PHASE 2: Motor TestsPurpose: To test our motors in our groups. We will see how much thrust our certain paring gives. We will be shooting each motor by lighting it up with a match. Group Members: In this project my project members were Isabel and Sammie. ____________________________________________________________________________________________________ Making the Motor: To create our motor, Andrew simply asked for our combination of size, burner, and fuel. We wrote it down on one of the cardboard motors, and Andrew got them and created each motor over the week. Beforehand thoughts: I wasn't sure how our pairing would go. I was confident in the End Burner/Black Powder combination, for I thought we would get a lot of thrust from that. But I wasn't so sure about our size of 3/16s. We chose to go smaller than everyone else, we were not sure how that will work, whether it will be an advantage or not. I hoped that our motor would work efficiently and that we would get a large amount of thrust. ____________________________________________________________________________________________________ What Happened? - A motor story! Instead of only a portion of groups going, we decided that everyone in the class would be going. Along with Brian's 9th graders who were doing a similar project on rocket motors as well. Each group was required to write a paper with all the information; fuel type, burner, size, name , etc. The paper would be put in front of the go pro before filming. We walked down to the bay, and by random, Andrew and Brian picked out motors and called the groups to test them. We were then called up to go. We are excited to see how the motor would perform. And as we stepped back to watch it, we sadly watched it puff out a cloud of smoke. When we pressed the button, Andrew said that the match wasn't working well. We tried multiple times, about 3 or 4 times. The match wasn't being cooperative! Frustrated, we let another group go instead of us. Andrew and Brian told us that we would go later in the day. We came back after lunch, maybe 4th or 5th period. It was us, and another group from our class, along with Brian's freshman. We walked back to the bay, back to the center of the field. My group members and I waited until it was our turn again. After awhile, the wind was growing stronger, and the air grew colder. We finally were able to test the motor. This time, IT WAS A SUCCESS! We were unsure of how much thrust it gave at the time, but then we just watched as it was performing successfully. Happy with ourselves, we all cheered gladly at out working motor. It didn't have such a powerful sound when it was being tested like the other groups, but it still emitted the shot of power on the end like it was supposed to. We noticed that it was starting to drizzle. Sammie and I requested to go back, and as we were walking it began to pour. It was raining extremely hard, and we had to stop all motor tests. Sammie and I ran back to school with the rain pouring down heavily on all of us. This is the video taken on the GoPro Andrew had. Motor Thrust Curve: Based on this video, we took it and slowed it down on a video program, looking frame by frame to see what the thrust was for each frame increment. After doing a large spreadsheet on google spreadsheet, we then transferred our data into a table chart. It was a line graph that showed the amount of thrust per 1/30th of a second.
To do this we: We put this on a video editing program, and slowed it down. Frame by frame we referred to the thrust for each 1/30th of a second. Our video itself was 8 seconds long, but our thrust began shooting up from 0 at exactly 2 second in. So technically we had a 6 second long video. If we have 1/30th of a second entries, then this means that we have 30 entries per 1 second. Since we have 6 seconds in total, our whole entry total would be around 180 entries. (in our case we had more, it was a little over 6 seconds.) On our spreadsheet, our group worked together to have one person say the different thrust numbers while everybody else fills it into the spreadsheet. We got 187 entries in total. AFTERTHOUGHTS Motor Test Results: Sadly our motor didn't do as well as we thought it would. I had good expectations for it, but sadly compared to everyone else, our thrust was significantly low. I think the reason for that is because of our motor core size of 3/16. The highest our thrust went was 364. Which is not high at all compared to thousands that other groups reached with their rocket. I noticed that everyone else had chosen sizes like 1/4th rather than ours which was 3/16. With our graph as you can see, the thrust doesn't shoot up right away like a normal rocket would. It is only gradually, only after a few moments where it shoots to the highest thrust point. Compared to everyone's graphs, our was the only one that gradually went up and gradually went down. Everyone else's shot up and shot down, a huge spike in the data. The huge spike in the graph means that there was a powerful shoot of thrust happening in the beginning of the launch, then once it reached it's peak it shoots down as well. But with ours, the gradual rising up to the highest point meant that we did not have a strong start. It didn't shoot powerfully into the sky like every other rocket would. It started off small and gradually worked its way up to the peaking point. Which is not what we're looking for if we want a high rocket launch. Other groups used the same gun powder and the end burner combination. I have yet to find out exactly. Questions I had/Researched?
What I enjoyed? I enjoyed watching our motor work finally. The success of being able to see your product work, just like the previous rocket project. The experience was definitely different because we didn't actually build the motor ourselves. We had Andrew make them all, so we didn't really experience the whole process. I feel that I would have enjoyed it more if I felt the whole process of building the motor. What could've been done better? Differently?
Group Work: I feel that I contributed to the group well on this project. We all equally did research beforehand, and I also took the opportunity to draw out our motor and nozzle diagram. We all documented equally and we all helped with the graphing and data plotting of the motor thrust curves. ____________________________________________________________________________________________________ Our Thrust Results: Our thrust results were not the lowest nor were the highest. Here were our results:
OUR FINAL DECISION: We will not be using our original motor design, we chose to use Autrina's motor design instead. Why did you choose not to? We thought ours did work, but did not work most efficiently. We got a good amount of thrust, but based on our graph, we didn't like the thrust curve ended up like. For our rocket we kinda want to do one that has an immediate shoot up in thrust that then goes down quickly, rather than what we have that shoots up and gradually goes to the peak of the thrust then slows down. It is not that our motor was unsuccessful, it was more on the fact that we want a stronger launch for our rocket. Why did you pick the new motor design? We picked Autrina's groups design because we saw a lot of things that we wanted for our rocket. They had a more significant amount of thrust than us, amounting to 43054, and on their graph the peak point was around 2000 g's of thrust in around 4 seconds. The time it took to reach the highest thrust was almost half the time we had, and in their graph it displayed a immediate shoot into the peak thrust. We were looking for this to happen with our motor. We will try to use their design for our future rocket. Hopefully it will be successful. Here is their design: Fuel Type: Black Powder Core Size: 3/16" Nozzle Size: 1/4"
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