From: "Jay K. Jeffries" <bottomgun@mindspring.com>
Reply-To: personal_submersibles@psubs.org
To: <personal_submersibles@psubs.org>
Subject: RE: [PSUBS-MAILIST] MIR aft planes
Date: Tue, 21 Aug 2007 15:59:28 -0400
Brent,
Instead of "guessing" all of the time, please do some real research.
Neophyte PSUBers often take as gospel any information that is found here on
the PSUB list and can lead to misconceptions on their part in the
future.some of which may be dangerous if not down right deadly. You will
note that many of us refrain from making replies here unless we have some
expert knowledge to bring. A number of us have to waste a good deal of
time
better spent on other endeavors dispelling misinformation that is either
represented as fact or not clearly labeled speculation by a non-engineer or
scientist.
I did not respond to this particular request by Joe as I do not know why
the
Russians have used this configuration but I can tell you it is not because
the water is not disturbed yet and vortex shedding is not an issue here.
Both issues are related to speed here and speed is not one of Mir's fine
points. You can not tell whether it is a Kort nozzle, a Rice nozzle, or
simply an entanglement guard without viewing the cross section of the
nozzle
or someone more closely associated with the Mir submersibles making a
response. Due to the small size of most all submersibles, there is little
reserve buoyancy that can be effectively designed in.all of them have
handling issues on the surface. While a lot can be learned from images and
visiting various submersibles, hard calculations along with weight and trim
spreadsheets are necessary prerequisites for a successful submersible with
a
long, safe lifespan. How do you know you are not looking at a given
submersible's weak point or a poor design?
I can tell you from an early proposal for building the Mir subs that they
are size constrained for carrying in aircraft holds and the fins on top are
probably a means for shortening the overall length due to deck housing
issues (this is a factor in a number of submersible designs).but it is pure
speculation on my part.
A dunce can appear brilliant if he holds his tongue.
Jay K. Jeffries
Andros Is., Bahamas
A skimmer afloat is but a submarine, so poorly built it will not plunge.
From: owner-personal_submersibles@psubs.org
[mailto:owner-personal_submersibles@psubs.org] On Behalf Of Brent Hartwig
Sent: Tuesday, August 21, 2007 2:39 PM
To: personal_submersibles@psubs.org
Subject: RE: [PSUBS-MAILIST] MIR aft planes
How about a non educated guess. ; )'
Thanks for the link to the pic Joe. I would "GUESS" that the aft plane is
controlled my the pilot directly or by hydraulics or the like. The
swept-back feature is for coolness factor Joe. Na for that I would say it
helps if you lightly hit some thing you'll just bounce off and keep going
instead of braking the aft plane, but more importantly I would say its for
reducing entanglement issues. That is why I like to have surfaces on my sub
rounded over and swept back to some degree, with no item protruding forward
like the weapons systems on the Star Wars X-wing fighter.
On another note since the aft plane is acting like a planes elevator,
having
the said aft plane up and out of the way of the swirling water coming off
the subs hull, gives the pilot more control then if its down and directly
behind the sub. This is why allot of ships are now using forward facing
props, that pull instead of push. This is more efficient since the water
hasn't be really disturbed yet and you can get a better directional bit
into
it.
I would say that the whole stabilizer assembly also really helps to deal
with vortex shedding. But for that I would use a larger assembly.
I like the Kort nozzle on the sub, or is that a Rice nozzle? From what I
understand the Rice nozzle is more efficient.
I wish they would add some soft saddle tanks to the Muir subs, to give them
more freeboard staybility. Allot of people get really sick in them when at
the surface. Watching the Zodiac cowboys try to attach the crane cables to
the subs in rough water is one of the reasons I started designing trimaran
subs. I know that adding tanks to the subs gives them more hydo drag, but
that is another one of these trade-offs we have been talking about.
Regards,
Brent Hartwig
> From: joeperkel@hotmail.com
> To: personal_submersibles@psubs.org
> Subject: [PSUBS-MAILIST] MIR aft planes
> Date: Tue, 21 Aug 2007 12:15:46 +0000
>
>
> Can someone please explain to me the precise function and mechanics of
the
> aft planes / stabilizer on the MIR submersibles?
>
> In this image, you can see it rotated at an exaggerated angle, which
makes
> me wonder if this was done mechanically by the pilot from within, or the
> unit is "free pivoting" for some reason which escapes me.
>
> http://www7430.nrlssc.navy.mil/7432/hydrates/images/Muir_1.jpg
>
> Why then I also wonder, the extreme sweep-back of these planes? You see
this
> in aircraft for aerodynamic purposes in the transonic flight envelope
> (airliners) but, why here? This is repeated in both MIR's as well as the
> proposed Alvin replacement.
>
> Any info is most appreciated, even an educated guess.
>
>
> Joe
>
>
>
>
>
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