Aviation of World War II
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A further development of the Yak 1M airframe and powered by the M-105 PF engine VISh-105 SV propeller combination, the Yak 3 was the smallest and lightest combat fighter to see large scale production and use during World War II. The Yak 3 was also the first Russian fighter with a superior performance to contemporary Luttwatle fighters in use on the Eastern Front. At this stage of the war. the Soviet Union was out producing Lultwaffe aircraft in both quantity and quality. The excellent power loading of 4.83 Ib/hp allowed exceptional performance for the Yak 3s relatively low power. A Yak 3 could complete a full 360° turn within 18.5 seconds, something the Lultwaffe pilots could only dream of!
Further attempts to improve the Yak fighter began during the summer of 1942 when K.V. Sinelshchikov was assigned the task of redesigning the Yak to improve endurance, fire power, and combat capabilities. With all modifications directed toward decreasing weight and improving performance a standard Yak 1M fuselage was used as the Yak 3 prototype, which had been fitted with a newly designed wing with a reduced span from 32 feet 9.75 inches to 30 feet 2.5 inches. Original intentions had been to mate the new M-107 powerplant with an anticipated 1500 to 1600 hp, in the event the new engine did not materialize and the M-105PF was retained. A number of aerodynamic refinements were introduced, such as a recounted red oil cooler intake and a one piece frameless windscreen which provided the pilot with excellent all-round visibility. The production version received an enlarged oil cooler under the fuselage resulting in removing the front oil cooler from beneath the nose. The first production batches were equipped with the Yak 1M standard armament of an engine mounted 20mm cannon, and a single 1 2.7mm Berezin UB machine gun in the port upper engine decking, but main production aircraft received an additional similar machine gun in the starboard decking.
Prototype flight trials began during early 1943 in Moscow with high-speed flight trials far exceeding expectations. 410 mph at 9.840 ft and 422 mph at 12.140 ft with low level characteristics being particularly pleasing. The loss of the prototype due to a structural failure during aerobatics delayed full State Acceptance until October of 1943. but demands from front line pilots for a more efficient fighter forced the Red Air Force to introduce the fighter into Service before completion of State Acceptance.
The Yak 3 saw action for the first time in June of 1943 at the end of the German OPERATION ZITADELLE in the Kursk area, and pilot's comments were enthusiastic about the combat value of the new weapon. The Yak 3 provided a real challenge to the Messerschmitt Bf 109F and G and the Focke Wulf Fw 190A Ideally suited for low altitude combat operations, light stick pressure produced fast and accurate snap rolls and all maneuvers could be performed precisely and smoothly. But it demanded careful handling at low speeds, stalling speed was high and the Yak-3 tended to drop a wing during the landing approach unless speed was kept up. It tended to swing on take off and landing, and ground loops were not uncommon among green pilots.
Large scale production of the Yak 3 was begun at GAZ 115 and GAZ 286 during the spring of 1944, only reaching front line fighter regiments in quantity during the summer of 1944. Technical and structural problems had delayed development for some time. The undercarriage in particular was considered unreliable on hard field conditions.
A total of 4560 Yak-3 was built during 1944 - 1945.
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* Forcing of the engine during 10 minutes.
** On speed making 90 % from maximal.
The Yak-3P (cannon) with three B-20 cannons of 20 mm caliber was a modification of the serial Yak-3 aircraft with a VK-105PF2 engine and differed from it mainly in armament.
Instead of a ShVAK motor cannon with a supply of 120 rounds and two synchronous UBS machine guns with a supply of 150 rounds each, the Yak-3P was equipped with one B-20M motor cannon (120 rounds) and two synchronous B-20S (130 rounds each) . In this regard, the layout of weapons installations has changed. The mass of weapons and ammunition became 11 kg less than that of the serial Yak-3P, the mass of weapon mounts remained practically unchanged. Fire control for all three points on the aircraft was pneumoelectric and was carried out by two combined systems. Pneumatic reloading has been introduced for the motor gun instead of a mechanical one. Experimental cannons B-20 in synchronous and motor versions passed state tests at the Research Institute of the Air Force and were adopted by the GKO decree of October 10, 1944.
