Aviation of World War II
V. Ya. Klimov
Fighters A.S. Yakovlev with engines M-105P and M-105PA at the beginning of the war had some advantages over the Me-109E. But with the appearance at the front of its new modification Me-109F, equipped with a more powerful engine and having improved aerodynamics, the question of urgent improvement of the flight data of Soviet fighters arose very sharply. By this time, the design bureau of V. Ya. Klimov had developed and tested at the stand the M-107 engine, which had a significantly higher power compared to the M-105. The use of this engine would dramatically improve the basic flight data of fighters. However, the M-107 was a completely new design, and its development required time and major restructuring at the factories, which was unacceptable in the conditions prevailing in the first half of 1942. Then, on the initiative of the Air Force Research Institute and the Design Bureau of A.S. Yakovlev, the M-105P motor was re-adjusted in such a way that, due to a slight decrease in altitude, it significantly increased its power. Tests of the engine at the stand showed that with such a boost, its resource practically did not decrease, and it was accepted into production under the M-105PF brand. For the sake of fairness, it should be said that for the serial production of the M-105PF, it was necessary to make some design changes, which are described on the previous page.
Let's just note that the takeoff power on the M-105PF engine became nominal (Table 1). Since 1944 motors V.Ya. Klimov began to be designated by his initials: VK-105PF, VK-106, VK-107, etc.
An interesting work was carried out in the Design Bureau to create a motor with a high altitude. At the beginning of 1941, a two-stage PTsN* was installed on the M-105P engine, which was developed by V.A. Dollezhal. This motor received the designation M-105PD. Two-stage monitoring stations (Fig. 1) provide a significantly higher degree of pressure increase than single-stage ones, even with two rotation speeds. Consequently, with two stages of compression, it is possible to obtain a higher altitude. In practice, even a two-speed single-stage monitoring station cannot provide a design height of more than 5.5 - 6 km.
The M-105PD motor had a rotational speed of 2400 rpm, the boost pressure in takeoff mode was 1140 mm Hg. Art., in the nominal mode at the first design altitude of 1100 and at the second 1080 mm Hg. Art. The installation of the monitoring station and related improvements made the motor 75 kg heavier. The fuel consumption of the M-105PD was noticeably higher than that of the M-105PA. M-105PD motors were installed on the I-28 and Yak-9PD experimental fighters.
Subsequently, two-stage monitoring stations found application on British Rolls-Royce Merlin and American Allison engines, which were installed on Spitfire, R-51, R-63 high-altitude fighters. Combined pressurization systems using turbochargers (TC ) are more efficient: the power consumption for the TK drive is incomparably less than for the monitoring station drive. Combined pressurization systems, however, have hot pipelines for supplying exhaust gases to the TC, which leads to certain inconveniences. These pipelines must be tight and well insulated, which is not easy in itself. Damaging them in battle can lead not only to the failure of the pressurization system itself, but also to a fire on the plane. Therefore, for fighters, for which the efficiency of the engine is of secondary importance, motors with a two-stage monitoring station were more acceptable, especially since constructively creating a motor with a two-stage monitoring station was relatively simple: it was enough to provide an output of the drive shaft of an additional monitoring station and modify the intake manifold system and automation. Pressurization systems with TK were used mainly on engines intended for high-altitude bombers, as well as on some high-altitude fighters, for example, on the American Republican "Thunderbolt" R-47, the engine of which provided a design altitude of about 10 km. However, in the USSR, the problem of the altitude of engines for front-line fighters was not paramount at that time.
The practice of hostilities has shown that the pursuit of altitude is not so necessary: most air battles took place at altitudes up to 4 km, and it was there that the maximum excess power was required. Therefore, in 1943, the M-106P (VK-106P) motor was created with a single-speed monitoring station and a design height of only 2000 m, but with increased supercharging compared to the M-105PF (see Table 1). This made it possible to obtain some gain in power compared to the M-105 and M-105PF at altitudes of 1-3.5 km. Its specific gravity at face value was only 0.48 kg / l, s, and even less in take-off power - 0.44 kg / l. from. This was the minimum specific gravity achieved on Soviet piston engines. Despite the outstanding data of this motor and its complete interchangeability with the VK-105PF, it did not go into large-scale production, only a small series was made. The reason was simple: lack of production capacity and insufficient engine tuning. At this time, preparations were underway for the production of the VK-107 engine, and in large-scale production there were already two M-105P and VK-105PF motors in two modifications each. A lot of motors were required, automobile factories were also involved in their production, therefore, it was possible to put into the VK-106P series only at the cost of reducing the production of serial motors and slowing down the development of VK-107.
