Final Blog Post

Overall, our bottle rocket experience was not only stressful, but also inventive, an opportunity to stretch our creativity through the practical application of science. We had our share of achievements and failures during the constructing process which began with only fins on February 28, 2011 at 2 - 3 seconds of flight time. That day, we had difficulty setting up our launching station because the relapse clip failed to attach to the launch pad. To save time we went to another station where we launched the ¼ filled H20 rocket.

Attempting to create a constant in our study, we filled the bottle to about ⅓ of it, realizing it maximizes the pressure inside when air is pumped into it. 50 psi powered our first launch, increasing to 80 psi by the end of the project: the increase in air pumped was directly related to the pressure inside the bottle, increasing distance traveled. By launch #3, we added rocks taped to the nose of the rocket to increase the center of mass, stabilizing it while in flight. We also added tabs at the top of the rocket to help the attached cone come off at apogee, allowing the parachute to deploy. According to Science Olympiad Student Center, the tabs help prevent the cone from getting stuck due to the opposing weight and friction in launch.

As we added modifications, our traveling time increased from 2 to 5 to 7 seconds. Our highest flight time was 9 seconds, however, on judgment day we made 6 seconds because we adjusted our parachute size and our cone broke, making us use the larger cone which disabled the tabs. Even though we didn’t make 10 seconds, we learn a lot through trial and error, realizing that you can never perfectly replicate something; hopefully one day, we will understand our rocket and exceed our goal of 10 seconds.

For the most part, it seems that by the end of this project we began to understand the science concepts behind this including thrust, weight, lift and drag. Thrust was created by the pressurized air in the rocket. Weight was created by the rocks that we taped on top of the rocket. Lift and drag are the opposing forces which act through the center of pressure. In class we learned that the center of mass should be above the center of pressure. We used more mass in opposition to thrust, which allowed the rocket to lift into the air. Drag was created by the smoothness of the rocket. Also, because of our duct tape adding more air friction, our rocket had drag. Overall we learned a lot through this project about physics concepts.

Sources

"Bottle Rocket - Science Olympiad Student Center Event Wiki." Scioly. Web. 11 Mar. 2011.

"Rocket Aerodynamic Forces." Space Flight Systems Directorate / Glenn Research Center. Web. 11 Mar. 2011.

Launch #5

Our fifth water bottle rocket launching was a bit disappointing. In order to improve our time, we created a larger parachute from a garbage bag in the physics classroom. We also incorporated a larger cone to the body of our rocket. When we arrived at the field to launch our rocket, we felt very confident in our launching. Our first attempt was a rather failed endeavor for the parachute did not deploy resulting in a four second launch. Our parachute failed because the cone was fastened on the water bottle rocket too tight. For our second launching, we placed the cone loosely on the top of the water bottle rocket to not suffocate the cone. After launching the rocket, it had landed by the dining hall staircase because our parachute did not deploy. This launching was our longest airborne attempt with 6.3 seconds. The defect with this launching was that the parachute became stuck within the cone, thus causing a failed deploy. We attempted three more times (ranging from three to five seconds) with many unsuccessful results for the cone was either stuck onto the bottle or the parachute was becoming stuck within the cone. We were very disappointed with our results and decided to return back to our old parachute, which was rather smaller than our current parachute. We also decided to go back to our original cone, which is more compact than our cone from today. These last minute modifications can hopefully improve our time to at least nine seconds, so we can achieve a longer airborne time. We will retry tomorrow during lunch in order to reclaim victory and achieve an A on this launching. My group is not going to give up on our mission to achieve an A on this project and get nine to ten seconds in our launching. We will succeed!

Launch #4

Photo from: http://www.paksc.org/

Today, launches were successful: we tinkered with 4 factors that greatly affected our goal-launch-time of 5 seconds or more. Nicole and I perused various websites on “how to deploy parachutes.” One of the websites said to make tabs, attached to the top of the water bottle rocket, ones that kiss the circumference of the nose cone; so, we cut out small rectangular tabs, covered them in duct tape, and duct-taped them to the bottle rocket, all equidistant from each other. The tabs allowed the bottle rocket to tip, while at the top of its trajectory, so that the cone would fall off, allowing the parachute to deploy. We also did the “trail and error” routine when it came to folding the parachute: the best way was to scrunch the parachute, loosely stuffing it into the cone, making sure that they don’t get stuck to the exposed, sticky tape on the tabs. After 2 or 3 trials, we tightened the nose cone to maximize the amount of time it stays on, allowing a greater trajectory height. Adding more water helped increase the time, along with more pressure pumped into the rocket. We are looking to adjust the size of the next parachute, hoping that it will increase our 6-second launch.

Launch #3 Videos

Launch #3

Today was the third launch day, in which we performed two launches.  Our previous rocket design on the second launch day consisted of 4 triangular fins.  In the most recent design we have made a some major modifications including new fins, a cone, weights and a parachute.  Video 1 shows our first trial:

The air time for this rocket was 7 seconds. Video 2 shows our second trial:

In our second trial Taylor added another rock to the top of the bottle to create more mass.  This seemed to increase our height and time in the air.  In both trials there was no deployment of our parachute.  This is due to the fact that the nose cone is pushed on against the top of the rocket when going up and becomes pushed down so hard that it does not fall off in descent.  According to TopBits.com, the point where the rocket starts its descent is called apogee.  I researched parachute deployment and this site, http://scioly.org/wiki/Bottle_Rocket, gave me information on how to help the parachute deploy.  It suggests  supporting the cone with tabs or a margarine lid so that it does not become stuck onto the bottle and at apogee, will the parachute will deploy.  For our next modification we will try tabs on our rocket to support the cone.  Other than that modification I feel that our fins, which were more streamline and lower on the bottle created better stability.  Our cone works well but with the new modification should fall off at apogee.  The increased weight we added to the top of the rocket was a good modification because it increased the airtime.  We still donʻt know how the parachute will fair but hopefully we will get the chance to see it on Launch 4 day.

Launch #2

Today, we had our second trial for launching our two-liter bottle rockets. The trial runs were somewhat successful, and our group was able to launch each bottle on its first attempt. For our first bottle, there were no modifications added. The whole entire launching was basically the same as yesterday except our water bottle rocket was set up a bit crooked, which is why our bottle landed in a tree and stayed there for a few minutes. For our second bottle, we added some modifications, which included the fins towards the bottom of the water bottle for stability. We attached three fins made of cardboard to the bottle using the hot glue gun, so we would have an idea of what this sort of modification would do to the rocket launching. As seen in our video, the water bottle spent less time in the air from our previous trial because of the addition of mass (four second launching). Next time, we plan on using a parachute in order to prolong the amount of time our water bottle rocket experiences. We will also make the fins a little curved, so that it creates more drag when coming down making the rocket stay airborne longer. We learned from physics class that you need to make the rocket longer, so it can be more stable because of inertia and also there needs to be more mass placed on the top of the rocket. Because of this information, our group places on placing a cone on top of the rocket to make our launching more successful. We will surely be prepared for our third launching and cannot wait to display our designing skills.