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Re: vindicator power
Thanks Gary,
I'm happy your daughter is enjoing her trip in Italy, the weather now is not
the best but not too bad for the season.
I really appreciate the information you gave me, I know the problems related to
the props and the trial-and-error procedure which is quite usual to anybody has
a boat.
I'll try to determine my design in a virtual environment before to build it,
I've access to hi-end CAD and analisys resources and I hope I'll get useful
information from this approach.
It would be very nice if trolling motors could be used even at higher depths
(250 to 300 feet) but I'm also studying the inside-body motor application.
I'm now professionally involved on DPV design (for production purpose) and
personally interested on a p-sub design and construction for wreck-diving
assistance at depths ranginng from 150 to 300 feet.
I'm thinking about a rather small vehicle but with a good visibility which
means a wide enough plastic window, probably a dome shaped see-trought nose.
One of the most challenging task will be represented by the sizing of the unit,
it should be small and light enough to be carried aboard a mid-sized dive-boat
(11 to 15m in lenght - the boat) not requiring a big vessel for transportation
to the diving site.
I'm now wondering about different shapes and solutions but I'm more oriented on
controlled flight rather than on descend asset, this means I could consider the
prone position like in the "deep flight", it seems to give the pilot a closer
visibility/contact with the environment he's exploring (maybe it's more natural
for divers).
I'm really enjoing the cooperative and enthusiatic attitude of this site, I'll
try to contribute on myself when I'll have some more advanced designs
available.
Have a nice day
Paolo
Gary R. Boucher ha scritto:
> Paolo,
> I think you are the fellow from Italy? Just a side note here in that
> my daughter Jenelle is now in Italy on a Summer college trip enjoying the
> culture. Says she loves it!
> The prop that I use on The Vindicator was one that I purchased from
> Michigan Wheel several years ago. It is 15 inches in diameter, made of
> bronze, but actually looks like brass. It is three bladed with an 8 inch
> pitch. It is called a sailors prop because it is constructed for low speed
> propulsion of sail boats that for whatever reason are not under sail at the
> time. There is thus a small inboard engine that propells the boat at show
> speeds much like a sub. Most ski props are like 30+ inches of pitch for
> high speed. I got a naval architech hired by Michigan wheel to tell me
> what type of prop he thought I needed. He asked me what my RPM was going
> to be along with the output horsepower that I plan to deliver to the prop.
> Also he asked me what the "Inflow Velocity" was going to be. This is a
> difficult thing to determine. It is in essence the speed of the sub.
> Here is the problem with matching a prop; the speed of the sub is
> determined by two factors, the drag force from water flowing around the
> hull etc. and also the thrust. When the thrust is equal to the drag the
> boat is in unaccelerated cruise. But since the thrust is one of the
> determining factors to speed and inflow velocity is closely related to
> speed and thrust is related to inflow velocity, each of these curves
> relates to each other in a closed relationship. Here is my point; it is
> very difficult to match a prop 100 percent to the engine without trial and
> error. For one thing it is difficult to find the drag vs velocity curve
> for a given sub geometry. That is outside of my expertise. In my case I
> took a wild guess at the inflow velocity (I assumed it to be the speed of
> my boat). I guessed 3 knots for cruise. I was very low. My boat does 7+
> knots. Now if I had a slightly higher pitch the prop would propel my sub
> even faster. Let me tell you though that 7 knots in a sub, especially in
> low visibility, feels like driving at 80 MPH with your lights off at night.
> What someone should do is experiment with a given trolling motors to
> determine a set of curves for maximum thrust vs velocity of the trolling
> motor through the water. I like the idea of trolling motor propulsion for
> small subs but they MUST be compensated for pressure in the proper manner
> and connected to safe and contollable electrical sources.
>
>
> Gary Boucher
>
> ----------
> > From: Paolo Velcich <pavel@mail.nauta.it>
> > To: personal_submersibles@psubs.org
> > Subject: Re: vindicator power
> > Date: Tuesday, June 02, 1998 8:19 AM
> >
> > Are you using that prop on a trolling motor or on a custom design? I
> would be
> > interested on having some more details on it. I'm now testing a
> > ZEBCO-Motorguide 52p trolling motor for a custom DPV I'm designing. But
> I'm
> > also going in the development of a traditional design with an electric
> > motor/reduction unit and sealed shaft from inside the body as I'm not
> sure the
> > trolling being an appropriate solution. I'm going to apply 600rpm on the
> prop
> > shaft plus a pwm digital controller for the speed management.
> >
> >
> > Gary R. Boucher ha scritto:
> >
> > > ... I use an 8 inch prop pitch. This
> > > propeller was actually designed for sail boats that us it as aux power
> if
> > > no wind is blowing.
> > >
> > > ----------
> > > > From: STEVE McColman <steve_mccolman@hotmail.com>
> > > > To: personal_submersibles@psubs.org
> > > > Subject: vindicator power
> > > > Date: Monday, June 01, 1998 6:51 PM
> > > >
> > > > Hi Gary,
> > > > Have you ever determined what thrust power your sub has???
> > > > Or could you make an educated guess!
> > > >
> > > >
> > > > Steve McColman, Vancouver Island
> > > >
> > > >
> > > > ______________________________________________________
> > > > Get Your Private, Free Email at http://www.hotmail.com
> >
> >
> >
> > --
> > Paolo Velcich
> > industrial designer
> >
> > **********************
> > KORUM DESIGN
> > Viale Tricesimo 5/6
> > 33100 - UDINE - ITALY
> > Tel. (+39)432-603654
> > Fax. (+39)432-601213
> > GSM. (+39)348-2611707
> > ----------------------
> > e-mail:
> > pavel@mail.nauta.it
> > ----------------------
> > http://www.x-plora.com
> > ----------------------
> > **********************
> >
--
Paolo Velcich
industrial designer
**********************
KORUM DESIGN
Viale Tricesimo 5/6
33100 - UDINE - ITALY
Tel. (+39)432-603654
Fax. (+39)432-601213
GSM. (+39)348-2611707
----------------------
e-mail:
pavel@mail.nauta.it
----------------------
http://www.x-plora.com
----------------------
**********************