Aviation of World War II
Created on its basis, the first serial version of the Yak-7 was the trainer Yak-7UTI. Its development began after the first flight of the I-26. The UTI-26-I prototype had much in common with the I-26-II, primarily the M-106 P engine. The same. as on the I-26, there were main landing gear racks and their doors. Disadvantages were also common: engine overheating, oil spillage that splattered the front of the canopy, and a tendency to hood. The chassis was completely unsuccessful, the diameter of the wheels of which did not correspond to the mass of the car. The locks holding the main pillars in the released or retracted position turned out to be unreliable. This caused an accident during state tests - the left leg of the main landing gear broke, and the aircraft's tests had to be interrupted for eleven days.
UTI-26-I, of course, had a two-seat cockpit, communication between the pilot and the cadet was carried out using the RPU (rubber speaking tube, respectfully called the device). The armament consisted of two ShKAS machine guns with 500 rounds of ammunition per barrel. Despite the existing shortcomings, the need for such an aircraft was so great that it was decided to put it into mass production after eliminating the identified shortcomings. The fact that such an aircraft is needed was once again confirmed during state tests, when the UTI-26-I was transferred for two days to the 11th IAP (fighter aviation regiment) in order to retrain the pilots who were supposed to fly the Yak-1 military fighters. series.
Changes and improvements were introduced on the second prototype - UTI-26-II, which was built along with the first one. The chassis underwent significant alterations: the diameter of the wheels of the main struts was increased to 650 mm, and the tail wheel to 300 mm. New landing gear and locks were installed to hold them in their extreme positions, as well as shields for the main landing gear (more on them later). The next important change was an increase in the area of the stabilizer and rudder: from 1.82 m & # 178; up to 1.93 m² and with 1.12 m² up to 1.23 m² respectively. This significantly improved the aerobatic properties of the aircraft, and its stability in flight. There were also other changes, of which the most interesting was the new way of attaching the propeller spinner, copied from the German Bf-109; now its dismantling is greatly simplified.
At the end of the state tests, which took place from January 1 to February 14, 1941, the UTI-26-II received a much more positive assessment from the employees of the Air Force Research Institute than the I-26 six months ago.
The plane was easy to fly, it was difficult to enter a tailspin (and if it was specially forced to do this, then it got out of this situation without problems), takeoff and landing were not difficult. It was just as easy to perform various aerobatics. There was a comfortable cabin and a good view from it.
The prototype was finished so well that after testing it was sent for further operation to the 12th IAP. He served there until another interesting experiment was carried out - in 1942, two DM-4S jet engines were installed on him. However, they shifted the center of gravity of the aircraft forward so much that it “pecked” with its nose on any irregularities. Great was the danger of fire fuel tanks. Therefore, the results of the experiment were considered unsuccessful.
The need to equip flight schools with the new aircraft was so great that, in accordance with the order of the People's Commissariat of Aviation Industry dated March 4, 1941, aircraft plant No. 301 in Moscow had to stop production of the Yak-1 and start manufacturing training aircraft, which received the designation Yak-7 UTI.
The first serial machine number 01-02 was flown on March 18, 1941 by the famous pilot P.Ya. Fedrovi. Although the prototype of the Yak-7 UTI aircraft had the same drawback that constantly haunted Yakovlev's designs - engine overheating, but in serial machines this was avoided by reducing the engine speed from 2700 rpm to 2350 rpm. The design of the aircraft was also simplified due to the abandonment of the right ShKAS machine gun and the mechanism for cleaning the rear wheel.
Moscow factories produced Yak-7 UTI from April to September 1941, i.е. until the moment of evacuation, then production was resumed at plant number 153 in Novosibirsk. A total of 186 machines of this modification were manufactured (after deducting 62 manufactured Yak-7 fighters, it follows that in 1941 145 Yak-7 UTI left the factory workshops).
In the assignment for 1941, the construction of 6,000 training machines was laid down, but the war prevented the implementation of these plans. The front demanded fighters and in the production of "sevens" there was a break that lasted seven months.
Some of the training aircraft, after installing the AFA-1M camera in the rear cockpit, were used as reconnaissance aircraft under the designation Yak-7R, however, it was not officially approved.
