pressurized buoy

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covey12
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Tue Mar 02, 2010 4:56 pm

i know this isn't a cannon, but was wondering if this would work, would a pressurized buoy ( probably just a 4" pvc pipe with two endcaps) at 100psi have more buoyancy than with out the pressure?

im thinking of making a topwater ROV and was wondering if this could compensate for the weight of all the gear

edit by MrC: Not exactly sure what this had to do with combustions, it's like you just randomly selected a topic section without reading, or thinking for that matter. Topic moved.
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velocity3x
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Tue Mar 02, 2010 5:02 pm

Internal pressure has nothing to do with buoyancy. Buoyancy is determined by weight and displacement.
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covey12
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Tue Mar 02, 2010 5:04 pm

ok so it wouldn't affect how much it would float at all? thanks
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Tue Mar 02, 2010 5:10 pm

If you put more pressure in it, it will be less boyant because of the extra ( minimal) weight of the air..

A vacuume would create slightly better boyancy..not noticable but still..
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covey12
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Tue Mar 02, 2010 5:28 pm

ok thanks for the feed back
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Lentamentalisk
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Wed Mar 03, 2010 1:32 am

That said, if you plan on taking it super duper deep, having some internal pressure in the pipe to counteract the immense pressure from the water might not be a bad idea...
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Fri Mar 05, 2010 6:06 pm

Bouyancy = weight of the water displaced by the object - weight of the object.

Any part of the object that is out of the water contributes to the weight but not to the volume of displaced water.

Air at 1 ATM weights about 1g per liter. 1 liter of water weighs 1000 grams. You chamber probably weighs a couple hundred grams. So the gas inside the chamber contributes relatively little to the total weight of the chamber. If you used air at 2 ATM you would increase the total weight, and decrease the bouyancy, by 1 gram. (Roughly the weight of 20 drops of water.)

If you pumped the chamber down to a full vacuum the bouy would be able to lift (bouy) about 1 more gram than with air at 1 ATM.
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Fri Mar 05, 2010 6:34 pm

jimmy101 wrote:Air at 1 ATM weights about 1g per liter.
WRONG. It's 1g per mililiter. :D
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Fri Mar 05, 2010 7:51 pm

Gun Freak wrote:
jimmy101 wrote:Air at 1 ATM weights about 1g per liter.
WRONG. It's 1g per mililiter. :D
Pure water weighs 1 gram per milliliter...last time I checked...air was lighter than water.

He's a heck of a lot closer than you are. If I decide to trust wikipedia ( :roll: ), I get 1.2grams per liter.

http://en.wikipedia.org/wiki/Density_of_air
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Fri Mar 05, 2010 10:29 pm

Oh crap, I thought he said water :oops:
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