Kirk G
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- Jan 9, 2012
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Long story short: An older rocketeer cleaned out his low-power rockets and trickle down left a completed Big Bertha for me.
There are no support materials, no instructions, no supplies.
The rocket is in great shape.
Upon pulling the nosecone off, I find there is no parachute tucked inside. It must be replaced.
(1) Does anyone know what size mylar chute the Big Bertha "takes"... 12", 15", 16", 18" ?
I have some replacement JonRocket chutes that I can cut to size, if I knew what this requires.
Second, the original owner had a piece of woven elastic shock cord mounted on a teabag anchor that looks to be in good shape.
The free end of the shock cord has been looped and tied back onto itself, leaving a small 1/2" loop available.
The nosecone features a short "pig-tail" portion of the same type of shock cord tied to the base of the nosecone. The "free end" is just that...
it is not looped nor tied to anything... though it appears at one time that it might have been tied in a loop or to something.
(2) What would the strategy of having two shock cords be?
(3) How would they be configured? (There is no evidence that it snapped or failed. The ends are clearly cut squarely.)
I'm thinking that perhaps the loop was designed to fasten a self-tightening fishing swivel 'hook', so that a different parachute could be used on different days, different wind conditions.
But I'm not clear how the nosecone would secure if it had an identical small loop in it's shock cord. I can't imagine that someone would simply loop the fishing swivel through both small loops:
That would make the fish swivel the weak link, and if it failed (or either of the shock cords) the rocket tube and nosecone could/would freefall without recovery air-breaking.
Or am I over-thinking this?
The last club launch is tomorrow, Saturday, and I forgot I had to deal with this until today.
Thanks.
There are no support materials, no instructions, no supplies.
The rocket is in great shape.
Upon pulling the nosecone off, I find there is no parachute tucked inside. It must be replaced.
(1) Does anyone know what size mylar chute the Big Bertha "takes"... 12", 15", 16", 18" ?
I have some replacement JonRocket chutes that I can cut to size, if I knew what this requires.
Second, the original owner had a piece of woven elastic shock cord mounted on a teabag anchor that looks to be in good shape.
The free end of the shock cord has been looped and tied back onto itself, leaving a small 1/2" loop available.
The nosecone features a short "pig-tail" portion of the same type of shock cord tied to the base of the nosecone. The "free end" is just that...
it is not looped nor tied to anything... though it appears at one time that it might have been tied in a loop or to something.
(2) What would the strategy of having two shock cords be?
(3) How would they be configured? (There is no evidence that it snapped or failed. The ends are clearly cut squarely.)
I'm thinking that perhaps the loop was designed to fasten a self-tightening fishing swivel 'hook', so that a different parachute could be used on different days, different wind conditions.
But I'm not clear how the nosecone would secure if it had an identical small loop in it's shock cord. I can't imagine that someone would simply loop the fishing swivel through both small loops:
That would make the fish swivel the weak link, and if it failed (or either of the shock cords) the rocket tube and nosecone could/would freefall without recovery air-breaking.
Or am I over-thinking this?
The last club launch is tomorrow, Saturday, and I forgot I had to deal with this until today.
Thanks.