For 1941-1944. 6399 Yak-7 aircraft were produced in various versions. Initially created as a two-seat training aircraft, the Yak-7 was converted into a fighter at the start of the war. It turned out that the Yak-7 is superior to the Yak-1 both in terms of armament and survivability. The single-seat combat and two-seat training versions of the Yak-7 had few structural differences and their production was unified, which was of great importance during the war.
It is possible to distinguish the Yaks 1 and 3 from the "sevens" and "nines" in appearance by their characteristic features. The presence of a second cabin led to a shift in the center of gravity of the aircraft, so the water radiators were moved forward. This allows for quick identification: in the Yak-7 and 9, the front edge of the radiators is at the level of the front edge of the cabin, while in the Yak-1 and 3, the front edge of the radiators was located in the middle of its length. In addition, when the planes are on the ground, there is another sign by which it is easy to distinguish between these two lines of fighters: the "ones" and "troikas" had a shield on the main landing gear consisting of two parts, and the "seven" and "nine" - solid.
* On speed making 90 % from maximal.
Yak-7A had the following design improvements:
1. A transceiver station was installed (from the 31st aircraft of the 16th series), which included: an RSI-4 receiver ("Malyutka"), an RSI-Z transmitter ("Eagle"), a radio station control panel, Umformers RUN-30 and RU-11-A, antenna. The receiver was on the right panel of the dashboard, and the transmitter was behind the back of the pilot's seat. The control panel of the radio station is above the right control panel of the cab. The antenna is two-beam, stretched between the mast and the upper part of the lantern behind the pilot. The antenna is equipped with a shock absorber to ensure tightness and integrity of the cord under various aerodynamic loads on the antenna beams. The descent drive is inserted inside the hollow mast. All units of the radio station are interconnected by shielded cables. To ensure a good counterweight to the radio station and eliminate interference with radio reception from alternating electrical contacts, the aircraft was metallized (from the 15th series) - all metal parts are interconnected by conductors (copper tape, film or wire).
2. According to the recommendations of TsAGI, the aerodynamics of the aircraft has been improved. The tail wheel is made partially retractable (from the 19th series). The strut, rigidly connecting the upper part of the crutch with the fuselage truss, was replaced by a pneumocylinder for cleaning the crutch. In the released position, the crutch was held by a ball lock of the pneumatic lifter, and in the retracted position, by corded rubber shock absorbers. The hole in the fuselage after cleaning the tail wheel was closed by a frontal shield.
Additional guards have been installed to completely cover the cutouts for the wheels in the wing when the landing gear is retracted. The shields were released under the action of springs, and were removed using a special mechanism when the wheels were pressed.
The movable part of the rear cockpit canopy was replaced by a plywood cap that leans to the starboard side (from the 17th series). In the closed position, the cap provided a smooth transition from the cockpit canopy to the rear fuselage fairing. The cap was held by a lock opened from the cockpit. The design of the machine gun gas pipes has been changed (from the 17th series). Holes in the hood for gas pipes are closed with removable plugs on clamps. Powder gases were removed from the gas pipes forward.
Reduced the radius of the chute for machine guns in the engine hood.
3. To reduce the takeoff run, the afterburner control of the engine is installed; forced opening of the throttle valve of the supercharger, which increased the volume of air entering the engine and, therefore, increased its power. The afterburner control knob was installed on the left panel on the same axis as the normal gas sector and the altitude corrector.
4. A system for filling gas tanks with neutral (exhaust from the engine) gas (from the 14th series) was installed according to a modified scheme, tested in flight and approved by the Air Force Research Institute.
5. Electric petrol meters were replaced by mechanical float-type ones installed on the right and left wing consoles on the middle gas tanks (from the 16th series). Gasoline gauge pointers are located under the upper skin of the wing and are covered with plexiglass, which allows the pilot to follow the gas gauge needles from the cockpit.
6. The instrument panel was re-arranged (from the 31st aircraft of the 16th series). Plexiglas was removed from the dashboard, which served to evenly distribute the light flux on the instrument scales. The instrument panel was illuminated by reflected light using a bulwark. A voltammeter was removed from the right panel (due to the lack of a device) and an electric gasoline meter pointer with an alarm of the gasoline level in gas tanks (due to the replacement of an electric gasoline meter by a mechanical one). On the left panel of the dashboard, in addition to the landing gear position signaling, a tail wheel position signaling is installed.
