Re: [PSUBS-MAILIST] Thruster ideas

James,

I am wondering (and perhaps Vance can speak to this), if "conduction" through the mountings to the external case, is sufficient for a directly immersed air-filled thruster.

Joe

From: "Lil Brother LLC" <lil_brother_llc@bellsouth.net>
Reply-To: personal_submersibles@psubs.org
To: <personal_submersibles@psubs.org>
Subject: Re: [PSUBS-MAILIST] Diver Lockout.... serious question here!!
Date: Sun, 29 Jul 2007 11:08:27 -0500

Vance,

Air is the least effective means to cool something that is enclosed. The problem with air, if it is exchanged in a fast enough rate, it works great. On the other hand....if you can't exchange the air, you end up with an oven. Oil on the other hand can carry more heat away faster. The density is the factor here. Air is not very dense, so it will only absorb so much thermal energy per unit.Oil will absorb many more btu per unit than air. Also because oil will thermocycle.....the oil will transfer the heat to the container that contains it faster.

I think an air filled thruster would work good too, but there are problems with compression. If there are any bearings housed within the casing......they will bind under extreme pressure if filled with air. An oil filled enclosure will not compress as far. There will still be compression problems, but not to the extent of an air filled unit.

There was a project a few years ago....a guy made a gaming computer that used oil to keep all the expensive parts cool. You should look it up. It worked really well. (Oil cooled computer)

I do not plan at this point to run a reduction gear. BLDC motors are real good at direct drive.

I would like to build smaller thrusters that can go very deep.

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

----- Original Message -----

From: vbra676539@aol.com

To: personal_submersibles@psubs.org

Sent: Sunday, July 29, 2007 8:55 AM

Subject: Re: [PSUBS-MAILIST] Diver Lockout.... serious question here!!

James,

Serious DLOs have dive chambers separate from the crew compartment. And as for your thrusters, in my experience AIR transmits heat faster than oil. How deep are you building these things for? HBOI, for instance, runs aluminum cans and PM motors in air to 3000 feet, with no real problems. The commercial units that Nuytco uses ARE oil filled, I believe, but have a higher pressure rating, and no reduction gear.

Vance

-----Original Message-----
From: Lil Brother LLC <lil_brother_llc@bellsouth.net>
To: personal_submersibles@psubs.org
Sent: Sun, 29 Jul 2007 12:29 am
Subject: [PSUBS-MAILIST] Diver Lockout.... serious question here!!

I've got into some pretty serious questions lately......and I've done a little reading about diver lockout (archives), but the archives raised a question. If you have a 1 atm sub, with a diver lockout........how do you lock a diver back in? Are there any 1 atm subs with a lockout? If there are......if the lockout has been pressurized to the outside pressure........what method is used to depressurize it back to 1 atm? (these questions are redundant I know) And the last....the important one.....is this on the dangerous side? If you depressurize to fast......the bends. I was reading about the nice sub.....(the Krata I think.....please don't quote me ....I've had a very long two days)......but I didn't notice if it was 1 atm or not. Some one learn me on this. :-) (Hey....at least I know what a VBT is for now.) James Long Owner/Designer Lil Brother LLC (Instrument Division) ************************************************************************ ************************************************************************ ************************************************************************ The personal submersibles mailing list complies with the US Federal CAN-SPAM Act of 2003. Your email address appears in our database because either you, or someone you know, requested you receive messages from our organization. If you want to be removed from this mailing list simply click on the link below or send a blank email message to: removeme-personal_submersibles@psubs.org Removal of your email address from this mailing list occurs by an automated process and should be complete within five minutes of our server receiving your request. PSUBS.ORG PO Box 53 Weare, NH 03281 603-529-1100 ************************************************************************ ************************************************************************ ************************************************************************

AOL now offers free email to everyone. Find out more about what's free from AOL at AOL.com.