WINGED JEEP

Before the war air-6 was one of the few specially designed domestic passenger aircraft, as the main force of the aviation industry was focused on building combat aircraft.

 

 

 

 

 

At the end of the great Patriotic war of OKB A. S. Yakovlev developed two four seat multipurpose aircraft with a 145-horsepower souped-up engine air-cooled M-11M: free-carrying low the Yak-13 with retractable landing gear and strut-braced high-wing monoplane Yak-14, repeating the main design solutions successful pre-war air-6. Both aircraft had an enclosed passenger cabin and slightly differed in mass. During the tests conducted in 1945, the Yak-13 was higher maximum speed, climb rate, ceiling and range of Aircraft recommended by the results of testing in a series of Yak-14, later to be designated Yak-10, were evaluated as being more simple to handle and operate. Soon the Yak-10 was launched at Moscow aircraft factory No. 468 in Texas, to build 40 aircraft in several versions, including the Yak-10V — export with dual controls and Yak-10S — sanitary. In 1946, test pilot F. L Abramov took to the air, the Yak-10S with more powerful 160-horsepower M-11FR-1 — a modification of the same engine A D Shvetsov developed in the twenties for the U-2. Increase of engine power has improved flight characteristics of the aircraft. It became possible to transport two patients on standard stretchers and accompanying medical worker. In the winter of 1947 the Yak-10 with M-11FR-1 ski version ispitati in GosNII GVF; flight characteristics of the aircraft is decreased so that it is recommended to operate only from airfields and rolled wheel option. Also unsuccessful was the attempt to use a UC-10 float options: in 1946 were limited to factory tests Yak-10G. In 1947 the government of the thirty-Yak-10 was sent to the Ministry of Geology of the USSR.

 

October 20, 1947, test pilot OKB-115 F. L. Abramov soared to a new light aircraft designed DPJ used as a coherent and sanitary in the air force, as well as passenger — for local airlines civil air fleet. He received the designation Yak-12 (product 21A). While maintaining the General design decisions on the aircraft performed a number of modifications to improve landing characteristics and requirements of potential customers. Slightly reduced wingspan and wing area, along its entire front edge of a fixed slat, so as to reduce the aerodynamic drag of the aircraft instead of a strut in the design of the pyramidal landing gear has introduced a profiled tape sling, connecting the wheel axle with the mount corded rubber cushioning. Empty weight of the aircraft and the runway remained unchanged These and other improvements have allowed almost twice to reduce the takeoff run of the aircraft during takeoff. The maximum speed of the Yak-12 was reduced by 37 km/h and practical potomok decreased by 500 m. At the same time, the Yak-12 was significantly superior ispolzovalsya for the same purpose polikarovsky-2 not only flight performance, but also comfort for passengers.

 

The Yak-12, as the preceding passenger aircraft of the OKB, was distinguished by simplicity of design up to production machines from domestic materials and limited use of aluminum. Two-spar wooden wing had plywood leading edge and a surface adjacent to the flaps of the flaps and ailerons, and a fabric covering on the rest of the surface. The canvas as tight fitting dural set flaps-the flaps, ailerons and tail. As the spar in the flaps, ailerons and rudders were used dural tube. Spatial truss made of steel pipes had and fuselage. The hood of the engine with individual cylinders and fairings covering the forward fuselage is of sheet duralumin. Behind the cab the outer fuselage formed by two wooden garrote — top and bottom, and the wooden shuttering that is installed on the side bars of the farm. Truss of the fuselage was determined almost triangular shape of the cargo door located on the left side. Not advocating for the contours of the floor of the cargo compartment, the two rear passenger seat in the folded position and the folded-forward the backrest of the right seat pilot is allowed to download through the door of the compartment of a standard stretcher with the patient. From the rear fuselage cargo cabin, separated by a linen partition, mounted on the frame N 5. The aircraft mounted the required minimum flight navigational and radio communication equipment, including radiolucent, RPKO-10M, radio RSI-6M radio and RS-6К47К. At the end of 1947 the Yak-12 has successfully passed state tests and was put into production. With a maximum takeoff weight of the aircraft run-up amounted to 185 m, rate of climb at ground — 2.3 m/s and the maximum speed is 170 km/h. in Addition to the basic variant, the design Bureau has also developed specialized versions: sanitary and Yak-12S and agricultural — Yak-12Сх. In the latter embodiment, in place of passenger seats installed a special tank for fertilizers and pesticides, and under the wing and the fuselage — a device made of profiled aluminum sheet for spraying liquid substances or mechanism with chicken pox to spread seed or granular fertilizer.

 

In 1949 the Yak-12 was equipped with float gear, but the flight characteristics obtained during the test were due to the weak power of the plane below the expected. With two passengers and fuel on the 690 km take-off weight exceed 1300 kg, the run increased to 490 m, and the maximum speed was below 162 km/h For pilot training landing on instruments created Yak-12УТ with dual controls and additional equipment, the supply of which was provided to vetrocamera-Thor. It successfully passed flight tests.