7. Fixed the moving part of the canopy in the rearmost position (to prevent the canopy from moving forward spontaneously in flight); a cylinder was installed that provides the installation of wing flaps in two positions: 0 and 55 ° (instead of 0 °; 15 ° and 55 °). A deflection of 15°, which was supposed to be used to shorten the length and time of the run-up and to reduce the radius and time of the turn, turned out to be unnecessary; the handle for adjusting the tension of the shoulder belts with the adjustment mechanism was removed from the left console; the gun reloading system was removed (from the 31st aircraft of the 15th series); left mechanical reloading system; the reducer of the pneumatic system was removed, in connection with which the air pressure in the network increased from 35 to 50 atm.
The armament of the Yak-7A did not differ from the armament of the Yak-7 and consisted of a ShVAK motor gun with 120 rounds of ammunition and two ShKAS synchronous machine guns with a total of 1000 rounds of ammunition. Made only a few constructive improvements in the installation of weapons.
Plant N153, mastering the serial production of Yak-7A aircraft, allowed a deterioration in their flight characteristics: compared to UTI-26-2, the maximum speed decreased near the ground to 476 km/h, at an altitude of 5000 m - to 550 km/h ( on skis - 440 and 520 km / h), the climb time of 5000 m increased to 6.8 minutes. As a result of improved aerodynamics, the maximum speed of the Yak-7A compared to the Yak-7 increased over the entire range of altitudes with a ski chassis by 10 km/h and with a wheeled chassis by 20 km/h (up to 495 km/h near the ground and up to 571 km/h). h at an altitude of 5000 m); the climb time of 5000 m was 6.42 ... 6.8 minutes. In the winter of 1941-1942. The Yak-7A, like the Yak-1, was produced and operated with a ski chassis and winter chalky paint. On skis, the maximum speed in the entire range of altitudes decreased by 30 ... 40 km / h, the time to climb 5000 m increased by 0.7 ... 0.9 minutes, the flight range decreased by 0.9 maximum speed at an altitude of 5000 m for 50...60 km. The length of the takeoff increased by 100 m, the length of the run decreased by 130 ... 150 m (due to greater ski friction on the snow).
Deterioration of flight data of the Yak-7A with a ski landing gear is explained by the increase in resistance due to the insufficiently tight fit of the skis to the wing, as well as an increase in the flight weight by 73 kg.
Winter chalky coloration reduced the maximum speed by 7...10 km/h and slightly worsened other flight characteristics.
In terms of piloting technique, the Yak-7A with a ski chassis was almost no different from the Yak-1. As for the landing, it was even easier, because in case of errors (landing with a roll), the plane almost did not "goat".
The lead Yak-7A, the standard for serial construction in 1942, was a serial aircraft Yak-7 N 14-11 of factory N153, on which the A.S. Yakovlev Design Bureau made the above changes to restore flight characteristics that deteriorated during serial construction. The aircraft was modified at the end of 1941 and passed joint tests (factory and state) from January 16 to February 22, 1942 at the plant N 153.
The Yak-7A was produced at the N153 plant in January-May 1942, a total of 277 aircraft were built, including 13 in January-February.
The Yak-7A proved to be excellent in air battles with Me-109 and FW-190 fighters. The illustrious 434 IAP (32 Guards) Hero of the Soviet Union I.I. Kleshchev shot down 90 enemy aircraft from June to August 1942, and in total during his stay on the Stalingrad front 163 enemy aircraft, i.e. more than any other division.
The Yak-7A had a high survivability. After damage in battle, the aircraft behaved perfectly. There was a case of a safe return of the aircraft to its airfield, when: the right aileron was broken, a piece of the plane with skin and ribs up to the ailerons was torn out; the toe of the wing was torn off to the front spar; the fabric covering of the rudder and from the entire sidewall of the fuselage was demolished; half of the stabilizer console and part of the elevator were broken off; the landing flaps control rod was broken - the aircraft landed with one released and one freely hanging flap; spars belts, aileron rods and other vital structural elements were repeatedly pierced.
