Building Our First Rocket Motor

Aerospace Aug 16, 2020

Rockets are at the pinnacle of innovation and we at SEDS BITS Hyderabad want to develop research and development in the aerospace sector on campus. In the months that followed our preparation for the 2021 Annual Spaceport America Cup, we decided to build and test our own rocket motor. This motor was a sub-scale model of the motor that we would be using, as our rocket has an expected apogee of 10,000 feet.

We also fabricated a thrust stand, complete with a 5kN load-cell, and an adapter that can handle bigger motors than the one we tested. This test was conducted to demonstrate and analyze a new propellant formulation and cooking procedure. Propellant Formulation The standard ratio of constituents for KNSU is 65% Potassium Nitrate and 35% Sucrose, by mass. Viscosity of the melted slurry is strongly dependant upon the Oxidiser/Fuel ratio. The standard Oxidiser-Fuel (O/F) ratio of 65/35 is not pourable, and must be scooped into the casting mould. If a 60/40 O/F ratio is used, the viscosity has been found to be sufficiently less that pouring (with some scooping) can be done.

Takeaways: A proper analysis of different propellant formulations, burn rates and preparation techniques. The following motor grain lacked a core, due to the lack of availability of a suitable core rod. Hence chamber pressure calculations were inconsequential. The motor was classified as E type, with an average thrust of 41 N with a maximum thrust of 63N. The motor produced valuable thrust for only 0.732 seconds.

The test demonstrated the the nominal operation of our thrust stand. However, there is a a lot of work left to figure our better propellant formulation, and ways to measure chamber pressure.

Follow SEDS BPHC on Facebook and Instagram to stay update with our progress as we gear up for the next edition of Spaceport America Cup. While we are safely in quarantine now, we hope to be back operational soon!

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SEDS BITS Pilani, Hyderabad

Students for Exploration and Development of Space is a student chapter aimed at developing aerospace culture at BITS Hyderabad. We currently are the only BITSian team to compete in SA Cup in NM, USA

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