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 Performance of turbo train
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The performance of the simplest turbo train


To understand the problem of applying gas turbines to railroad, let's make up the most simple turbo train. Non-recuperated two shaft gas turbine is it's motive power, its transmission is mechanical, single-speed gear box and no torque converter. To make it easy to compare with the M1 Abram's power pack, the output of the train's power pack is set 1500 horse power.
Start notch man mini and design the turbine powered railcar equipped with 1500 horse power class power pack.

The transmission type is the single speed  and direct drive. The designed speed is  200 km/h for semi-high speed regional or commuter rail.
Turbo train 1  is made up of 6 cars, 2 motive cars and 4 trailer cars.
Turbo train 2  is made up of 6 cars, 3 motive cars and 3 trailer cars.
Turbo train 3  is made up of 6 cars, 4 motive cars and 2 trailer cars.
To compare with DMUs,  one more train is created.
Train 4  is made up of 6 cars, all motive cars equipped with 750 horse power diesel engines with hydraulic transmission and 2 speed lock-up mechanism.. This is the assumed setting of DMU the class 180 currently in service in the British Rail. 

Notch man mini operation process is shown below.

The next is the power pack selection window. The engine performance is AGT1500 class output but thermal efficiency is considerably worse due to the simple cycle small gas turbine.
The free version cannot specify the fuel consumption data by users.


Makeup of the train and its information window.

The designed speed selection window

This is the performance curve of generated trains. The running resistance (air and friction) and total mass of the train is reflected.

The Y axis represents the acceleration force, the unit is kg/t. You can get kilometer per hour per second from kilogram per ton by this equation.
For example, 50 kg/t is almost the same as 1.764 km/h/s and 28.3447 kg/t is 1 km/h/s. 

This value is equivalent to the resistance of grade represented by the unit "permillage". So that the balancing speed of the train at the specific grade can be read from this graph.
For example, the green lined train's balancing speed at the grade of 20 permillage is about 195 km/h and the blue lined train's is about 143 km/h.

Three lines, yellow, red and green colored, represent direct drive single speed turbine powered trains.
(Yellow: 2 motive cars, 4 trailer cars) 
(Red: 3 motive cars, 3 trailer cars) 
(Green: 4 motive cars, 2 trailer cars) 
From this graph, you can understand their insufficiency of the acceleration at slow speed. Two shaft gas turbine's high torque at low speed is not sufficient for train operations. But relatively high acceleration can be attained at the middle to high speed range.

Blue is DMU, this performance curve is very similar to that of the class 180. The hydraulic converter gives the train very high acceleration from its start to low speed range. But this ability is less useful for high speed trains.

Scenario 1: Flat double track section.

For this scenario, I've made one imaginary route by Notchman mini.

The generated route has few curves, their radius is larger than 4000 meters, moderate grades and its total length is 376553 meters. This is the vertical profile of the generated route. The maximum height difference is about 370 meters. Although difficult to see in this magnification, green lines in this figure represent the distribution and radius of curves.

In this simulation, trains stop all stations. The average distance between stations is 25 km.

Default values are used for the operation.

This is the generated running curve.

The feature of each train is well reflected on the speed - distance curve. DMU accelerates well at the low speed but the flat torque feature of the diesel engine does not allow the acceleration at the speed of using the final gear especially on the mild slope (red arrow).  Total output of "DMU 750hp 6M" is 4500 horse power, equal to that of "Turbo train 2 3M3T".
The torque advantage of a gas turbine is well represented in this graph.

But as shown in the next graph, when the distance between stations is short,  the hydraulic transmission exhibits its power and makes up for diesel's shortcoming.

The total operating time is calculated like this table.

The powering time and percentage is calculated like this. 

This is the operation time displayed in a time table like format.

More details are shown tables below. The fuel consumption of each train is also displayed.


1.8 to 2.4 times much fuels are consumed by turbo trains in comparison with a diesel train. 

Scenario 2: Single track mountainous section

To simulate the performance of turbo trains on local lines, create the single track mountainous route. The generated route is 400916 meters in length, more rich of steep curves and grades. The radius of most curves is 400 to 600 meters, most grades are 10 to 25 permillage. 

The next is the vertical profile of the route. The maximum height difference is about 460 meters.

Curves distribute among the route like this.

There are 36 stations and trains stop at 6 stations on the way.

Each station has severe speed limits due to low grade turnouts and trains cannot pass stations with the high speed. 
The rough necessary time is listed the next table.

In such a route, The hydraulic DMU demonstrates good performance due to its high acceleration feature in low speed range. Only 4M2T high power turbo train can run faster than DMU in this route.

There is a bigger difference in fuel consumptions. The next table shows this.

Consist fuel consumption
2M4T 2454.25 kg
3M3T 2920.82 kg
4M2T 3368.68 kg
DMU 6M 1244.28 kg

To run on this section of the route within approximately the same time, the turbo train consumes nearly 3 times as much fuel as DMU.

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