In the last article, we examined the issues related to the installation of Nikloss boilers on the Varyag - the bulk of the Internet battles around the cruiser's power plant are devoted to these units. But it is strange that, attaching such great importance to the boilers, the overwhelming majority of those interested in this topic completely overlook the steam engines of the cruiser. Meanwhile, a huge number of problems identified during the operation of the "Varyag" are associated with them. But in order to understand all this, it is necessary first to refresh the memory of the design of ship steam engines at the end of the last century.
In fact, the principle of operation of a steam engine is quite simple. There is a cylinder (usually located vertically on ship machines), inside which is a piston capable of moving up and down. Suppose the piston is at the top of the cylinder - then steam is supplied under pressure to the hole between it and the top cover of the cylinder. The steam expands, pushing the piston downward and so it reaches its lowest point. After that, the process is repeated "exactly the opposite" - the upper hole is closed, and steam is now supplied to the lower hole. At the same time, the steam outlet opens on the other side of the cylinder, and while the steam pushes the piston from bottom to top, the spent steam in the upper part of the cylinder is displaced into the steam outlet (the movement of the exhaust steam in the diagram is indicated by the dotted blue arrow).
Thus, the steam engine provides the reciprocating movement of the piston, but in order to convert it into rotation of the propeller shaft, a special device called the crank mechanism is used, in which the crankshaft plays an important role.
Obviously, to ensure the operation of the steam engine, bearings are extremely necessary, thanks to which both the operation of the crank mechanism (transmission of motion from the piston to the crankshaft) and the fastening of the rotating crankshaft are carried out.
It must also be said that by the time the Varyag was designed and built, the whole world in the construction of warships had long since switched to triple expansion steam engines. The idea of such a machine arose because the steam spent in the cylinder (as shown in the upper diagram) did not completely lose its energy at all and could be reused. Therefore, they did this - first fresh steam entered the high-pressure cylinder (HPC), but after doing its work it was not "thrown" back into the boilers, but entered the next cylinder (medium pressure, or HPC) and again pushed the piston in it. Of course, the pressure of the steam entering the second cylinder decreased, which is why the cylinder itself had to be made with a larger diameter than the HPC. But that was not all - the steam that had worked out in the second cylinder (LPC) entered the third cylinder, called the low pressure cylinder (LPC), and continued its work already in it.
It goes without saying that the low pressure cylinder had to have a maximum diameter in comparison with the rest of the cylinders. The designers did a simpler thing: the LPC turned out to be too large, so instead of one LPC they made two and the machines became four-cylinder. At the same time, steam was nevertheless supplied simultaneously to both low-pressure cylinders, that is, despite the presence of four “expansion” cylinders, three remained.
This short description is quite enough to understand what was wrong with the steam engines of the Varyag cruiser. And "wrong" with them, there was, alas, so much that the author of this article finds it difficult to know exactly where to start. Below we describe the main mistakes made in the design of the cruiser's steam engines, and we will try to figure out who, after all, was to blame for them.
So problem # 1 was that the design of the steam engine obviously does not tolerate bending stresses. In other words, good performance could only be expected when the steam engine was completely level. If this base suddenly begins to bend, then this creates an additional load on the crankshaft, which runs along almost the entire length of the steam engine - it begins to bend, the bearings holding it quickly deteriorate, play appears and the crankshaft gets displaced, which is why the crank bearings already suffer - connecting rod mechanism and even cylinder pistons. To prevent this from happening, the steam engine must be installed on a solid foundation, but this was not done on the Varyag. His steam engines had only a very light foundation and were in fact attached directly to the ship's hull. And the body, as you know, “breathes” on the sea wave, that is, it bends during rolling - and these constant bends led to the curvature of the crankshafts and “loosening” of the bearings of steam engines.
Who is to blame for this design flaw of the Varyag? Without a doubt, the responsibility for this lack of the ship should be assigned to the engineers of the firm of C. Crump, but … there are certain nuances here.
The fact is that such a design of steam engines (when those without a rigid foundation were installed on the ship's hull) was generally accepted - neither Askold nor Bogatyr had rigid foundations, but the steam engines worked flawlessly on them. Why?
