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Joe, for a pilot you sure are catching on
quickly. This isn't exactly your turf, but, so far you've made more sense
than some of the stuff I've seen. I get the impression you actually want
to solve some problems and not just ramble on about concepts.
:-)
I hear you, lot's of
similarities. I am envisioning the longitudinal supports (minor stringers) only
to maintain a fair surface since the framing is in essence, a plug. Still, I
would like to not have to do that, but I cant see how to laminate the thin
layers without them?
But, longitudinal support (major
stringers) in addition to the monocoque skin is
also length and weight dependent is it not?
OK, now - the longitudinals. If the skin is
thick enough they should be self forming around the bulheads. I'll be
using so many of them that the skins really will have no place to go than around
the edges. Very thin sheets would require skantling for sure.
Any ambient ply design is going to
need a "boatload" of lead. You and I need to be careful about structural
integrity with regard to the concentrated ballast (and it's going to be a lot!).
I don't think I could get away with purely monocoque at my length and be
comfortable in any kind of wave action.
I'll be keeping my lead right under my seat.
I'm visualising the cockpit/lead setup as a balloon/weight analog. The
heavier built cockpit will take the stresses entirely.
As you so aptly pointed out, in a seaway the
changing stresses could lead to difficulties. Magical Child's twin keels
(mainly for bottoming) will run from far aft right up forward. Inside the
nosecone I'll be using bracing in the form of ply sheet to take hard wave
action. I'll be transferring the loads (on the inside of where the
external keels meet the hull) adjacent to the twin keels.
A 15 footer like MC has a completely different set
of stressors than your Nautilus. Same concept, but the
load!!!
Clear my mind, will you? Are you still envisioning
that 35 footer? Or have you actually decided to downsize for the first
one?
Rick L
----- Original Message -----
Sent: Saturday, December 17, 2005 2:20
PM
Subject: Re: [PSUBS-MAILIST] Curved
surfaces and ballast release
Rick,
'Now, I may be a little more concerned with
the cockpit. I'll have to think this one out."
As I work this out on paper I am seeing either
a short, squatty and lighter caricature of a military boat, or a
longer truer to scale but more heavily constructed version with a tiny crew
module and almost all flooded fairings. As they say in Texas, "big hat no
cattle"!
Truly a lot of details to consider.
Joe
From: "Rick and Marcia" <empiricus@telus.net>
Reply-To:
personal_submersibles@psubs.org
To:
<personal_submersibles@psubs.org>
Subject: Re:
[PSUBS-MAILIST] Curved surfaces and ballast release
Date: Sat, 17
Dec 2005 12:13:00 -0800
Joseph - it seems we're looking at building the
same boat!!!
I'm avoiding longitudinals and sticking with a
monocoque. I agree with all the transverse frames (bulkheads) being
the main support or guides for the epoxied skins. Magical Child (i.e.:
Typhoon) will have simple curves (arcs) both port and starboard,
deck and bottom. The simple curve in the cold moulds will be sufficient
support; IMHO, the longitudinals are extra work. Longitudinal strength
comes from the skin.
Now, I may be a little more concerned with the
cockpit. I'll have to think this one out.
Temporary support while the epoxy cures along
the bulkhead edging will come from wrap-around straps or even cinched
up rope (trucker's tightener). A good 60 grit sanding along the
bulhead edging will give some tooth for the epoxy to hold.
I'll be using rather thin (1/4 inch) ply
for bulkheads - should work as long as they're filleted with epoxy and
glass strips. Cockpit bulkeads will be heavier.
Rick L
----- Original Message -----
Sent: Saturday, December 10, 2005
6:14 AM
Subject: [PSUBS-MAILIST] Curved
surfaces and ballast release
The recent discussion regarding spherical
mock-up construction has me taking another look at something I had in
mind.
To form the curved surfaces of my ambient
marine ply design, I have in mind epoxy laminating thin layers of ply
over longitudinal supports notched into traditional transverse frames. I
need those frames to baffle a whole lot of free flooding spaces and soft
tank spaces anyway, so they have to form the hull exterior. (The crew
compartment is modular and hidden from view and structured to contain the
lead ballast).
As I apply this to my 3d model, I see a
lot of material taking up a a lot of displacement volume and therefore
requiring additional compensation ballast.
Suggestions on how to cut down on the
framework volume and still maintain fair curves with rigidity would be
greatly appreciated.
A second question is regarding mechanisms
for release of a heavy lead keel. If someone could point me to examples to
look at?
Joe
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