RE: [PSUBS-MAILIST] Thought experiment

Subject: RE: [PSUBS-MAILIST] Thought experiment

From: Philip Ridenauer <akula151@yahoo.com>

Date: Thu, 19 Jul 2007 16:11:04 -0700 (PDT)

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To Paul, Ian and Joe,

Thanks for taking the time to reply. Paul, thank you for the oil VBT idea. Ian, my concern about a vacuum was the (presumed) tremendous force needed to pump out a tank w/o some means of replacing the fluid. It seems it might be easier than I thought. Joe, I was figuring a droppable solid ballast as an emergency ascent measure, but to do so as a means of continually controlling an ascent puts me back in limited resources limiting the endurance and range of the vehicle.

Thanks once again to all.

PR

Joseph Perkel <joeperkel@hotmail.com> wrote:

Phillip,

Sorry for the delayed response but, I had to think about the question and, take a peek at C-BUG again. I find the question itself interesting because fine buoyancy control, is of particular interest to me, (although by different methods). So this is an exercise in basic buoyancy control for me as well.

In our application, we have buoyancy and thrust as our 2 ways of changing depth....correct? For the glider method,...... eliminate thrust.

I'm not quite clear on the "suspending" piston idea but, in thinking about this "non-powered" mode of changing depth, we're left only with manipulation of buoyancy...correct?

This had me thinking about , what manner of "ballast control", would I personally feel comfortable with in this application and,... like you,.... I feel air is unattractive for the ascent phase as..."failure is not an option".

So for my "glider", in the negative buoyancy phase, descent would be initiated from a positive buoyancy condition on the surface by, standard venting of soft tanks. The positive buoyancy ascent phase, would be by releasing lead shot via some type of failsafe release mechanism, (electromechanical).

Hope to be of some help and, thanks for the mind bender!

Joe

From:  Philip Ridenauer <akula151@yahoo.com>
Reply-To:  personal_submersibles@psubs.org
To:  personal_submersibles@psubs.org
Subject:  [PSUBS-MAILIST] Thought experiment
Date:  Sun, 15 Jul 2007 13:47:00 -0700 (PDT)





I've been running a thought experiment in my head for an ambient dry glider (though I suppose a 1atm sub could do the same). The idea is to have
the sub ballasted negatively and use gravity as the propulsion source. At max depth (depending upon how much pressure the pilot was willing to risk/withstand) enough ballast is expelled to provide positive bouyancy. The ballast taken on and expelled should be forward of the CG to provide nose down attitude at neg. bouyancy and nose up at pos.

Query: is there a means of expelling ballast water mechanically so that one does not have to carry an inordinate amount of compressed air to achieve this effect?

I have an idea for a suspended weight acting as a piston but don't know if this is feasible.

Just toying with an idea.

PR

ps My computer and server are sloooow, so I don't ck my email every day. It might take me a while
to reply to any questions.




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RE: [PSUBS-MAILIST] Thought experiment
- From: "Joseph Perkel" <joeperkel@hotmail.com>