There are two different things to think about when making a rocket motor: How the motor is going to burn, and what the motor is going to burn. Two basic ways a motor can burn is an end burner, and a core burner. An end burner is a completely packed motor. When lit, the fuel burns from one end to the other, evenly. A core burner has a core cut in the middle, that lights all the way through. The motor burns from the inside out. What's burning inside the motor is another factor. We were given the option to pack motors with black powder, or potassium nitrate and sugar. Black powder is a fuel that burns fast, and powerful. This would make your rocket go up really high really quickly, and then fall. A sugar motor, or "candy motor," burns a bit slower. This would make a rocket accelerate for a longer time, but not as quickly. After Andrew made the motor, we got to go outside and test it. The motor was set upside down on top of a scale, so that we can measure the amount of thrust the motor gave off. after about 2 seconds, because the throat was too small, our motor CATO'd, which means Catastrophe At Take Off. The video is below. Using the data in the video, we were able to create a graph showing the thrust curve for our motor. We can analyze this to figure out how much weight the motor can lift, and how high it can lift it. Below is the thrust curve analysis paper.
Using the data from our test, we can figure out our burnout time, our how long the motor will burn, and our total thrust. The paper that we were given access to used this information to tell us how much weight our motor can lift. Ricky and my motor can lift up to 307.56 grams. However, our motor cato'd after .7 seconds. We won't be able to use this for our final motor. So, we looked at other people's motor tests. We decided for the next section we want to use Phillip and Gabriel's motor. It got a little more thrust than ours, plus it didn't cato. It was a full black powder, cored all the way through at 3/16's of an inch. We will use it in the final section, when we make a new rocket to launch. ReflectionLooking Back: Our motor worked to the extent that it lit and produced thrust. After two seconds, however, it blew off the end cap, and flew off of the scale. We can still use this though, By creating a thrust curve for the design. Looking Beyond: Our motor blew up because we made our nozzle throat too small in diameter. The pressure inside the motor couldn't get out fast enough, so it blew the end cap off. Looking Inward: I think our results were definitely desirable. It may have blew up at the end, but it gave the most thrust out of the whole group. If we had made a larger nozzle, then it would have been perfect. One thing I am worried about though, is how fast it blew up. Was it already to the potassium nitrate? If so, then our motor would have only three or four seconds of thrust. That's not enough for a big rocket. Looking Outward: I worked with Ricky, and I will be working with him the the final section of the project as well. We will base our final rocket off of our shared motor test. We did a great job working together, neither of us doing too much more than the other. The worked was shared equally. I contributed to the group by designing the motor that we tested based on my research, and I helped graph the thrust curve as well. Looking Forward: If I were to do this project again, I would use a wider nozzle throat. That way, the pressure could be released faster, and the motor would have a lower chance of blowing up. Take Away's: I learned some new things during this project. I got a better understanding of combustion reactions, and how to measure them. I learned how to create a thrust curve, as well as how to look at it and understand what it is I'm seeing. I can use these new skills and knowledge during the final section of the project. |
AuthorThis blog has post's of all the cool projects I've done in chemistry class. Archives
December 2015
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