The mass of a second salvo for the Yak-3P is 3.52 kg/s; for comparison: Me-109G-6 had 2.74 kg / s, Me-110 - 2.85 kg / s, FW-190A-8 - 3.44 kg / s, Spitfire IX - 3.10 kg / s, "Aerocobra" P-39Q-10 - 3.18 kg / s. When firing from B-20 cannons in the entire range of speeds and with all evolutions, the Yak-3P behaved stably. The impact on the aiming of the fire had little effect.
The middle parts of the ribs were also reinforced on the aircraft; locks were installed on additional chassis shields; improved gasoline meters with a scale increased to 160° were installed; the Venturi tube was moved from the water radiator tunnel to the wing fairing; radio receiver RSI-4A was replaced by RSI-6M.
The modification was made by OKB A.S. Yakovlev by the decree of the State Defense Committee of December 29, 1944. This decree provided for the development of two copies of the Yak-3P by January 15, 1945 and the organization of their serial production from February 1945. March 23 to April 9, 1945 (pilot V. G. Ivanov, chief aircraft engineer I. A. Kolosov, armament - A. G. Aronov). 37 flights were made with a total duration of 17 hours 39 minutes.
According to the results of state tests, it was noted that an aircraft with three B-20 guns is needed for the Air Force.
At the same time, an attempt to install B-20 guns on La-7 ended in failure due to the low reliability of these guns. Of the three aircraft (serial numbers 45214414, 45214415, 45214416) that took part in the tests, none of them managed to achieve the required indicator of 5000 shells fired from one aircraft without failures. For all three aircraft, failure occurred after a little more than 3,000 rounds had been fired. Reliability indicators were achieved only with the installation of NS-23 guns on the aircraft.
The Yak-3P was serially built at factories N 292 in Saratov and N 31 in Tbilisi from April 1945 to mid-1946. From August 1, 1945, all Yak-3P VK-105PF2 were produced with only three guns B-20. A total of 596 Yak-3Ps were built.
Yak-3U with air-cooled radial engine ASh-82FN A.D. Shvetsov and a VISH-105V4 screw with a diameter of 3.1 m was a single-seat front-line fighter and was a modification of the Yak-3 VK-105PF2 production aircraft.
The modification pursued a dual goal: firstly, replacing the capricious, unreliable VK-107A engine with a more powerful, reliable and improved ASh-82FN and, secondly, creating a fighter that would surpass all those in service in all respects Air Force fighters with both liquid and air-cooled engines.
To achieve this goal, in addition to installing the most powerful engine available (takeoff power 1850 hp), it was planned to make the structure as light as possible and improve the aerodynamics of the aircraft.
In addition to changes in the VMG (new engine mount, hoods, exhaust system, oil system, etc.), the following main measures were taken on the aircraft: the wingspan was increased from 9.2 to 9.4 m 0.5 m²); the wing in relation to the fuselage is shifted forward by 219 mm to increase the anti-bonnet angle; soft gas tanks were installed instead of metal ones; the capacity of gas tanks is increased by 110 l; changed the contours of the middle part of the fuselage; to improve forward visibility, the cockpit is raised up by 84 mm; plywood sheathing and fuselage formwork, canvas sheathing of the ailerons, wooden stabilizer and keel, as well as steel elevator rods were replaced with duralumin; to ensure ease of movement of manual control, the latter is mounted entirely on ball bearings; to prevent suction of the landing shields and landing gear, as well as spontaneous loss of the tail wheel in flight, they are all equipped with additional locks that hold them in the retracted position.
The armament consisted of two B-20S synchronous guns with 120 rounds of ammunition. The special equipment was similar to the equipment of the serial Yak-3 VK-105PF2.
As a result, compared with the Yak-3 VK-105PF2, the flight weight increased by 113 kg and amounted to 2792 kg according to the calculation; empty weight - 2273 kg, payload 519 kg (pilot - 90 kg, gasoline - 340 kg, oil - 35 kg, ammunition - 54 kg).
