Question. You know that little ring that slinks onto the exterior of an AMW-style casing? At what point do you suppose those suckers would fail, allowing the motor to slide up into the rocket?
In the old days, I used a hose clamp as insurance - a backup, right under the ring. The rocket I am working on now is going to be light (which helps - a heavy rocket's inertia would cause more stress on the ring). All the same, I don't want that sucker failing.
Has anyone ever had one of these rings fail? Note that this question may be better posted under the commercial propellants section, but here it is 🙂
it would take a TREMENDOUS amount to make it fail. Even if ground down. I would say your airframe will fail before it does. Ive seen them hold rockets with alot of mass under thrust of great deals. Again if you can break that thing... you had to do something WAY wrong. Did I stress WAYYYYYYyyyy wrong.
Due to the way the groove is ground and the way the split ring fits into that groove, I think you'd have to have a helluva lot more thrust than any AMW motor can provide to blow through that ring. I've never heard of such a failure.
W
You can go to
http://www.smalley.com/
They have tables for the force it would take for the ring to fail.
A quick lookup shows that a similar ring to the one on AMW cases the ring fails at 12930lbs with a safety factor of 3 and the groove (most of the time the limiting part) fails at 4950 lbs. This is with a material yield strength of 45 kips and a safety factor of 2. 6061 Al that we use has a yield strength of 35 kips, and ultimate strength of 45 kips. Our cases are going to be less, but still in the thousands of pounds.
Hope this helps.
Edward
Thanks, Edward - that makes me feel better. My rocket will weigh about 24# loaded x a paltry 20 gees. Should be good-to-go.
I have other things I'm worried about for this flight, but at least the ring failure seems to be something I can quit losing sleep over 😯
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