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[PSUBS-MAILIST] Re: KEN MARTINDALE (was Big Motor..)
Captain Nemo wrote:
> "I looked back in my annotated "20,000 Leagues Under the Sea," to get the
> numbers Verne used. In Prof. Aronnax's first private interview,
> Captain Nemo privides all the number in metric. That Nautilius displaced
> 1500 tons, was 228 feet long and cruised at 15 knots. Quite a respectable
> psub."
>
> Sounds like the one Carsten's building now! ;-)
That was exactly my thought.
> " What I see in my exploration is that most smaller boats would not benefit
> from too much mathmatics. Five horsepower is quite enough."
>
> Generally, I agree. Unless the objective is a high performance minisub,
> most small boats all seem to share similarly slow speeds and limited ranges
> of operation when using most common propulsion systems; so, for my purposes,
> knowing precisely whether it was going to go 3 or 4 mph at full power wasn't
> an immediate concern. But then again, the abiity to accurately calculate
> performance would be really important when designing a bigger sub with
> greater intended range capabilities; so yeah, I'd like to know how that's
> done.
Busby says that somewhere, I think. Thinking too much about the
power system doesn't seem to be worth it, for most practical
applications.
> " I have three-views and sections of Disney's Nautilus. It must be seen as
> a work of engineering art. Working up the numbers on that shape would be
> daunting."
>
> Yep! That's how it looked to me, too.
I used to look at Disney's boat and shudder. Verne's Nemo was lucky
no one thought of hydrophones. But it really is beautiful, kinda
like a Lamborghini.
> "That's exactly it. I've just not been able to work out how to relate the
> elements. I'm hampered by training that conentrates on accounting and
> computers, education that centers on the mind of man and old textbooks which
> were not written a reference books."
>
> Begins to look like a wind tunnel or the like might be necessary to really
> know for sure; but calculations should be able to provide a fair
> guesstimation of performance, even in the case of an unusually shaped hull,
> no?
Some sort of experimentation is expected, by the writers of the books
I have. Most of them require model testing, actually. I don't
have room for a wind tunnel. To do that would require a bicycle shop,
traditionally. Weston Farmer explains his plans for a model-testing
rig, in his book "From My Old Boat Shop."
I think, between careful duplication of the math and referring to
similar
boats, we can work out a pattern for horsepower estimation.
Mike