 

Vulnerable point of the Yak-12 was the takeoff performance, dissatisfying the customer. In 1947 the production of engine M-11FR-1 transferred from the Moscow plant № 21 at the Zaporozhye engine plant No. 478, on which the life of the engine in two years increased to 400 hours. At this enterprise in the 30 years attempts have been made to develop on the basis of the M-11 with more powerful engines: 220-horsepower 7-culinray M-48 and 9-cylinder 280-horsepower M-49, but the factory and flight tests due to the lack of the enterprise of means for their production have not been conducted. When in 1949, in Kiev under the leadership of chief designer And G. Ivchenko developed the engine more power and with dimensions suitable for installation on Yak-12, it was installed on the plane. Even with a half-cocked 250-horsepower engine M-14 takeoff performance improved significantly: the length of the run has dropped in half, and the rate of climb doubled.

 

In the summer of 1950, OKB-115 commenced factory testing liaison aircraft Yak-12R with engine takeoff power 260 HP M-14P (this became tested a year ago the Zaporozhye engine). About the author of this model: Alexander Yakovlev recalled.

 

“One evening in the spring of 1950 I was called H. A. Bulganin, who was then Deputy Chairman of the USSR Council of Ministers and Minister of defence, and said that he speaks on behalf of Stalin, who had asked to speak to me: wouldn’t I create a plane that could take off from the small, unprepared areas and to raise, in addition to the pilot, one or two passengers? “Comrade Stalin said that you are a specialist in light airplanes and the job closer to you than the other designers. Think two days to give an answer” — ended the conversation Bulganin. I don’t know why this case was given such a hurry. On another evening, without waiting period, Bulganin called again: “Well, thinking about light aircraft?” Fortunately, the question I have already been worked out and I was able to answer positively. Literally two days later, on 6 April 1950 there was a decision of government, which our design Bureau was instructed in a very short time to create such a machine.”

 

On the plane, in addition to the new engine M-14P with a variable-pitch propeller VISH 502/530В, set all-metal wing with advanced mechanization and new bonnet cylindrical shape; to reduce mileage set front tail wheel brake Shoe with pneumatic drive. Also provided for installation on the aircraft altimeter RV-2, Radiotechnika “friend or foe” “Barium-M”. Half a meter increased wingspan and stabilizer.

 

During factory testing of the aircraft were obtained the following characteristics of the Yak-12P: the run 42 km on the odometer 48 m, landing speed 40 — 45 km/h, the maximum speed of the earth 185 km/h. in the Summer of 1951, OKB-115 was transferred to the state tests in NII No. 15 Navy experienced float version of the aircraft Yak-12R engine with the M-14P and screw-503Р-D11. This time on the Yak-12 and installed a new metal floats and wooden, designed by famous aircraft designer V. B. Shavrov before the war for aircraft air-6A. Been refining and bonnet: plate shutters replaced shaped frontal; on the edge of attack of the propeller established metal fittings. Normal flight weight of the aircraft increased to 145 kg compared to the land option. This happened due to the strengthening of the airframe, installation of additional equipment and increased fuel capacity from 120 to 186 L. In the tests were obtained the following characteristics: maximum speed at sea level — 180 km/h, the length of the run in accelerated version — 166 m, service ceiling — 4360 m.

 

In September 1951, during a stay in the Caucasus, Stalin decided to check on fulfilled his Commission. Next to the cottage, located in a deep ravine in the mountains, he measured in steps of 50 meters and ordered that he delivered mail on a Yak-12 on this site. The pilot performing this task, was not able to sit on a makeshift runway that had no approaches to ensure the safe completion of the flight. Mail delivered to the country of Stalin Mi-1. The situation with the Yak-12 after this check is complicated by the fact that on the same day in the Moscow military district during takeoff crashed another Yak-12 with two generals on Board because of gross violations of flight discipline. Yakovlev was summoned to a meeting of the Presidium of the Council of Ministers and was accused of defrauding the government. Production of the Yak-12 was shut down. It was resumed only after Stalin’s death in 1954.

 

 

Production Yak-12R at this time instructed the Leningrad plant № 272. In 1954 Yak-12R upgraded — it is the standard for production in 1955 received the designation Yak-12M; main differences can be seen on the agricultural version of the new modification (serial number 4640216) received for routine tests in NII GVF. The standard of 1955 was different from the airplanes of this modification of the previous series has been reduced from 40 to 20° deflection angle of the flaps; reinforced main landing gear; increased to 2.5 atmosphere pressure in the tires; the absence of a brake Shoe and actuator; an oil-pneumatic damping tail wheel instead of rubber; the reduced area of the tail of the new form; increased to 25 l capacity oil tank and a 600 mm length of the fuselage, which required the installation of additional frames in the farm of the fuselage.

