Soda bottle sub and stabilizing fins.
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tattersett
- Posts: 1
- Joined: Sun Nov 16, 2008 12:35 pm
- Occupation: Mother of student
- Project Question: My son is working on project on sub and stabilizing fins. We have taken two tries at the sub and cannot get the balance right. Following the directions on HowToons resulted in the propeller being heavier and regardless of how much water was added, the propeller would not spin because it was hitting the bottom of the bath. For v2 we added various weights to the front end of the sub but they are either too heavy or not heavy enough regardless of ballast (water inside the bottle). Thanks.
- Project Due Date: Rough draft due 11/17/08
- Project Status: I am conducting my experiment
Soda bottle sub and stabilizing fins.
My son is working on project on sub and stabilizing fins. We have taken two tries at the sub and cannot get the balance right. Following the directions on HowToons resulted in the propeller being heavier and regardless of how much water was added, the propeller would not spin because it was hitting the bottom of the bath. For v2 we added various weights to the front end of the sub but they are either too heavy or not heavy enough regardless of ballast (water inside the bottle). The rough draft for his project is due tomorrow and I am at my wits end. Thanks in advance for any suggestions. Jane
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kgudger
- Moderator
- Posts: 421
- Joined: Wed Sep 17, 2008 9:20 pm
- Occupation: electronic engineer
- Project Question: n/a
- Project Due Date: n/a
- Project Status: Not applicable
Re: Soda bottle sub and stabilizing fins.
Hi and welcome to the science buddies forum. Hopefully you are following the science buddies example: https://www.sciencebuddies.org/science- ... g&from=TSW. 
Is the depth of water in the bath more than a soda bottle? You may need 12 or more inches of water for this experiment to work. If your water container is deep enough, you should be able to find a neutral buoyant point that is close enough. Once you get the sub off the bottom so the propeller can spin, you should be able to point the sub in a horizontal direction.
If you are still having problems, please respond again and I'll try to think of more ideas. Even if you can't find neutral buoyancy, can you make it work on the surface of the water, like a boat? I would think that might work too? Let us know.
Keith
Is the depth of water in the bath more than a soda bottle? You may need 12 or more inches of water for this experiment to work. If your water container is deep enough, you should be able to find a neutral buoyant point that is close enough. Once you get the sub off the bottom so the propeller can spin, you should be able to point the sub in a horizontal direction.
If you are still having problems, please respond again and I'll try to think of more ideas. Even if you can't find neutral buoyancy, can you make it work on the surface of the water, like a boat? I would think that might work too? Let us know.
Keith