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Re: [PSUBS-MAILIST] KL-250's Syntactic Foam Data
Brent Hartwig wrote:
Hi Jon,
** Sure I'll see what I can do. The Captian did at least one
unmanned dive test of every K-250 he and his crew built, to 500 fsw,
except mine, according to his book. Mine was later tested to at least
500 ffw by Dr. LeShack. Kittredge took a K-250 to the US Navies test
chamber at General Dynamics and the blown dome imploded at 824 feet,
which was very closely to George's calculations. Page 249 in his book.
Using 500 feet as a max depth for a K-250 design leaves no safety
margin. George tested to 500 feet because it was near the calculated
crush depth of the hull design and provided a 2:1 safety margin which he
could use as advertising. He didn't intend for the K250 design to
operate at that depth.
The new 1.5" thick cast acrylic conning tower will be able to resist
more pressure then that. I'll have to gather more data and run the
FEA on that part and the rest of the new assembly and see where I'm at
from there. I'm shotting from the weakest part, and/or assembly to
have a FOS of 2.5. So 1,250 fsw minum. I might not be able to
comfertabley do 500 fsw, once all the figuring is done. But I might
have even more. We'll see what we see.
I was not planning on factoring in the syntactic foam for dealing with
the external hydrostatic load for the FOS of 2.5. But if I was able to
obtain good data on the mechanical properties of the type of syntactic
foam I go with, then that area of the design might very well be able
to with stand far more then 500 fsw. Because I'm using syntactic foam
between the support ribs. I don't plan on needing the horizontal
weldments I had once planned to use, for collision protection and
resistence to external hydrostric load. Because I have a good source,
I might go with Divencell micro spheres, and a high grade infusion
molding vynel ester resin
I'll wait to see the results since I'm doubtful that you'll have the
ability to engineer and apply the syntactic foam as you suggest.
I fully expect to need to replace the forward viewport welded in
seating ring, and thicken up the acrylic. I'm considering increasing
the current 14.75" viewing to 16 or 17. I'm currently working thru
the detials, and getting ready to run the FEA. According to your
conservative viewport calculator for a 16" Di, and a operating depth
of 500 feet, it would have a OD of 20", a thickness of 3.20". With the
failure depth being 3,300 feet. That's an odd thickness, so I'll
likely got with 3 or 3.25". I had guessed I would need about a 3"
thick window there, so I must be getting better at this. ;}
Yes, you may find that 3 inch is sufficient. If you play with the
calculator to find out what water depth 3inch material will get you, you
should be able to determine what safety factor you get with it.
I'm planning on installing a full set of K-350 type A516 gr70 steel
support rubs. Right next to the extisting A36 rolled angle iron one.
This way I get the extra strength, and I have a flang on both sides of
the void space to better hold in the syntactic foam. The current rubs
have a ID of 32.50". The new surport ribs will have a ID of close
to 33" so they can overlap the current flanges, and a OD of would need
to be about 35" to allow them to go over the top of the current weld
bead that is against the inner hull surface.
Well it will certainly provide some additional strength, but I think
you'd be better off adding the new ribs equi-distant from the existing
ribs. The ABS hull calculator might help here.
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