[PSUBS-MAILIST] PSUB PROPULSION METHODS...

A couple weeks ago I mentioned I'd like to re-open that old discussion about advanced propulsion systems for minisubs. I received many helpful replies on everything from the factual (BIONIC DOLPHIN) to the theoretical (vortex propulsion); and first off I'd like to say THANK YOU to everyone who took the time to contribute. Your input was informative and greatly appreciated!

There were also inquiries about the closed-circuit engine system test model I built back in the mid 1980's; and in replying to these, I rediscovered the truth of that old saying "we learn by teaching". Going back over my notes from those days made me re-evaluate the worth of that system, and return to some realizations I'll share with you now, in the interest of safety.

Closed-circuit engine systems which employ exhaust-cleansing / oxygen-replenishing methods are EXTREMELY DANGEROUS. Back in the mid-80's I did manage to make a systems-test model that worked; but it didn't work well; it burned out the engine in a short period of time; and I'm probably lucky it didn't blow up on me. I'm still not saying it can't be done, as this would conflict with the fact that Navies of the World are doing it at this time. But I feel obliged to point out that these are very sophisticated systems; they'd make highly-challenging projects for the backyard craftsman; and considering the possible consequences of failure, they might be best left alone.

Some 40-odd years ago, the U.S. Navy built a minisub designated X-1, originally intended for closed-circuit engine propulsion. It exploded. They eventually switched to electric power. The history of closed-circuit engine propulsion has many similar stories.

Basically, what we're talking about here is locking ourselves inside a hermetically sealed chamber with a potential BOMB. The use of oxygen in a closed-circuit engine is hazardous in the extreme; the potential for fire and/or explosion is high, and the results of such a failure inside a small submarine would be catastrophic.

For these reasons, I am tossing the closed-circuit engine concept in the garbage can, so to speak. I am still interested in building a dual-propulsion submarine (engine and electric); but it will breathe air from a snorkel and/or tank storage, and WILL NOT be of the "oxygen replenishing" variety. As Alec pointed out, this safer engine-drive will still give the minisub great speed and range on the surface, and for short runs underwater. And how fast do we want to go when the visibility is limited, anyway? Once submerged, electric motor propulsion still seems adequate to most practical needs.

Where increased performance is the goal, I like the Zinc/Air fuel-cell system presently under development by METALLIC POWER, and scheduled for marketing by TORO in 2002. I also like the electric car systems scheduled for 2003 or thereabouts. I think the first five years of the new millennium will bring improved electric systems into being that will give us performance greatly improved over what we have now; and I already have one hull set aside for them when they do.

I say all this in the interest of SAFETY because I believe that's what the experimenter working with homebuilt submersibles should concern himself with first and foremost. I re-opened the subject of closed-circuit engines; it generated a lot of enthusiasm; but I just want to make sure everyone realizes the potential dangers involved. This post puts my conscience to rest on that issue.

Again, thank you all, and good luck with your projects. Those of us here at the Vulcania Submarine Boatyard wish you all a Happy Holidays and a Mellow Millennium.