Short- range Bomber First flight: 1939 Yakovlev

The Yakovlev Yak-2 (BB-22) was a short range bomber with two Klimov M-103 V-12 engines.

In the Yakovlev Design Bureau, which until 1938 was engaged exclusively in light-engine aviation, L. Shekhter proposed the idea of ​​creating a high-speed twin-engine multipurpose aircraft. The main "highlight" of the project, he considered obtaining the highest flight speed, which should have been provided by the minimum size of the machine, equipped with two M-103 engines with a capacity of 960 hp. These motors were created on the basis of licensed French 12-cylinder engines of the Hispano-Suiza company with liquid cooling. With a design flight weight of 4000 kg, the specific power load was record low - only 2.05 kg / hp. (for comparison: the Soviet I-16 type 24 fighter has 2.09 kg / hp, and the German Bf 109E-3 has 2.44 kg / hp). The wing area of ​​the new aircraft in the draft design was determined to be 27 m², which provided a rather high specific load on the wing at that time - 148 kg / m². In order to reduce the weight, the designers decided to use a one-piece all-wood wing with a span of 13.5 m and a truss (made of steel pipes) fuselage, i.e. use a scheme already well tested on light Yakovlev sports aircraft.

In the Air Force Research Institute, during the tests in the fifth flight, it was possible to accelerate "aircraft number 22" to a maximum speed of 567 km / h at an altitude of 4900 m (taking into account the compressibility of air - 558 km / h). It took only 5.75 minutes to climb 5,000 m, and the ceiling exceeded 10,000 m. According to these data (without taking into account the carrying capacity and flight range), the new aircraft took one of the first places among the machines of its class both in the USSR and abroad ... Comparison with Italian Breda 88, French Breguet 690 and Pote 63, Polish PZL-38 "Vilk" was favorable for our aircraft. The test report emphasized that the speed obtained was not the limit: it could well have been increased to 600 km / h with an improvement in the engine cooling system, a change in the exhaust system and a better selection of propellers.

Plant No. 1 named Aviakhim, one of the most powerful in the country, in March 1940 presented a serial BB-22 with serial number 1012 for testing. The production performance of the machine was so poor that its maximum speed at a design altitude of 5000 m did not exceed 515 km / h.

The lead aircraft, the so-called "aircraft of the first ten" or "aircraft of the military series" in the spring of 1940 passed military tests at the Air Force Research Institute. Their results looked, to put it mildly, disappointing. Once again, the lack of knowledge of the propeller group, the insufficient strength of the wheels of the main landing gear struts. Poor visibility from the navigator's cockpit made it difficult to navigate and reach the target. The armament of the aircraft again turned out to be unsettled: the bomb bay doors did not open, huge efforts were required to drop bombs using the MSH-8, the rear gun mount could not be used for its intended purpose, since the pneumatic system for raising the canopy and the arc of the turret did not have time to work properly.

According to the test pilots, the machines were distinguished by a relatively high landing speed, an unusually steep glide path, and insufficient lateral and track stability. At high alignment, the aircraft would quickly fall through, and the rigid shock absorption of the landing gear was unable to effectively absorb the resulting shock. From the point of view of the operators, the BB-22 was a real nightmare: it took a good half hour to dig up and bury the engines alone. Access to the units turned out to be inconvenient, there were more than 20 drain taps in the cooling system ... The general bleak picture was completed by the vibration of the tail unit, due to which the military tests had to be stopped.

On machines built in the summer of 1940, it was necessary to increase the flow area of ​​the radiator channels again, introduce one more oil cooler (eight-inch) with an air intake on the inner (facing the fuselage) surface of the engine nacelles, and install the twin wheels on the main landing gear legs. The midsection of the engine nacelles has grown somewhat due to the turn of the water coolers perpendicular to the air flow. To improve the defenses on serial vehicles, the gargrot behind the navigator's cabin was lowered according to the model tested during military trials. A DI-6 rifle mount with a ShKAS machine gun was mounted in the navigator's cabin. Starting with vehicle No. 1045, the BB-22 began to install a standard turret of the high-speed aircraft TSS-1, which provided an increase in firing angles and was distinguished by higher reliability.

