Aviation of World War II
V. Ya. Klimov
Compared to its predecessor, the engine has undergone a fundamental modification. To increase power at low and medium altitudes, a two-speed driven centrifugal supercharger with gear ratios of 7.85 and 10 was installed on the motor, which allowed not only to increase power at low altitudes, but also to avoid a significant power "dip" at altitudes from 3 to 6 km.
Compared to the M-103A and M-104 engines, it underwent significant structural improvements, the main of which was a fundamental change in the circuit of the motor itself:
to improve the filling of the cylinders on each of them, two intake valves were installed instead of one, and the free cross-section of the intake valves increased by almost one and a half times, and the exhaust valves - by 15%. This made it possible not only to boost the engine in terms of speed, but also to lay the foundation for a further increase in power, since the M-105 had a higher takeoff power with a lower boost than the M-103A and, with the same boost, high power in the entire altitude range ...
There are two exhaust valves instead of one. Counterweights were installed on the crankshaft to reduce the loads on the main journals.
Of course, such a radical change in the motor circuit led to a complete redesign of the block design and the gas distribution system. Among other design changes, we note: a new two-speed transmission to the monitoring station, significantly improved in comparison with the M-104; increasing the compression ratio to 7.1; installation of counterweights on the crankshaft to reduce the loads on the main journals.
The motor turned out to be very successful and was installed on many production aircraft, in particular, on the Yak-1, Yak-7 and LaGG-3 fighters, Pe 2, Ar 2 and Yak-4 (BB-22) front-line bombers, and many experienced planes. It had several modifications, of which it should be noted the M 105R with a reduced gear ratio (0.59 instead of 0.666) for bombers, and the M-105P, which allowed the installation of a gun in the collapse of the blocks.
The M-105 engine modifications
M-105 Basic modification.
M-105R Installed on bombers, had a reduced gear ratio (0.59 instead of 0.666).
M-105RA Modifications in 1941. Further design improvements, in particular, reinforcement of the crankcase and the main connecting rod, hyperbolic boring of the crankshaft bearings to reduce wear, installation of a more reliable floatless carburetor.
M-105PA Improved design. By reducing the altitude, the power was increased.
M-105P "Cannon". Allowed the installation of a gun in the collapse of blocks.
M-105PF (VK-105PF, instead of the M-motor, designated by the name of the designer - Vladimir Klimov). Forced version of the M-105P engine. By slightly lowering the altitude compared to the M-105P, the M-105PF engine significantly increased its power. For serial production, it was necessary to strengthen the piston pins, modify the crankshaft, strengthen some parts of the PNTs and other units. The M-105PF engine was quite reliable and simple in large-scale production. During the Second World War, about 91,000 M-105 engines of various modifications were manufactured, of which more than 28,000 were M-105PF engines. VK-105PF engines were installed on LaGG-3, Yak-1, Pe-2, Yak-7, "105" and others.
M-105PF-2 (VK-105PF-2) VK-105PF-2 piston engine. The capabilities of the M-105PF (VK-105PF) model were exhausted precisely on this modification without a radical redesign of the design. VK-105PF-2 had characteristics slightly exceeding the characteristics of its prototype VK-105PF and, most importantly, did not require additional equipment and tooling in the development and production of additional equipment and tooling, which allowed serial plants to switch to its production from the previous modification almost without stopping. The uprated engine had a takeoff and rated power of 1290 hp, and an altitude rating of 1240 hp. at an altitude of 2200 m. The VK-105PF-2 engine was installed on the same aircraft as the VK-105PF, and it was also installed on one of the best Soviet Yak-3 fighters.