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Hi Rick,
Thanks for your thoughts on the bouyancy
question.
Best Regards,
Jim Kocourek
----- Original Message -----
Sent: Wednesday, September 20, 2006 10:31
PM
Subject: Re: [PSUBS-MAILIST] hydraulic
efficiency questions
Yes - don't do it.
Hi, Jim - u/w stability is based on moment arms
or leverage generated by either buoyancy or weight. Highly placed weight
will either topple (roll) your vessel over or create nasty
unstability.
Review every sub diagram you can get your hands
on. You'll see it's a universal concept: the physics doesn't
lie.
Compensating for cargo, passengers, etc. can be
achieved, not by removing hard ballast necessarily, but, rather, by admitting
water as ballast into a hard tank or blowing that tank to create
buoyancy.
Cheers,
Rick L
Vancouver
----- Original Message -----
Sent: Monday, September 18, 2006 4:40
PM
Subject: Re: [PSUBS-MAILIST] hydraulic
efficiency questions
I am considering having all hard ballast near
the top of the sub similar to the location of Michigan - Dan's soft ballast
tanks on his PSUB. My thinking is that I would like to have more potential
to change depth and payload without moving lead weights. This will probably
require 6 separate tanks to minimize free surface diufficulties. I have not
heard this discussed before. Does anyone have thoughts on this.
Thanks in advance,
Jim Kocourek
----- Original Message -----
Sent: Monday, September 18, 2006 6:17
PM
Subject: RE: [PSUBS-MAILIST]
hydraulic efficiency questions
John,
It is
funny that you should reference that web site. Have a look at the
following URL within that site: http://www.allstar.fiu.edu/aero/jay.htm
Years ago, I was one of the original developers of the web site?at
that time we built approximately 1200 web pages for aerospace education on
the web site.
I agree
with you that hydraulics have their applications. If you work
through the physics for a 6 HP motor driving a hydraulic system, you will
only get about 1.8 HP out of the prop after all the losses. Jet
drive systems are even more inefficient. I am sure your system will
work but is it the most efficient for your money and ease of
construction?
The
latest aircraft designs are moving to electrically driven systems
replacing all hydraulics. Hydraulics had previously been used for
their dependability and the linear force that could be developed at a
remote location.
R/Jay
Respectfully,
Jay K.
Jeffries
Andros
Is., Bahamas
It is
the mark of an educated mind to be able to entertain a thought without
accepting it.
-
Aristotle
From:
owner-personal_submersibles@psubs.org
[mailto:owner-personal_submersibles@psubs.org] On Behalf Of John
Gaertner
Sent: Monday,
September 18, 2006 5:20 PM
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST]
hydraulic efficiency questions
For those of you who are
intersted in hydraulicly driven systems, you might want to take a look at
the following web site: http://www.allstar.fiu.edu/aero/Hydr08.htm
You can learn a great deal about the basics of hydraulicly driven systems
from this site. From my own research, I would personnally say that
they can be operated at much more efficient levels than has been
described recently. I, for one, am designing my entire propulsion system
around a 6 HP, 24V hydraulicly driven pump system. There are a great many
valuable resources on the Net about hydraulics and their safe, efficient
operations. I would encourage folks to look
further....
Regards,
John Gaertner
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