Greg,
Thanks for the advice & offer.
I live in NewZealand, so it might be cheaper to buy
an oven
than send the dome over & back.
I have been on to the plastics manufacturer about
annealing
& he ensures me it will all be done by Stachiws
book. I will
pass on more information to him but I was expecting
a picture of
the finished dome yesterday, so it may be too
late.
That was an eye opener about the unannealed dome
failing at 50ft.
I had thought I'd be safe to this range without
doing an unmanned test.
Regards Alan
----- Original Message -----
Sent: Tuesday, May 25, 2010 1:27 AM
Subject: Re: [PSUBS-MAILIST]
Rudders
Make sure that the fabricator is going to anneal the dome- this is
where the strength comes from. Ask them to give you the annealing
schedule. For a 1" thick dome it should be 179 F held for 24 hours in a
convection oven, Then cool at no more than 10 F per hour for 6 hours,
fan off. If you're not convinced that they know how to do this then give
me a call and I'll do it here.
Greg C.
--- On Sun, 5/23/10, Alan James
<alanjames@xtra.co.nz> wrote:
From:
Alan James <alanjames@xtra.co.nz> Subject: Re:
[PSUBS-MAILIST] Rudders To:
personal_submersibles@psubs.org Date: Sunday, May 23, 2010, 10:14
PM
Thanks for the confirmation
Greg.
I'll leave off the dive plane for now
& see how it goes.
Had a photo a couple of days ago
of my sheet of acrylic bolted down ready for
blowing.
So after a year of waiting I may
hopefully have a dome this week.
Alan
----- Original Message -----
Sent: Monday, May 24, 2010 2:09
AM
Subject: Re: [PSUBS-MAILIST]
Rudders
I agree with Vance on the problems associated with trying
to vector up and down with thrusters that are also used
for propulsion (although I don't have any experience with
rudders). The solution I prefer is to have a dedicated
vertical thruster. The additional benefit is that a vertical
thruster allows the sub to descend while set for slight
positive buoyancy. In this configuration, it is the thruster
(with variable speed control) that pushes the sub down to the
desired depth, then the thrust is reduced to the point where
the sub is "hovering". Then the main thrusters provide
propulsion only. The major safety benefit is that the sub will
naturally return to the surface in the event of a
system failure just by cutting power to the vertical
thruster. I found it to be more relaxing to dive a sub set for
positive rather than neutral or (heaven forbid!) negative.
Greg C.
--- On Sat, 5/22/10, vbra676539@aol.com
<vbra676539@aol.com> wrote:
From:
vbra676539@aol.com <vbra676539@aol.com> Subject:
Re: [PSUBS-MAILIST]
Rudders To: personal_submersibles@psubs.org Date:
Saturday, May 22, 2010, 8:05 PM
There
are some issues with using pivoting thruster pairs for this
sort of double duty, especially in small thrusters on
heavier vehicles. When you vector down or up, or need to
correct steering, forward thrust is lost. Also, the lack of
control surfaces means that any correction must be powered.
Vehicles will not continue to turn, for instance, once the
power is switched off. You can do very well without those
control surfaces, of course-----until you use a rudder and
dive planes for awhile-----then you see what you've been
missing.
Vance
-----Original
Message----- From: Alan James
<alanjames@xtra.co.nz> To:
personal_submersibles@psubs.org Sent: Sat, May 22, 2010
5:23 pm Subject: Re: [PSUBS-MAILIST] Rudders
Thanks Pierre,
is there a discount on the
posters with Psubs membership?
Alan
----- Original Message -----
Sent: Saturday, May
22, 2010 11:23 PM
Subject: RE:
[PSUBS-MAILIST] Rudders
Yes
that’s me! Please stand in-line for a signed
poster.
A
good design to control sub with 2 motor is to have them in
the center of mass (from front to rear) and as far away
from each other (side to side).
I
also have mine so they can rotate on the shaft. So I can
use them for up/down movement.
Pierre
Sorry
Pierre, It's clicked who you are.
The
world famous owner of "big".
Your email
name through me out.
below
is a link to a glossary of submarine terms found on
the
"Deep
search site" that's quite good.
-----
Original Message -----
Sent:
Saturday, May 22, 2010 4:13 PM
Subject: Re:
[PSUBS-MAILIST] Rudders
Any
photos of your sub you can refer me
to?
-----
Original Message -----
Sent:
Saturday, May 22, 2010 2:37 PM
Subject:
RE: [PSUBS-MAILIST] Rudders
Hi
Alan,
My
use a very similair design with one motor on each side
and I don,t have a rudder. With one full foward and
one full backward, I can almost turn on the spot. Same
as a bulldozer.
So
no, I would not waste time on rudders.
I
have been looking at some videos of a small 1 person
semi-dry ambient sub in action.
This
sub doesn't have a rudder & just uses differing
motor speeds to turn.
As
I'm building a small 1 person sub of a similar size
with two PWM controlled motors I'm wondering
wether
a rudder is going to be a waste of time for me. I did
have a rudder in my original
design.
Any
thoughts on this thanks.
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