For a time Hitler's Germany did not pay much attention to the projects of gas turbine power plants for land vehicles. So, in 1941, was assembled the first such unit for the experimental engine, but his tests are quite quickly turned because of economic inexpediency and the availability of higher-priority programs. Work in the direction of gas-turbine engines (GTE) for ground vehicles was continued only in 1944, when especially clearly manifested itself some negative features of the existing technology and industry.
In 1944, the Directorate of armament of the land forces launched a research project on the topic of GTE for the tanks. In favor of new engines cited two main arguments. First, the German tank at that time took a course on the weighting of combat vehicles, which required to deliver an engine with high power and small size. Secondly, all available armored vehicles were used to some extent scarce gasoline, but it imposes certain limitations associated with the operation, economy and logistics. Promising gas-turbine engines, as considered by the German leaders of industry, could consume less than high-quality and cheaper fuel. Thus, at the time, from the point of view of economy and technology the only alternative to gasoline engines were GTE.
At the first stage development of a promising tank engine was entrusted to a group of designers with Porsche, which was headed by engineer O. Back. To assist the engineers from Porsche have been several related businesses. In particular, the project has attracted the research Department of engines of the SS headed by Dr. Alfred Muller. This scientist from the mid-thirties was engaged in the topics of gas turbine units and participated in the development of several aircraft jet engines. At the beginning of creation GTE for tanks Mueller has completed the project, turbocharger, later used on several types of piston motors. It is noteworthy that in 1943, Dr. Mueller has repeatedly made proposals concerning the beginning of the development tank of gas-turbine engines, however, the leadership of Germany had left them without attention.
Five options and two draft
In time for the start of the main works (mid-summer 1944) leading role in the project was transferred to the organization, headed by Mueller. At this time were defined the requirements to prospective GTE. He had to have a capacity of approximately 1000 HP and air consumption of about 8.5 kilograms per second. The temperature in the combustion chamber was asked the technical task at the level of 800°. In view of some characteristic features of gas turbine power plants for ground vehicles before the development of the main project I had to create several secondary. A team of engineers under the direction of Mueller has developed and considered five options for the architecture and layout of GTE.
"The German project tank of gas-turbine engines"
Schematic diagrams of the engine differed from each other by the number of stages of the compressor turbine and power turbine arrangement associated with the transmission. They also discussed several options for the location of combustion chambers. Thus, in the third and fourth versions of the layout of GTE proposed to divide the air flow from the compressor two. One stream in this case had to go into the combustion chamber and thence to the turbine rotating compressor. The second part of the incoming air, in turn, injected into the second combustion chamber, giving the hot gases directly into the power turbine. Options were also discussed with the different position of the heat exchanger for preheating the incoming engine air. In the first embodiment, the promising engine, which have reached the stage of full design, one axle had to be diagonal and axial compressor and two-stage turbine. A second turbine was to be placed coaxially over the first and interlock with the transmission. At that power a turbine, feeding power to the transmission, was proposed to be mounted on its own axis, not connected with the axis of the compressor and turbine. This solution could simplify the design of the engine, if it were not for one serious drawback. Thus, when the load is removed (e.g., during shifting), the second turbine can spin up to speed where the risk of damage to blades or hub. To solve the problem was proposed in two ways: either working to slow down the turbine at the right moments, or to take it from Gaza. Test results show that chose the first option.
And yet finalized the first version of the tank the GTD was too complex and expensive for mass production. Mueller went on to further studies. To simplify the design some original parts replaced by the relevant units, borrowed from jet engine Heinkel-Hirt 109-011. Furthermore, from the construction of the tank motor was removed a few bearings that held the axis of the engine. The reduction in the number of supporting elements of the shaft to two, simplified the Assembly, but was forced to abandon a separate axis with a turbine that transmits torque to the transmission. Power turbine mounted on the same shaft, which was already the impeller of the compressor and two stage turbine. In the combustion chamber provided original rotating nozzle for fuel atomization. In theory they allow more efficient to inject the fuel, as well as helping to avoid overheating certain parts of the construction. An updated draft was ready in mid-September 1944.
