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RE: [PSUBS-MAILIST] Hull design
David,
You've got it right. The pointy end goes first. The sub tends to turn
about the center of volume (or somewhere near there. Not knowing exactly
where is part of my problem). When the pointy end swings around the Cv upon
turning, the flow separates from the hull on the side that you are turning
towards. The flow separating causes a vacuum on that side which pulls the
sub further over in that direction until the submarine has done almost a
full 180 turn and the flow reconnects. Generally, you would run into
something before completing the spin, unless you were in a lot of water.
I believe you can avoid this phenomenon if you can force the submarine to
rotate about fins which are placed farther forward, but I have only seen the
failing case, so I'm not sure. In any case, even if it does work the fins
might need to be so big that they would cause more resistance than you are
gaining by using this hull form. So I'm asking you guys because I thought
you might have tried it.
Wade
-----Original Message-----
From: owner-personal_submersibles@psubs.org
[mailto:owner-personal_submersibles@psubs.org]On Behalf Of David Buchner
Sent: Monday, August 14, 2000 6:31 AM
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] Hull design
>Has anyone ever built or does anyone know anything about a high speed
>laminar flow type hull [....]
>The opposite of a tear drop shape). I am wondering how one might overcome
>the dynamic stability problems. [....] Laminar hulls are very
>prone to flow separation when they are turned out of the flow path and tend
>to "skid out" (they just keep turning and never come back. That's not
>exactly a technical term, I just made it up because it's pretty descriptive
>of what happens).
I think I get it. Like pushing a shopping cart backwards, right?
You're talking about a teardrop going pointy-end first, correct? Why
wouldn't the fins do the trick? Maybe I'm not getting it; maybe I need a
diagram...
--
David
Osage MN USA
buchner@wcta.net - http://customer.wcta.net/buchner