In this project activity, my team will develop the actual rocket height and compare it to the theoretical results. We are expecting that our result will be close enough to the theoretical. There are some factors would influence our results; those factors are the propulsion mechanism and wind effects. That is why my team decided to launch the rocket straight up, not with an angle. The concept for the bottle rocket has been applying for many serious products. In modern industry, people are using this method to produce a new type of CNC cutting machines. These machines using the jet engine with compressed air at 50,000 psi or more. With that amount of pressure, the jet engine could cut through various type of material. Furthermore, replace the old model of CNC machines with the new model using jet engine, we could save millions. The old model of CNC used cutting tools that made by hard material. When the machine is in use, it gives a lot of heat. With the jet engine, we will no longer worry about heat why cutting material. In military, most of aircraft using this method to launch from USS aircraft carrier.In the modern world, NASA is using the same procedure for rocket launching. They also provide guild line for student able to hand-on the concept of rocket. We combined some information from NASA website and information we learned from fluid class on this project. The different in pressure lead the different in high. Based on NASA website, and for safety, the pressure inside the bottle will not be excess 60 psi. We will determinate the high of the rocket with the maximum pressure at 50 psi.Methods and Materials
The bottle rocket consisted of a two liter Coke plastic bottle. The launch pad base material is wood. The assembly of the launching device used in our experiment consisted of four metal L brackets with holes in them secured on to the base by wood screws. Two pairs of the L brackets set across from each other and used to secure the bottle down. Two holes were drilled in between the two pairs of L brackets. A flat bracket with two holes at each end and one hole in the middles was sat on top of two nuts put on the bolts and secured with two other nuts on top. A rubber stopper with a tire valve stem was inserted through the hole in the middle of the flat bracket. Two long nails were used as the release mechanism of the rocket.The experiment used the energy of pressure to launch a plastic bottle in to the air. The procedure began by filling the bottle with approximately two cups of water. Once that was done the bottle was secured on to the stopper which prevented the water to leak out. Most plastic bottles have a hard rim on the mouth were the cap sit on. This rim was used to secure the rocket while pressure is being applied. Once the mouth was on the stopper the flat bracket was adjusted so that the two nails where inline with the rim of the mouth. The nails where set through the two pair of L brackets right on top of the hard rim of the bottle mouth. A string was attached to the nails that they could be removed fast and at the same time. A tire pump with a pressure gauge was connected to the tire stem valve. Air was pumped into the bottle until the pressure desired was achieved. Once the pressure was met the nails that held the bottle in place were pulled off by the string and the bottle shot up in the sky. Below are images of the bottle rocket and assembly.
From the results it is clear that experimental and theoretical results are different. The variation in the obtained results can be attributed to the errors that may arise during the experiment. The variance in the experiment and the theoretical value can be due to the approximation that used in the calculation of the heights and the time taken. The assumption that the bottle goes up in a straight line may not have hold since there exist other externalities that the environmental set up of the experiment could not control. The argument that the fat end top of the bottle will travel up and down in the lead may not hold since the external forces may tilt the bottle and thus changing the path taken by the bottle in its movement. The effects of the gravitational pull may also contribute in the variance. We also assumed that the drag force is the same but that may not be the case since the shape of the bottle is not uniform and the experiment is not being done in a vacuum. There is definite energy loss as the bottle gains height and thus this may also contribute to the changes in the velocity.Looking at the relationship between the height and pressure, we see the linear relationship between the height and pressure. As the bottle gains height the pressure increases. When looking at the velocity and pressure, we also observe the linear relationship and thus as the velocity increases the pressure also increases. The principle can be employed where both height and velocity increase will result in the rise in the pressure. This application can enable the deployment of the technology in many uses as suggested in our initial arguments.