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Centuri Sure Shot Ignitors

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Charles_McG

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I'm looking for tips on using the old Sure Shot igniters. I've accumulated a small pile of them. From my youth, I seem to recall that hand wrapping the supplied nichrome around the pyrogen 'stick' was a pain in the arse.

Maybe I'll just use a little of the stick in Estes starters that didn't burn through the first time.
 
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milehigh

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Lucky dog that you have some of those. I used to use them exclusively back when they were readily available. I don't believe I ever had an igniter burnout with one, they were that reliable. Perfect for cluster rockets. All it takes is a couple loops of nichrome wire around the center of the wick, bend the wick in half and insert it fully into the engine nozzle. I drew a little bit of an illustration for you here. Man, this is going back about 35 years into the mists of time, but I still remember how to do this like it was only yesterday! 20161129_072238.jpg
 
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Charles_McG

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I'll have to check tonight, but I think the wicks have gotten brittle. IRCC, that was the problem I had with them pre-BAR ('80s) - the wick would snap in half.
 

cerving

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I'm with milehigh, those were the best igniters ever. You just loop the nichrome around the wick twice, then stick it in the nozzle. Hold it in with some masking tape and you're good to go. 100% success rate, and not at all fragile like the Estes igniters.
 

milehigh

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Sure-shot igniters were also a component of a multi-staging technique using flash bulbs from old-school camera flash cubes. This technique was very useful for reliably igniting upper stages on scale models, where there was substantial distance between stages. The system was built into a payload section as part of the booster stage. A Sure-Shot wick was taped to the side of a flash bulb, and inserted into the upper stage engine nozzle. The flash would be set off by a mercury inertia switch that would close when the model decelerated after booster engine burnout. The flashbulb generated enough heat to set off the igniter wick. Power was usually supplied to the flashbulb via an appropriate sized electrolytic capacitor. A battery was sometimes used, but the modeler would run the risk of having the second stage ignite on the pad if the model was accidently bumped, closing the mercury switch. There were a few work-arounds to this; installing a small external on/off switch in the circuit that could be manually turned on just prior to launch, or an umbilical cord that would allow leaf-type switch contacts to close as the rocket lifted off. Still the best way was to go was the capacitor route. The cap could be charged on the pad just prior to launch. Another advantage of this system was that a regular short delay engine could be used in the first stage for deploying a recovery system, since the model didn't rely on the usually 'series blowthrough' method of upper stage ignition.
The flashbulb system was also useful for reliable cluster ignition.
 

shreadvector

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Old Sure Shot wicks get very brittle and will crumble apart if bent or flexed. When they were new, they were much more flexible, but they have not been "new" for several decades.

If you try to use them, do not bend them. If you try to cut them, they will likely crumble apart to dust. Leave them straight and wrap nichrome wire around the wick and secure the wire to the wick with a small bit of masking tape or self-adhesive label material. Then secure into the nozzle with a "thong" of masking tape. Do not cram wadding or a plug as this will crumble the brittle pyrogen.
 

Micromeister

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more or less ditto Shreads post:
However I usually use a small FP wadding ball to secure the wick in the motor nozzle. you just don't cram it in too hard.
 

tab28682

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I was given a couple of feet of 1.5 mm-1/16" green cannon fuse a while back. Might be interesting/nostalgic to make a sure shot style "starter" with nichrome wire and a 1/2" length of the green "wick" folded over.

Seems as legal as any other type of home made starter. Burn time on this wick would be as fast or faster than the old Jetex wick.
 
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