Making the model of the submarine wasn't easy at all. I had to make some modifications here and there.
I followed the steps below.
1. Cut the bottom half off a 1.5-L soda bottle using a pen-knife, as shown in Figure A, to make a propeller shape that has five separate curved blades. See Figure A for a picture of the finished propeller.
2. Drill 2 holes in both the small water bottle cap and the propeller, one in the center and another just off center.
3. Straighten one end of one of the paper clips and feed it through the hole in the top of the bottle cap and through the center hole of the propeller. The propeller fins should be facing down, curved away from the bottle cap.
4. Bend the inside ends with the needle-nose pliers, looping it through the second off-center propeller hole to secure the paper clip and two pieces together.
5. Mark out measurements on the propeller (ie 9cm, 8cm, 7cm etc). You will reduce the length of the propeller to test how the length of the propeller affects the speed of the submarine.
After which, I made the body of the submarine, following the steps below.
1. To make the submarine, drill two small holes in the bottom of the water bottle, just like the holes in the propeller—one in the center and one slightly off-center.
2. Straighten one end of the second paper clip and use chopsticks to insert the straight end of the paper clip through the hole of the water bottle, from the mouth of the bottle into the centered hole at the end of the water bottle.
3. Once you get the straight end out, use the pliers to bend the end over and hook it into the other off-center hole to secure it.
4. Use the chopsticks again to hook a rubber band onto the paper clip hook inside the water bottle submarine.
5. Without letting go of the rubber band, hook the other end of the rubber band loop through the paper clip hook inside the bottle cap propeller. If it is too difficult to pull the rubber band using chopsticks, use another paper clip to make a hook and use this to pull the rubber band to the hook in the bottle cap propeller. Make sure the rubber band is tight—the submarine’s rubber band needs good tension or it won’t be able to move. See Figure B.
6. Use ice cream sticks for stabilising fins. Use a rubber band to tie 2 sticks side-by-side, 4 on the front and 2 at the back of the submarine body.
7. Using the waterproof sealant, make sure that the paper clip holes are fully sealed. Water can easily move in and out of the submarine if there are still holes, which will affect the experiment. Give the sealant enough time to dry before proceeding with the experiment—see the sealant’s instructions.
How the submarine should look like:
Figure A (propeller)
Figure B (Propeller + body)
Here are the pictures on how I made the submarine:
Making the body of the Submarine
Making the Propeller (1)
After making the propeller, I put the submarine test. However, the experiment was a failure and the propeller was not able to generate enough kinetic energy to propel the submarine forward. The body of the submarine was fine, but it lacked stabilising fins, thus it could not balance.
Things that the submarine was lacking in:
- The plastic used to make the propeller was not stiff enough, making it flimsy.
- There was not stabilising fin.
- There was no gap between the blades of the propeller.
Modifications:
- Use a soda bottle which is stiffer and stronger than a mineral water bottle- Allows the propeller to whip the water with more force which will generate more kinetic energy.
- Use ice cream sticks and chopsticks to act as the stabilising fins.
- Use a soda bottle- the bottom of the soda bottle curves in, which makes the gap between the propeller more obvious.
So with that, I embarked on the second try of making the propeller of the submarine!
Making the Propeller the Second time
*I used the flame to heat the screwdriver so that it would be easier to drill the hole in.
Time for the experiment with the modified submarine!
