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Re: [PSUBS-MAILIST] speedo
Hi,
I think there would be quite a bit of value in knowing
the vessels water speed, regardless of how well you know
you throttle positions. Move the throttle for 0 to 50%
and you will be accelerating for while (until you hit
terminal velocity), i.e. not traveling at a constant speed,
so knowing the your water speed will know when you've
finished accelerating. I recall not having a good
sense of acceleration when in a sub, so just going on
throttle position alone won't give you much sense of
speed or position.
And don't forget the coriolis effect if you are trying
to determine position! :)
Cheers,
Ian.
-----Original Message-----
From: Alan James
Sent: Oct 31, 2010 9:32 PM
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] speedo
Hi Jim,
No you're not missing anything, I think I'm having trouble thinking this
through.
Yes, If you knew your boat speed at various increments of your throttle
then there
wouldn't be much more of an advantage having a speed indicator, other than
it would indicate your
speed as you got up to speed. Because of current speeds relative to the
Psub norm of 3 knots,
any accuracy with reguard to real speed or tracking of distance travelled
would go out the window.
I think this has something to do with the theory of relativity.
Alan
----- Original Message -----
From:
JimToddPsub@aol.com
To: personal_submersibles@psubs.org
Sent: Monday, November 01, 2010 2:50
PM
Subject: Re: [PSUBS-MAILIST] speedo
Alan, doesn't the equipment you described measure the sub's
water speed so that it would indicate the same at a given power
setting regardless of no current, head current, or tail current? Only
the ground speed would be different. Or did I miss something
completely? Wouldn't be the first time or the last.
Thanks,
Jim
In a message dated 10/31/2010 8:43:23 P.M. Central Daylight Time,
alanjames@xtra.co.nz writes:
David,
In hindsight ignore the bit about a current indicator.
If you were being carried along in a
10 knot current you would be flowing with the water
& the indicator would
hardly indicate.
Alan
----- Original Message -----
From:
Alan James
To: personal_submersibles@psubs.org
Sent: Monday, November 01, 2010 2:26
PM
Subject: Re: [PSUBS-MAILIST]
speedo
Hi David,
I'll keep the idea percolating. I have some ideas;
it could be used with the rotary pot.
The beauty of the position sensor circuit (wich I
didn't design) is that the circuit can
be tuned by two pots to light the full range of LEDs
even though the magnetic potentiometer
might be used only through a small degree
of it's range. So it can be easily adapted.
It might be a good water current indicator. If you
were mid ocean with no visual reference &
you knew what your boat speed should be by
experience, & found that you were going faster or
slower according to the speedometer, then you could
calculate the current. That's providing the
current isn't coming from the side.You would
probably need another one for that.
I believe another Psubber was working on
an expensive system involving a computer & using
all sorts of data input to log their
progress.
Regards Alan
Original Message -----
From:
David Bartsch
To: personal_submersibles@psubs.org
Sent: Monday, November 01, 2010
1:07 PM
Subject: RE: [PSUBS-MAILIST]
speedo
Alan,
Being able to determine
the speed at which you are traveling while submerged when no visual aids
are there to help you would be of great importance to me. This idea you
mentioned would be a much desired device. I would like to encourage
you to undertake its development as the end product would be worth the
while.
I had considered a paddle that would be forced
against a spring to give a mechanical indication of speed but your idea
looks much better.
David Bartsch
From: alanjames@xtra.co.nz
To:
personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST]
speedo
Date: Mon, 1 Nov 2010 08:55:54 +1300
Hi David,
You've got me thinking on this speed indicator
idea.
On my projects page is the "Position sensor". I'm
using a rotary magnetic potentiometer,
but there is a linear magnetic potentiometer shown
also.
You could have a slider over the top of the linear
potentiometer, with a vane that is pushed
by water movement against a spring. The vain
portion has the magnet & as it slides further
along the potentiometer it changes the voltage
wich is registered on the circuitry also on
my projects page. You could have the speed
indicated by the LEDs as is, or output to a
panel meter. This could be calibrated in a
swimming pool by either adjusting the spring size
or tension, the size of the vain, or by adjusting
the display range with the pots on the circuit board.
Regards Alan
----- Original Message -----
From:
David Bartsch
To: personal_submersibles@psubs.org
Sent: Sunday, October 31, 2010
10:10 PM
Subject: [PSUBS-MAILIST]
speedo
Can anyone describe how a speedo speed indicator system
works and would such a system be suitable for small submarines? Is'nt
such a system deployed on the R-300 Cliff?
David
Bartsch
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