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.

Attached Thumbnails

               

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Bob
S.A.M. # 0014

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?

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

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.

Gary said after I informed him of my test results that Quest will not be pursuing staging applications of the Q-Jet motors.

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Bob
S.A.M. # 0014

A trick that is commonly used by European space modelers (especially for staging scale models, or old-rules Altitude competition models, with long first stage airframes) should provide reliable ignition of Q-Jet motors used in upper stages. It is a "blast tube," a thin-walled fiberglass "funnel" (which fits inside the upper end of the first stage [and "intermediate," if any] motor or motors), whose neck is long enough to fit up into the upper stage motor's nozzle (or nearly so). A pinch or two of black powder, placed inside the "funnel," jets enough flame forward/upward into the Q-Jet motor's nozzle to ignite its propellant. One or two of Stuart Lodge's books (see: https://www.google.com/search?sxsrf...HTLRCZ8Q4dUDCA0 ) covers/cover this device and how it is used.

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NAR #54895 SR

That is interesting enough I will have to give it a try in the spring 2021. I had never heard about this technique. Now that I am done with getting started on my latest hobby. Coop and run all built and the girls are in production.......

The European flash tube method is somewhat different from what you suggest. The European booster motors, unlike Estes booster motors, are not simply open propellant at the upper end. Instead, they have a small paper diaphragm with a tiny hole in the middle. A small amount of loose black powder is sprinkled onto the diaphragm to create a flame source to propagate up the flash tube. The lower end of the tube sits into the upper end of the booster motor. The upper end of the flash tube does not insert into the sustainer motor. Instead, it rests just below the sustainer nozzle with a small air gap. This serves the same function as the vent holes in U.S. style gap staging. I only know of one contestant who uses a flash tube with Estes booster motors and I seriously doubt such an arrangement would add any benefit to trying to ignite Q-jet sustainer motors.

I would try the fuse in a non- staged launch of a Qjet first.

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