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Re: Re: [PSUBS-MAILIST] Re: Variable Ballast Calculations, Bill

Hi Dan.
 
I understand what you mean about the valving having to be large in order to allow the air to expand fast enough and push the ballast tank water out and keep from
 
overpressurizing between 33ft and the surface using dive planes only during a very rapid accent. Even with the valves fully open and letting the hull's compressed
 
air expand as quickly as they could to allow the water to be pushed out and the atm to expand to a normal 1 atm, if you rocketed up using your dive planes only,
 
I can see where it might still create some overpressure in the boat until it had time to equalize unless the valves were very large as you say. But it might be slight
 
overpressure and perhaps not even enough to worry about, AND this is assuming that you forgot to pump the air down and the overpressure valves are having to 
 
initiate an emergency blow of the tanks FOR you, to make up for you forgetting. So if you pumped it out like you should and didn't forget, and didn't rocket to the surface
 
with full tanks using your dive planes only to go up, that situation wouldn't occur.
 
Oh well, it was just an idea to perhaps enable an ambient or even a fully 1 atm sub to beome a hybrid and perhaps dive a bit deeper than it normally could. But you
 
and Carsten make good points about the complexity of it all being a lot to juggle and it probably would be better to just build and operate a TYPICAL 1 atm sub and
 
just build it to go as deep as you wanted without worrying about compressing its atm to allow it to go deeper. I got fascinated with this interesting no air loss ballast
 
system and thought it might be applicable to a modern design. But even though it would work, it might be more trouble than it would be worth.
 
At least we know it works and can be done, and maybe we can just keep the principle in the back of our brains until we might have a use for it in some application.
 
 
Bill.
 
 
 
 
----- Original Message -----
From: Dan H.
Sent: Thursday, November 17, 2005 8:06 AM
Subject: Re: Re: [PSUBS-MAILIST] Re: Variable Ballast Calculations, Bill

Bill,
 
Thanks for the explanation.  I better understand how your arranging the venting but still see a problem if your hull isn't built to withstand it's max possible internal pressure when at the surface. 
 
Remember, all it takes is a slight change in your ballast situation, and your heading either up or down. I can't see how you could start transferring ballast water out of the tanks with air from the hull and expect to keep one atmosphere below the surface while your pumping down.  As soon as you blow a small portion of your ballast, your coming to the surface, like it or not! 
 
The other problem I see is that any automatic valving you have has to be so large that the hull air pressure is reduced and the ballast water is blown out in the time it takes you to float upward from 33 feet.  And remember, once you start dumping ballast your floating up REAL FAST. 
 
On the Hunley , it was the best they could come up with at the time.  True looking at things done in the past can sometimes point out where technology got off track, but I don't feel there is much to gain in the case of the Hunley.  It was the best they could do and a engineering marvel of it's time, but we can do much better now. 
 
Please note, I'm not trying to argue but just don't see an advantage. 
Dan H.
 
 
----- Original Message -----
From: Akins
Sent: Thursday, November 17, 2005 2:07 AM
Subject: Re: Re: [PSUBS-MAILIST] Re: Variable Ballast Calculations, Bill

Hi Dan.
 
My hybrid design ideas were towards enabling a person who was going to build an ambient ANYWAY, to enable them to go a bit deeper.
 
You wrote...." If you put in safety valves to release any positive pressure you had in the hull in case you rise too close
 
to the surface and they release air, you won't have the air to put in the tanks later on."
 
 
You would only have a hull interior overpressurized situation if you were accending while ONLY using your dive planes to power
 
you upwards, because if you were accending other than using your forward motion and planes, you would be using your ballast
 
tanks to accend and would therefore be pumping the air down and not have an overpressure situation right?
 
So the only time overpressurization would occur, is if you were forcing her up with the dive planes only, while your
 
ballast tanks were full, and you forgot to pump down the interior air and push it back from the hull's interior into the ballast
 
tanks that would push the water out. If that occured, your overpressure valves would automatically open those ballast tank
 
valves to the hull interior and would pump the water out automatically. The overpressure valves would be your backup so you never overpressurized.
 
Those overpressure valves could open your ballast tank's water inlet valve and using the compressed air volume of the hull's
 
interior push the water out of the tanks using either your hulls expanding atm and then you would be equalized at the surface. So you would NOT
 
lose any air out of the hull or the ballast tanks and the overpressure valves would compensate for you automatically if
 
you did not remember to pump the air down. 
 
I hope I explained it good enough and the above was what you were asking if you were missing Dan.
 
The latest posts show that even Carsten says it will work. But he has the same question as you do of "WHY?"
 
His concerns about the hybrid's complexity for no depth gain over a typical 1 atm sub's depth capability,  make a
 
lot of sense, as do yours.
 
So after thinking about it, I think the best thing would be to go ahead and build a 1 atm sub and make THAT
 
sub a 1 atm/ambient hybrid. Imagine an already 1 atm sub design that had a max operating depth of say 400 ft. If you built
 
your ballast system like this for it, you could compress the atm in the sub by filling the ballast tanks and having those tank's
 
valves open to the hull interior, then you would close off those valve and seal the hull again,  and be able to dive even your
 
1 atm sub deeper than you safely normally could. At least we know the 1atm/ambient hybrid idea can be done. It can be done
 
looking at it from the view of a normally ambient that sometimes become a sealed hull that allows it to dive deeper than a normal
 
ambient, or we can look at it from the view of a normally 1 atm sub, that also uses a hull air compressing system to allow it
 
to dive deeper than normal also. We know they did it with the Hunley, perhaps we could use that same principle on a modern fully
 
1 atm sub design to increase her depth.
 
I appreciate your helpful comments and valid points as do I everyone's.
 
Thanks.
 
Bill.
 
 
 
 
----- Original Message -----
From: Dan H.
Sent: Wednesday, November 16, 2005 8:26 PM
Subject: Re: Re: [PSUBS-MAILIST] Re: Variable Ballast Calculations, Bill

Maybe I'm missing something.
 
Why all the fuss to build a sub that you need to be careful not to surface all the way before shifting air from one place to another. 
 
First of all you can't control your depth that easily.  You don't always have the option of stopping your assent as 33 feet or where ever as a diver does.  Some times you hardly know your moving until you see the surface right there a foot above you.  If you put in safety valves to release any positive pressure you had in the hull in case you rise to close to the surface and they release air, you won't have the air to put in the tanks later on. 
 
Since your building a pressure hull anyway, why not use 1/4 inch plate instead of 3/16, or whatever.  Build a one atmosphere sub.  You'll have a safer sub and a simpler sub to operate with no need to take extra precautions with hatches, viewports, and valves for an internal positive pressure situation.
 
Please explain if I'm missing something.
Dan H.