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ffff Black Powder for Ignition Reliability of Clusters
I have a question,… plus I’m looking for your feedback on the subject.
My goal is to increase my reliability of getting all engines to ignite in my cluster rockets. So I was thinking and an idea came to me is; what if once I install the igniter in the engine, that I then put in a very, very small pinch of ffff black powder, and make sure the black powder gets down in and around the igniter, then push in a small wad in wadding down in on top of the black powder to hold both the black powder and the igniter in place. Also I need to let you know that I make my own igniters with nichrome wire. First; is this OK to do? Second; if this is OK, should I use ffff black powder or ffff pyrodex ? If this is a really dumb idea and is way out of line, please be kind.
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Have a good day Bob NAR 77103 |
#2
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Bob:
1st the legalities: A person is supposed to only purchase Bp if they are using it for antique fireams; on the other hand, we all know a lot of people pay no attention to that fact: with that said what you are basicaly describing is a BP igniter. Yes the additon of BP wil enhance the ignitability; you only need a smidgen other alterntives include blackmatch and quickmatch: http://www.unitednuclear.com/quickmatch.htm another alternative is using a spider : http://www.meatballrocketry.com/spider.htm another alternative get yourself a pyrogen kit and add a little to the igniter and or "paint" the BP grain regardless of what ultimately decide to do, a hi amperage battery is always the best idea with clusters; as is a relay launcher I wouldn't use pyrodex as it has a higher ignition temperature than BP. I'm not familiar with ffff pyrodex? hth terry dean
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"Old Rocketeer's don't die; they just go OOP".....unless you 3D print them. |
#3
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If you're talking about model rocket motors, the only thing you really need to do is make sure you use, as Terry suggests, a high-current launch controller. BP ignites quickly and the igniters are very reliable. If your controller delivers enough amps, all the motors will light.
-- Roger |
#4
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Thanks to both of you for your reply.
Yes, I do use a 12 v relay launcher. And my reliability is probably 99%. I'm currently building a Saturn V that will be 5 engine cluster. I'm just thinking out loud about how I can get a higher reliability in cluster moter ignition. I'll have to look into a Pyrogen Kit and see how it would help me reach my goal. Thanks again.
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Have a good day Bob NAR 77103 |
#5
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Quote:
From what I've read, pyrogen won't really be any more reliable than nichrome that has been packed against the BP with a bit of wadding (with a good 12v source). It will help keep the nichrome insulated a bit to make sure the heat is all the way to the end of the igniter, so it would aid reliablity in that regard. Another area to address is making sure the iginters are solidly planted and don't get pulled away from the BP. |
#6
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I think you'll notice that nearly all pyrogen formulas are harder to ignite thanthe BP in BP motors(I don't know of any that are easier but they might exist). If you are clustering APCP motors, you'll want to use a pyrogen dipped igniter as they burn hotter/longer than a conductive primer igniters (First Fire type) but shouldn't be required for BP motors.
You best bet with BP motors in clusters is high amperage battery (car battery sized) and igniters that have the same resistance that are properly installed so that they do not pull loose and are in full contact with the exposed BP of the motor. -Aaron |
#7
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That is my exact thinking to add the BP after I install the igniter and then the wadding to hold the igniter in place. My thinking is the pinch of ffff BP would provide me some insurance just in case one igniter pulls loose away from contact of the BP of the engine.
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Have a good day Bob NAR 77103 |
#8
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Last month one of our club members (an engineer by trade) led us in the construction of capacitance discharge launch controllers made from salvaged single use disposable cameras.
The basic concept is that a small battery is used to charge a bank of capacitors which then dump big current instantly when triggered. This same member had a cluster failure last summer launching off our club's equipment so he went home and built a variant of the capacitor ignitor which he now attaches to his clusters when launching with club equipment. The box is connected to his rocket's ignitor leads and then the club's leads attach to the box. The box is triggered by the club's controller just as if it was an ignitor. This little box (about the size of an iPod) is powered by a double A battery but delivers enough power that the standard Estes igniters have to be hooked in series (those of you more electrically inclined than me will understand) and they vaporize with a pop when triggered. Very, very, impressive. |
#9
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I've heard of a few capacitor systems that would vaporize the ignitors so quickly that not enough heat would build up in the propellant to ignite it. I have no idea of the discharge rate or the type of igniters as this was a topic on r.m.r. years ago. One big plus for a capacitor system is that enough juice is dumped that you don't have to worry about varied resistance on igniters. They should all heat up instantly.
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