Tube Capacity

[mister p]

Does anybody know the tube (air) capacity of an average 6m RIB in litres?

[falcon0310]

well if you say 50 cm x 35 x 12 mts give you ruff idea

[mister p]

So 12 x 0.5 x 35 = 210 litres of air in a 6m RIB?

Doesn't sound enough. I was guestimating closer to 1000 litres.

What's the 35 element?

[mister p]

Using pi x radius squared (as the cross section area) of a , 3.14 x 0.25m x.0.25m x 12m ( tube length) = 2.4 cubic metres.

1000 litres in a cubic metrre. 2400 litres.

???????????

[mister p]

I'm trying to work out whether it's worth bothering filling the sponsons with helium based on the fact that helium has a lift of 1gram per litre. It's sounding like it may lighten a 6m by about 3 kg........negligible for the effort involved.

[Timw44]

I wouldn't bother. Helium will diffuse through the tube material and is from 3-5 ppl so it becomes an expensive 3kg saving.

[Pikey Dave]

Originally Posted by mister p

I'm trying to work out whether it's worth bothering filling the sponsons with helium based on the fact that helium has a lift of 1gram per litre. It's sounding like it may lighten a 6m by about 3 kg........negligible for the effort involved.

Complete waste of money. You'd never keep the helium in the tubes due to the very small molecules & Helium was about 2p/litre the last time I looked.

[falcon0310]

as said aprox, tube would be 50 cm wide so x 12 now i see why you want that, i agree with dave

[mister p]

That's what I thought, I was hoping I'd got my maths wrong and I would somehow find 30-40 kilos somewhere.........maybe not.

[Cookee]

Originally Posted by mister p

That's what I thought, I was hoping I'd got my maths wrong and I would somehow find 30-40 kilos somewhere.........maybe not.

Funnily enough that's the answer everyone comes up with when they ask this question!

[Dry Run]

I don't see it would be a problem to keep helium from escaping from your tubes. Surely the relevant "bladder" inserted into the tube could solve the problem. However, do agree that it's a waste of time and money. If you look at the helium balloons they sell in shops you'll see that even a fairly big one can be weighed down with something as small as a 2p piece, so I reckon a couple of tubes full probably wouldn't even give you 2-3kg. I think this discussion is just a lot of hot air............ah, hot air, there's an idea?

[GordyP]

I recommend simply having an enormous turd just before leaving the dock, that'll save you more weight.

[kerny]

Originally Posted by GordyP

I recommend simply having an enormous turd just before leaving the dock, that'll save you more weight.

If most on here did that this forum would float up into the sky

[m chappelow]

Me old man said that they put helium in some of the b 29 super fortresses tyres as a weight reduction on some of the fuel critical long distance flights but they would go flat in a week or so if not topped up ,

rough guide ,,,,a 15 cubic foot volume (not compressed )balloon of pure Helium would lift or give neutral bouyancy in air at sea level of about a pound in weight .

In the future there has been talk by the producers that there may be a world shortage of helium gas so the price will go up even more just about outstripping it for certain uses . (Not a pun .

[kerny]

Originally Posted by m chappelow

Me old man said that they put helium in some of the b 29 super fortresses tyres as a weight reduction on some of the fuel critical long distance flights but they would go flat in a week or so if not topped up ,

rough guide ,,,,a 15 cubic foot volume (not compressed )balloon of pure Helium would lift or give neutral bouyancy in air at sea level of about a pound in weight .

In the future there has been talk by the producers that there may be a world shortage of helium gas so the price will go up even more just about outstripping it for certain uses . (Not a pun .

My late dad used to have a family business running one of these a few years ago, obviously he switched to helium because most of his punters smoked in those days.

http://www.rajankhanna.com/wp-conten...phy-poster.jpg

[Wightdiver]

Originally Posted by Timw44

I wouldn't bother. Helium will diffuse through the tube material and is from 3-5 ppl so it becomes an expensive 3kg saving.

And if the local kids find out they will be breathing from the valves to talk like Donald Duck!!