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The Yak-7B M-105PA was a further development of the serial Yak-7A and differed from it in more powerful armament and aerodynamic improvements.
The armament of the Yak-7B consisted of a ShVAK motor gun with 120 rounds of ammunition and two UBS synchronous machine guns with a total of 400 rounds of ammunition (left machine gun - 260, right - 140). In addition, six RS-82s or two bombs from 25 to 100 kg each could be suspended under the wing. The armament was successfully tested on the Yak-7B N22-03 in June 1942. 25 flights with a total duration of 7 hours 57 minutes were performed to shoot the weapons. According to the GKO decree of May 10, 1942, the Yak-7B was produced without RSs.
The Yak-7B was fully implemented TsAGI recommendations to improve aerodynamics. In addition to what was done on the Yak-7A, the following activities were carried out.
In order to make better use of the velocity pressure and increase the altitude limits of the aircraft, the intake pipes of the engine have been improved. The entrance to the branch pipes is made flush with the surface of the fairings of the wing and is slightly bent down. The mesh is tilted and recessed inwards. Channels sealed.
The tail wheel was made fully retractable according to the UTI-26-2 type; Improved exterior trim of the aircraft, as well as the fit of shields, fairings, hatches, sections of the engine cowl, etc. To increase the engine speed from 2350...2600, 2550...2700 rpm, which was necessary to improve the takeoff and other characteristics of the aircraft, the adjusting ring was removed from the propeller hub, as a result of which the angle of installation of the VISH-61P propeller blades to small gas decreased from 23 to 20 °.
After state tests, the GKO decided to transfer serial production from the Yak-7A to the Yak-7B. Aircraft Yak-7B M-105PA were produced at the plant N 153 from April to July 1942 and a total of 261 aircraft were built. These aircraft performed well in the battles near Stalingrad and in the Kuban.
An increase in the mass of weapons led to a shift in centering forward and an unacceptable decrease in the anti-bonnet angle. Therefore, in order to avoid nose-over of the aircraft, from May 20, 1942, an additional gas tank with a capacity of 80 liters (60 kg) was installed in the rear cockpit. The pilots were dissatisfied with the installation of such a gas tank, moreover, unprotected, since this increased the flight weight and, consequently, worsened the aircraft's flight performance and, moreover, increased the fire hazard. During the Battle of Stalingrad, this tank was recognized as unnecessary, and to facilitate it, it was everywhere removed from aircraft without any instructions from above. Officially, this was sanctioned by the GKO resolution of September 22 and October 1, 1942.
The commander and military commissar of 202 Iad Jansen and Loban, giving an assessment of the combat qualities of the Yak-7B aircraft according to the experience of using it, wrote that the Yak-7B aircraft in terms of its flight tactical data and armament is the best fighter aircraft of the KA Air Force, especially in comparison with LaGG-Z and MiG-Z aircraft. The Yak-7B aircraft is simple in all types of piloting techniques, stable in flight, and easy to operate. From the experience of many air battles, the following conclusions can be drawn: 1. The Yak-7B easily conducts air combat with the Me-109 on turns and on verticals. On horizontal figures, the Yak-7B has an advantage and quickly enters the tail of the Me-109. The horizontal speeds of the Yak-7B and Me-109 are the same. 2. The Yak-7B lags behind the Me-109F on vertical figures. This is explained by the fact that the Yak-7B is slowly picking up speed, and the Me-109F "goes for gas." In terms of horizontal speed, the Yak-7B is inferior to the Me-109F, while diving it also lags behind, although practically horizontally and diving our pilots had to chase the Me-109F for a very short time, so full conclusions cannot be drawn. Perhaps, with a long horizontal flight and diving, the Yak-7B can catch up with the Me-109F.
The main disadvantages of the Yak-7B: 1. Heavy, which makes it difficult to quickly gain speed. 2. High resistance due to water and oil coolers. 3. Does not have a view back. 4. Bad celluloid in the canopy, which makes it difficult to see and makes it impossible to fly with a closed dome. 5. The engine (especially not forced) does not correspond in its power to the weight of the aircraft. 6. When firing, you have to remove your hand from the gas sector and transfer it to the triggers, which worsens the control of the aircraft, and also knocks down the accuracy of the sight. 7. The lengths of the run and run of the aircraft are large, which requires good "sites" along the length.