Despite this, the flight weight was a record low for aircraft with engines of comparable power. For example, it was 192 and 473 kg less, respectively, than that of the experimental Yak-3 VK-107A of mixed design and La-7 ASh-82FN. The installation of the ASh-82FN engine on the Yak-3, while simultaneously reducing the flight weight and improving aerodynamics, should have significantly improved its flight characteristics. According to the calculation, the speed compared to the serial Yak-3 VK-105PF2 at the estimated height increased by 65 km / h to 705 km / h (at an altitude of 6100 m), and the climb time of 5000 m decreased by 0.55 min to 4.0 min. However, the forward displacement of the wing, which had a positive effect on stability and controllability in flight, led to an unacceptable decrease in the anti-bonnet angle: up to 21 ° 20 'for rear centering and up to 18 ° - for forward centering, which made the aircraft dangerous for taxiing and landing.
The Yak-3U was built by OKB A.S. Yakovlev by order of the GKO in one copy from January 20 to April 23, 1945 (construction started in Novosibirsk and completed in Moscow), passed factory tests from April 29 to June 9, 1945 at the Central Airfield of Moscow. The first flight took place on May 12, 1945. 19 flights were made with a total duration of 8 hours and 40 minutes. Lead test pilot P.Ya. Fedrovi, lead designer V.V. Barsukov, lead test engineer A.M. Druzhinin and mechanic A.M. Gusev.
A speed of 682 km/h at an altitude of 6000 m and a climb time of 5000 m of 3.9 minutes were obtained.
After completion of factory tests, the aircraft was returned to the design bureau on June 15, 1945 for revision, during which a metal wing was installed instead of a wooden one; increased efficiency of the elevator trimmer; the anti-bonnet angle has been increased to 25° due to an increase in the chassis offset by 80 mm and an increase in the angle of installation of the pivots; the engine hood was sealed and some other work was done. The flight weight due to the metal wing was to be reduced from 2792 to 2740 kg.
The finalization was completed on September 25, 1945. The aircraft turned out to be generally successful. However, by the end of the war, it was no longer needed, so the tests did not pass and all work on it was stopped.
The aircraft stood in the workshop for eleven months, and then was transferred to the flight test station of the Design Bureau "for storage", where it was subsequently decommissioned.
On the basis of the Yak-3U, a machine for a different purpose was created - the Yak-U training aircraft ("training fighter") with an air-cooled ASh-21 engine, which in the series received the name Yak-11.
The Yak-3 with the VK-108 engine was a modification of the Yak-3 with the VK-107A shifter. This work was essentially experimental in nature and was aimed at obtaining comparative characteristics of aircraft with VK-107A and VK-108 engines.
The Yak-3 VK-108 differed mainly in the new propeller group and armament: instead of the VK-107A engine with a rated power of 1500 hp. with. installed VK-108 with a nominal power of 1550 liters. with. with a very intense thermal regime; instead of two 20 mm B-20S synchronous cannons with 120 rounds of ammunition, one HC-23 23 mm caliber motor gun with 60 rounds of ammunition was installed.
In connection with the installation of a new engine, the following main changes have been made to the VMG of the aircraft: the propeller VISH-107SV-1 has been replaced by VISH-107LT-5; slightly modified motor mount; installed water cooler OP-624 and oil cooler OP-622 (instead of OP-554 and OP-555), which had a greater cooling capacity; the water radiator tunnel is lowered down by 60 mm; exhaust manifold replaced with separate exhaust pipes; the top cover of the hood is made without grooves for gun barrels; the suction pipe is brought out under the engine; fuel capacity has been reduced from 390 to 350 kg, and oil has been increased to 55 kg.
Some changes have also been made to the design and equipment of the aircraft: the cockpit canopy is made like that of the experimental Yak-3 VK-107A "Doubler"; more thorough sealing of the rear fuselage; the ailerons are sheathed with duralumin instead of canvas; the rear bulletproof glass was removed and an old-type armored back (Yak-1) was installed, etc.
