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Re: [PSUBS-MAILIST] Drag

Hi Rick,
Yes been awhile....busy at home and with studies, but always time to jump on the learning curve here as applicable.
Sure...to explain. Simply that any equation where "drag" and it's different types (as there are various types of drag), ....in all cases, velocity is the variable with the most effect. 

For example.....
drag force = ½ρV2 × coefficient of drag × area (where ρ (the Greek letter ?rho?) is the density of the fluid) 

Notice that the velocity component is squared.
This does not need to be calculated for a particular PSUB, it is simply to demonstrate the velocity component.
So if I am puttsing around in my little K-sub along a reef @ < 2kts, I need not worry much about appendages like a manipulator, ROV cage, specimen basket...etc, causing excessive drag, it's not a worry. Entanglement safety will have to be compensated with operational guidelines / limitations.
However, as you remember my original concept, (the diesel electric ambient), that would have been subject to streamlining to take most advantage of theorectical hull speed... Hull Speed = 1.34 * (LWL)1/2. Where with a LWL of 22', would have been 6.29 kts, on the surface.
Since then, I'm convinced that I am better off with a k-350 based, research capable submersible for this area. I will have more utility and fun with that than the War replica, which would only be good for sneaking around at periscope depth (fun to scare boaters perhaps) but, a potential for collisions and other problems.
One caveat, I've not yet calculated power and thrust requirements. I see that I will need to account for a theoretical prevaling current, and determine what is required to "hold station" and "make way" against x current. Lot's to learn still....... 

Joe




From: "Rick and Marcia" <empiricus@telus.net>
Reply-To: personal_submersibles@psubs.org
To: <personal_submersibles@psubs.org>
Subject: Re: [PSUBS-MAILIST] Drag
Date: Wed, 20 Sep 2006 20:33:07 -0700

Hi, Joe - it's been a while  :-)

What do you mean by psubs speeds?

Rick L


----- Original Message -----
From: "Joseph Perkel" <joeperkel@hotmail.com>
To: <personal_submersibles@psubs.org>
Sent: Monday, September 18, 2006 6:10 PM
Subject: RE: [PSUBS-MAILIST] Drag


> Kory,
>
> Always a worthwhile effort of course.... and a good point!
>
> Some degree of "streamlining" and or stabilization / tracking, may in fact 
> be more useful for surface towing at 4 - 5 kts. But for submerged ops
> induced / parasitic drag would still remain negligible at psub speeds as
> demonstrated by JSL, and a host of other research submersibles.
>
> Still....at this point, I expect to have a fair amount of protrusions, so > preset operational guidelines / limits will have to make up the difference 
> for safety as you point out. Reasonable free ascent parameters will be a
big
> part of those guidelines as well as pre-dive planning.
>
> Joe
>
>
> >From: "kory mosteller" <hardcoremosteller@hotmail.com>
> >Reply-To: personal_submersibles@psubs.org
> >To: personal_submersibles@psubs.org
> >Subject: RE: [PSUBS-MAILIST] Drag
> >Date: Sun, 17 Sep 2006 20:45:58 -0700
> >
> >
> >for me, the streamling isn't so much for drag, as to reduce the risk of
> >entanglement.  it's always the last thing you expect that gives you the
> >most grief.
> >-km
> >
> >
> >
> >
> >
> >>From: "Joseph Perkel" <joeperkel@hotmail.com>
> >>Reply-To: personal_submersibles@psubs.org
> >>To: personal_submersibles@psubs.org
> >>Subject: RE: [PSUBS-MAILIST] Drag
> >>Date: Sun, 17 Sep 2006 23:12:30 +0000
> >>
> >>
> >>
> >>Nothing demonstrates Jay's statement quite like the JSL.......
> >>
> >>
>
>>http://oceanexplorer.noaa.gov/explorations/05deepscope/logs/aug31/media/ei
ts_on_sub_rs.html
> >>
> >>This submersible convinced me not to bother with fairings for the
external
> >>air cylinders and battery pods.
> >>
> >>Joe
> >>
> >>
> >>
> >>
> >>From: "Jay K. Jeffries" <bottomgun@mindspring.com>
> >>Reply-To: personal_submersibles@psubs.org
> >>To: <personal_submersibles@psubs.org>
> >>Subject: [PSUBS-MAILIST] Drag
> >>Date: Sun, 17 Sep 2006 19:00:14 -0400
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>At the typical speeds a PSUB travels at, protrusion drag is very small. 
> >>There are other issues you should focus on.
> >>
> >>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
> >>ShellyDalg@aol.com
> >>Sent: Sunday, September 17, 2006 6:52 PM
> >>To: personal_submersibles@psubs.org
> >>Subject: Re: [PSUBS-MAILIST] Flow testing-freeboard and swamping.
> >>
> >>
> >>
> >>
> >>Ron. Keep adding your 2 cents. I was thinking of a way to add inflating > >>ballast to give more freeboard when at the surface. Maybe hidden behind 
a
> >>retractable fairing to minimize drag when submerged.
> >>
> >>
> >>Frank D.
> >>
> >>
> >>
> >>
> >>
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