The production quality of the airframe was still low: the wing skin had waviness, was not smoked, the painted surfaces were rough. The flight weight of the vehicle increased again and reached 5660 kg. At the same time, the specific load on the wing increased to 192.5 kg/m². The maximum flight speed, measured on the serial BB-22 No. 1041, at a design altitude of 4600 m dropped to 478 km / h even in the absence of bombs on the external sling! With a load of 400 kg of bombs in the fuselage and two FAB-50s under the wing, the car could no longer accelerate faster than 445 km / h. Thus, in terms of flight speed, it practically equaled the SB!

Little by little it became clear that in order to turn the BB-22 into a full-fledged bomber, it would not be possible to do with the elimination of the identified defects. Improvement of flight (especially stability in flight) and performance of the machine could only be achieved by radical changes in the geometry and design of the airframe.

Photo	Description
	Drawing Yak-2
	The M-103 engine of # 22 airplane
	Yak-2 with M-103 engine

Tactical Reconnaissance Aircraft First flight: 1939 Yakovlev

The first copy of the aircraft No. 22 had no weapons - it was built only to obtain a record speed. When this goal was achieved, Yakovlev suggested using the aircraft as a close reconnaissance aircraft, the main defensive "weapon" of which should be a speed greater than that of all fighters of those years. The scout was named R-12. Its crew consisted of two people - a pilot and a navigator. They had at their disposal an AFA aerial camera, a ShKAS machine gun on a pivot mount (less convenient than a standard turret, the pivot mount also had a limited firing zone, but it was lighter, simpler and did not go beyond the fuselage midsection) and a second ShKAS mounted motionless in the cockpit pilot.

Reconnaissance flights already at the beginning of the war showed that neither powerful defensive weapons nor altitude can adequately protect the aircraft from attacks by enemy fighters. Only speed could guarantee the safety of the car and the crew.

The R-12 was a cantilever twin-engine monoplane with very clean aerodynamic shapes. In its manufacture, the most common materials in our country at that time were used: Siberian pine, birch plywood, mild steel pipes, canvas. Dural was used only for small hoods and bent parts of the internal set of rudders and ailerons.

The wing of the two-spar design did not have spanwise connectors and was made integral with the middle part of the fuselage. To transport the aircraft by ground transport, it was supposed to undock not the consoles, as usual, but the nose and tail sections of the fuselage. The wing spars are box-shaped, with pine shelves and plywood walls. The longitudinal set of the wing also included several pine stringers, and the transverse set included ribs made of plywood and pine slats. Plywood wing cover. It was equipped with duralumin landing shields and ailerons with linen covering. Wing profile - Clark YH.

The middle part of the fuselage was also solid wood with plywood sheathing. Welded steel trusses of the nose and tail parts of the fuselage were docked to it. At the same time, the nose was sheathed with duralumin caps, and the tail with a canvas. The keels and stabilizer were two-spar wooden, and the rudders were metal with fabric covering. The exterior decoration was done very carefully.

The power plant of the aircraft is two 12-cylinder V-engines M-103 with variable pitch propellers VISH-22K. Water radiators with flaps and air intakes successfully fit into the tail sections of the engine nacelles. Gas tanks were located in the interspar part of the wing to the left and right of the engine nacelles, oil tanks - in the wing toe. In the fuselage between the spars on the R-12 there was a bomb bay for 8 lighting bombs of 20 kg caliber.

The navigator's cockpit, equipped with an AFA aerial camera and a ShKAS pivot machine gun to protect the rear hemisphere, was located behind the bomb bay, in the middle part of the fuselage. The pivot ShKAS was completely hidden in the fuselage, while the plywood fairing of the rear fuselage was lowered down for firing.

Photo	Description
	Drawing BB-22

Attack Aircraft First flight: 1941 Yakovlev

The designers-gunsmiths G.M. Mozharovsky and V.I. Venevidov came up with the idea of carrying out accompanying shooting at a target, in which the barrels of the weapon automatically turn at a certain angular velocity following the moving object of attack. It is not surprising that they made such a proposal. Mozharovsky and Venevidov had extensive experience in the field of aviation weapons, they were the authors of many types of turrets, sights and ammunition systems, knowing well the advantages and disadvantages of these systems. Mozharovsky made his first invention - a periscopic sight for a machine gun - back in 1925, and Venevidov's activity in this field began even before the revolution. Their joint work began in the design department of the experimental aircraft sector of TsAGI under the supervision of A.N. Tupolev, where Mozharovsky led the laboratory that developed rifle installations, and Venevidov was engaged in bomb weapons. Talented and energetic designers quickly worked together, and a team of experienced workers, skillfully selected by them - locksmiths, machine operators and modelers of the highest qualification, made it possible to quickly solve the most complex tasks.

