The acquisition of 5-AT and high-test peroxide proved to be outside the allotted project budget. I will proceed with my alternate project. The new project still centers around the regression rate of liquefying hybrid rocket fuels, so the experimental design, mathematical construct, and much of the procedure will remain the same. However, the independent variable is changed from the concentration of an additive to the melting point of the hydrocarbon fuel. Due to the formation of a hydrodynamically unstable melt layer at the fuel surface, the melting point of the fuel should play a critical role in the rate of regression. The relationship is theorized in the "Development and Testing and Testing of Paraffin-Based Hybrid Rocket Fuels." The melting point of a linear hydrocarbon is decreased as the number of double bonds in the chain increases. Also, longer hydrocarbon chains are responsible for higher melting points. Along with paraffin, several other saturated and unsaturated fats will be tested to achieve a variety of melting points. Sugars will also be investigated. The addition of a -nitro group onto the sugar may increase its energy content and burn rate. If there is time, this will also be investigated. I hypothesize that:
If there is a relationship between melting point and regression rate, then as melting point decreases an increase in regression rate will be observed at some or all oxidizer flux levels.
The oxidizer will instead be nitrous oxide, a standard in the field of amateur hybrid rocketry. Nitrous oxide is safe and easy to handle. Also, it is self-pressurizing due to its vapor pressure of 747psi at 20 deg C. This will simplify oxidizer injection techniques, but limit the achievable chamber pressure. A cavitating venturi will still be used to measure and control oxidizer flow rates over time.
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