Explanation & Thoughts on the Water Bottle Rocket

The picture above shows our final water bottle rocket that Lydia and I created.  Throughout our water bottle project, Lydia and I learned A LOT of information we did not know previously.  From the very first day of this project, we were equipped with lot of information about how these water bottle rockets work and how they should be created (from the various listing of websites that people listed in the blog entries).  The two websites Lydia and I found helpful were: http://www.nasa.gov/audience/foreducators/topnav/materials/listbytype/Water_Rocket_Launcher_Directions.html & http://www.pack236.org/Water%20Bottle%20Rockets%20Guide%20for%20Expo.pdf.  The first day of launching was kind of scary but really impressing.  For our first launch, we basically were just familiarizing ourselves with how the bottle works and how the amount of water and pressure affects the height in which the bottle travels through the air.  On our first launch, we used just the bottle itself and the standard 500 mL of water with 40 psi.  The bottle lasted in the air for approximately 6 seconds.  We were stoked about this result because we assumed after making modifications it would definitely hit the marked time of 10 seconds.  For the second launching, Mr. Blake required that we make some type of modification to our bottle.  Both the websites that we found gave us the idea that we should add a nose cone to the top of the bottle.  The nose cone would help center the bottle and make a smoother flight.  Mr. Blake hinted at us that we should use a sturdy nose cone because a flimsy piece of paper just would not do and wouldn't help the rocket.  We decided that we should buy those orange cones that little kids use in soccer games and use that as our nose cone.  It is very sturdy and we felt that it would help the bottle travel through the air very smoothly.  The second day of launching we launched the bottle with and without the cone on top of our rocket.  Both times were 6 seconds each.  After these results, we were kind of stumped.  We thought that maybe with the nose cone, our time would have increased, but it didn't.  By the next class, we needed to make more modifications to our rocket so Lydia and I decided that maybe if we just attached wings to it, it would give us a couple more seconds in the air.  We believed that the wings would help the bottle stay balanced, give a little weight, and stabilize the bottle during its flight.  Before we got to class, I grabbed a cardboard box and cut 4 wings.  I was oblivious to the fact that maybe I should have cut the wings in proportion to the size of the bottle.  The requirements to this third launching also called for a parachute to be attached to the bottle, but it did not necessarily require it having to be deployed.  When we went to go launch our rocket, the bottle did not go very high and the parachute did not deploy.  On this launching we needed to reach a minimum of 3 seconds.  After the launch, our bottle barely made the 3 second requirement.  Lydia and I were kind of mad because after making more modifications to the bottle, the time shortened!  Over the weekend, we thought and and felt that we needed to recreate our rocket.  We got a new bottle and recut new wings, made a new parachute, elongated our bottle (with a second bottle), and added a weight in the middle.  Adding the weight would help the center of pressure.  We got this idea from: http://home.comcast.net/~timhesterberg/HowToRockets/HowToRockets.html.  In doing this, it really helped our fourth launch.  We needed a minimum of 5 seconds for the fourth launch.  After launching, the bottle lasted 8.5 seconds!  We processed this result and realized that maybe we need to add more pressure and water to our bottle.  On the final launch day, we added about 800 mL of water and 80 psi.  We launched three times on our last day.  The first two launches were 6 and 5 seconds.  This was because the cone would not come off during flight so the parachute could not deploy.  We decided to make the cone super loose on the rocket.  On our third launch, the cone finally came off and the parachute deployed! This left us with a 10.4 second flight!! We were soooo happy!  After our third launch we tired a last launch to try and get a better time, but that was a fail.  Our fourth launch was a total of 6.625 seconds.  On this last launch, our cone did not come off yet again and it broke during its fall.  Thank God we met the 10 second requirement!  In conclusion, we learned that the more water and pressure you place in the bottle, the more pressure will be created to push the bottle farther up.  Wings help to stabilize the rocket and the cone helps the rocket fly straight.  The weight in the middle would help the center of pressure so that it can come down due to gravity.  And, the parachute catches the air to help keep the rocket in the air for a longer period of time.  Overall, this was a very fun, exciting, and muddy project.  I'm so happy our rocket last 10 seconds. :)

Final Launch !

