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Frank,
A couple of things you and Brent are going
to have to consider are synchronous movement of the flaps, and velocity
resistance. Since so far everyone has been talking about independently
controlled flaps (whether built into a motor or not), I think that unless you
are able to move the side thrusters at exactly the same pitch, at exactly the
same time, one side or the other will "catch" more water and cause the vessel to
move in some direction other than straight. My experience in a K-250 was
that it was difficult to judge matching the pitch of the side thrusters while
underwater, in motion, and looking around your environment outside. The
density of water being what it is, any pitch difference between thrusters is
going to result in a large difference of resistance between them which will
affect the direction of travel. Having the fins on your motors will more
than likely multiply this effect.
The other issue which I think needs to be
considered, but has not been mentioned, is that some investigation should be
done to determine how much force is going to be required to move the speed
flags, or fins, in water at a given velocity. The effort required to turn
the flaps against the water medium to stop, is going to be dependent upon
velocity and the area of the brake flap. It's feasible that given some
combination, you may not have the strength to fully turn the flaps into a
vertical position for stopping. No doubt some amount of turn will be
possible, but therein lies the danger. Unless you can go completely
vertical with the flap, you are either going to pitch up, or down, which may be
worse than just backing off the power and letting the vessel slow due to drag in
the water.
Jon
Frank D.
Well....... Yes but with your fins / dive planes attached as they are,
you have to trade off between, do I use the dive plane to slow me down or do I
use the thrust of the thruster to slow down. I bet the thrusters
win!!!
Actually I doubt very much you'll see much difference in your subs
operation with the fins or without. Unless you have a really big
thruster somewhere else on your sub you won't be going that fast to give them
much effect. You'll see far more effect from the thrusters
themselves.
I see your rigging your side thrusters with remote operators. I was
considering that when I was building also. I was thinking of doing it
electrically, with two gear motors. Now that I have it in operation with
simply two handles on the inside of the sub that manually rotate the motor
pods, I see that it's important to have better control then I would have had
with what I was going to do. I find that, sometimes I want to rotate the
thrusters a full 180 degrees from forward to stop fast. It's more
effective then reversing the props and it's quick. When I need to do
this, I want to do it fast!!!
When cruising the bottom, I sort of float the handles up and down slowly
as I want to go closer of lift up a bit. Slow speed on the props, slow
speed of the sub and subtle movements for rotating the thruster pods.
You will find it useful if you has a way to vary how fast your pods can
be flipped from one location to another. To tell you the truth,
most of the time I needed a quick reverse, I'm surfaced
and maneuvering in and around boats at the docks and not under
water. I guess I usually error on the side of caution under water and
don't go very fast. With the limited visibility in water, even
relatively clear water, if you go too fast when submerged you don't see
much.
One thing I wish I did, and may still do, is mechanically connect both
side thruster pods together. Originally I thought I would need to work
them independently but I never do. If they were connected, it would free
up one hand more. I very often operate the thruster props separately,
but very rarely rotate the pods separately.
Dan H
----- Original Message -----
Sent: Friday, August 29, 2008 2:43
AM
Subject: Re: [PSUBS-MAILIST] Stopping
Flaps
Hi Dan. That's what I was thinking. My side motors have dive planes
attached, and by rotating them to vertical, would act as brakes a little
bit.
Here's a sketch of how it works. These are done now but I don't have a
photo of them yet.
I'll get some more newer pics up soon. Frank
D.
It's only a deal if it's where you want to go. Find your travel deal
here.
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