Obviously, the deformation of the crankshaft will be the more significant, the greater its length, that is, the longer the length of the steam engine itself. The Varyag had two steam engines, while the Askold had three. By design, the latter were also four-cylinder triple-expansion steam engines, but due to their significantly lower power, they had a significantly shorter length. Due to this effect, the body deflection on the Askold machines turned out to be much weaker - yes, they were, but, let's say, "within reason" and did not lead to deformations that would disable the steam engines.
Indeed, it was originally assumed that the total power of the Varyag machines was supposed to be 18,000 hp, respectively, the power of one machine was 9,000 hp. But later Ch. Crump made a very hard-to-explain mistake, namely, he increased the power of steam engines to 20,000 hp. Sources usually explain this by the fact that Ch. Crump went for it because of the refusal of the MTK to use forced blast during the tests of the cruiser. It would be logical if Ch. Crump, simultaneously with the increase in the power of the machines, also increased the productivity of the boilers in the Varyag project to the same 20,000 hp, but nothing of the kind happened. The only reason for such an act could be the hope that the cruiser's boilers will exceed the capacity established by the project, but how could this be done without resorting to forcing them?
Here already one of two things - or Ch. Crump still hoped to insist on conducting tests when forcing the boilers and feared that the machines would not "stretch" their increased power, or for some unclear reason, he believed that the boilers of the Varyag and without forcing, a power of 20,000 hp will be reached. In any case, the calculations of Ch. Crump turned out to be mistaken, but this led to the fact that each cruiser machine had a power of 10,000 hp. In addition to the natural increase in mass, of course, the dimensions of the steam engines also increased (the length reached 13 m), while the three Askold machines, which were supposed to show 19,000 hp. rated power, should have only 6 333 hp. each (alas, their length is, unfortunately, unknown to the author).
But what about "Bogatyr"? After all, it was, like the Varyag, two-shaft, and each of its cars had almost the same power - 9,750 hp. against 10,000 hp, which means it had similar geometric dimensions. But it should be noted that the Bogatyr's hull was somewhat wider than that of the Varyag, had a slightly lower length / width ratio and, on the whole, seemed to be more rigid and less prone to deflection than the Varyag's hull. In addition, it is possible that the Germans strengthened the foundation relative to the one on which the steam engines of the Varyag stood, that is, if it was not similar to those that were received by more modern ships, it still provided better strength than the foundations of the Varyag. However, this question can be answered only after a detailed study of the blueprints of both cruisers.
Thus, the fault of the engineers of the Crump company was not that they had put a weak foundation for the Varyag machines (as, it seems, did the rest of the shipbuilders), but that they did not see and did not realize the need to ensure the inflexibility »Machines with a stronger body or a transition to a three-screw scheme. The fact that a similar problem was successfully solved in Germany, and not only by the extremely experienced Vulcan, who built the Bogatyr, but also by the second-rate and having no experience in building large warships according to its own design by Germany, testifies far not in favor of the American constructors. However, in fairness, it should be noted that MTK did not control this moment either, but it should be understood that no one set the task for him to monitor every sneeze of the Americans, and this was not possible.
But alas, this is only the first and perhaps not even the most significant drawback of the steam engines of the newest Russian cruiser.
Problem No. 2, which was apparently the main one, was the flawed design of the Varyag steam engines, which were optimized for the high speed of the ship. In other words, the machines worked well at close to maximum steam pressure, otherwise problems started. The fact is that when the vapor pressure drops below 15.4 atmospheres, the low-pressure cylinders ceased to perform their function - the energy of the steam entering them was not enough to drive the piston in the cylinder. Accordingly, on economic moves, the "cart began to drive the horse" - the low-pressure cylinders, instead of helping to rotate the crankshaft, were themselves set in motion by it. That is, the crankshaft received energy from the high and medium pressure cylinders, and spent it not only on the rotation of the screw, but also on ensuring the movement of the pistons in two low pressure cylinders. It must be understood that the design of the crank mechanism was designed for the fact that it was the cylinder that would drive the crankshaft through the piston and the slider, but not the other way around: as a result of such an unexpected and non-trivial use of the crankshaft, it experienced additional stresses not provided for by its design, which also led to the failure of the bearings holding it.
