Tuesday, March 29, 2016

A Rocket Takes Shape

Today's update on the rocket won't be very long, since neither is our rocket. We have decided to only use one 18" body tube in conjunction with our 9" nosecone, resulting in a pretty stumpy looking rocket. The reason we did this was that the body tube and coupler were heavy, and with relatively modest fins, we can still maintain a stability of 1.3 calibers. So far, OpenRocket is predicting a 645 meter apogee and our ideal rocket scenario gives about 3,600 feet. The one test launch that has been conducted by someone to test OR's accuracy showed that it underestimated apogee by about 33%, so we are eyeballing a predicted altitude of 3,200 to 3,400 feet. This thing should really take off, assuming it holds together!

With the design completed and CADs submitted, we have begun assembly, which seems relatively simple. The engine mount assembly is in one piece with the shock chord (surprise! there's a shock chord we didn't know about!) attached. Our next step tomorrow will be to attached the engine mount assembly within the body tube, install the parachute and altimeter, and cut and attach our fins.

The last part is the only thing that has me a touch nervous. We need our fins straight and evenly spaced, and I think I know how to do this, but I need to find some scrap wood - even just one block will do. My plan is to make a guide with a cutout for the body that covers 90 degrees of arc and with sides normal to the curve's endpoints. This will let me use it initially to keep the fin straight for the first one, and then space the rest off of that fin, keeping them all straight. So our team's current task is to beg/scrounge/obtain about a 6" x 6" piece of wood and have the machine shop cut it to our specs for us. That or talk our project leader into letting us use the laser cutter for that, too...

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