January xth : This week in STEM, my group tested several nozzle designs and a launch mechanism. Our first nozzle design was an inner tube that was wrapped around a valve for a bike pump. We plugged in an electric pump, and waited until the plug would pop out and launch. We realized that the hole on the top of the bottle was far from ideal, so we drilled a 5/8” hole in the cap of the bottle. We then just stuck in the bike valve, around 1/2” deep. We filled the bottle up with 750 ml of water. The pressurized pump turned on, the blast shield was put in position, and we waited. We ended up waiting for »45 seconds until we were startled by a loud bang. The bottle had exploded. We concluded that the valve was pushed too far into the bottle cap. We are going to attempt a second launch with a ¼” insertion.

Work is also being done on the design of the body of the rocket. We want to attach 4 fins to control the direction that the rocket will fly. Furthermore, we are going to put a parabolic cone on top of the rocket. There is an opportunity to 3D print this cone. These small, but significant modifications will hopefully aid in the creation of a better rocket.

Another factor that needs improvement is our launch mechanism. For the last two launches, we have simply placed the rocket on the ring of a ring stand, and waited for it to go up. A more controlled launch system will be necessary for a quantitative reproduction of the rocket. A mechanism that will release at a given pressure would allow us to have much more control over the exact conditions of the launch. Furthermore, as work is done on a more advanced system, an abort valve that would allow the rocket to safely release pressure is an essential safety mechanism.

In order to study the various characteristics of the rocket, we will attach it to a string and record the speed in which it travels around a fixed point. This set up will allow us to accurately study the force of the rocket with relation to the change in mass and thrust. There will be an opportunity to mathematically predict the force at a given point along a curve. In the coming week, we are going to mainly focus on an improved nozzle and launch mechanism.

February 8th:

This week I worked on converting the Sketchup file of our launchpad to an SVG. The CNC machine that we use only accepts SVG files, so we have to convert the file. We initially tried exporting the file as a .dwg file, and then converting it to an svg on an online converter. This didn’t work, because SVG files are two dimensional and .dwg files are not. We then exported the file as a PDF. We then successfully converted the PDF to an SVG on image.online­convert.com/convert­to­svg. The issue was that the PDF exports a picture of the 3D model, and not a 3D model. I then realized that I had to take apart the model, lay the pieces flat on sketchup, and export a PDF from a bird’s eye view. I then converted the file to an SVG successfully.

February 15th:

 

This week I worked on converting the Sketchup file of our launchpad to an SVG. The CNC machine that we use only accepts SVG files, so we have to convert the file. We initially tried exporting the file as a .dwg file, and then converting it to an svg on an online converter. This didn’t work, because SVG files are two dimensional and .dwg files are not. We then exported the file as a PDF. We then successfully converted the PDF to an SVG on image.online­convert.com/convert­to­svg. The issue was that the PDF exports a picture of the 3D model, and not a 3D model. I then realized that I had to take apart the model, lay the pieces flat on sketchup, and export a PDF from a bird’s eye view. I then converted the file to an SVG successfully.

Febraury 22:

 

After successfully exporting the Sketchup model to an SVG file, I uploaded the SVG to Easel. Easel is the software that the CNC machine runs off of. I decided to machine a wooden model of the launchpad first, before machining a metal model. I measured the width of the wood and the amount of tabs I wanted in my model. I printed the first model successfully, but the CNC machine cut too deep. When I printed my second piece, I adjusted the width of the material and solved the problem.

 

February 29th:

This week in class, my group prepared for our presentation to the institute. Nanak is going to present on his work on a wind tunnel to experiment with the aerodynamics of the water rocket. Declan will be presenting on his theoretical work around the rocket. I will present on the successes and failures I’ve had while building a launch pad.

March 14th:

This week in class I assembled the wooden model of my launch pad. I hot glued the pieces together and attached the arms. The resulting launch pad was a success. I then shifted to working on a release mechanism. I’m planning on attaching a string to the arms. I will attach the arms on a swivel. Then, when the string is pulled down, the arms will pull out. I need to work on a pad for the bottle to be held down onto. There will be a hole in the pad for an air valve. We will attach a bike pump that has a pressure gage. Then, when we want to launch from a particular pressure, we have control over the variable.

 

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