Thrust Curve Tool
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Thrust Curve Tool
ThrustGear.com
Rev. 11/01/2006, v1.06
John@ThrustGear.com
Introduction
The Thrust Curve Tool was designed to analyze rocket motor thrust data and to produce
standard ‘.eng’ files for use with flight simulators such as Wrasp and Rocksim™. The program
makes it easy to visualize the thrust curve, determine the motor’s specifications, plot the data, and
produce an optimal ‘.eng’ file. It’s now possible to go from motor test firing to rocket simulation in
just a few minutes!
This software tool is useful for both amateur/experimental rocket motor builders and model
rocketeers. If you have a test stand and a data acquisition system, you may load the raw output
data into the Thrust Curve Tool in a variety of formats. It will compute the total impulse, peak
thrust, average thrust, specific impulse, burn time, and standard NAR/TRA motor designation. You
have the options of filtering the data and choosing the number of points for the “.eng” output while
interactively generating a “best fit” compact thrust curve.
The “Auto Optimize” feature further automates the curve-fitting process. By selecting this
option, the program finds the least number of points needed to reproduce the thrust curve shape
while maintaining the original total impulse. In most cases, a simulation program will produce the
same flight profile with this minimized ‘.eng’ file as it would with the raw data points. If you wish to
override the results, the Thrust Curve Tool lets you increase the number of points while
automatically reshaping the optimized curve and adjusting the total impulse.
The program also reads in existing ‘.eng’ files. This feature is useful if you wish to visualize and
plot a rocket motor’s thrust curve, or verify any manual modifications you may have made to an
‘eng’ file. For example, a delay at the beginning of the thrust curve is useful when simulating a
cluster with air-started motors.
The interactive display allows you to resize the plot while automatically scaling and labeling the
axes. A JPEG image of the graph may be saved to a file or copied to the clipboard and pasted into
other programs.
Installing & Running
The program runs on any computer that has the Java runtime environment (JRE) installed. This
package is available for free from Sun Microsystems for Windows, Macintosh, and Linux. For
people with Mac OS-X, the JRE comes installed from Apple. To download and install Java, go to:
http://www.java.com/en/download/manual.jsp
Copy ThrustCurveTool.jar to a working folder where you’ll keep your rocket motor data files. If
you downloaded the example data files, save them in this folder as well.
To run the program, double-click on the ThrustCurveTool.jar icon. If Java is installed properly
on your computer, the program will open and display the file selector dialog. If it does not run,
change the properties of the ThrustCurveTool.jar file to associate it with Java (usually called
“Java(TM) 2 Platform Standard Edition” or something similar on Windows).
Or, you can run the program using the TTC.bat batch file on Windows computers. Put this file
in the same folder as ThrustCurveTool.jar. You may also create a short-cut to the TTC.bat and
place it on your desktop.
For further assistance with installation of the program and configuration of your computer please
visit our website at: www.ThrustGear.com
.