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EngineSim Version 1.5f


This is a beta 1.5f version of the EngineSim program, and you are invited to participate in the beta testing. If you find errors in the program or would like to suggest improvements, please send an e-mail to


With this software you can investigate how a turbine (or jet) engine produces thrust by changing the values of different engine parameters. You can also investigate the effects of engine performance on aircraft range by using another interactive applet called RangeGames. If you are an experienced EngineSim user or are using Internet Explorer, it is recommended that you use a slightly different version of EngineSim which does not include these instructions. There is also a special version of EngineSim with some additional features for undergraduate engineering students.

If you experience difficulties when using the sliders to change variables, simply click away from the slider and then back to it. If the arrows on the end of the sliders disappear, click in the areas where the left and right arrow images should appear, and they should reappear. To return to the original default conditions, click the red Reset button at the lower right of the program.


The program screen is divided into four main parts:

  1. On the top left side of the screen is a graphic of the engine you are designing or testing. In the Design Mode, the drawing is a schematic, while in Tunnel Test Mode the drawing is an animation.
  2. On the top right side of the screen are the results of engine performance calculations. The output can be presented as numerical values of certain parameters, graphs of engine performance, or as photos of the engine parts with descriptions of their purpose. Performance results are shown in black boxes with yellow letters. You may select the type of output displayed by using the red choice button labeled "Output Display" on the bottom right panel.
  3. On the lower right side of the screen you will always see the overall engine performance displayed as thrust, fuel flow, airflow, and computed engine weight. You can make choices concerning the type of engine to design or analyze, the type of output to be displayed, and the units to be used in the calculations. To operate a choice button, click on the arrow in the choice box on the right and make your selection.
  4. On the lower left side of the screen various input panels are displayed. You can select the input panel by clicking on the name or the component in the graphic at the upper left. To change the value of an input variable, you can simply move the slider. Or you can click on the input box, select and replace the old value, then hit Enter to send the new value to the program. Upper and lower limits are set for each input variable.


You can choose from four different types of engines: a simple turbojet, a jet with afterburner, a turbofan engine, or a ramjet. Selections are made on the graphics window by clicking on the engine name. The chosen engine is shown in yellow.

Design variables include Flight Conditions (airspeed, altitude, throttle), Engine Size (frontal area), Inlet (pressure recovery), Fan (pressure ratio, efficiency, and bypass ratio), Compressor (CPR, compressor efficiency), Burner (maximum temperature, efficiency, pressure ratio), Trubine (turbine efficiency) and Nozzle (maximum temperature, efficiency, A8/A2). As you choose a different component the part of the engine being affected is highlighted in the graphic by changing from its default color to yellow. If you change the Output Display to Photos you can view an actual photograph and description of each engine part. As the Engine Size changes, the grid background changes in proportion to the change in engine size. The distance between any two grid lines is 1 foot.

CHOICES: Mode, Units, Output Display

The program works in two modes: Design or Tunnel Test Mode. In the Design Mode, you can change design variables including the flight conditions, the engine size, the inlet performance, the turbo machinery compressor and turbine performance, the combustors or burner performance, or the nozzle performance. For a turbofan engine design you can also vary the fan performance and the bypass ratio. When you have a design that you like, you can switch to the Tunnel Test Mode, where you can vary only the flight conditions (airspeed, altitude, and throttle setting). In Tunnel Test mode, you can load models of existing turbine engines for comparison with your design. You can always reload your design to continue testing. In Design Mode, you can use the existing engine models as good starting points for your design.

The calculations can be performed in either metric or English units. You can always return to the default conditions by pushing the Reset button.


The program will calculate an average weight of the engine that you design. The thrust to weight ratio of the engine is displayed in the numerical output and is a measure of the efficiency of the engine. The weight depends on the number of stages in the compressor and turbine, the diameter (frontal area) of the engine, and the component materials. The program begins with standard materials for the components, but you can change the materials and see the effects on weight of the engine. Just push the blue Materials choice button on any component input panel. You can also select to define your own material by choosing My Material from the menu. Just type in your own values for material density and temperature limit. The program will check the temperature throughout the engine design against the material limits. If you exceed a limit, a flashing warning will occur in the schematic. You can see the temperature limits by choosing Temp Variation in the Output Display. (For the afterburner and the ramjet, the graphical temperature limits are based on the flow temperature, not on the material temperature, and are slightly higher than the material limits. Cooling airflow is often used along the walls of these components to keep the material temperature within limits.)


