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Test Equipment - Thrust curve measurement software


An application was written specifically for the static test stand to assist in converting the raw data captured by the data logger into meaningful thrust curves. The application performs all the necessary data processing such as filtering, offsetting and scaling.

The application uses start and end markers positioned on the time line to allow the user to perform various functions between them.

Screen shot of the thrust analysis and export application

Trimming - Clicking the Trim button discards any time line data outside the markers.

Calibrating - Selecting a time segment on the thrust curve after the rocket stops producing thrust (i.e. the rocket is empty) with the start & end markers and clicking the "Empty" button the application will calculate the average value in the time segment and sets this value to be the "Zero thrust" value for the other calculations. (see top of document)

Selecting a time segment on the thrust curve with the rocket empty and the 1Kg weight applied and clicking the "Empty + 1Kg" button the application again calculates the average for that time segment and sets that as the other calibration mark.

The difference between these two calibration marks represents 9.8N and is used as the amplitude scaling factor by all calculations for the waveform.

The application also automatically generates a 5 point moving average waveform from the raw data which essentially eliminates most of the "ringing" seen at the start of the raw waveform.

Time measurement is achieved by using the start and end markers. Positioning these on events the Time Delta field displays the time between these markers. Clicking the "Set T-0" button resets the zero time to start at the start marker.

Calculating total impulse - The start and end markers are positioned either side of the waveform and clicking the "Total Impulse" button calculates the area under the raw data curve and the zero thrust line. The value is displayed in Newton seconds. Clicking the "Total Impulse 5pt" button calculates the total impulse based on the averaged waveform.

You can position the start and end markers on any part of the waveform and calculate the total impulse only for that segment. This is useful for calculating the total impulse portion attributable to say the water phase or the air phase. 

Calculating average thrust - This is done the same way as calculating the total impulse but the "Average thrust" button is clicked instead. Average thrust can be again calculated on portions of the waveform based on the position of the start and end markers.

Clicking the Export button will export the current data to a CSV file allowing further processing in Excel.

This application is available on request.


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