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< BioDiesel Static Test (
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The BioDiesel performance was about 4% lower than the RP-1, but both tests worked well.
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We built a rocket for the Mythbusters TV show that they did not use, so we used the rocket to test whether BioDiesel would work as a rocket fuel. The test showed that the BioDiesel has nearly the same performance as the RP-1 kerosene that it was originally designed for. BioDiesel is a renewable, low toxicity fuel and it could potentially be made from crops grown on mars. It also has a slightly higher density than RP-1, allowing for more fuel to be loaded into the same size tank. Our rocket uses fire extinguishers for propellant tanks so we can’t run the Atlas vernier engine at full pressure and thrust without overstressing the tanks. As it was we got 840 lbs of thrust with the RP-1 and 820 lbs with the BioDiesel.
The rocket was first loaded with RP-1 rocket fuel and liquid oxygen. The engine was run for about 6 seconds, long enough for the pressures to stabilize. We took data on LOX (liquid Oxygen) pressure, fuel pressure and chamber pressure. For a rocket engine, the thrust is proportional to the chamber pressure, so this gives us a way to measure of the thrust.
Then the rocket was loaded with B-100 instead. We ran the same test and measured very nearly the same pressures. The chamber pressure was 2% lower, the fuel pressure was 4% lower and the LOX pressure was 3% lower. Because the BioDiesel is 9% more dense than the RP-1, and the DeltaP from the fuel tank to the rocket chamber was 7% lower, the mass flow rate of Biodiesel was 1% higher. (Mass flow rate is proportional to sqrt(DeltaP*density)) If the Biodiesel had the same performance as the RP-1, his should have resulted in a 1% higher thrust, but we saw a 3% reduction in thrust. This means that the BioDiesel had about 4% lower performance than the RP-1. However, the mixture ratio with the BioDiesel was richer. More testing at various mixture ratios would show if the difference is less at other ratios. Also the effectiveness of Biodiesel as a coolant in the regenerative cooling jacket on the rocket motor was not evaluated. We are planning to launch the rocket in a few weeks with BioDiesel.
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