Today was our final launch, me and melody fortunately achieved the launch time by getting a final launch time of 10.4 sec. The weather today was not exactly launching conditions, it was cold, rainy, and windy. The wind I think definitely impacted the time that we got for our final launch, because when our parachute deployed, the wind helped keep the rocket afloat in the air for a longer time. At first, we got launch time of 6 sec, but then we found the problem. We cut slits in the nose cone so that the air could blow the cone off so that the parachute could deploy, because the problem with our launched was that the parachute didn't deploy because the cone wouldn't come off in flight. We cut slits in the cone, and we   taped the cone to the bottle very lightly, we also tied a string connecting the cone to the bottle so that when it comes off, we wouldn't lose it in the process of the launch. When we solved this problem, we found it to be much for effective, because we got the time we wanted. We also used a suggestion from this article http://www.pack530.org/PDF%20FILES/Building%20A%20P-530%20Rocket.pdf on how to fold the parachute so that it could deploy correctly. "Grab the chute between two fingers, in the center, and pull it up toward the ceiling. Let the chute fold naturally as you lift it. Once you have the chute pulled up, fold it once in half at the center. You don't want to fold the chute too tightly but you can fold your chute into thirds if space is a factor. Wrap the excess string loosely around the chute. Fold the straw armature sections onto the chute but not part of the excess string wrap." We found this to be very effective, because our parachute deployed correctly. Today was a success (: 

5 Second Launch

Today we launched for our 4th time.  This weekend I knew we had A LOT of modifications to make to our rocket.  Because we glued our wings onto our last rocket and the wings were too big, I decided that we should just start from fresh.  So I got a new bottle, exactly like our last green one, and then got two more 2-liter bottles from my neighbors trash and cut those bottles.  I got the idea that I should put some weight inside our rocket.  I got this idea from: http://home.comcast.net/~timhesterberg/HowToRockets/HowToRockets.html.  The weight I decided to use is watered down shredded paper.  At the bottom of the green bottle, I placed one of the cut up coke bottles and then I put the watered down shredded paper. I taped down this watered paper and then placed the topping of our bottle and closed it off so the water wouldn't evaporate.  For our parachute, we placed a toothpick and knotted the string and put it in the bottle before closing it off.  This was a secure way that the parachute would not come off.  After stringing the string through the top of the bottle, we attached a black trash bag to the top.  The trash bag was cut into a square.  I thought of the types of parachutes that people use when they go parachuting.  Our launch lasted 8.5 seconds! We were so happy.  We put about 600 mL of water and 60 psi for our rocket to launch.  Inflight, the cone came off and the parachute came off, and the rocket landed safely on the ground.  By next class, I think the modification we need is to not make the cone come off so early.  During the flight, I think the cone came off to early and cut off the path in which it was going.  We need only 2 more seconds! Hopefully it works by next class.

3 Second Launch with Modifications

Today we had to complete a launch that lasted a minimum of three seconds, with our parachute on. Me and my partner Melody thought that if we added fins, and a cone, that it would make our rocket stay in the air for a longer amount of time. However, we found that our launch lasted exactly 3 seconds, our launch wasn't as successful as we thought it was going to be. We picked out problems, that we thought was the cause of our unsuccessful launch. We think that our fins were to big, and they weren't evenly placed on the rocket. We also thought that our parachute wasn't big enough, because it didn't catch any wind at all when the rocket was falling after it reached its maximum. Also, with our next launch to plan to make our rocket longer, because observing from other groups, the ones that had the longer rockets stayed in the air for a longer amount of time. 

Modified Launch

Today in class we timed out bottles without any modifications.  We again used 500 mL of water and filled the bottle, then did the same thing we did on the first launch.  After timing it, we noticed it was only 6 seconds.  For the final we need to keep the bottle in the air for 10 seconds.  So we only did one small modification to see if it helped the bottle stay in the air for a longer period of time.

As you can see in the second video, the modification we added to the bottle was an orange one on the top.  We thought that by doing this, the surface area of the bottle would be smoother and there would be less resistance as it traveled.  When we tested it, it went about the same height and stayed in the air for about the same length of time.  After both testings, both times with and without the modification was a total of 6 seconds.  Tonight we will try to add maybe some wings to it and maybe a parachute to help it stay in the air longer!