In fact, there might not have been a particular problem in this, but only under one condition - if the design of the machines provided for a mechanism that disconnects the crankshaft from the low-pressure cylinders. Then, in all cases of operation at a steam pressure lower than the set one, it was enough to "press the button" - and the LPC stopped loading the crankshaft, however, such mechanisms were not provided for by the design of the "Varyag" machines.
Subsequently, engineer I. I. Gippius, who led the assembly and adjustment of destroyer mechanisms in Port Arthur, carried out a detailed examination of the Varyag machines in 1903 and wrote a whole research paper based on its results, indicated the following in it:
“Here the guess is that the Crump plant, in a hurry to hand over the cruiser, did not have time to adjust the steam distribution; the machine quickly got upset, and on the ship, of course, they began to fix the parts that suffered more than others in the sense of heating, knocking, without eliminating the root cause. In general, it is undoubtedly an extremely difficult task, if not impossible, to straighten a vehicle that was initially faulty from the factory by ship means."
It is obvious that Ch. Crump is entirely to blame for this shortcoming of the Varyag power plant.
Problem number 3, in itself, was not particularly serious, but in combination with the above errors gave a "cumulative effect". The fact is that for some time, when designing steam engines, the designers did not take into account the inertia of their mechanisms, as a result of which the latter were constantly exposed to excessive stress. However, by the time the Varyag was created, the theory of balancing the forces of inertia of machines had been studied and spread everywhere. Of course, its use required additional calculations from the steam engine manufacturer and created certain difficulties for him, which means that the cost of the work as a whole increased. So MTC in its requirements, unfortunately, did not indicate the obligatory application of this theory in the design of steam engines, and Ch. Crump, apparently, decided to save on this (it is difficult to imagine that he himself, and none of his engineers have anything about this they did not know the theory). In general, either under the influence of greed, or because of banal incompetence, but the provisions of this theory when creating the Varyag machines (and, by the way, Retvizan) were ignored, as a result of which the forces of inertia rendered "very unfavorable" (according to I. I. Gippius) action on cylinders of medium and low pressure, contributing to the disruption of the normal operation of machines. Under normal conditions (if the steam engine was provided with a reliable foundation and there were no problems with steam distribution) this would not lead to breakdowns, and so …
The blame for this lack of steam engines "Varyag" should, most likely, be placed on both Ch. Crump and the MTK, who allowed the vague wording of the order.
Problem # 4 was the use of a very specific material in bearings for steam engines. For this purpose, phosphorous and manganese bronzes were used, which, as far as the author knows, were not used widely in shipbuilding. As a result, the following happened: due to the above reasons, the bearings of the "Varyag" machines quickly failed. They had to be repaired or replaced with what was at hand in Port Arthur, and there, alas, such delights were not found. As a result, a situation arose when the steam engine worked with bearings made of materials of completely different qualities - premature wear of some caused additional stresses in others, and all this also contributed to the disruption of the normal operation of the machines.
Strictly speaking, this is perhaps the only problem whose "authorship" cannot be established. The fact that Ch. Crump's suppliers chose such material could in no way cause a negative reaction from anyone - here they were completely in their own right. It was clearly beyond human capabilities to assume the catastrophic state of the Varyag power plant, to foresee its causes and to provide Port Arthur with the necessary materials, and it was hardly possible to supply the necessary grades of bronze "just in case" there, taking into account the huge amount of all materials for the squadron. the need for which was known for sure, but the needs of which could not be met. Blame the mechanical engineers who repaired the Varyag machines? It is unlikely that they had the necessary documentation that would allow them to foresee the consequences of their repairs, and even if they knew about it, then what could they change? They still had no other options.
Summing up our analysis of the power plant of the cruiser "Varyag", we have to state that the shortcomings and design errors of steam engines and boilers "splendidly" complemented each other. One gets the impression that Nikloss's boilers and steam engines made a sabotage pact against the cruiser on which they were installed. The danger of boiler accidents forced the crew to establish a reduced steam pressure (no more than 14 atmospheres), but this created conditions under which the steam engines of the Varyag had to quickly become unusable, and the ship mechanics could not do anything about it. However, we will consider in more detail the consequences of the design decisions of the Varyag machines and boilers later, when we analyze the results of their operation. Then we will give the final assessment of the cruiser's power plant.
