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.

The Moment of Truth

 

Okay, so this was the moment of truth for every group in class today. The final launch was due and the time to get was 10 seconds. This is where, all of our work really paid off. So, as a group we fixed some of the modifications on our rocket, so as to avoid mishaps from last class, like cutting down the fin size and making sure that our parachute was secured to our rocket. With our rocket in hand and our confidence high, we went out to the field to launch. On the first trial, we launched with a little under 800ml of water, and 20 pumps (which is around 50psi). This actually got us all the way to 9 seconds on the first try! This boosted our moods considerably, so we kept going to try for 10. Eventually, the parachute came off again, so we had to repair it. We launched a few more times, until finally (mostly thanks to some heavy wind) our rocket sailed through the air, parachute deploying at its apex, and floated down the hill towards ʻAkahi. Thankfully, it avoided the roof, and netted us 10 seconds of air-time! So, we'd finally done it and now, hopefully, we'll get a good grade for the rest of the project. Well, at least it was really fun!

P.S.: Good job to everyone else, too. Let's beat period 4 for average time!

Bottle Rockets Rain or Shine

Unfortunately it was rain and high winds for my physics class. The average class time for our rocket bottles was about four seconds and the minimum time each group needed was five seconds. The average class time for period four was about six seconds, but at the same time they did not have to weather the rain like us. Before my group tested the rocket again we added fins to the bottle.

My group particularly had a hard time dealing with the conditions. Our first launch was about three seconds, probably because our parachute broke. In the rain we fixed the parachute and launched it a second time but once again the parachute broke leaving us with a time of still about three seconds, so we decided that we needed to go back to class and make a new parachute. Before we could launch the rocket bottle for a third time the rain really picked up and class was going to end soon, so we didn't get to the minimum five seconds. The thing that concerns me the most is that we don't know if the fins helped our bottle or not because the variables (weather) was different. One thing that the group knows for our next launch is that we need to change our cone because the cone that we are now using is packing the parachute to tightly.

Rocket Post #4

Hey so today we had our third launch already.  This time it was our modified rocket with a parachute attached.  As you can see from the video I'm adding with this post, well lets just say that the first time wasn't exactly perfect.  This was the first of two launches that we did today and the parachute didn't deploy at all.  However after seeing the first time we figured out what was wrong with it and corrected it for the second try.  Unfortunately we didn't film the second try but it did in fact work!!  After seeing that the parachute was too tightly wrapped we decided that maybe we should open it a bit so that it would open up faster, which it did and turned our day into a success.  Though it may seem like we are just messing around with rockets, we are actually getting valuable scientific information for our project.  We have learned that though we did increase the mass of our projectile, it has given it a different shape, which in turn causes it to fall differently in comparison from how it originally was.  Not only that but the parachute also helps slow the decent of the rocket down because it changes the surface area of the rocket,  which in turn causes more wind resistance to the rocket.

Rocket Post #3

Hey, everybody. Today we launched a bit more and tested out some of our modifications. First, we started out with launching an unmodified bottle to give us something to base our results on. We used 500ml of water as fuel, and pumped it 11 times. This got it to stay in the air for 5 seconds, which is half-way to our quota time. The second launch was with the modified bottle, which we made longer by adding another bottle on. We used the same amount of fuel, but pumped it 15 times. This time, the rocket stayed in the air for 6 seconds, which doesn't seem like much gain, but it's still progress. In the next post, we'll be launching with a parachute attached.