Nosecone advice for Wildman Darkstar Ultimate

egp said:

I am making good progress on my Darkstar Ultimate, but have a few questions. While there are lots of Wildman Ultimate build threads on the forum, very few show details about the nosecone.

The nosecone assembly consists of a beautiful 6:1 Karman fiberglass nosecone, a fiberglass coupler, and a fiberglass bulkhead for attaching an eyebolt and the parachute/shock cord. Instead of epoxying the bulkhead into the nosecone, I am instead thinking of using a plywood centering ring (have a bunch of spares), and then attaching the bulkhead to the CR using screws and T-nuts. Also, I am weighing the pros & cons of attaching the CR into the nosecone, or inside the coupler. The latter would offer the advantage of having the eyebolt right at the end of the nosecone assembly, vs. 10 inches inside.

If anyone has photos of their Wildman Ultimate nosecone assembly, I would appreciate seeing them!

Thanks, Eric

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mikec said:

I like to use button-head screws to attach the coupler to the cone (just tap the coupler fiberglass for them.) That gives you complete access to the volume of the cone for whatever you want and you can pack everything and put the nose cone on last, which is useful for tracking electronics.

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egp said:

Thanks for the advice, so far! I think I'll go with this plan:

Glue CR into nosecone. Glue coupler into nosecone, abutted to the CR. Attach bulkhead to CR with 6 8-32 stainless-steel screws (ultimate tensile strength = 70,000 psi) with T-nuts on the back of the CR. That would give a maximum static load of 9000 lbs force which, for a 50-lb rocket, would be well in excess of 100 g deceleration with a healthy factor of safety. That should be sufficient.

Although your math may be correct - the weak point won’t be 6 threaded holes - but instead will be the wooden bulkhead itself. I would prefer FG bulkhead. I’m sure you will be ok - bu I had a wooden centering ring let go on an energetic NC that was much lighter. Not trying to scare you - just want to point out the weak link. I would’ve posted sooner but just saw your thread.




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Nick@JET said:

egp said:

Thanks for the advice, so far! I think I'll go with this plan:

Glue CR into nosecone. Glue coupler into nosecone, abutted to the CR. Attach bulkhead to CR with 6 8-32 stainless-steel screws (ultimate tensile strength = 70,000 psi) with T-nuts on the back of the CR. That would give a maximum static load of 9000 lbs force which, for a 50-lb rocket, would be well in excess of 100 g deceleration with a healthy factor of safety. That should be sufficient.

Although your math may be correct - the weak point won’t be 6 threaded holes - but instead will be the wooden bulkhead itself. I would prefer FG bulkhead. I’m sure you will be ok - bu I had a wooden centering ring let go on an energetic NC that was much lighter. Not trying to scare you - just want to point out the weak link. I would’ve posted sooner but just saw your thread.

Sent from my iPhone using Rocketry Forum

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Nick,

Thanks, but everything is now securely epoxied in place and I'm nearly done with construction. Hope to do some ground testing on it soon.

Eric

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