Aluminium Frame

[onibnasir]

Hey guys. I am designing my ROV with an aluminium frame. There are certain reasons why I have to use the aluminium frame. The fabricator says it would weigh at least 10 kg. Would the bilge pumps provide any propulsion?

[DavidF]

If the rov is nutrally boyant weight doesnt matter its the frontal area that gives the resistance.

[onibnasir]

So despite the weight of my ROV, if i make it slightly positive buoyant (which i intend to do), the weight would not bother me and the bilge pumps which i am using of 1100 GPH would provide the propulsion to my ROV?

Need some professional advice here with people who have worked on ROVs.

[sthone]

Actually the weight does matter, because the Thrusters will have to move the mass of the Rov no matter if it is neutral buoyant or not. The buoyancy only means it will not sink or float but remain at a certain depth.

Think about it like this... if you had a full size Submarine that was neutral buoyant would you be able to push it forward like you were pushing a stalled car?

-Steve

[Racer]

Catia V5 Nice

[DavidF]

oh ok so whats harder to push a feather or a brick?? neither of wich have any weight as they are nutrally boyant?? so maybe there is another variant,,, mass ??? Oh I love this kind of stuff!!! and NO im not trying to be a smartazzz or anything it just makes for an interesting discussion.. yes force verses mass, but if weight isnt an issue (nutral boyant) then mass would be relative with time and force and break down into the speed???? Whooa!!! Darn those nasa geeks!! lol

[thegadgetguy]

Fun stuff! Another aspect of having a heavier ROV is that it's more weight to lug around when you're transporting it above ground. It might not seem like a big deal, but it can be a real pain!

[DavidF]

sitting here thinking of this one... If a rov is nutrally boyant, technically it has no weight, pushing the rov thru the water it would require some force to get the mass into motion but it is the frontal area that gives the resistance thru the water. That being said, a small thruster could move a large rov but the speeds it could reach would be limited by the resistance and not the weight.
Pushing a stalled car on land, yes that takes some effort, but pushing that same car floating on the water takes little effort.

and for some real thought, if you put a bilge pump on the side of the submarine, and there were no other forceses applied to the sub other than the thrust of the bilge pump than the sub would be moved by the bilge pumps thrust.

[martinw]

http://en.wikipedia.org/wiki/Inertia

Martin

[sthone]

David.... while resistance does play some part in this, you wrong about the weight. A boat even floating on the water has very little resistance but have you ever tried to push one around... it is not easy.

I don't claim to be an expert but I know from experience if you build a heavy Rov (no matter how streamlined it is) and put a small thruster on it, it isn't going to go move any faster than a crawl.

-Steve