Dumb idea?

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Lister
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Dumb idea?

Postby Lister » Mon Nov 16, 2015 6:20 pm

Vance and I were talking a while back about doing a 2 stage like this.. thinking of doing a couple of interchangable first stages with a cluster and another with a 75mm mmt.. is this asking for trouble, I know staging is hard enough with one motor as is igniting a cluster simutaniously on the ground let alone in the air.. thats why im thinking 29mm motors with e match's for igniters.

The booster is a 2.56" airframe with a 2.1" mmt and an L990BS and the sustainer is a 4" airframe with 6 29mm clusters, a central I243 with 5x H255BS, all CTI motors.

Once I get a new rrc3 I will see id it will ignite 6 e matches.
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SpaceManMat
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Re: Dumb idea?

Postby SpaceManMat » Mon Nov 16, 2015 9:29 pm

Not sure its necessarily a dumb idea. But your going to want to take this step by step. It is many times more complicated then what a normal single stage rocket. First project learn clustering, second project learn staging. If you can get both down pat then consider combining for your third project. If you're eager, which I'm sure you are, you could consider doing project 1 and 2 at the same time.

Also I suggest you read up on the capabilities of your RRC3 before you try and use it rather then risk frying the output circuit. You use to be able to get a cluster-o-matic from PK to fire a bunch of motors like you are thinking.
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crom
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Re: Dumb idea?

Postby crom » Tue Nov 17, 2015 8:24 pm

What is the Cp / Cg ratio for the sustainer alone?

I've had mixed success using the clust-o-matic. Successfully fired three igniters with an RRC3 on the bench, will be testing the RRC3 in flight again for air starting motors at the next trip to Westmar.
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Lister
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Re: Dumb idea?

Postby Lister » Tue Nov 17, 2015 9:12 pm

crom wrote:What is the Cp / Cg ratio for the sustainer alone?

I've had mixed success using the clust-o-matic. Successfully fired three igniters with an RRC3 on the bench, will be testing the RRC3 in flight again for air starting motors at the next trip to Westmar.

Do you have a link to the rocket your talking about?
Igniters I wouldnt expect an rrc3 to be able to ignite reliably.. but 6 e matches are more realistic and with some Ragifications im sure I can get those to ignite as the required current is much less compared to the igniters provided with CTI .

Ahh you read my mind Mat, im going to be building the sustainer section first to make certain I have the bugs ironed out. I have done a couple of 2 stage lpr rockets but I will be building a h&i powered 2 stage so I can figure out the best design for the ISC and figure out if I will drag separate the stages or go for the vented ISC and ignite it off the booster.

I have a list of rockets to build over the summer, so im in no rush to get this airborne.. i will be taking my time with this project so I can learn and make sure its as failure proof as possible.
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2 stage cluster stage 1.jpg

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crom
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Re: Dumb idea?

Postby crom » Wed Nov 18, 2015 10:13 pm

You're right, for igniters read e-matches.

This is on-board video from my rocket: https://www.youtube.com/watch?v=QDewCutEIlY

Where will the electronics be mounted for air-starting the 6 motors?

Looks like a great project and the sort of challenge that keeps rocketry interesting.
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ASC.png
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