ReCirculating Oil Ballast System

[redboat219]

I was surfing the net when I came upon this.

http://www.soc.soton.ac.uk/JRD/HYDRO/argo/design.php

The system is relatively simple and is similar in principle to Dr. Art's RCAB system but it's based on recirculating "oil" instead of air - ReCirculating Oil Ballast System.

[raalst]

The plus of this system

The plus of this system is, that the volume of the bladder will not
go down when pressure rises, because the oil cannot be compressed.
The air bladder of the RCABS will be compressed when going "deep".

[Guest]

RCABS bladder compression

Ronald,
Trimming of the model so that the boat is at slight negative buoyancy when the bladder is fully deflated, negates the possibility of further compression of an already flat bladder as the sub submerges deeper. Compression of the air in the bladder is not a problem with the RCABS.

[raalst]

true !
and it

true !
and it was not meant as a critique on the RCABS as such.

[redboat219]

here's another link which describes

here's another link which describes the working of the ballast system
http://ams.allenpress.com/perlserv/?req ... -0426(2001)018%3C0982:PAAOAI%3E2.0.CO%3B2#S4

[hakkikt]

As I see it, the

As I see it, the disadvantage of the system is that you displace water by oil, which does not increase buoyance as much as in displacing water by air. So you would need a much bigger bladder for the same buoyancy increase.

[Guest]

Why is that then?

After all,

Why is that then?

After all, the only weight change in the sub is the water in the ballast tank- the oil is just a shift in the weight of the submarine, so you may need to compensate by having a trim system of some kind, unless the receiver tank was mounted on top, below or side by side with the ballast tank.

Andy

[hakkikt]

You are right, there is

You are right, there is a knot in my physics. What basically counts is the amount of water that is displaced, not what displaces it (as long as the weight of the sub stays constant).
The total weight of the sub will increase because of the oil, though; so more buoyancy will be required to make it float, requiring a larger displacement volume... unless the system saves weight in other areas compared with other buoyancy control methods.

[Guest]

Seems a decent enough system,

Seems a decent enough system, although I fail to see much advantage over using, say, a water pump and bag for our purposes.

For the best trim, piston tanks still reign supreme.

Andy