An MX igniter experiment

[kuririn]

I was musing if there was a better way of igniting MX motors other than heating the bare nichrome bridge wire in contact with the propellant. Not a real problem for single motors but there are a couple of commercial MX cluster kits that were available plus I scratched a few of my own. An energetic igniter that would reliably light all motors in a cluster is the goal.

Off the shelf pyrogen dip kits make a sludge that results in a coating that would be too thick to fit the narrow throat of MX motors. So I decided to experiment with fingernail polish.


Will let this thoroughly dry before proceeding.
Want to evaluate the performance of the coating, not the solvent.
TBC.

 

[Antares JS]

Following... I only manage to light both motors in my Diminutive Deuce about half the time.

 

[Cape Byron]

So I decided to experiment with fingernail polish.

Slippery slope. You'll be wearing high heels next.

 

[cls]

Maybe try Testors silver enamel paint, lots of aluminum in it?

 

[kuririn]

Fingernail polish, Testors Silver paint, and nitrocellulose (pingpong balls) dissolved in acetone are all candidates.
I just happened to have an old vial of fingernail polish handy.
And it's a lot cheaper.

 

[Ronz Rocketz]

As a result of the testing, Gary's fingers will either be missing or fabulous.

 

[cwbullet]

I am interested in your results. I have done similar dips on Estes White ones.

 

[Joekeyo]

I did the same as CW. Used black finger nail polish that had nitrocelluose in it. Blazed a couple. Incrementally brighter than plain white ignitors.

 

[cwbullet]

I did the same as CW. Used black finger nail polish that had nitrocelluose in it. Blazed a couple. Incrementally brighter than plain white ignitors.

Very happy true and they actually produced a flame and not just sparks.

 

[kuririn]

First test was the baseline.
Stock igniter, no coating.
6 volt electron beam controller,
View attachment 0309231538[1].mp4

The bridge wire glows red hot.


Next test, igniter coated with fingernail polish
View attachment 0309231542[1].mp4

No sparks or flame, but smoke from the combustion process.
I have read that smoke directly coming off from combustion is very hot, but rapidly cools in the air due to the small size of the soot particles. So perhaps the heat of the smoke in the confined space will ignite the powder even if the nichrome is not directly contacting it.

Sidebar: Nothing to do with the topic of this thread, but since I had the hardware out I decided to do one more test. Will a 6v controller light a composite motor ignitor? I had read somewhere that you need a 12v. power source. Hooked up a First Fire Micro to the controller and let 'er rip.
View attachment 0309231550[1].mp4

It works!

Later: Fingernail polish coated with fine grained BP.
TBC.

 

[Ronz Rocketz]

First test was the baseline.
Stock igniter, no coating.
6 volt electron beam controller,
View attachment 567609

The bridge wire glows red hot.


Next test, igniter coated with fingernail polish
View attachment 567611

No sparks or flame, but smoke from the combustion process.
I have read that smoke directly coming off from combustion is very hot, but rapidly cools in the air due to the small size of the soot particles. So perhaps the heat of the smoke in the confined space will ignite the powder even if the nichrome is not directly contacting it.

Sidebar: Nothing to do with the topic of this thread, but since I had the hardware out I decided to do one more test. Will a 6v controller light a composite motor ignitor? I had read somewhere that you need a 12v. power source. Hooked up a First Fire Micro to the controller and let 'er rip.
View attachment 567615

It works!

Later: Fingernail polish coated with fine grained BP.
TBC.

I remember one time when my DIY controller wasn't working and switched to the Estes 6v controller. I wasn't able to ignite a 24mm composite but I think I could with an 18mm composite. It could be a problem with the individual motor.

 

[kuririn]

I remember one time when my DIY controller wasn't working and switched to the Estes 6v controller. I wasn't able to ignite a 24mm composite but I think I could with an 18mm composite. It could be a problem with the individual motor.

Could also be the smaller ignitor.

 

[Ronz Rocketz]

Could also be the smaller ignitor.

I was having that issue Saturday trying to fit a Jr into a F20. I gave up and used the F44 in the Doorknob. Afterwards I realized that only a Micro would fit. It was one of Jake's old motors. Now I'm curious if I can ignite the F20 with a Micro and the 6v controller on Sunday. Hmm...

 

[kuririn]

If it's one of Jake's old motors, don't put it in anything expensive.

 

[Tom Flint]

I've lit a 7 MMX cluster with "flash in the pan" ignition, i.e. a piece of aluminum foil fitted over the motor cluster with a little 4F black powder in it and one Estes igniter to light the powder.

 

[kuririn]

I've lit a 7 MMX cluster with "flash in the pan" ignition, i.e. a piece of aluminum foil fitted over the motor cluster with a little 4F black powder in it and one Estes igniter to light the powder.

I've heard that chars the back end of the rocket.
I've also heard of spiders and flash pans for cluster ignition, but engineering a custom spider seems like a whole lot more work than I'm willing to do.

