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Shear pins for interstage couplers on Two stage rockets

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Jclark

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Does anyone use shear pins on their two stage rockets? I have a PML Thunder N Lightning, last time i tried to fly it, the sustainer failed to ignite due to drag separation. What methods can be used to prevent this? My personal preference would be to have the timer mounted in the sustainer, but that is not an option for this rocket.


Jeremy
 

ben_ullman

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shear pins would work but I would rather have it in the sustainer as you describe.

I would start with 2 or 3 2-56 and see how it goes.

Ben
 

BsSmith

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If you want to go through the trouble, I would reccommend igniting the sustainer from the sustainers e-bay. That is the way I'm doing my Thunder n Lightning. The wires will run through conduits running down the side of the rocket. At the separation points, there will be brass strips glued to the side of the coupler and the inside of the tube.

That way, the booster will have a separation charge that blows it off at burnout. No toasted booster, higher altitude, and really cool looking.

But, yes. shear pins could work too. You might toast the booster a little bit though.
 

Jclark

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Thanks for the responses. I think I'll give the shear pins a try, the rocket is already built, and that is a small e bay, if you follow the build instructions. I mostly scratch build all my rockets now; when i design a two stage, it will be with the timer in the sustainer.

Jeremy
 

ben_ullman

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Is useing one shear pin a no-no ?

I put one on my Wildman Jj ... thinking less nylon to shear ... less force needed.
It worked OK on my first flight. Should I put one or two more.
Is useing only one more likley to bind ?
Well, it depends, on larger rockets if you have just one it could snag because you have more force needed to break on one side than the other. so I always do a minimum of two. Its hard to have to much pin (I.E. to many and to big) but its easy to not have enough and loose a main at apogee.

Ben
 

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