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There is a convex curve at the inside base of my come
that adds more detail the the drawings. If you imagine what it looked like with
the flange still on it, before machining, what your seeing on the close up cross
section view drawing, is part of the inside curve of the dome as it transitioned
to the flat bottom of the flange that was removed. So there is a convex curve
for the first .25" before the curve starts to go concave for the main interior
curve. The thickness varied a bit at the base. I used the thinnest measurements
to be on the safe side, since I was planning on using the part for FEA work.
============================================================ Old KL-250 Dome Specs
Outside curve radius of 173.69 degrees making it a
173.69 degree dome
The dome specs on the K-250 plans call for a 12" high
+- 1/8" 180 degree dome.
My dome is well under that, at 11
5/16" (11.3125") high
23 29/32" (23.9063") OD
22.6963" ID but changes after only .25 to
22.5663
This is using the thinnest thickness measurements of
.605" and .670 respectively
The bottom edge is .670" to .690"
thick
The .25" up from the bottom edge is .605" to .640"
thick
============================================================
Outside Height is 11 5/16"
(11.3125")
Inside Height is
10.95"
Making the thickness at the apex of the dome
.3625 which is just under 3/8" (.3750") thick
Regards,
Brent
From: Brent Hartwig
Sent: Thursday, August 20, 2009 12:25 AM
To: PSUBSorg
Subject: [PSUBS-MAILIST] Original KL-250 Blown Dome
Specs Greetings SMMOMS,
I've been analyzing the original acrylic
blown dome, that came on my KL-250, and made the assembly model of it, to put on
the CAD assembly of the whole sub as it was configured when I received it. Then
later I'll put a modified version of it on a assembly model of the K-250 as
it is configured in the Captains plans.
I've noticed that the bonded on rim ring on my dome is
made up of four strips of .25" thick by .75" wide acrylic joined at a 45 degree
angle. The thickness at the apex of the dome is just under 3/8"
. I'm working of obtaining the exact shape of the dome, but
currently I think have a reasonably good facsimile. I've begun to run
some FEA testing on the dome assembly I currently have worked
up. No surprises there so far, with the higher stresses being on the
thin top area, and the inside seating area. I still need to obtain a few
material property specs on the Acrylite G and Polycast cell cast
acrylic to obtain more accurate data. The CosmosWorks software I use has a
cyclic fatigue analyzing engine, so I'll have to put it to good
use.
My rendering software and computer were playing nice
together, for this session, so some interesting renderings came out, with out me
feeling like pulling out my hair. ; }'
I can clearly see on the old dome that it was retained
in two different positions about it's axis. It was held in
one position for a long time, and I could see where the metal
holding cleats pressed against the outer surface of the blown dome. This makes
me think that for this type of dome, that there could be a retaining ring with a
rubber gasket under it, instead of the metal cleats. I see Alec changed his out
for plastic ones.
Alec, are those made out of
UHMW?
Also in both said holding positions, there is fracture
damage to the blown dome. One area in particular took some serious damage. Some
of fractures might be from tightening the cleats down to hard, and/or the
hatch was dropped or obtained the damage in a particular holding position
when the sub suffered a hydrogen explosion inside and blew back the hatch with
out it being latched inside or out.
Regards,
Szybowski
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