Passing fire to header

[Swede]

Add grog to the clay plug, the same as for the nozzle? Give it some "tube bite?"

 

How about a special rammer tip just for the clay plug, that has a tapered point in it, so when you ram the plug, it creates a sort of "reverse nozzle"; you now have a passfire hole. Stick your BM into the hole, or tamp some BP in there to passfire to the header match.

[Aquarius]

Tried that idea Swede and it works to some degree. The problem was that without the tapered spindle , the hole would crumble when extracting the last rammer, it sticks quite well, esp when pressing. And you need to have thight control of the amount of clay you use, or you end up with a passfire with a small endplug in it..

[tentacles]

You'd probably still have to drill out the passfire hole (to make sure you're getting fire from the grain) but it would probably work. You really don't need grog OR wax/oil if you use the half-milled kitty litter as above. The kitty litter itself acts as grog. I do recommend adding a bit of graphite, though. Makes HUGE difference in releasing from the spindle. Frank, what was the percentage of graphite for nozzles? (I need to get one of those bottles from you)

[FrankRizzo]

Tenacles: I'm using 7% graphite, but there's nothing really magical about that number. I had been doing it simply by "the squirt" before and was getting the same results. I imagine anywhere from 5-10% would work fine.

 

Swede: You don't want to have the passfire hole directly in the center of the plug, you want it near one side of the tube. The comp underneath the plug burns away in a cone shape, which means that your passfire hole gets exposed prematurely if it's in the center.

[Swede]

Good deal. I've got 20 pounds (!) of kyanite which can be considered a grog substitute... the price was right. I also have some graphite, so a few deluxe rocket nozzles are definitely on the horizon. I have not attempted any large nozzles yet, but the small ones released OK, probably because of my tendency to use too much wax.

 

Thinking back to the polyurethane glue experiments, you could use this material to create a physically strong cap, a delay, AND a potent means to passfire to the header. Pour in a slurry of the poly glue ( 75% perc, 10% coloration such as strontium or barium, 15% glue, MEK to thin.) In a 1/2" tube, a disk of this mixture 1/8" thick is going to have a predictable burn delay, as the mix is definitely not the fastest, but the flame is intense, and the structural soundness of such a disk is beyond questioning. Just a thought... you might be able to kill three birds with one stone, no drilling holes, and get a colorful delay

 

Better than Strontium or Barium salts would be spherical Al, Ti, or silicon; sparks/heat galore.

Edited December 21, 2008 by Swede

[Yankie]

Thinking back to the polyurethane glue experiments, you could use this material to create a physically strong cap, a delay, AND a potent means to passfire to the header. Pour in a slurry of the poly glue ( 75% perc, 10% coloration such as strontium or barium, 15% glue, MEK to thin.) In a 1/2" tube, a disk of this mixture 1/8" thick is going to have a predictable burn delay, as the mix is definitely not the fastest, but the flame is intense, and the structural soundness of such a disk is beyond questioning. Just a thought... you might be able to kill three birds with one stone, no drilling holes, and get a colorful delay

 

Better than Strontium or Barium salts would be spherical Al, Ti, or silicon; sparks/heat galore.

 

 

Might I say, THAT IS F*CKING BRILLAINT, If it works that is. For those who do not have the polyurethane glue, any star composition with like 20% dextrin could work too possibly?

[Swede]

, If it works that is. For those who do not have the polyurethane glue, any star composition with like 20% dextrin could work too possibly?

 

Haha, that's the problem, I'm not sure if it would work. It might. The Poly glue stars I messed with required a pretty good prime. The very high pressure (plus heat/flame, of course) in the tube may easily set off the base of the glue disk. If it does, then I think it would work. If not, perhaps sprinkle a bit of very coarse BP onto the top of the fuel stack, then simply pour in the glue delay. It would best be done as a batch process... lay out a dozen or two rammed tubes on the bench, calculate the amount of delay comp to cap them all, mix and pour. The pot life of the poly glue comp is not more than 5 to 10 minutes max. The disk cannot be too thick, or it may foam too much.

 

It's one of those deals where quite a few experiments might be in order... a captive rocket tube, delay disk, and a piece of BM taped in place so you can verify passfire. If the delay is excessive, you might have to modify the length of the time fuse to the burst, or the delay, plus time fuse, might find the shell well on its way back to earth before bursting.

 

A star comp might work, but it needs to have the requisite characteristics - safe to ram (if it needs ramming), takes fire, has strength, and delays predictably.

[Mumbles]

There is no need to add 20% dextrin to anything. Hell, if I see more than 6% in a composition I tend to automatically think the inventor of said formula is not the sharpest knife in the drawer. I'd assume you're thinking about making a slurry out of a star comp. This would almost certainly soak into the fuel grain, the tube, and ruin whatever star comp you have. You could always just take said star comp, make it bound with an alcohol based binder, slightly dampen it, and press it down with hand pressure. This would be a far more efficient and logical manner of doing the same thing should one lack the ability to go the Poly glue method.

[Aquarius]

A nice and easy delay wich gives a good spary of white/silver sparks is to add some coarse al to your delay mix, in the 5 to 15 precent range.

I even tried to add 5% al to the fule mix on a few rockets, and it work: A brilliant white spray of sparks.

Nothing fancy, nothing new, no mystery chems, but hey! It works!

[rev.redneck]

I have added a TT mix before the plug just to see how high my rock has gone , I have not gotten to headers yet.

[tentacles]

Flaming Shit is a nice delay comp in rockets... I thought I had posted a video to pyrobin before, of one of Linda's FS delay rockets from PGI. Guess not.

[moof]

I don't mean to go off topic since this is suppose to be about passing fire, but I am intrigued by using a delay to signify the height of a rocket. For a delay, I have been using David Sleeter's method of adding baking soda to black powder, but I'm wondering if I could use the comp listed here: http://pyroguide.com/index.php?title=Delay_Powder? I'm assuming I ball mill it for a few hours and then add a coarse metal such as magnesium or aluminum to achieve the effect Aquarius describes. Another question I have is would my described delay mix be sufficient to pass fire to a header if I decide to use one? Thanks.

[Aquarius]

I guess any burning comp that is compatible with the rocket fuel will work. That means watch out for chlorates/sulfur especially, be careful with metals that react with water and take care when drilling the passfire if using grog/glass/flint in your bulkhead clay.

 

And as Frank posted before, if you use a clay bulkhead and drill a passfire hole, drill it off center.

 

The "problem" as I find it is to get the flame from the delay/fuel to ignite the header. Of course a QM might be used, the trick is to have a positive ignition.

If you use a small passfire hole off center, you kind a have to align it with your QM. Again, this is where I use delay as a bulkhead, with a timed passfire hole.

When the delay reaches the hole, most of the delay is consumed and burns whith a rather good flame to ignite your header.

 

 

But each to one's own...

[Mumbles]

That would be the chrysanthemum of mystery composition from Shimizu. It is commonly used by Steve LaDuke. He adds a few percent titantium to it (somewhere less than 5% IIRC), and it makes this beatuiful lacy glittering pattern. It's too high to see any charcoal really, but the titantium kind of strobes in the sky. A very atttractive effect.

[psyco_1322]

Every time I try and use win20 as a delay, thinking it would look really nice, it fails Something about it being in a tube cause it to burn really slow and with about zero effect.

 

*An idea on the polyglue comp:

- Has anyone tryed it with a Chlorate? That would surely bring up its burn rate, if it was compatible.