As a result of these, as well as some other smaller changes made specifically to lighten the aircraft, the flight weight has decreased to 2896 kg.
The Yak-3 V K-108 was built in the design bureau in two months - from August 1 to October 1, 1944 and passed factory tests from October 7, 1944 to March 8, 1945 with a flight weight of 2830 kg (reduced by removing weapons and incomplete refueling with gasoline and oil).
Test pilot V.L. Rastorguev, lead test engineer A.N.Kanukov, mechanic F.3.Sbitnev. The first flight took place on December 19, 1944. In total, five flights were made with a total duration of 1 hour 17 minutes.
The aircraft showed outstanding flight characteristics. The maximum horizontal speed at an altitude of 6290 m, obtained in flight on December 21, was 745 km / h and was close to the world record of 755 km / h, set in 1939 on a specially modified racing version of the Me-109. Climb time 5000 m - 3.5 min. The takeoff run was noticeably reduced - the plane took off from almost three points.
Since the Yak-3 VK-108 differed little from the Yak-3 VK-107A in terms of design, it also had the disadvantages of the latter. The experimental VK-108 engine had a very intense thermal regime (high heat transfer). For example, during the flight on December 21, the oil temperature on the "site" reached the maximum allowable value of 110°C. Due to the lack of knowledge of the engine (shaking, smoking, frequent failures), factory tests were accompanied by long delays. After the flight on December 21, they were interrupted to replace the engine, and on March 8, 1945, after the first flight with the new engine, they were discontinued due to unsatisfactory engine operation.
In 1945, another attempt was made to install the VK-108 on the Yak-3. The work was carried out under the guidance of the chief engineer of the Design Bureau V. G. Grigoriev from August 1 to November 1, 1945. The aircraft differed from the previous one only in that it had two B-20S synchronous guns with 120 rounds of ammunition (as on the Yak-3 VK-107A ). This attempt also did not give the desired results. The order of the NKAP dated May 28, 1946 provided for the construction of three experimental Yak-3 VK-108 aircraft at the N31 plant (by September 1, October 1 and November 1, 1946), but in fact the Yak-3 VK-108 remained in one instance.
Further work was not carried out due to the lack of knowledge of the engine, as well as the need to transfer the work of the Design Bureau on combat aircraft to jet topics.
Comparative Analysis of Designs and FTD of Soviet and German Fighters that Took Part in the WWII
Flight Technical Data - FTD
The final milestone in the development of the Yak-1 design was the Yak-1M, which appeared in mid-1943 and was renamed Yak-3 when it was launched into series. The main differences from the previous modifications: metal spars and wing ribs were used instead of wooden ones, which gave tangible weight savings. The wing itself is reduced in span and area, and the stabilizer and keel are also slightly reduced. Instead of one oil cooler located under the engine, two smaller sizes are installed, transferred to the root of the wing. The linen covering of the aft fuselage was replaced with plywood. The outlines of the cockpit canopy have become smoother and smoother. The takeoff weight of the vehicle dropped to 2690 kg.
The M-105PF-2 engine (hereinafter - VK-105PF-2, since since 1944 the engines in the USSR were given new designations according to the initials of their developers: VK - Vladimir Klimov), boosted to 1250 hp. at an altitude of 2000 meters. The armament consisted of a ShVAK motor-gun and one (in the first 197 copies), and then two synchronous UBS heavy machine guns.
The aircraft was produced in large series since March 1944. A total of 4,200 aircraft were built, but some of them were already built after the end of the war.
Due to a decrease in take-off weight, improved aerodynamics and an increase in engine power, the Yak-3 had the highest flight performance of all Yakovlev fighters that took an active part in the Great Patriotic War. Its specific power load was 2.12 kg/l with (like the Bf 109F-4), the maximum speed reached 644 km/h at an altitude of 4000 m, the rate of climb at the ground was 22 m/s, and the minimum turn time was 21 s. These numbers can certainly be considered outstanding. According to its flight data, the Yak-3 was superior to the later modifications of the Messerschmitt, with the exception of speed at high altitudes.