Final Post! FIGHT!

Finally down to the final post of this project!  Throughout this project we have launched a total of five official launches, and many many tests (and failures *ahem*). However, we've finally reached our target time of ten seconds. You must be thinking, "BUT HOW DID YOU DO IT?!?"  Well we have a quite elaborate way to tell it, but it would be much easier to show you through test times, videos and design.  At first we had a really hard time even getting close to 10 seconds with our first launch being 5 seconds.  This was done with 500mL of water and about 25 psi.  Though that test was a naked bottle, we still had our work cut out for us.  At first we tried to improve the time of it by adding an extra bottle on the top of ours in order to add more height to it and make the center of gravity different.  Our second launch was a bit better, but we think that it might have been just by luck.  It was either that or because we filled the bottle with 500mL and about 30 psi.  Though we got a second longer, there was still 4 more seconds that we needed to get.  On our 3rd launch we added on a nose cone and a parachute.  With the newly added length and mass, we only got 5.5 seconds.  From this we learned that in order to get a better time we would need to streamline the nose of bottle so it would have less wind resistance on the way up.After more tests and trials, we eventually figured that our bottle needed something to add more stability. Therefore, we added fins. Initially, our fins were too large and actually threw off the equilibrium of the rocket. It brought our next launch time to about 3 seconds |:( This brought us to the conclusion that our fins needed to be trimmed down, which we did. At the next launch day, which was our final day, we added our new nose cone as well as our new cut fins and proceeded to start testing.  Thankfully with our newfound modifications, we were able to achieve an initial launch time of 9 seconds, with 800mL of water and at 50 psi. After fixing our parachute that broke from this launch, we tried again and, with no small amount of luck (*cough cough*), finally reached the mighty 10 second :D with 850mL and about 55 psi.  In the end we found out that the wind really helped keep the bottle in the air.