The Grain Design Program (GDP) is a software package to design rocket motors and other gas generating devices. GDP comes in two versions. The Light version (GDP-Light) has the following features:
Capable of calculating ALL 2D-grains, like stars, moonburners, slotted grains, BATES grains, etc. Geometries are devided into 4 categories:
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Modular motor configuration. Each design may consist of several segments (grains). Each grain can be selected from one of the three groups above. The screen copy below shows the main grain edit menu. In this case the rocket consists of three different segments. Detailed information of the current segment is shown together with a picture of the current design on scale.
Segment editing allows copying and modifying of all other elements already in the design. Burn-back of each segement can be carried out, before calculating the complete design. In this way each segment can be evaluated individually. The picture below shows the burn-back of a star-grain. The grain was drawn in a CAD program, and then exported to a .pcx file. Note the full burn-back, including slivers. Calculations can be interrupted (and resumed) to show the obtained segment characterists.
Propellant burn rate and thermophysical characteristics are inputted in the propellant menu. The temperature sensitivity is used to evaluate motor performance at different ambient temperatures. Different burn rate equations can be used in different pressure intervals (e.g. for slope-breaks in the burn-law).
The nozzle is defined by a diameter or effective surface. Other input values may include expansion ratio, divergence angle, efficiency, discharge coefficient and diaphragm burst pressure.
Ambient conditions are given by ambient pressure and temperature.
After all data is fed into GDP, the program calculates the burn-back of the motor. Calculation results are presented as graphs, or summarized in a report file. The plots may contain properties from the following list:
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