The KABB-MV installation is a combined artillery-bomber battery of Mozharovsky and Venevidov. It included two ShVAK guns and two or four ShKAS machine guns mounted on a common frame rotating in a vertical plane. The ammunition was placed between the cockpit and the engine. The movable frame drive consisted of a 350 W electric motor, two worm gears and a traction system. Due to the rear location of the engine, it was possible to provide the pilot with the best view for detecting a target and conducting aimed fire with large tilt angles of the battery "under himself". The movable frame of the weapon carried an arc to which the K-8T sight was attached. As the angle of deflection of the barrels increased, the aiming point moved synchronously, and the pilot could correct the fire when firing. The angular velocity of rotation of the weapon was variable depending on the altitude and flight speed, which were set by the pilot before the attack by means of special switches on the control panel of the installation. To cover extended and area targets, it was possible to fix the weapon in any intermediate position and fire using the "watering" method. The combination of the attack made it possible, according to the authors, to suppress its resistance with artillery fire and deliver a bombing strike in one approach to the target (this is why the designers called their brainchild "combine").

State tests of the machine at the Red Army Air Force Research Institute were carried out in March-April 1941 under the guidance of a military engineer of the 2nd rank Romanov. The flights were performed by Captain Shevarev. In the conclusions on the tests, it was noted that the installation "KABB-MV with guided weapons most successfully resolves the issue of arming modern attack-type aircraft." Firing from mobile weapons increased the density of destruction in the target area by 2-3 times. The installation made it possible to carry out effective accompanying shooting from strafing flight to a height of 500 ... 600 m and at the same time aimed bombing (for an instantaneous explosion - from heights of at least 300 m). By setting the weapon at an angle of 0 degrees, it was possible to hit point targets from a dive and attack enemy aircraft in the air. At the same time, the testers also identified a number of shortcomings of KABB-MV. So, in the law of aiming weapons, it was necessary to take into account the reduction in the firing distance as it approached the target, which required a variable speed of rotation of the movable frame. It was recommended to automate the release of bombs during the attack, since it was difficult for the pilot to simultaneously control the aircraft and determine the moment of release. The idea was expressed of the need to stabilize the position of the weapon in space in order to compensate for the influence of aircraft vibrations during the attack. In addition, Romanov proposed to increase the caliber of the battery guns to 23-37 mm to suppress small-caliber anti-aircraft artillery at ranges of more than 1000 m before launching a bomb strike.

In general, the opinion of the Air Force Research Institute on the new weapons installation, approved by Major General A. Filin, was positive. But in the process of debugging the installation, it turned out that the carrier aircraft for it was chosen unsuccessfully: the production of the Yak-2 and Yak-4 was stopped. The same fate awaited an attempt to install a battery on the SB. The issue of introducing KABB-MV into the series again turned out to be hanging in the air. As for the BSh-MV, its developers also faced significant difficulties. The project carried too many new ideas, and almost all of them were crude, requiring a long fine-tuning. But the main thing turned out to be that Mozharovsky and Venevidov were a little late with their project. The stage of transition to a new generation of technology in the USSR was ending - three new types of fighters, light and dive bombers, as well as the Ilyushin armored attack aircraft, had already been manufactured and put into series, and these "tits in hands" on the eve of the war were much more valuable than even the most promising projects. In the existing system of weapons of the Air Force, there was no place for such successful aircraft as the I-185, Su-6, and even Tu-2! "Combine" never had a chance to harvest its harvest on the battlefield - it was not built, and the outbreak of war put an end to the history of the BSh-MV.

Armament. Two 20-mm ShVAK cannons and two 7.62-mm ShKAS machine guns (300 rounds for cannons and 1,000 rounds for machine guns). 20 × AO-8 or AO-20 in two cassettes KD-1-1038 or 4 × FAB-50 (FAB-100).

• "The history of designs of planes in USSR 1938-1950" /Vadim Shavrov/
• "Planes of Stalin falcons" /Konstantin Kosminkov and Dmitriy Grinyuk/
• "Stories of the aircraft designer" /Alexander Yakovlev/
• "The Soviet planes" /Alexander Yakovlev/