Aluminum frame boyancy

[superarp]

I found this pipe http://www.eztube.com/ on the forum and was wondering: If I filled it with high density foam, would it still be positively boyant?? I am a high schooler trying to design an ROV that can get to 220 feet for a school competition. I know that foam wil reduce the boyancy, but it will also make it stronger and bend resistant.

[Seadragon]

I think the real problem will be the foam getting compressed and the air also. with thin walled aluminum you could experience crushing of the tubing. if you used holes and made the tubing free flooding it would work structurally. You can adress the bouyancy issues in other different ways.

I don't know what limitations you have for the project but you could use mineral oil if the tubing wont let it leak to the environment, this would provide bouyancy which you could adjust for neutral with weights or such(sand bags). It will also prevent the tubing from being crushed.

Hope that helps

[superarp]

Hmmmm......where could I get said mineral oil??

[SoakedinVancouver]

Pharmacies.

[derelicte]

what about olive oil?

[Unorthodox]

Mineral oil is positively buoyant and glycerol is not, neither is conductive. So if you had a pressure vessel you could fill it with a ballast layer of glycerol and a floatation layer of mineral oil taking up all the void pace, giving you a fluid filled hard to compress pressure hull with no conductivity

Both available at your local pharmacy!

If this is for a school project though, you would probably do better with PVC, either free flooding the parts you can flood, or liquid filled if you cant flood them. PVC is pretty tough, but if you go to a place like Home Depot be sure its not foam core drainage PVC because that is not pressure rated and WILL fail. You want solid core PVC.

[superarp]

The problem that we face with PVC is that it's round. Seeing as we have the machine shop capabilites of robotics team (really the same people), I think we will go with aluminum. Thanks though!!!

[Seadragon]

how are you adressing the bouyancy issues? slightly negative bouyancy is good for heading to the bottom and to slow drift rate. just seeing I have been busy for awhile and catching up.