Dual-Deployment: How often is one deployment charge used with motor ejection? (H-J)

JohnCoker said:

No, I mean that the coupler is on the fincan section, so there is less chance of a zipper which means there is no path for the ejection charge to reach the drogue bay.

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watermelonman said:

I may be missing an important detail here, but would it be possible to simply use an open coupler along with a different form of cord mount? Perhaps an industrial version of the old Estes mount, or an upside down Aeropack minimum diameter retainer -

That said, I prefer using electronics and avoiding the motor charge entirely when possible.

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JimJarvis50 said:

I'll bite. The rocket on the left in John's picture has an open coupler (like what you're suggesting). The problem is that when the drogue deploys (or the main if you put it in that position), the fin can has to change direction - from pointing forward to pointing backwards. The harness stresses the open coupler, and the result can be a zipper. The rocket on the right has the zipperless coupler (a coupler tube mounted to the fin can, having a bulkhead or two, and a U-bolt on the top for attaching the harness). Now, when the fin can changes direction, there is nothing to zipper. It's a much better approach (IMO), and you can poke holes in the bulkheads so that you can still use motor deploy if you want to. Zipperless couplers also make a handy place to retain the motor.

Jim

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