Igniters and Ejection Charges

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Trenman

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In my 98mm mongoose I will be running a RRC2 Mini as my secondary altimeter becase I have one laying around. My other electronic packages are going to be a complete Loki kit (ARTS2, 900 GPS etc...). This is my first DD rocket (I know its a lot of rocket to handle and even more to lose) which is why I am doing extensive research and ground testing before I take it out next summer. Here is my question keeping in mind on my ebay (4" x 12") I have 2 black powder recepticles for the ejection charges:

1) I will be running 2 altimeters as mentioned, does this mean that I will need to run TWO e-matches to each BP recepticle (4 total)?
~1A) If so, is there enough room for all those wires? I only see 2 tiny holes for the leads to go through on the base of the
ejection charge recepticle.

If people use 2 altimeters with one e-match kindly enlighten me. The way I see it is if both altimeters work but I get a bad ematch, then all that prep work will be for nothing and I will lose a multi thousand dollar rocket. Logically it must be that people use 2 sets of ematches but I just dont see the room for the leads. I suppose one could always drill 2 more holes....
 
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dixontj93060

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It is simple to have two entry points into an ejection charge well, but you may just widen the existing single hole a bit to run two sets of wires through it. After doing so if you have a bit of to much open space just give a small squeeze of hot glue at the hole area to quickly close it up before packing your BP. I always have a hot glue gun handy to seal off the small openings into your avionics bay, etc. as needed.

Saying that, since you are already running redundant electronics, redundant cross charges like you describe is typically overkill. I prefer one charge for each of the two altimeter/controllers allowing them to run independently. There are likely failure scenarios where one altimeter goes crazy or conducts faulty readings and fires a charge. If the e-matches are cross coupled into each charge well you corrupt what might be normal operation on the "sane" altimeter. Although, this doesn't mean your flight still doesn't go awry depending on the failure, it will make the operation more independent and predictable.
 

sylvie369

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If I were you I'd fly it several times using just the RRC2 Mini, with the ARTS stuff sitting safely in my range box until you're comfortable and confident with dual deployment.

Altimeters are reliable, when set up correctly.
E-Matches are reliable, as long as you're ground-testing first to make sure everything is set up correctly, and you're testing the resistance of the e-matches before you install them.

If you do all of the testing correctly, you can expect a one altimeter setup to be more reliable than motor ejection. If you ground test correctly, you're more likely to have problems with things like drogue placement and tangling the main parachute than you are with anything directly related to the electronics.

I don't know that I've heard of anyone using two altimeters into a single ejection charge. I agree with Dixon: if you're using two altimeters, use two charges. You can program the RRC2 to delay the apogee and main charges anything from 1 to 15 seconds, so you should be able to set things up so that both charges don't go off at the same time.
 

blackjack2564

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Trenman........
I think the confusion is happening because most people have not seen the set up. You can use 2 altimeters and run an e-match from each to the same canister. This is usually done on small diameter projects to save space, where there is only 1 canister on each BP , BUT 2 altimeters in the bay.

As your Moongoose comes there are 2 canisters on each end of the Bulkplate. There is ample room for 2, so the 98 goose is set up that way.

You only use 1 e-match per canister.

Each altimeter should be set up totally separate from the other. Meaning only one match from 1 altimeter going to 1 canister on each end of the bay.

4 canisters......4 e-matches.

Hope this helps. Continue to ask anything you need about the project, I will try and help anyway I can.

Jim H.

100_3358.jpg
 

Trenman

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Where did you get those ebay tops??


Trenman........
I think the confusion is happening because most people have not seen the set up. You can use 2 altimeters and run an e-match from each to the same canister. This is usually done on small diameter projects to save space, where there is only 1 canister on each BP , BUT 2 altimeters in the bay.

As your Moongoose comes there are 2 canisters on each end of the Bulkplate. There is ample room for 2, so the 98 goose is set up that way.

You only use 1 e-match per canister.

Each altimeter should be set up totally separate from the other. Meaning only one match from 1 altimeter going to 1 canister on each end of the bay.

4 canisters......4 e-matches.

Hope this helps. Continue to ask anything you need about the project, I will try and help anyway I can.

Jim H.
 

blackjack2564

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Where did you get those ebay tops??
What are you referring to? The red caps?

Bulkhead plates? Ejection canisters?

Or the whole assembly? The whole assembly's [2 bulkplates that go on the ends of the e-bay, with the eyebolts canisters etc,] are part of the 98 Mongoose]
 

cwbullet

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Jim,

What are the red caps from?
 
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