Re: [PSUBS-MAILIST] Newbie Questions

[Peter McKellar <submckellar@earthlink.net>]

Hi Mark,

Looks like the group is kinda thin on the ground this week :(  I myself havent read my emails for 3 days.  Aplogies for taking so long to get back to you.

1.  The propellors on the fins sounds like a good idea, but only being at the design stage myself (and with no previous hands on construction experience) I cannot say this for sure.  typically there are always trade-offs, my bet would be drag and control issues with the motors mounted on the fins' control surfaces.

2.  I think these exist - almost certain re military subs (was actually reading something to this effect on the net somewhere).  I also saw Dan (Persistence) had some trouble getting bouyancy right - the adjustments take some time to take full effect, resulting in frequent over-compensation :(  that drift dive over a few months (posted here in the last couple of weeks) back in the 60's had their bouyancy controlled very well and this may provide some guides.  The ABS has some rules regarding centre of gravity calculations and the ability to maintain trim when crew and payload is moved around the sub's cabin.

3.  You are 100% right here.  It is the pressure gradient over both sides of the viewport that is at issue.  In an ambient there is never any gradient, and if shatter qualities and durability werent an issue you could use window glass.

cheers
peter

-----Original Message-----
From: Mark <gadgetsboy@ntlworld.com>
Sent: Jul 8, 2004 10:28 PM
To: Personal_Submersibles@psubs.org
Subject: [PSUBS-MAILIST] Newbie Questions

Hi and hello to you all

I am a newbie to the world of submersibles and currently trying to design my own 2 man ambient pressure sub.
I really like the design of the sportsub and have been basing my designs on the outward appearance of it but 
have a few questions i dont seem to be able to find answers to.

1) what are the advantages/disadvantages of mounting propellers on the
    dive planes as opposed to a static rear propellor

2) are any details/plans available for the construction of Auto bouancy control
systems as i can imagine trying to maintain neutral bouyancy manually would 
take the thrill away from the exploration.If not what is the easiest method of controlling
bouyancy manually

3) Am i correct in assuming that the viewports in an ambient pressure sub dont need the same consideration
as in a pressurized hull


Many thanks for your patience

Mark




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