[PSUBS-MAILIST] Progress report

hank pronk via Personal_Submersibles personal_submersibles at psubs.org
Sun Aug 17 07:40:59 EDT 2014


Brian,
My last sub had the problem Alec is talking about.  The sub was very stable when surfaced and very stable when submerged.  The transition while submerging was very wild because the water can rush from one end to the other in an instant.  Very scary :-)   On Alec's suggestion I compartmentalized the tanks and it was a gigantic improvement.  
Hank On Sun, 8/17/14, Brian Cox via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

 Subject: Re: [PSUBS-MAILIST] Progress report
 To: "Personal Submersibles General Discussion" <personal_submersibles at psubs.org>
 Received: Sunday, August 17, 2014, 12:29 AM
 
 That front trim tank will hopefully
 keep the nose up
 
 --- personal_submersibles at psubs.org
 wrote:
 
 From: hank pronk via Personal_Submersibles <personal_submersibles at psubs.org>
 To: Personal Submersibles General Discussion <personal_submersibles at psubs.org>
 Subject: Re: [PSUBS-MAILIST] Progress report
 Date: Sat, 16 Aug 2014 17:14:42 -0700
 
 Brian,
 You get first prize for thinking outside the box.  You
 would be well advised to split the MBT's or she will stand
 up.  It is not hard to keep up with the air compressing
 assuming you only have a small amount of air to start with.
 If you come for a ride in Gamma, I will show you what I
 mean.  
 Hank
 
 
  Subject: Re: [PSUBS-MAILIST] Progress report
  To: "Personal Submersibles General Discussion" <personal_submersibles at psubs.org>
  Received: Saturday, August 16, 2014, 5:40 PM
  
  Thanks Alec, That means a
  lot coming from you.  Your project was the first one that
  peeked my interest the very first time I found the Psubs
  web site.    The inside is actually baffled but not
  really on purpose.  There are ribs that are part of the
  frame work on the inside every 18 inches.  However I was
  worried that the air trapped in there would make for less
  control ( not being able to keep a neutral buoyancy
  condition)  because Ideally you want your soft ballast
  tank completely flooded, so I put holes at the top of the
  ribs so I could completely flood the soft ballast. 
  But listening to Vance tell about "riding the
  bubble" I'm really not sure what the best procedure
  would be.   I have bottom vents in two locations, the
  front vent I will probably cap off because if the front
 got
  too high air could potentially escape from
  there.   I don't want to get
  into a situation where the shrinking air bubble, while
  descending, sends me to the bottom before I can
 compensate
  for the reduction of the buoyancy
  .  Brian     
  
  ---
  personal_submersibles at psubs.org
 wrote:
  
  From: Alec Smyth via Personal_Submersibles
  <personal_submersibles at psubs.org>
  To:
  Personal Submersibles General Discussion
  <personal_submersibles at psubs.org>
  Subject: Re: [PSUBS-MAILIST] Progress report
  Date: Sat, 16 Aug 2014 10:34:34 -0400
  
  Hi
  Brian,
  I really enjoyed that
  because its in every way so radically different to any
 other
  design. I've always wondered how you would see anything,
  and that the sphere end might make a better bow for that
  reason, so the most interesting comment to me was that you
  intend to use go in one direction when diving and the
  opposite direction on the surface or mid-water. I never
  thought of that. My other big concern would be the free
  surface effect of such long MBTs. Are they baffled or
  sub-divided? If not, I'm afraid I'd you could have
  serious instability when MBTs are partially flooded, which
  is to say when diving or surfacing the boat. The
 instability
  could also end up putting the boat in a position such that
  the vents are no longer at the highest spot of the
  MBTs.
  
  Thanks,
  Alec 
  
  On Sat, Aug 16, 2014 at 3:25 AM, Brian Cox
  via Personal_Submersibles <personal_submersibles at psubs.org>
  wrote:
  
  I did a video of the
  present state of my sub.  Been making some significant
  progress,  once the conning tower and hatch are on I'll
  feel a lot better - and the viewports.
   https://www.youtube.com/watch?v=luabNVU0QW0 Brian
  
  
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