 

Significant changes occurred in the composition of aircraft equipment: a more powerful generator GSK-1500, the rsiu-3 and automatic radio ark-5. The aircraft is also equipped with two options selhozarteli: sprayer or a pollinator. The normal flight weight of the aircraft increased to 1450 kg; takeoff and landing performance of the aircraft has deteriorated in comparison with the basic version of the machine. The plane is still produced in several versions: passenger, ambulance, patrol, communication, educational and agricultural. Tests were conducted on cables in the field with the Yak-12: the aircraft was mounted with the coil cable, which is unwound from them at low level flight of the machine at a speed of 120 km/h were tested, but not commercially built float Yak-12MM.

 

In may — June 1958 in the air force Institute passed the state tests-and-rescue variant of the Yak-12МС established by a joint technical task force and GVF on the training version of the Yak-12M Machine differed from the standard Yak-12M additional equipment to facilitate the search of distress, — direction finding device of the ARC-VHF (“Inflow” to the antenna amplifier type УА1), to improve visibility in the cabin doors installed blisters. Dismantle the removable parts dual control in front of the right seat, at the workplace of the Navigator near the right rear seat mounted air navigation Vizir AB-52. Under the fuselage on the beam holder 7Ш-756 in Palautordera position in the niche between frames No. 2 and No. 4 was placed a special cylindrical container, developed in OKB-115, or soft parachute bag PDM-47 and the serial parachute containers for liquids PDTG-120. In the compartments of the container, or PDM-47 fit the radio station AVRA-45 carbine of 1944, axe, shovel, rocket launcher, smoke bombs, rockets, ammunition for the rifle, a thermos of water, food and medicines, sunglasses and rope.

 

The radio equipment of the aircraft allowed from a height of 3 km pelengovat radiation emergency radio “Camellia” that is installed in an open area, range up to 60 km and support while two-way radio. When placing an emergency radio station in the forest and reducing the height of flight of the Yak-12МС range of aircraft equipment emergency radio “Camellia” decreased during the flight at an altitude of 600 — 1000 m — 23 — 30 km in open areas up to 18 — 20 km in the forest. The range of detection and the accuracy of determining the bearing of an emergency radio station was also affected by the metallic container, developed in OKB-115: while suspension range direction finding of radiation was reduced from 30 to 15 km; the errors of determination of bearing reached 80 — 90°, which was unacceptable in the rescue efforts, the accuracy of the output plane without the metal container on the suspension or PDM-4 on the emergency radio station was 50 — 100 m when flying at an altitude of 200 -1000 m. the Tests, conducted by a leading test pilot major Ball, leading the assault-nom test-Lieutenant Colonel Zavialov and pilots flying by Colonel Brovtsev, colonels of new summer Podolny and major Mikheev, the plane survived, but could not be recommended for serial construction in connection with the decision to create a wrecking machine on the basis of An-2 and Mi-4 with higher performance characteristics and the possibility of delivery of emergency crews with their landing in the disaster area.

 

The last mass modification of the aircraft — the Yak-12A was built in 1957 For the machine has developed a new trapezoidal all-metal wing with fabric covering and automatic slat, located in front of the Aileron. The main power element of the wing was the caisson formed by the metallic leading edge of the wing and the main spar; the root portion of the spar is bifurcated in the form of the letter And in the plan. The surface of the metal plating was increased to the rear wall of the spar. In place of the fork spar each console mounted fuel tanks with a larger capacity. The number of struts of the wing was reduced to one. The aircraft was fitted with a new engine more power M-14ФР with two-bladed propeller and improved forms. Once again in connection with the increase in maximum takeoff weight, strengthened the chassis. The cab is more comfortable, with upholstered seats; the control knob was replaced with olusturulan, improved visibility from the cab through the windshield and side glass. Despite the increased weight of the maximum speed due to better aerodynamics increased by more than 30 km/h the Yak-12A was built in Leningrad at the aircraft plant № 272 until 1959.

 

In 1955 the production license of Yak-12M bought Poland. After processing of the design documentation under the guidance of the chief engineer of the plant WSK-4 in Warsaw stanisław Las grids, in 1956, produced the first 20 aircraft. Licensed production of engines M-14P mastered at the plant in Caliga. In 1959 WSK-4 mastered the production of Yak-12A, which continued for two years. Only in Poland built of 1,054 Yak-12M and 137 Yak-12A. In 1958, the Polish experts on the basis of the Yak-12M has developed its own modification of the aircraft PZL-101 “Gawron” with increased up to 500 kg payload. In the 1960 — 1969 built 325 “Davronov”. Except for Poland licensed production of the Yak-12 was mastered in China, which produces them under the name “Shenyang” type 5. Soviet Yak-12 was supplied to Hungary, Yugoslavia and Czechoslovakia.

 

In our days you can sometimes see in the sky Yak-12. Restored by aviation enthusiasts, they are still participating in aviation meetings and training camp, held in our country. One of these cars — the Yak-12M was restored tulyak, a former military helicopter pilot S. F. Porechnaya.

 

N. JAY