expanding body umbrella?

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Well-Known Member
Jan 20, 2009
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Has anyone ever built a rocket in which the body tube itself it split into 4 long strips which, upon firing of the ejection charge, pop open (hinged at the base of the NC) like the blades of the Skywinder? The difference would be that the body itself would be what is popping open.

Now here's the twist: inside the tube, and connected to the inside of the tube sections, are pieces of chute material that will stretch out between the expanded pieces like an umbrella, or bat wings.

Just an idea that sprung into my head...

I think Bill Spadafora made a rocket similar to this, it had a little drink umbrella in it for the nose and it was spring loaded so when the motor popped it came out and opened, if this is any help.
well yes but I'm doing experiments on flying a Micro-Mary Poppin's figure with the umbrella recovery:D She'll have a shock cord to let her down easy;) The tirck to these umbrellas is finding ball points pens with the right size springs.
But I don't think these umbrella rockets are what WW is thinking about, I wish I had a few shots of some of the various configurations some of my buddies and I came up with way back when. had a few rear fold outs the turned into a helicopter for recovery. Another BT-20 od had drycleaner bag Pleating folded inside and around a BT-5 core. when the burn string snapped the body opened to a full canopy, fin side down. Another had staggered "rotors" on paper hinges that spread out and sort of interlocked at the body auto-gyrating down. I think that one was a BT-50...Way to long ago for good recollectionsl:(
What configuration are you looking to do WW?
End result would look similar to the paper umbrella with shock cord attached, but with the following differences:
1) nose cone is solid plastic (standard Estes NC)
2) Body tube is what makes up the solid framework of the umbrella
3) webbing between the framework would be nomex/aramid (gonna try and get some scrap from the local firefighters)
4) Lower retaining ring is a slip ring that holds the 4 (or maybe 6) parts of the BT in place during flight
5) Ejection charge forces entire body split body tube, NC, and webbing forward, driving it out of the slip ring and allowing it to expand.
6) Directly down center of rocket (almost to the MMT) is a dowel rod, similar to the "handle" of the paper umbrellas to which the shock cord and fin can assembly are attached.

Clear as mud?

Ahh! very clear: Should workout pretty well, the drycleaner bag canopy BT-5/Bt-20 I discribed worked in much that way. The mini motor vented out 3/16" holes spaced around the forward end of the core tube with a BNC-5V nosecone. the brun string was placed about mid body passing through the BT-5 and around the 6 bt-20 spines/ bottom retainer fin can. worked very well but didn't get a lot of duration.
Slip ring retainers should work OK as long as the spines don't create to much friction. Kewl Idea, Can't wait to see the pics closed and open:)

I've got the tubes cut (sorry, no pics since I don't have a digital camera). I say tubes because I'm using a tube coupler at the end to fit into the slip ring so the outer surface remains as smooth as possible. This coupler was glued to the inside of the "body" tube, then quartered along with the rest of the body.

Now here's the question: How do I hinge this thing? Are there hinges small enough to fit onto a tight curve? I'm using a mailing tube that is only 2.1" OD, and I'm planning on putting the hinges on the outside for simplicity.

I considered using a partial cut through the cardboard tube as a hinge, but failure would be inevitable, especially if subjected to a hard opening.

I seem to recall seeing nylon or some similar plastic hinges for r/c planes somewhere, but are there small metal ones at home and hardware stores?