B-2 is not an aircraft diesel
From the very beginning, it is worth making a reservation and dispelling all doubts: the B-2 was not originally born as an aircraft engine. The situation with this unit is a little more complicated than it seems. At the beginning of the 30s, at the Kharkov steam locomotive plant, the process of developing a whole family of diesel engines under the BD-2 index was launched (it is he who is the predecessor of the legendary B-2, this was discussed in the previous part). We were engaged in diesel engines in three design bureaus. The smallest of the engines was the 1-cylinder, 2-stroke BD-32. And the largest is the 18-cylinder V-shaped 18BD-3, which was planned to be installed on river vessels. Most, of course, were 12-cylinder engines, of which only the BD-2A could be called purely aviation.
It was mounted on the P-5 reconnaissance aircraft at the end of 1935, but the tests had to be interrupted and the development of this modification was postponed altogether. Then they rightly considered that it is much more important to focus on the tank version of the BD-2. Therefore, it would be more correct to say that the B-2 and its predecessor were born as multipurpose diesel engines with remarkable potential for boost and development. In the post-war period, at least 30 modifications of this motor were used in the national economy, which by that time had already been brought to mind.
Engineers-developers of a tank 12-cylinder diesel engine were constantly being driven by senior officials from specialized departments. Everyone tried at all costs to put the diesel on the conveyor. At the same time, many apparently forgot that such a motor had not been developed anywhere in the world before. Even in the homeland of Rudolf Diesel in Germany, they did not dare to take such a step - to develop an expensive and difficult-to-manufacture tank high-speed diesel engine. At the same time, in the USSR, already in 1934, after unsuccessful tests of the BD-2 on the BT tank, they decided to build production facilities for the new engine in Kharkov. Two years later, the modified motor again could not withstand the 100-hour bench tests, and a number of improvements were made to its design. Strengthened the cylinder block and crankcase, increased the stiffness of the crankshaft and optimized the profile of the camshaft cams, and also supplied powerful water and oil pumps. Further, the cylinder liners were nitrided, the piston and connecting rod pins were reinforced. All this was the result of the small experience of domestic engineers with high-speed diesel engines - shock loads on the engine components were unprecedented, and they could not cope with them.
The government understood that the Kharkovites could not cope with their own efforts, and a group of specialists in aviation diesel engines, headed by the famous Timofei Petrovich Chupakhin, was transferred from Moscow. He worked at the Central Institute of Aviation Motors (TsIAM) and was engaged in the development of the AN-1 diesel engine. Timofey Chupakhin in Kharkov received the post of deputy chief designer and by March 1938 (in just a year) managed to bring the B-2 to state tests. To do this, at least 2,000 changes of various scales had to be made to the diesel engine. The motor worked for the prescribed 100 hours, withstood an increase in its own power by 50 hp. with., then another 100 liters. with., which ultimately provided 550 liters at once. with. with an estimated 400 liters. with. Comparative tests of the novelty in comparison with the gasoline M-5 and M-17 showed a higher specific gravity of the engine (even in the "stock" 400-horsepower version), a significant advantage in fuel consumption and an almost twofold increase in the power reserve of the BT-7 tank. However, gasoline engines had a much longer warranty life of 250 hours. And Chupakhin, who by that time had become the chief designer of the engine instead of the repressed Chelpan, generally spoke of a power of 1000 liters. with., which could be achieved by installing a turbocharger. By the way, it was the specialists from CIAM who taught the Kharkovites to make the most critical parts - precision pairs in the fuel pump, bearings, crankshaft, connecting rods …
Growing up period
Timofey Chupakhin is perhaps one of the most underestimated engineers-heroes of the Great Patriotic War. We are used to admiring such geniuses of arms business as Koshkin, Degtyarev, Shpagin and Ilyushin, and the name of the chief designer of the V-2 Chupakhin is undeservedly forgotten. But it was he, being the head of the "400" department, who, together with the team, insisted that the engine should not be put into service prematurely. It was he who brought diesel to mind already in the Urals during the war years. By the way, at one of the moments Timofey Petrovich left the duties of the head of the "400" department and plunged headlong into only one problem - the fine-tuning of a tank diesel engine. In particular, he was very worried about the problem of the gas joint between the block and the head, which did not meet the requirements of tightness. The designer even worked out the idea of a single monoblock and, if not for the war, this solution would have appeared much earlier on the B-2 family. And then they had to confine themselves to a more rigid block head and a new gasket, which quite reliably kept the gases inside the engine. By February 1939, the tank diesel was again brought down in a duel with the M-17T, which the B-2 won uncertainly, but nevertheless. In particular, the commission revealed a high fire safety of a tank with a diesel engine, as well as a reliable start due to the absence of capricious electric ignition. After these tests, the warranty period for the B-2 was recommended to be raised to 200 hours, it was roughly outlined how to achieve this, and on September 5, 1939, it was recommended for production. In total, at first there were three diesel engines: V-2 for BT tanks, V-2K for the KV series, as well as derated up to 375 hp. with. V-2V for the Voroshilovets tractor. In the version for heavy tanks, power increase up to 600 hp. with. was due to the increase in engine speed and average effective pressure. Naturally, this reduced the engine resource to only 80 hours. In January 1940, the first tanks equipped with new diesel engines came from the factories: in Leningrad, Stalingrad and Chelyabinsk.
The Defense Committee, inspired by the success of the new engine, issued a plan for Kharkov in 1940 for 2,700 engines at once, and in 1941 this number increased to 8,000! The only thing that saved the situation was that the production of tanks in the USSR was seriously lagging behind the notorious plans. The first problem in the development of a diesel engine was the unpreparedness of workers for such a high culture of diesel engine production. Accustomed to assembling gasoline engines, factory workers often did not keep up with the tolerances, which invariably affected the quality. At the same time, the shops were equipped with the latest technology with foreign machines, which had to be installed and adjusted without foreign specialists - considerations of secrecy in this case prevailed. This was one of the reasons for the slow introduction of the new motor into the series. Often, the reason for the shortage of working V-2 diesel engines at tank factories was due to the banal absence of high-pressure fuel pumps. And this situation was not resolved until the very end of the war. People's Commissar Malyshev, back in November 1940, complains that the B-2 has too little guaranteed working life and once again demands to increase it to 150 engine hours, and later to 200 in general. This cannot be done, and by the time of the Great Patriotic War, the service life of tank diesel engines, even in the new version of the V-2-34 (it is clear for whom it was intended), did not exceed 100 hours.
In August 1940, a special design department and a motor-building bureau of the Stalingrad Tractor Plant unexpectedly appeared, which offered to abandon the Kharkov diesel engine altogether in favor of their own project. A note with such a proposal was sent to the Central Committee of the All-Union Communist Party (Bolsheviks), where V-2 was formally mixed with mud and offered their own engine, which, they say, would withstand a fantastic 500 engine hours. A number of sources claim that in November 1940 the Stalingrad Tractor still received an order to develop its "unique" tank diesel engine, but by March 1941 it had not provided anything adequate. As a result, the plant was made another site for the assembly of a competitor B-2. Also, the Leningrad plant No. 174 began to prepare for the production of the Kharkov diesel engine.
The end follows …
