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For the second iteration, we only wanted to change a few parts of the rocket, so we can better understand how a rocket flies. One of the main issues we saw was with the stability of the rocket. Often times the main cause of this issue is the center of pressure (CP) being above the center of gravity (CG), when measured from the bottom of the rocket. We used OpenRocket to estimate the CP and the CG and found that, in theory, the rocket should be stable. We think that the main issues with our rocket could be with the launch sequence and the fins, so we changed those.
Fins
Instead of a straight fin, we tried a curved fin. We hope that the curve will generate spin to make the rocket more stable during flight. The fins still have the same taper has the version 1 fins. The back edge of the fin is also curved in the shape of a circle, to have a better fit on the rocket.
Launch Station
We still didn't have acess to a laser cutter to recut a new launch station, so we are still using the same pieces from the first launch. We did have an extra circle, so we glued that to the base. We are also using a longer 1/8" steel rod. We are using a longer rod so we can put part of the rod into the ground. We hope with these changes, the guide rod will be much more rigid. We are also using more tin foil to better protect the launch station.
Test Launch
Our second launch went very well. The improved launch station helped launch the rocket straight up. After reviewing the slo-mo video, the rocket started to fly off course once it left the guide rod. So, we will use a longer rod for the next launch. The curved fins caused a lot of rotation during flight, which made the rocket much more stable. The parachute system did not work. The knot tied came apart when the ejection charge fired. The parachute didn't produce much drag on the nose cone. For the next version, we will make the rocket bigger to fit a bigger parachute. To compensate for a bigger rocket, we will consider using more than one Estes A8-3 engine.
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