First gastromony Assembly for armoured vehicles
First gastromony Assembly for armoured vehicles
This option was also not without flaws. In the first place, the claims have caused difficulties with maintenance of torque on the output shaft, effectively representing a continuation of the main shaft of the engine. The perfect solution to the problem of power transmission could be the use of an electric powertrain, but the copper deficiency forced to forget about this system. Alternatively, electrotransmission considered hydrostatic or hydrodynamic transformer. When using these mechanisms the efficiency of power transmission is slightly decreased, but they were much cheaper system with generator and electric motors.
The GT 101 engine
Further elaboration of the second version of the project led to more revisions. So, to maintain health of GTE under impact loads (for example, when a mine explosion) was added to the third shaft bearing. In addition, the need for harmonization of aviation compressor motors resulted in the change of some parameters of tank GTE. In particular, about a quarter of the increased air flow. After all of the improvements project tank engine got a new name – GT 101. At this stage, the development of gas turbine power plant for tanks has reached the stage where I was able to begin preparations for the construction of the first prototype, and then GTE and equipped tank.
However, the fine-tuning of the engine was delayed and by the end of autumn of 1944, work on the installation of a new power plant on the tank has not begun. At that time German engineers had worked only on placement of the engine using existing tanks. Originally it was planned that the base for experimental GTE will become a heavy tank PzKpfw VI "Tiger". However, the engine room of the armored vehicles was large enough to accommodate all the necessary units. Even with a relatively small amount, the GT 101 engine was too long for "Tiger". For this reason I decided as a basic machine for testing use a tank Panzer V, also known under the name "Panther".
At the stage of finalizing the GT 101 engine for use on the tank "Panther" customer in the face of weapons of land forces and the contractor decided on the requirements for experienced machine. It was expected that GTE will increase the power density of the tank with a combat weight of about 46 tons to the level of 25-27 horsepower per ton, which will greatly improve its handling characteristics. At the same time, requirements for maximum speed almost not changed. Due to the vibration and bumps that occur when moving at high speeds, significantly increased the risk of damage to chassis parts. As a result the maximum permissible speed limited 54-55 miles per hour.
Gas turbine plant GT 101 in the tank "Panther"
As is the case with "Tiger", the engine room of the "Panther" was an insufficient size to accommodate the new engine. However, engineers under the direction of Dr. Miller managed to enter GTE in the GT 101 available volumes. However, the large exhaust nozzle of the engine had to be placed in the round hole in the stern armor plate. Despite its apparent strangeness, this decision was deemed convenient and suitable for mass production. The engine 101 on an experimental GT "Panther" was planned to be placed on the axis of the housing, with a shift upward to the roof of the engine compartment. Next to the engine, only in the shelves of the housing, the draft had put a few fuel tanks. The choice for transmission is found directly under the engine. Air intake devices brought to the top of the hull.
To simplify the design of the engine 101 GT, because of which he lost the individual associated with the transmission of the turbine, led to a difficulty of a different nature. For use with the new GTE had to order a new hydraulic transmission. Organization ZF (Zahnradfabrik of Friedrichshafen) in a short time has created a three-stage torque Converter with a 12-speed (!) transmission. Half of the gear was intended for road traffic, the other – to overcome the terrain. Power pack the installation of an experimental tank also had to introduce automatic monitoring the operating conditions of the engine. A special control device was supposed to monitor the engine speed and the respective need to raise or lower the transmission, preventing the release of GTE on invalid modes.
