[PSUBS-MAILIST] HP and replicas (was: What's happening here.)

["Michael B. Holt" <mholt@richmond.edu>]

Captain Nemo wrote:
> MIKE!      If this is about those pages from Busby's book, STOP!!!  I just
> bought a copy of MANNED SUBMERSIBLES via eBay.  Muchly appreciate your
> efforts, but I no longer need the Busby stuff.   Thank you anyway, though!

OK, will do.

> > My Visual Basic programs to calculate resistance and horsepower is
> > now working.  Problem is that the HP numbers are VERY low.  I'm
> > not sure if this is because of too little understanding of the
> > formulae, improper programming or -- maybe -- it really doesn't
> > take much power to move something underwater.
> 
> Sure doesn't.  Partly, I think, because an object at neutral buoyancy is
> essentially weightless, and their's not much inertia to overcome.  Surface
> (form) drag is the big thing.  My boat is actually pretty pointy and the
> fins cut the water well.  Once it gets going, it wants to keep going.  Hard
> to stop.

I'm using the formulae in Alan Hoar's book "The Submarine Torpedo Boat."
Displacement isn't a part of the formula for resistance.  It is,
however, significant in wave-making resistance.  Busby's formula for 
submerged HP requirements does require displacement (in tons).  I need 
to think about this.    

> Again, no longer any need.  My copy of MANNED SUBMERSIBLES should be here
> soon.  Glad to hear there's a chapter on pressure hulls.  Does he get into
> computing crush depth? 

I just looked, and didn't see anything about that.

> I've based my designs on what I know of proven
> designs and past experience with watertight devices I've taken to depth
> while SCUBA diving.  Then, I overbuild and remained extra shallow.  

This is the mindset that I see in Busby.  

> I sometimes think the actual reliability of computed crush depth with
> homebuilt submarines is less than reliable, because there might be
> non-standard design and construction methods used. 

IO think that's a major worry.  Without saying it that way, I 
think Busby was wholeheartedly in favor of using methods that
had been used before.  I'd not be surprised to learn that he
had nightmares about someone's hull collapsing, after which there
would be Federal regulation of pressure hull design at home.

> Still, I'd like to be
> able to calculate crush depth to at least have some idea of what various
> designs might be able to tolerate.

I guess the book John Brownlee found is the way to go for that.
The math is beyond me right now.  (I have found a book called
"The Design of Circular Shells," which is about designing roofs
for large buildings, but I've not bought it.)

> Speaking of plans, I sent you the plans for the 50" NAUTILUS last week by
> priority mail; should be at your place soon.  Be on the lookout for a long
> cardboard tube.  ENJOY!!!

Thanks.  I'll watch for it.
 
> The SEAVIEW is a neat looking sub with great possibilities for forward
> visibility through those bow windows.  Dual thrusters, too.  Nice boat.
> Might be able to find a copy of the plans.  I'll browse around and let you
> know if I find a source.

Taubman Plans Service had the exterior stuff.  I heard Abe Taubman was
ill and that he'd kinda retired a little.  I'll ask again.

The problem with SEAVIEW is the length.  It's really suitable for
one person prone, or the proportions will be all off.  

Other problems appeared when I was doing tank tests with the Aurora
model.  I towed it in the plastic swimming in my back yeard, when 
I was about 15.  Those silly damn manta fins tend to force the 
bow down.  The observation nose is a greater diameter than the
hull.  (It takes forever to fill the model through the two mounting
holes in the keel, and longer to empty it.)
 
> If you really want to blow minds, build a SEAVIEW complete with a FLYING
> SUB!!!    ;-)

Or have missile tubes that launch.   Hmmm .....



Mike