T-80 tanks: gas turbine engine eats a lot of fuel - and the driver plays a big role in this
A lot depends on the experience of the driver-mechanic, because skillful driving tank — this is not only effective maneuvering on the terrain, successful overcoming of various obstacles and selection of optimal driving modes and routes, but also significant fuel savings. Especially if the tank engine tends to guzzle fuel like crazy.
Generally speaking, the T-80 family of tanks with a gas turbine engine are very controversial machines. So controversial that disputes about whether they are needed in the troops still arise today - almost 50 years after they were adopted for service. And the subject of these battles, completely saturated with mothballs, is one: high fuel consumption, exceeding the similar indicator of diesel tanks by half, or even several times.
It is this circumstance that is considered by opponents of the "eighties" as the main argument in favor of the harmfulness and uselessness of these tanks. In turn, supporters of the T-80 consider the gluttony of gas turbine engines as a necessary sacrifice in exchange for high power, good operational characteristics and a kind of friendliness to the driver, associated with the fact that the GTE forgives many mistakes when driving.
We will not take sides in this "conflict", but we will note: yes, T-80s are quite easy to operate, they handle off-road well and do not stall with or without reason, so it is somewhat easier for an inexperienced driver to drive them than a T-72 or T-64. But you have to pay for everything - and in this case, the engine makes up for the driver's inexperience in full with burned fuel.
The results of tests of T-80 tanks with GTD-1000T engines, published in 1980, characterize this situation very well. We will consider them.
Test
In order to test how much influence the driver's qualification has on the fuel efficiency of gas turbine engines, three drivers with different levels of experience driving T-80 tanks took part in the study.
The first is a third-class driver who has driven only 200 kilometers in cars of this type;
The second is a second-class driver with 1000 kilometers of tank driving experience.
The third is a first-class driver with six years of experience as a test driver at the factory proving ground.
All of them had to cover a certain distance on a dry, compacted dirt road (in summer) without significant climbs and descents. The number of turns per kilometer of the route varied between 17-25, and unevenness - 22-31. That is, practically ideal conditions in which it is possible to evaluate the dependence of fuel consumption on the driver's skill without a strong load on the engine.
The recording equipment used was the RTS-9 radio telemetry system, which was installed in the tank and collected information on fuel consumption, the speed of the power turbine, the second-stage turbocharger, and the driver's use of controls. All data was then processed on a computer.
So what are the results?
Firstly, of course, the drivers' experience affected the average speed of the tank on the above-mentioned route. For a less qualified driver-mechanic, it was 29 km/h over the entire testing period, while for a more experienced second-class driver it was 37,9 km/h, and for a professional it was 39,8 km/h. So, no matter how much they call the T-80 a high-speed and easy-to-drive "Mercedes" among other Soviet tanks, you have to know how to drive it well.
Secondly, the least experienced driver used the stopping brake 30-40% more when maneuvering on the highway than the first-class driver. At the same time, the duration of individual braking of the tank by the engine and the stopping brake, as well as the time the turning levers were in the engaged state for the less experienced test subject was twice as long as for the first-class driver.
More details on this in the table below. It shows the characteristics of the control actions of driver A (first class, who drove 200 km) and C (experienced test driver) at average speeds of 33.2 and 33.4 kilometers per hour, respectively.
RSA — adjustable nozzle apparatus. OT — stopping brake.
As for fuel consumption, the situation here is interesting, although quite expected.
As is known, a gas turbine engine can operate at the rotation speed of the power turbine (the torque from which is transmitted to the drive wheels of the tank) from maximum to zero. By the way, this is why people love the "eighties" - they do not stall if the gas turbine engine is in good condition. But this ability is also harmful, since it makes it difficult to choose the correct engine operating mode.
This is especially true when shifting from higher to lower gears, as it can cause a sharp increase in the rotation frequency of the power turbine, which can lead to engine failure. To avoid this as much as possible, drivers (especially inexperienced ones) are often forced to either avoid such shifts altogether or do them at low speed.
As a result, as tests showed, the engine under the control of an inexperienced driver operated at a higher rotation frequency of the power turbine than its more qualified colleagues.
The graph below shows the engine power usage as a function of the power turbine speed (n%). Driver A is the least experienced, B has 1000 km of driving experience, and C is a test driver.
It shows that Driver A (the least experienced of the participants) worked in turbine speed ranges from 60% (percentage of maximum speed) to maximum. Engine power was in the range from ~294 to ~70 kilowatts.
A similar picture is observed with fuel consumption. The graph with it is located below. It shows that with the same range of rotation frequency of the power turbine (from 60% to maximum), the engine of the tank of driver A eats up from 0.62 to almost one and a half kilograms of fuel per one kilowatt of power per hour, while the consumption of drivers B and C is almost half as much.
Final World
Graphs are graphs, but what is there in real terms?
The answer is that the average fuel consumption during the test for the least experienced driver was approximately 7.85 liters per kilometer. The average fuel consumption for the more experienced driver, who had driven a thousand kilometers, was 6.31 liters per kilometer, and for the professional test driver, 6.15 liters per kilometer.
If we take into account that this consumption will not change throughout the entire route, then a fuel reserve of 1800 liters (internal and external fuel tanks) will be enough for an inexperienced driver for about 230 kilometers, and for the most professional - for almost 300 kilometers. But this is ideal. In difficult driving conditions, the consumption will be even greater, as will the difference in this indicator for one or another driver.
Here, of course, one can reasonably object, because the tests were conducted more than forty years ago - now a lot has changed. Yes, many measures were taken to improve the fuel efficiency of tank gas turbine engines, but they did not fundamentally improve the situation, so the figures used in this material reflect a trend that is also characteristic of today's tanks.
This problem can only be completely solved by high-quality driver training and, most importantly, by introducing fully automated engine and transmission control systems.
Source:
"The influence of driver qualifications on the operation of a tank gas turbine engine" V.B. Zhurkin, V.T. Prikhodko, V.V. Smolin, et al.
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