[PSUBS-MAILIST] Control considerations

["Lil Brother LLC" <lil_brother_llc@bellsouth.net>]

Although I have not completely read the archives (I'm working on it), I have
some views on the considerations for the sub systems that I've not seen
addressed.

1 atm subs(internal pressure):

   We know the air will be come saturated with CO2, and I know a scrubber
is in the design phase. I haven't seen any response to the system.....but
I'm sure the design team is working on the idea.

   What is the common idea to replacing the used O2 within the sub? Pure O2
or just compressed air? I see compressed air as being a problem and waste of
scrubber material. I guess is it all a cost versus design/availability 
challenge. Also I'm not sure how hard pure O2 would be
to purchase. I know you can buy industrial O2, but I'm not sure if I want to 
be breathing it.

   Also what means of relieving the extra pressure within the hull are
being implemented? Compressor?(to the exterior ofcourse) Is anyone using a
device to relieve the internal pressure of added air?     How is it
controlled and what type of unit?

Propulsion:

   I know many of the designers are using thrusters, be it stationary or
movable, are most people enclosing themselves or buying already enclosed
motors? Internal or external?

   I would like to know, of the ones being enclosed, what amount of drag is
being placed on the output shaft? (seals, etc.)

   Also the control of such thrusters can be wasteful depending of the
electrical configuration of the motor (i.e.. 3 phase brushless motors, or
straight DC motors). Is anyone using PWM to control their     motors? Anyone
using brushless motors?

Flying surfaces(dive planes/rudder):

   This is the area.....I'm especially interested in. I've gone through it
in my head....and an electrical actuator would be my first choice to control
the dive planes/rudder. The failure of the through hull is less
likely to happen with a stationary item. The control coordination of the
actuator would then become a problem. The actuator would need to know it's
position to be efficient in it's operation.

   Hydraulics could be used....but then we have to worry about the
possibility of environment contamination. Pneumatics are also
available.....but even harder to control with respect to position.

I know I have a large number of questions.....which I guess is usual for the
"new guy". I'm trying to get a basic consensus of ideas.......and work with
those to implement my design.


James Long
Owner/Designer
Lil Brother LLC (Instrument Division)





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