Re: Anyone out there?

[Martin Sanderse <sanderse@hotstar.net>]

jon@zk3.dec.com wrote:
> 
> Nobody here but us subs...and we're all d
>                                           o
>                                             w
>                                               n
>                                                 !

	:)

> I've got the hull program ported and am now just working on the HTML
> interface.  I should be ready to link up by the time Ray has the pages
> online.  I really need to look up the books that provided the equations
> however.  Does anyone know what Poissons Ratio is?

The ratio of lateral strain to longditudinal strain for a given material subjected to 
uniform longditudinal stresses within the proportional limit.  The term is used in 
equations having to do with the strength of materials.

I guess it's how much it squishes sideways when you stand in it, or gets skinny when you 
pull on it.

Values for some materials are as follows:  (I can send more)

Aluminum	.334
Steel cast	.265
Steel high carbon	.295
Steel mild	.303

> Any sources out there for waterproof electric motors, or were most of you
> considering human power?

Well, most use those fishing motors.  If you want something deeper you can make a 
waterproof housing with mechanical seals.  Lip seals are good to 90 PSI or so, and 
packing for a great deal more than that.  The catch is through-hulls for power and the 
shaft.  BTW, the pressure shrinks the bearings around the shafts and makes them bind.  
Packing leaks.

I've got a brochure from the Franklin Electric Company for pressure compensated motors 
with internal fluid and bellows, but I hesitate to ask how much they want for those.  
Hydrovane makes some hydraulic thrusters for ROV's.
 
Here's a scheme I thought up once:

Make a hydraulic drive with the motor immersed in the tank, and the tank and the case of 
the motor pressurized with a bellows/bladder system.  That way you can use multiple 
motors and make a Diving Saucer configuration with hydraulic motor solenoids and 
joystick control intead of using jets.  Expensive

BTW, For a simple craft I think pedal is OK, but my knees have trouble with that motion, 
so I will be making an electric with a compressed air compensated electric motor, a 
double lip seal (in and out), and diaphram acting on the regulator to control pressure. 
 The regulator has to be one of those that bleeds access pressure to vent.  Cheap.


Martin