#1
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Staging Quest Q-Jets
Over on the White Lightning Q-Jet thread, a comment was made about how Quest Q-Jet C12 or D16 motors could be staged if used as the upper stage motors with a full case black powder booster motor i.e. a C6-0.
I decided to test out this idea at a rocket launch at Lucerne Dry Lake this past Saturday. I built a new Estes Mongoose kit (It was a quick build). I used a C6-0 taped to a C12-8. I prepped the rocket and stood off to take pictures of the flight. The C6-0 ignited smartly and the rocket rose off my Mantis pad. As I watched through my camera viewfinder I followed the rocket as it climbed, taking pictures in ‘burst’ mode. The sky was absolutely clear and I could follow the flight all the way. Staging occurred. Then nothing. No upper stage ignition. The upper stage went up-and-over and started down tail first (Live motor and plastic fin unit). The upper stage hit the ground. No damage. Since the recovery system was still packed and the motor was in-place, I put an igniter in the C12. Back to the pad. Ignition. Perfect flight and recovery. True, it was only one flight but I will let someone else do more testing.
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Bob S.A.M. # 0014 |
#2
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I think you need the label on the engine for it to work. Seriously, I have noticed some nozzle throats with flash or have swelled. Was there resistance to the igniter through the throat? |
#3
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What is the nozzle throat diameter on the q-jets? I have a pack of C12s and D16s but I haven't used them yet. It could be possible to stage them just as you attempted if you use a section of fast paper fuse to pass fire into the q-jet. Fast paper fuse works similar to the old thermalite fuse and burns at 0.1 or 0.4 seconds per foot (REALLY fast!) Fast paper fuse is just about 3mm wide so if the nozzle is too small, that obviously wouldn't work.
https://www.skylighter.com/collecti...se-white-gn1207 Legal to buy in the US and ship ground. I don't remember if its HazMat but I don't think so. $15 for 20ft so a single purchase lasts a long time. If the core is 3", I'd cut about 3 1/2" of fuse and wrap the middle 3" with a single wrap of masking tape leaving 1/4" exposed on either end. The 1/4" exposed at the nozzle end will gladly catch from the ejection of the booster motor and the 1/4" at the delay end should ignite the motor like any normal igniter. The tape will inhibit trying to ignite the motor from the nozzle end and give a chuff. I use this method to ignite 4x E12 outboards from a central F42 in a 5 motor cluster I have. (USR "F with multiple D" kit) I wire up the F42 as normal and each E12 has a section of fast fuse that is taped to the nozzle of the F42. Once that F42 starts going, it ignites the fuse which in turn ignites the BP motors and the E12s are going before it starts moving on the rod.
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Aaron Head NAR 83209 L2 TRA 11803 L2 |
#4
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How did you tape the two motors together ?
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When in doubt, WHACK the GAS and DITCH the brake !!! Yes, there is such a thing as NORMAL, if you have to ask what is "NORMAL" , you probably aren't ! Failure may not be an OPTION, but it is ALWAYS a POSSIBILITY. ALL systems are GO for MAYHEM, CHAOS, TURMOIL, FIASCOS, and HAVOC ! |
#5
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With tape.
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I love sanding. |
#6
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Hmmm...Gary Rosenfield said, both in his interview on the Rocketry Show/Model Rocket Show podcast (I forget which one) and somewhere on the interwebs that they’d successfully staged C/D QJets from Estes BP booster motors. He did say that the smaller QJets wouldn’t stage reliably because of the narrower nozzles. I have a couple D QJets with some crumbling around the nozzles that I’m going to try staging next time I do a personal launch on a friend’s farm - I wouldn’t want to try it at a club launch. Using fuze should work great but I’m going to try it like the OP did and see what happens.
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#7
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I would try the fuse in a non- staged launch of a Qjet first. |
#8
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I really doubt that nozzle size is the issue. We routinely gap stage European 10mm motors with much tinier nozzles, with no sustainer fuse, and that's over a distance of over 10 inches. I really think the issue with Q-Jets is that they are a composite formulation that requires a sustained higher temperature to ignite. So a piece of fuse may actually help.
I know a number of you have seen this but it explains very well what is going on at the upper end of Estes black powder booster motors at burn-through. https://www.youtube.com/watch?v=1Nhe5Y78PRQ |
#9
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A bit of oxidation forms on the surface of APCP over time. If it's possible to get something in there to rough it up a little, it should help, even on a fairly new motor. I'm sure Gary was testing pretty fresh batches when they staged them.
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I love sanding. |
#10
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We always use a tiny drill bit to rough up the inside of the sustainer nozzle, even with Estes motors. On the Euro motors we use a REALLY tiny drill bit, but have learned over time to scratch until we get a dusting of black powder. Not uncommon for those little hand made motors to have a bit of clay pressed into the nozzle.
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