According to calculations of scientists, gas turbine GT 101 c transmission from ZF could have the following characteristics. The maximum turbine capacity reached 3750 HP, 2600 of which were selected by the compressor to provide operation of the engine. Thus, on the output shaft remained "just" vary from 1,100 to 1,150 horsepower. The rotation speed of the compressor and turbine depending on the load, ranged between 14-14. 5 K rpm. The temperature of the gases before the turbine has been kept at a predetermined level to 800°. The airflow rate was 10 kilograms per second, the specific fuel consumption depending on the operation mode 430-500 g/HP-HR
The engine 102 GT
Having unique high power, tank gas turbine engine GT 101 possessed not less remarkable fuel consumption is about twice higher than similar indicators available at that time Germany had petrol engines. In addition to the fuel consumption of GTE GT 101 we had a few technical problems that required additional research and corrections. In this regard, has started a new project: GT 102, which was planned to preserve all the achievements and get rid of the existing shortcomings.
In December 1944, the command A. Muller came to the conclusion about the necessity of returning to one of the early ideas. To optimize the operation of the new GTE proposed to use a single turbine on its own axis, connected to the transmission mechanisms. Thus power turbine of the engine of the GT 102 was to be a separate unit, not placed coaxially with the main units, as suggested earlier. The main block of the new gas turbine power plant was a GT 101 with minimal changes. He had two compressor with nine stages and three-stage turbine. During the development of the GT 102 was revealed that the main block of the previous engine GT 101, if necessary, can be placed along and across the engine compartment of the tank "Panther". Did during the assembling of the experimental tank units. Air intake devices of GTE are now placed on the roof at the left side of the exhaust pipe is on the right.
Gas turbine plant GT 102 in the tank "Panther"
A node compressor of the gas turbine GT 102
Between the compressor and the combustion chamber of the main engine block provided for the pipe to bleed air to the additional combustion chamber and turbine. According to estimates, 70% of which is included in the air compressor had to go through the main part of the engine and only 30% through the extra power of the turbine. Interestingly the location of extra unit: the axis of the combustion chamber and power turbine were to be placed perpendicular to the axis of the main engine block. The units of the power turbine was proposed to be placed below the main unit and equipped with their own exhaust-pipe, dumped in the middle of the roof of the engine compartment.
"Congenital disease" applied to the GT 102 schematic of gas turbine engine was the risk of over-promotion of the power turbine, with subsequent damage or destruction. To solve this problem was proposed in the simplest way: put in the pipe that delivers air into the additional combustion chamber, valves to control the flow. At the same time, calculations showed that the new GTE GT 102 may have a lack of throttle response due to the characteristics of the relatively easy work of the power turbine. Calculation specifications, such as power output or power turbine main unit, remained at the level of the previous GT engine 101, which may be attributed to the almost complete absence of major design changes, except for the appearance of the block of the power turbine. Further improvement of the engine required new solutions, or even open a new project.
A separate work turbine for the GT 102
Before you design the next model GTE called GT 103 Dr. A. müller attempted to improve the existing layout of the GT 102. The main problem of its construction were sufficiently large dimensions of the main unit, which complicated the placement of engine in engine rooms available at that time tanks. To reduce the length of the power pack installation, it was suggested to run the compressor in a separate unit. Thus, inside the engine compartment of the tank can fit three relatively smaller blocks: a compressor, a main combustion chamber and turbine and the power turbine unit with its own combustion chamber. This variant TBG was called GT 102 Ausf. 2. In addition to removing the compressor in a separate unit attempts to do the same with the combustion chamber or turbine, but they didn't have much success. The design of the gas turbine engine is not allowed to divide itself in a large number of units without significant loss in performance.
Engine GT 103
Alternative gas turbine engine GT 102 Ausf. 2 with "free" layout of the units as available has become a new development GT 103. This time the German engineers decided to do not the convenience of accommodation and efficiency. The equipment of the engine has entered the heat exchanger. It was supposed that with its help the exhaust gases will be heated flowing through the compressor air, which will allow to achieve significant fuel savings. The essence of this decision was the fact that pre-warmed air would give us the opportunity to spend a smaller amount of fuel to maintain the required temperature before the turbine. According to preliminary calculations, the heat exchanger can reduce fuel consumption by 25-30 percent. Under certain conditions, this economy was able to make a new GTE are suitable for practical use.
