By Nicholas Loftin Of TuHS

Intro

Method

Results

Discussion

Bibliography

Return to research

 

Intro

Background information

          Of course, the importance of projectile weapons is to get an object to go a long distance with as little effort as possible. To get the optimal use out of your weapon, you want to make sure that you can get the perfect balance of range and power. You can get something to go a long ways, but it will take a lot of power. If you do not have enough power, then it will not go anywhere. In addition, if you have too much power, then you can blow up the weapon you are using to fire the object. For example, in a model rocket, if the engine you use is too big, then the rocket can blow up.

Statement of problem

          The purpose of this experiment is to find the optimal amount of methanol to use in the bottle to produce the most efficient launch distance and power. I will change the amount of ethanol in order to obtain this effect.

Review of literature

Ballistics in general has to do with the launching of projectiles from different weapons. A projectile is “any object that is cast, fired, flung, heaved, hurled, pitched, tossed, or thrown. The path of a projectile is called its trajectory” (Hart, 1). For a long time, many in war and science have used ballistics and projectile weaponry. Ballistics, in the time ofarrows, started when “Niccollo Tartagila described a quadrant, which was an instrument inserted into the gun to measure the angle of the barrel” (Toma, 1). It has progressed a lot over the years; in fact, it has progressed to the point at which we can make very sophisticated bullets used for many different purposes. Including, “soft point for maximum damage, hard point for maximum penetration, and many in between” (encyclopedia.com). Many people have done experiments with different vapors, including, “Michael L. Corradini and Riccardo Bonazza who are experimenting with the effects of cold water and molten metal that combust to form vapor explosions” (engr.wisc.edu). Lastly, an experiment with liquid ethanol vapor in which, “the ethanol is ignited to form an explosion inside the bottle and forces the stopper off” (sprott.physics.wisc.edu).

Hypothesis

          I believe that the launch velocity will increase proportionately with the amount of ethanol in the bottle untill a point at which it will level off and rise slowly, if at all. The amount of ethanol is defined as the number of drops put into the bottle. The launch velocity is defined as {(distance/time)^2+((9.8*time)/2)^2}^.5                                                                                                      TOP

 

Method    TOP

          In my experiment, I tried to keep my method as precise as possible, and I also tried to keep it consistent throughout to limit the amount of variation between launches. I would start by dropping in however many drops were required for that experiment, and then I would put the cork on the top. I tried using a rubber stopper, but there was too much friction between it and the bottle, so it did not launch at all. After I put the cork on the top, I would shake the bottle for about 15 to 20 seconds to vaporize as much of the methane as possible. Then I would strap it into the launching device with a small bungee chord as shown in the picture below. After I have placed the bottle securely on the launch device; which my dad and I built with our bare hands (and a few power tools), I would use the high frequency generator (zap thing) to ignite the methane and launch the cork. As soon as it launched, I would start my watch and then stop it when the cork hit the ground. This is where I would encounter my worst error to be discussed about later. I would watch the cork very carefully in order to see where it landed. I would the measure from that point until directly under the launching device. I would then dry out the inside of the bottle with silica gel packets so it would launch again. After a little bit, my lovely assistant (my mom) came out and helped me by drying out the bottle while I used another bottle exactly like it. We figure this saved me about two and a half hours of experimentation.

 

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Results            TOP

In the end, my results came back inconclusive, because I had trouble being perfectly accurate in some of the steps in my experiment. What did occur was in some ways concurrent with my hypothesis, yet some aspects were not. As you can see, 17 drops in the bottle experienced the highest velocity, yet all the others were relatively in order. In each of the different variables, the launch velocity varied greatly, as shown below. Some of them varied by as much as 3.5 m/s.

 

 

 

 

Discussion         TOP

As I stated before, my results were inconclusive, yet I know what I could do next time, especially if I had a bigger grant. My biggest error that I encountered was the inconsistencies in my timing. Part of it was my slow reactions, which I could fix by rigging up a device to start the time when the cork leaves the bottle then stop it when the cork hits the ground. Of course, this is not feasible to most people, so I recommend having two or more people timing, then average it out. It would also help if the experiment was performed inside a building so you would not have to worry about wind. As well, there has to be a way to regulate how much ethanol vapor is inside the bottle, because there is no way to regulate that in the way I was performing the experiment. One thing I noticed from just messing around was when I used a bigger bottle it shot much higher than when I put similar amounts of ethanol into them. I think that this is because there is more area for the ethanol to vaporize into, so there are more reactants to propel the cork.  I also did not notice much variation between the numbers of drops, so that is why my last two were at larger variables, because I was hoping for some better change. I think that if I had done that through the whole experiment, I would have noticed my distinct variations. It also took a while for me to find an amount at which it would launch, and I finally found that 15 drops did it. In the end, I am pleased with my experiment as a whole, and I had fun doing it.

 

 

Bibliography (in order of use)       TOP

http://www.hypertextbook.com/ by Glen Hart, 5:15              10/25/04    I used this website in order to further my

     knowledge on the mechanics of bullets.

http://www.tomacorp.com/ by Toma, 4:53 10/25/04 I used this in order to learn more about bullet ballistics.

http://www.encyclopedia.thefreedictionary.com by unnamed, 5:27 10/25/04 I used this in order to learn more about bullets and how they were made and used.

www.engr.wisc.edu/ by unnamed, 5:36 10/25/04 I used this in order to learn more about vapor explosions and their practical use.

http://www.sprott.physics.wisc.edu/ by Mr. Sprott, 5:39 10/25/04 I used this in order to learn how to build my apparatus.