[PSUBS-MAILIST] Topic change

[CWall@swri.edu]

Ed said:
I think a lot of discussion is going on concerning something that is WAY
OUT of our league. I thought this was a Personal Sub list to enhance our
potential and offer advice to built our own PSUB. I honestly don't
envision any of us building a flying sub.

I agree with Stan - "To me the flying sub is SiFi, like in Voyage to the
Bottom of the Sea. 2 different technologies that don t fit together."

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Yeah, I'd have to agree.  After 35 years of experimental aviation, if someone
put a gun to my head and said "build a flying submarine", I'd just take a
two-seat Goodyear Inflatoplane and use the passenger weight for a skeleton
chassis and electric propulsion system and be done with it. But it would be a
lousy submarine from a mediocre airplane....and who wants to waste their time?

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He's a new topic:  my dry sub design, as far as I've gotten (after a couple
hundred hours of design tradeoff studies) is a steel one-man cruising sub,
optimized for long range on the surface and shallow dives- mostly 30ft and
less.  

Here's the innovation (or at least I think it is, simply because I haven't
heard of anyone else suggesting it):   Propane is used for both fuel and
ballast blow.

All propane plumbing is external to the pressure hull.  The only thing
penetrating the P-hull are rotating valve actuators, steering linkages, and the
 prop shaft.

The drive is parallel hybrid, like a normal sub, but the carburetor for the
Honda 5hp long life horizontal shaft engine is at the top of the snorkel, again
 so that no pressurized propane enters the P-hull.   Propane used to blow the
ballast tanks is not lost but can be delivered to the engine for use as fuel
when on the surface.  

Additional refinements may include pneumatic  compounding (a reciprocating
motor used to extract the energy from the pressurized propane before delivery
to the engine and connected shaft-to-shaft, allowing the Honda to be run
extremely lean for increased range) and exhaust turbo-compounding for
additional battery charging. 

The design goals are: 200 miles of surface range, 2 miles submerged range, and
room to lay down and sleep.  I think I can get this accomplished in a boat
roughly 18 ft long, and it must be trailerable behind my little Isuzu pickup.  
 (This really depends of what steel I can get my hands on.)   I don't
contemplate wanting to go below 100 ft, so a 250 ft redline depth seems
appropriate.  I would anticipate most dives to be shallower than 30 ft.

The hull would be most likely fabricated from a section of steel tube 28 to 30
inches in diameter, perhaps more, with the pressure section absolutely round
but the ends darted and drawn to get a good "guppy" shape.   (Sort of like a
moderated sea kayak- I want to make way on the surface even if there are some
swells...)   Fore and aft free-flooding ballast tanks would enclose the propane
 tanks and trim tanks, so that propane leaks would be captured, and side
flooding ballast tanks would add bouyancy- syntactic foam would be used to get
nearly neutral trim with ALL ballast flooded.   A substantial droppable keel
and fore and aft shot hoppers would then get you to the surface if you ran out
of propane or went below the depth where the 90psi blow was inadequate.

I've been doing cardboard models to get the geometry from straight tubing with
cuts and welds, and I've been very pleased with the shapes I've been able to
generate.  I have some other projects ahead of this one, but I have a feeling
this one has life to it.

Craig Wall