 

[Tom Flint]

I've heard that chars the back end of the rocket.
I've also heard of spiders and flash pans for cluster ignition, but engineering a custom spider seems like a whole lot more work than I'm willing to do.

It may have left some black powder residue on the back of the rocket, but I did not find that to be problematic.

 

[kuririn]

Test with fingernail polish coated with fine grain black powder.
When loading the BP keep in mind that it has to fit inside the tiny nozzle of the MX motor.
So try to avoid clumping.
View attachment 0309232052[1].mp4

There were sparks and a brief flame.
Screenshot


Finally Testors silver paint.
View attachment 0309232055[1].mp4

There was a brief flame.
Screenshot

I only gave it about four hours to dry so don't know how much of that was residual solvent that hadn't flashed off yet.

All the enhancements seem to improve the energetics.
I will be making some fingernail polish w/BP ignitors and field testing them in some cluster rockets this Sunday. With a 12v. controller.
Laters.

 

[cls]

great stuff! thanks for posting.

 

[tjkopena]

Good stuff, @kuririn. What controller are you using for clustered configurations? I haven't measured myself, but from reading around my understanding is that the MMX igniters require more amperage to ignite compared to standard Estes igniters. Not a big deal normally, but you might need more juice to reliably ignite a cluster of them compared to an equal-count cluster of standard igniters.

 

[kuririn]

Good stuff, @kuririn. What controller are you using for clustered configurations? I haven't measured myself, but from reading around my understanding is that the MMX igniters require more amperage to ignite compared to standard Estes igniters. Not a big deal normally, but you might need more juice to reliably ignite a cluster of them compared to an equal-count cluster of standard igniters.

Vintage Estes Command Controller, 14.4 volts.
I also have an Aerotech Interlock controller connected to a 12v LiPo auto jump starter power source.
Either one should have plenty of juice.

 

[cwbullet]

I did not do a BP slurry. That seems to do the best.

 

[kuririn]

I did not do a BP slurry. That seems to do the best.

I have done Quick Dip on my regular igniters. The MX igniter has to fit in the very narrow nozzles of the MX motor. Regular pyrogen dips are too thick.

 

[cwbullet]

I have done Quick Dip on my regular igniters. The MX igniter has to fit in the very narrow nozzles of the MX motor. Regular pyrogen dips are too thick.

Have you tried thinning it a lot with acetone?

 

[kuririn]

Have you tried thinning it a lot with acetone?

Thought about it. Would that much thinning cut down the "energetics" of the pyrogen?

 

[cwbullet]

Thought about it. Would that much thinning cut down the "energetics" of the pyrogen?

Zero once it is fully dried (theoretically). It does do odd things to testors.

 

[Ronz Rocketz]

If it's one of Jake's old motors, don't put it in anything expensive.

I used one of his G40W in the DBCP and his F42T in the Leviathan but used the Micros with both. We'll see what happens on Sunday.

 

[gdjsky01]

Old white White Lightning motors are pretty notorious for the slot swelling closed or nearly so. When a WL motor is new, a 'normal copperhead' will fit all the way up with ease. As would a normal Firestar FS-12 or similar small dipped starter. When old and the grain has absorbed moisture, the slot swells shut or nearly so. I have encountered this is old F20s, F21s, etc. Plus I have SEEN first hand the swelling in old 29mm Hobbyline reloads. On SUs unless you just trash it, you have to drill out the slot by hand. How do you know how far to drill? You don't. You guess. And with some reloads, the swelling is so bad you can not get the grain into the liner. The slot becomes a wide 'V' or 'U'. Once you do manage to get a starter in, expect lots of chuffing. A lot. And expect the delay to go long (probably because of how far one drills). Ask me how I know this? (And how I know it more than a few times...") Old WL loads really are best with an Eggtimer Apogee or other electronic deployment (the ET Apogee is so small almost any rocket BT55 or larger can use it).

 

[kuririn]

I will be making some fingernail polish w/BP ignitors and field testing them in some cluster rockets this Sunday. With a 12v. controller.

I launched three Micromaxx clustered rockets today with the enhanced igniters.
Diminutive Deuce: Both motors lit.



Scratch MX Ranger. All three motors lit.



Leading Edge Micro Scrambler: Two of three motors lit.



I think the igniter for the motor that didn't light may have slipped out of the nozzle.
Packed the igniters in with tiny pieces of styrofoam.
Power source was an Estes Command Control launch controller.
87.5% success rate. I'll take it.
Video soon on the "Updates" thread and on the Ronz Rocketz You Tube channel.

 

[gdjsky01]

Updates thread?
Lookin' forward to @Ronz Rocketz video as usual. Interesting to see how he did with the video on these bang gone models.
Wow @kuririn you are a friggin rocket building machine! How many in your fleet are ready to fly on any given moment?
Lastly, just to be clear, what starters and enhancements did you wind up using? Did you use the old MMX starters? Those leads look pretty long. Or did you add more lead length?

Great report thank you!