Therefore, we had to limit ourselves to further forcing the VK-105PF. The forced motor was designated VK-105PF-2. The takeoff and ground power rating of this engine was 1290 hp. s at 2700 rpm, and the altitude rating is 1240 hp. s at an altitude of 2200 m. This engine was installed on one of the best Soviet fighters Yak-3.
Let's dwell on some of the features of the motors of OKB V, Ya. Klimov. Just as in the Hispano motors, in all V. Ya.Klimov's motors the original design of the connecting rod has been preserved: instead of tightening the connector of the main connecting rod with bolts, as was done on all other motors, here the connection of the cover with the connecting rod was used with shear conical pins pressed into the holes "Combs". The pins, having a very small taper (1:76), were pressed into the holes by the calibrated impact of a freely falling weight from a certain height. This design provides a small size and weight of the crank head, is quite simple to manufacture and has withstood (with some reinforcements, of course) an almost double boost of the motors (from 860 hp for the M-100A to 1650 for the VK-107A). True, the VK-107A engine had two rows of tapered pins instead of one in the VK-105PF. A similar scheme was used by V, Ya. Klimov to attach the crankshaft counterweights to its cheeks. Basically, the design of the block was preserved on the motors of this design bureau: it had a supporting jacket and was cast together with the heads. The sleeves, unloaded, wet, are screwed by the top into the block on the thread. The upper part of the sleeve is sealed with metal elastic rings, and the lower - by a system of rubber rings tightened with a nut.
On the OKB motors, as on the M-25 and M-85 motors, sodium-cooled exhaust valves, bearings filled with lead bronze instead of babbitt, and many other design and technological innovations were used.
Design Bureau V. Ya. Klimov had to constantly increase the power of the motors. The Germans continuously increased the power of their engines: in 1942 - 1943, Messerschmitts with DB-605 engines with a takeoff power of 1600 hp appeared at the front. from.
The capabilities of the VK-105PF without a radical redesign of the structures were exhausted on the VK-105PF-2 modification and the VK-106 engine.
However, back in 1942, the VK-107 engine with a takeoff power of 1650 hp was created. from. - almost twice as large as that of the original M-100A. As mentioned above, its introduction into the series was somewhat delayed. The reason for this was not only the fact that the significantly forced VK-105PF and VK-105PF-2 motors somehow satisfied the needs for motors and their large-scale production was well-tuned, but also that the VK-107 was significantly altered in comparison with these motors. Power increase by more than 300 hp required significant design changes, the main of which were:
completely redesigned cylinder blocks. To increase the flow area of the valves, each cylinder had not three, but four valves - two inlet and two exhaust;
changed valve timing and valve drive design;
modified designs of the crankcase and crankshaft, connecting rods, pistons, valves and a number of other parts and assemblies;
a new gearbox with a gear ratio of 0.5;
a new monitoring station with Polikovsky blades at the entrance.
In a word, it was not a modification, but a completely different engine, in addition still extremely forced - its liter capacity was 42.7 liters at a nominal value. s. / l, that is, exceeded that achieved on the most advanced models of foreign motors.
Naturally, it was very difficult to obtain such parameters, and it is even more difficult to provide a large engine resource with such a degree of boost. Nevertheless, in 1944 the VK-107A engine went into production and was installed on Yak-9U aircraft. The resource of the engine was unusually small - only 25 hours. Although the engine had a combat mode, they practically did not use it in operation, fearing a decrease in the already small resource. The disadvantage of the motor was also the location of the exhaust pipes inside the collapse of the blocks, which caused a lot of complications in operation. In general, this engine did not justify the hopes placed on it, neither the pilots nor the technicians liked it. This was the last serial piston engine of the V. Ya. Klimov design bureau. An even more powerful VK-108 with a takeoff power of 1850 hp created on its basis. from. was put on the Yak-3, and although with it an even higher maximum speed was obtained than with the VK-107A, it never went into production.
Engines V.Ya. Klimov's VK-105PF and VK-105PF-2 were quite reliable, relatively simple in large-scale production and were always at the level of aviation requirements. And in wartime it was not at all easy to ensure this! In fig. 4 shows the altitude characteristics of the engines of this design bureau in comparison with the best engines of this class.
The number of motors transferred to serial production according to the V. Ya.Klimov design bureau is very large: about 15,000 M-100 and M-103 motors in different modifications for SB and Ar-2 aircraft were manufactured, M-105 and М-105А of various modifications for Yak-1, LaGG-3, Pe-2 aircraft - more than 48,000, engines VK-105PF, VK-105PF-2 and VK-107 for Yak-3, Yak-7, Yak-9 and others - more than 28,000, and in total - more than 91,000 only for aircraft factories, not counting supplies to stock, for replacement, etc.
Note (admin) * PTsN - driven centrifugal blower.