mikec
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Kind of like I showed back in post #16.Make the sled itself the structural component (G-10).
Kind of like I showed back in post #16.Make the sled itself the structural component (G-10).
What about this??...
Make the sled itself the structural component (G-10). Provide some tabs at each end that fit through some slots in the end centering rings (both ends). In those tabs, drill some holes (located to coincide with both surfaces of the centering rings) that you fit some fiberglass 'pins' (say, 1/8" dia x 1/2" long) through (to hold the sled and rings together and in alignment --- this is what would transfer any structural load to/from the rings/sled) and then epoxy the assembly together (which would seal the area from any gas blow-by). This would make the sled/ring assembly one piece, structurally. G-10 has a tensile strength of 38,000 psi (roughly equivalent to steel), so it would be more than capable of carrying whatever load would be imposed - but, if in doubt, route some Kevlar alongside for insurance. A 1/16"t x 54mm sled would be about 0.13 sq.in. area (cross-section) - which would translate into something over 5000lbs tensile - more than 5x what a (steel) 1/4" all-thread rod could carry (and that's without deductions for thread depth).
This is something akin to the post reference Will Ferry mentioned (the 'roll pin' idea):
https://www.rocketryforum.com/showthread.php?123671&p=1433317#post1433317
I've got several 6' lengths of some 1/8" solid fiberglass rod that I'll hack off a bit and try to do a mockup.
I'm also tinkering with a CAD drawing on this and maybe able to upload once I figure out a few 3D items on the drawing.
-- john
I have also wondered why this isn't the standard. Look at all the hardware that could be minimized. Kevlar could be "glued" inside of the outer wall and passed straight through the bay. Use some putty as it goes through the bulkheads to seal them from gasses.
Kind of like I showed back in post #16.
I've been considering this exact idea for a while. The problem I see is that you'd need a large tab surrounding the attachment points. Imagine a .500" hole with .75" of G10 surrounding it at each end of your 54mm sled. We could use a thicker sled with most of the center milled out to achieve the same weight and strength though. Any material inline with the attachment point holes is just added weight anyway. So, we could use a 3/16" X 1" sled with and mill it into an I-beam profile leaving 2x .187" x .375" bars attached together with a .060" web between them. You could make a simple delrin block on each bulkhead and screw the sled to the block to keep the bulkheads in place.
Fiberglass rod? That is interesting. It should be strong enough.
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