The development of the heat exchanger requested "subcontractors" from the firm Brown Boveri. The chief designer of this unit was V. Hryniak, previously participated in the creation of the compressors to tank GTE. Subsequently, Hrinak became a well-known expert on heat exchangers and its part in the project GT 103, probably was one of the prerequisites for this. Scientist have used quite a bold and original solution: the main element of the new heat exchanger was a rotating drum made of porous ceramics. Inside the drum was placed a few special walls, which permitted the circulation of gases. When hot exhaust gases passed into the drum through its porous walls and heated them. This happened during the half rotation of the drum. The following half-turn used to transfer heat to the air passing from the inside to the outside. Due to the system partitions on the inside and outside of the cylinder air and exhaust gases are not mixed among themselves that exclude abnormal operation of the engine.
The heat exchanger was the cause of serious disputes among the authors of the project. Some scientists and engineers believed that the use of this unit in the future will allow to achieve high capacity and relatively low flow rates of air. Others, in turn, saw in the heat exchanger only dubious means which will not significantly exceed the losses from complicated design. In the dispute about the necessity of the heat exchanger defeated supporters of the new unit. At some point even there was a proposal to equip GTE GT 103: two apparatuses for preheating the air. The first heat exchanger in this case was to heat the air for the main engine block, the second supplementary combustion chamber. Thus, the GT 103 was actually a GT with 102 introduced into the design of heat exchangers.
The 103 GT engine was never built, because of what we have to settle for extremely calculation its characteristics. Moreover, the available data on this GTE were designed even before the completion of the heat exchanger. Therefore, the number of indicators in practice, probably would be significantly lower than anticipated. The power of the main unit produced by the turbine and absorbed by the compressor, should be equal to 1400 horsepower. Maximum design speed of the compressor and turbine main unit – about 19 thousand rpm. The flow of air in the main combustion chamber – 6 kg/s. it was Assumed that the heat exchanger would heat the incoming air up to 500°, and the gases before the turbine will have a temperature of about 800°.
Power turbine, according to calculations, should rotate at a speed of up to 25 thousand rpm to give the shaft power of 800 HP air Consumption of an additional unit was equal to 2 kg/s the temperatures of the inlet air and the discharged gases, were supposed to equal the corresponding characteristics of the main unit. The total fuel consumption of the engine with the proper heat exchangers would not exceed 200-230 g/HP-HR
The results of the program
Development of German tank of gas-turbine engines only was started in the summer of 1944, when the chances of Germany winning the Second World war thawed every day. From the East on the Third Reich is advancing Red Army, and on the West were troops of the United States and great Britain. In this reality, Germany did not have enough resources for full-fledged mass of promising projects. All attempts to create a completely new engine for the tanks rested on the scarcity of money and time. Because of this, by February 1945 there were already three full project GTE tank, but none of them even reached the Assembly stage of the prototype. All work was limited to theoretical research and experimental testing of individual units.
In February of ' 45 event occurred, which can be considered the beginning of the end of the German programme of creating a tank of gas-turbine engines. Dr. Alfred müller was dismissed as the head of the project, and the vacant seat was appointed his namesake, max Adolf Mueller. M. A. Mueller was also a prominent specialist in the field of gas turbine power plants, but his coming to the project has stalled the most advanced developments. The main task for the new leader began lapping the GT 101 engine and start its serial production. By the end of the war in Europe remained less than three months, because of what the change of leadership of the project failed to lead to the desired result. All German armored GTE remained on paper.
According to some sources, the documentation on the project line "GT" fell into the hands of the allies and those used in their projects. However, the first practical results in the field of gas turbine engines for ground vehicles that evolved after the Second World outside Germany, had little to do with developments both doctors Mller. As for gas-turbine engines, designed specifically for tanks, the first serial tanks with such a power plant left the Assembly plant only after a quarter of a century after German projects.
- Kay, L. E. History of development and creation of jet engines and gas turbines in Germany. – Rybinsk: "Saturn", 2006
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