The red Output Display menu allows you to change the contents of the output window in the top right side of the screen. You can choose to display output boxes with numerical values of the engine performance, as described below. Or you can display photographs and descriptions of each engine part. You can display the variation of the value of pressure and temperature at various stations through the engine. Or you can also display a T-s Plot or a P-v Plot, which are used by engineers to determine engine performance.

To generate your own performance plots, select "Generate" from the graphics window. The input panel will now display some additional buttons and sliders to generate a plot. Choose the variables to be plotted using the pulldown menus and then push the "Begin" data button. Set the value of the independent variable by using the slider or the type-in box. Push the blue "Take Data" button and a data point will appear on the graph. Set a new value for the variable and take another data point (up to 25 points in any order). When you are finished, push the "End" button and a line will be drawn through your data points. To start a new graph, push "Begin" and your old graph will vanish. When you are finished, push the red "Exit" button and you will return to free stream conditions.


Numerical Output from the program is displayed on two performance panels. The total engine performance is always displayed below the output panel and includes the engine net thrust, the fuel flow rate, the engine air flow rate, and the engine weight. An additional output panel shows the ratios of these engine performance numbers including the specific fuel consumption, the fuel-to-air ratio, and thrust to weight ratio. The engine pressure ratio (EPR) and engine temperature ratio (ETR), as well as the flight conditions; the free stream Mach number, pressure and temperature are also shown on the numerical output panel


The Learning Technologies Project will continue to improve and update EngineSim based on user input. Changes from previous versions of the program include:

  1. On 18 Mar 03 version 1.5f was released. This version includes a correction to the weight calculation when you change compressor face area.
  2. On 17 Sep 01 a special version for undergraduates was released. This version includes the ability to reset most of the limits in the program.
  3. On 22 Aug 01 version 1.5b was released. This version includes more corrections to the ramjet analysis and some slight changes to the variable limits. A "sleek" version of the program is now available for experienced users.
  4. On 19 Apr 01 version 1.5 was released. This version includes improved graphics and a more consistent input environment. There are also corrections to the ramjet analysis from previous versions.
  5. On 13 Oct 00 version 1.4 was released. This version includes material properties for each component and a calculation of the engine weight. Temperature limits for each component are also checked.
  6. On 26 Sept 00 version 1.3 was released. This version uses the "card format" for input and output. Component input panels are invoked from the engine graphic. Optional photos of the components are included on the output panel.

  7. On 31 Mar 00 version 1.2 was released. This version includes a ramjet simulation.

  8. On 2 Dec 99 version 1.1 was released. This version includes a variety of plots and an optional animation displays. This applet enables the student to interactively observe the effects of engine component performance on thrust and fuel consumption.

Button to Download a Copy of the Program


Set the following conditions in EngineSim:

Design Mode
English Units
Flight Conditions

The Airspeed should be 0, the Altitude 0, and the Throttle 100. Record the thrust
(F net) ___________and the Fuel Flow __________.
Now go ahead and change the altitude to 10,000 ft. and the Airspeed to 350. Did the thrust increase or decrease? Did the fuel flow increase or decrease? Thrust ________ Fuel Flow__.
What happens when you choose a different engine? Choose a jet with afterburner and record the thrust ___________ and the fuel flow ____________.
Choose a turbofan engine and record the thrust _____________ and the fuel flow________.
What can you conclude about the effect of an increase in altitude and airspeed on thrust? __________________________________ On fuel flow?__________________________
Which engine is most fuel efficient? _______________________________

Guided Tours
  • Button to Display Previous Page EngineSim - Engine Simulator: Button to Display Next Page
  • Button to Display Previous Page Parts of a Jet Engine: Button to Return to Guided Tour Page
  • Button to Display Previous Page Thrust Equation: Button to Return to Guided Tour Page
  • Button to Display Previous Page Calculating Fuel Flow Rate: Button to Return to Guided Tour Page
  • Button to Display Previous Page Turbojets: Button to Return to Guided Tour Page
  • Button to Display Previous Page Afterburning Turbojets: Button to Return to Guided Tour Page
  • Button to Display Previous Page Turbofans: Button to Return to Guided Tour Page
  • Button to Display Previous Page Ramjets: Button to Return to Guided Tour Page

Credits for EngineSim


Beginner's Guide to Aerodynamics
Beginner's Guide to Propulsion
Beginner's Guide to Model Rockets
Beginner's Guide to Kites
Beginner's Guide to Aeronautics

Button to Display Aerodynamics Index Button to Display Propulsion Index Button to Display Model Rocket Index Button to Display Kite Index

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byTom Benson
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