The Yak-7B with the upgraded M-105PF engine was a front-line fighter and differed from its predecessor, the Yak-7B M-105PA, mainly in the engine power increased from 1050 to 1180 hp. The increase in power near the ground and at medium altitudes was achieved by changing the adjustment of the automatic boost controller P-7 in the direction of increasing the boost pressure p_k from 910 to 1050 mm Hg.
To ensure reliable operation in forced mode, the piston pins have been strengthened and the adjustment of the carburetors has been changed. The M-105PF engine had no other design differences from the M-105PA.
The initiative to boost the boost of the M-105PA engine belonged to the Design Bureau of A.S. Yakovlev, which at the beginning of 1942 on the serial Yak-7A N22-41 aircraft conducted experiments to increase the boost pressure of the engine successively to 950, 1000 and 1050 mm Hg .st. and by definition in flight the effect that this increase had on the maximum speed and other characteristics of the aircraft.
The results of the experiments turned out to be very encouraging and served as the basis for the adoption of a government decision obliging V.Ya.Klimov to transfer the M-105PA engine from normal to forced operation as soon as possible.
Yak-7B late series
In addition to installing a forced engine on the Yak-7B aircraft (from the 22nd series), a number of measures were taken to improve aerodynamics and reduce the flight weight of the aircraft, mainly by improving and lightening structural elements, without reducing strength and damaging combat and operational qualities. aircraft.
The main changes were as follows: the fuselage truss was lightened; simplified and facilitated seat lifting mechanism (the seat was regulated only on the ground); a new softer and lighter seat back was installed, the plexiglass on the folding cap of the rear cab was replaced with plywood; mooring units were removed; lightened frame and sheathing of wheel domes in the wing; the fuselage formwork was re-made, the landing gear was lightened (towing rings were removed, new upper cups and axle shafts were installed; jet guns and wiring to them were removed; in connection with the forcing of the engine, an additional adjusting ring was introduced into the propeller hub, as a result of which the angle of installation of the propeller blades at a small pitch increased from 20 to 23°, gun pneumatic reloading system was removed.
There were no differences from the Yak-7B M-105PA in armament; in terms of special equipment, the only difference was that the cockpit was made in full accordance with the requirements for a standard fighter cockpit. In the report on the state tests of the Yak-7B M-105PF, it was noted that in terms of its volume and placement, as well as in terms of installation culture, the special equipment of the Yak-7B aircraft is one of the first places among similar types of aircraft, both domestically produced and enemy aircraft.
The Yak-7 with the M-105PF has a shorter flight range at speeds close to the maximum. So, at a speed of 0.9 maximum at the second altitude limit, the range decreased from 700 to 645 km. However, at operating modes of the boosted engine, similar to those of the M-105PA, the flight range practically did not change.
The Yak-7B N22-41 with the M-105PF boosted engine installed on it passed state tests at the Air Force Research Institute from May 30 to June 9, 1942. 36 flights were performed with a total duration of 23 hours.
In 1943, control tests of 13 Yak-7B M-105PF aircraft were carried out at the Novosibirsk plant - 0.6 minutes less. Based on the analysis of the data obtained, it was concluded that in 1943 the Novosibirsk plant complied with the GKO resolutions of November 2 and December 9, 1942 on the maximum speeds of the Yak-7B with a forced engine.
In the same 1943, joint (OKB and LII) tests of the Yak-7B of the 31st series (N31-01) with a forced engine were carried out. The main differences between the aircraft: the antenna and the antenna mast are retracted inside the fuselage; wing tips and plumage are polished to 30% of the chord; installed jet exhaust pipes of two options: OKB - 8 pcs. and the Air Force Research Institute - 12 pcs. The nozzles are enclosed in fairings of the Me-109 type; careful sealing of the propeller spinner and the entire aircraft was carried out to exclude air ducts and reduce drag; improved fit of parts in the air flow; work was carried out to ensure complete cleaning of the tail wheel in flight with a size of 300x125 mm, the socket for it was closed with double-leaf shields; the gaps between the rudders, etc., have been eliminated.
