilots to be at least the equal of any German piston-engined fighter. It was phased out in 1947 by the Soviet Air Force.
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 TsAGI (Central Aerohydronamics 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 Lavochkin La-5FN 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 had a top speed of 425 mph at a height of 20,180 ft, some 40 mph faster than the production La-5FN. It took 5.2 minutes to climb to 16,404 ft. 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 TsAGI’s 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 La-5FN. 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 gunsight was installed, and a new propeller was fitted. Three prototype 20 mm Berezin B-20 autocannon were mounted in the engine cowling, firing through the propeller, arming the 1944 standard-setter.
The prototype only made nine test flights in February and March 1944 before testing had to be suspended after two engine failures, but quickly proved itself to be the near-equal of the La-5FN. It was 180 kilograms lighter than the earlier aircraft, which allowed the La-7 to outclimb the other aircraft. However it was 20.5 mph slower at sea level, but only 2.5 mph slower at 19,685 ft. The flight tests validated Lavochkin’s modifications and it was ordered into production under the designation of La-7, although the B-20 cannon were not yet ready for production and the production La-7 retained the two 20-mm ShVAK cannon armament of the La-5.
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. Factory 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 prototype.
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 65 kilograms 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 16,404 ft increased by two-tenths of a second over the older model. More than 2000 aircraft were delivered before the war’s end, most by Zavod Nr. 21.
Production of the Lavochkin La-7 amounted to 5,753 aircraft, plus 584 La-7UTI trainers. The follow-up model, the Lavochkin La-9, despite its outward similarity, was a completely new design (Ref.: 24).