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.
> 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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