The improved aerodynamics of the Yak-7B M-105PF gave it an advantage over the three-point Me-109G-2 near the ground by 23 km/h and at an altitude of 1000 m - by 16 km/h. At an altitude of 5000 m, the Me-109G-2 outperformed the Yak-7B M-105PF by 23 km/h. Above 5000 m, the speed advantage of the Me-109G-2 became even more noticeable and reached 80 km/h.
The Yak-7B M-105PF was mass-produced at two factories - Novosibirsk N153 from August 1942 (from the 22nd series) to December 1943 (from the 50th series) and at the Moscow N82 - from May 1942 (from 1st series) to July 1944 (28th series). Aircraft of N82 plant had a flight weight of 25...30 kg more, and a maximum speed of 15 km/h less than aircraft of N153 plant.
A total of 5,120 Yak-7B M-105PF aircraft were produced. For the first time they took part in the fighting in August 1942 near Stalingrad.
Directly at the front, the A.S. Yakovlev Design Bureau team carried out work to improve the rear view from the cockpit of the Yak-7 M-105PF - the fairing was cut off, the lantern was given a teardrop shape. From November 17 to December 13, 1942 on the North-Western Front in 42 IAP (commander F.I. Shinkarenko) 240 IAD 6 VA military tests were carried out for combat use.
Test results: 242 sorties, 6 air battles, 4 enemy aircraft shot down, including: Me-109F - 2, He-126 - 1 and FW-189 - 1; their losses - one Yak-7B. The cockpit with improved visibility received positive feedback from pilots and was recommended for use on all fighter-type aircraft.
The Yak-7B M-105PF aircraft, designed to operate in the air defense system, were additionally equipped with an RPK-10 radio semi-compass, an FS-155 landing light on the left wing console, and an electric light signaling the retracted position of the landing gear. Yak-7B MPVO were produced in the following quantities: every 10th, every 100th or in series of 5 ... 10 vehicles. 20 Yak-7B aircraft were delivered monthly to the air defense system.
Tactical Reconnaissance Aircraft
Back in August 1941, on the instructions of the chief designer A.S. Yakovlev at the plant number 301 on the basis of the Yak-7UTI, two prototypes were manufactured in the version of the Yak-7R reconnaissance aircraft with the AFA-IM aerial cameras and the RSI-4 radio station. Metallization and shielding were performed on the aircraft, slats, armored backs, and special glass were installed. The armament consisted of one ShVAK cannon with 120 rounds of ammunition. These aircraft successfully passed state tests at the Research Institute of Special Services of the Air Force in September 1941, but were not serially built due to the great demand for a single-seat Yak-7 fighter.
The Yak-7B M-105PF in the version of a fighter - reconnaissance aircraft was an ordinary serial Yak-7B equipped with an AFA-IM camera and intended for reconnaissance from heights from 300 ... 400 m to 3000 m. A sample of photographic equipment was manufactured by plant number 82 in September 1943, according to the tactical and technical requirements of the Research Institute of Special Services. The installation of a 10 kg camera shifted the aircraft alignment back by 0.5% and increased the anti-aero angle by several tenths of a degree. The camera was located at the starboard side in the second cockpit of the aircraft between the 3rd and 4th fuselage frames, with the motor to the starboard side; the start button is on the control stick of the aircraft. For the passage of light beams in the AFA-IM, a 135 × 135 mm photo port was cut out in front of its lens.
The standard for serial production - the Yak-7B aircraft No. 14-10 of the plant No. 82 passed field tests at the Research Institute of Special Services in October 1943.
On serial Yak-7B aircraft, places with appropriate parts were provided for attaching the AFA-IM photo installation. Therefore, additional equipment of aircraft for photographic reconnaissance could be carried out by combat units directly in the field in accordance with the technical documentation attached to the aircraft. About 350 Yak-7B aircraft with photographic equipment for the AFA-IM camera were produced at factories No. 153 and No. 82.
Yak-7b from 275th IAD, 29th IAP, 1943