Correct pressure on comps

[MrB]

Lets not go there just yet. I tend to shoot them shortly after they are made, so we'll see about this new years celebration. I don't expect them to fail, but then, who ever does...

[dagabu]

From what I understand about commercially made whistle rockets, they are pressed in one increment and with a dampened mix. We make much larger rockets as amateurs so we are forced to use increments. Same goes with BP rockets of really any size, increments. It is also those increments that cause a sort of delamination (if that is the correct term) along the width of the grain.

 

Dave F did a lot of research with waxed tubes to eliminate wrinkles in tubes using higher pressures and subsequently found that if one lowered the pressure, the wrinkles would cease as well. Add wax to the inside of the tube and you also eliminate a lot of the axial breaking that happens when pushing a powder (non-aqueous fluid) so you get more consistent density throughout the increment. Dwell times as well as moisture also play "YOUGE" parts in density of the increments as well as the bonding that takes place between the faces of subsequent increments.

[MrB]

Spent 4 hours walking a soggy field yesterday, looking for my duds. Could have sworn i had 4 roundtrips, but found 5, so there is that... And they are all mine. Looks like they just didn't pass fire as supposed. 1%, which i guess you could say i'm happy with. It shouldn't happen, but at least it's not 10-25% or what ever. Going to cut in to them and find out what i can later. For now they are drying, so they can be handled...

Had 3 rockets that also didn't work as expected. No CATO, just didn't light. I'm going to let them dry out, and then i have to decide if i'll stick a new fuse in them, and see if they will play, or if i should cut them apart. I suspect these are from the batch with visco that just got folded over and stuck up the throat, rather then visco, folded over, dipped in a nc/bp slurry, dipped in BP, and then stuck up the throat.

The fuse burnt, there is some white residue, and no visco in the core, but the motor never started, so, fail on my part.

Other then that... Very pleased with the experience for this year.

 

But i really need to get me more mortars, it's not that fun to start reloading in the middle of the shoot. Luckily i have understanding friends, who stay at the distance, and cheer me on, while they toast for the new year. And, tonight, i will want all of those mortars to be fiberglass... Yes. Cleanup today.

 

On a personal note, i need to go back and work on my yellow. I didn't like it that much. I've been using the "standard" Veline variant, 55/45 - green / orange, but i think i will have to try and tweak the ratios a little.

Yes. I'm lazy in that sense. I use Veline exclusively for colors. And now i'm so far off-topic, that i'll leave, and get today's chores of hauling all the stuff back in to storage started.

[calebkessinger]

Sounds like you had a good time. Hopefully it's easy to see what went wrong with a few of those shells and you'll be whistling dixie as they go up and burst perfectly next time!

[MrB]

Not having done anything to them just yet, i suspect it's simply the spolette that failed to pass it's fire on to the burst charge.

Not entirely sure what i would do about that. i do what "everyone" else does, ram the spolette, stick a wrap on the inside part, stick a few strands of black match all the way down in to the spolette, and tie the wrap of, leaving the match sticking out. I went with a pointy rammer for the final increment this time around, just to make it trow more fire at the match, in the hope that it would stick, since that is historically the issue i've had. (Spolette burnt through from one end to the other, but never igniting the match.) f it's true again, i'll just make the rammer more pointy, but i'm not sure it actually will solve anything.

Oh well.

[dagabu]

Mr. B, are you puncturing the nosing on the spollette where the black match is sticking out? If not, it is a well-known issue that failure to puncture that nosing can oftentimes pull the paper right off of the black match without igniting the black match. Edited January 2, 2018 by dagabu

[MrB]

I put slits in it, before tying it. With the ties it generally ends up leaving crumpled openings, which should let out the "over pressure" in to the rest of the shell.

The wrap, nosing, have always been attached to the spolette when i dig in to the shell.

For larger shells it's not an issue, i just put 2 spolettes, and never have a failure.

The really small shells still get timefuse, but i'm running out, and buying more is... tricky, considering that customs now consider fuse a illegal pyro in it self, and lay their clammy sticky hands on it, so it just... goes away. (Well, so i've been told. Not actually tried ordering anything.) So i've been using single spolettes in 2-3" shells.

 

I might have to try something completely different with spolettes. Try making them as small, or rather, tiny, nozzle less, cored rockets, and add "to much" hot delay on top, and then peel the tube back until i have the desired delay. Once they burn in to the shell, the burning stuff is inside the shell and in contact with the burst already. A lot more labor intensive, but i suppose i can make use of fountain compositions and have a nice rising effect. Dunno. First thing first. Examine the evidence, and figure out if i still have the same issue. Made the match with as hot BP as i could produce thinking it would help, but at this point it looks like i didn't cure it..

[dagabu]

I'm sorry to hear about your time fuse issues. I know that in some other countries, they have had a friend from overseas send them a roll of ranchers rope or cattle rope and put caplugs on the end of the time fuse to disguise it. No, it's not legal and it's not ethical, blah, blah, blah.

[dagabu]

I still think regular black powder based spolettes are your answer. Hundreds of millions of them have been used since spolette was invented and very few fail so I would look at your process and read the Fulcanelli papers again to see if you are matching his design.

[MrB]

I used to. The only difference today is that i use a razor to cut slits in the wrap, and that i use a very slightly pointy rammer for the final whack. (freehanded it, the intent was 95 degrees from the edge but you know how it is when you do things by hand. Around 5degrees none the less. The idea was as i said, to get the flame front to break trough in the center just before it runs out, hoping it would throw more fire at the match. It works in the sense that it throws more fire. It didn't really do much difference on the actual issue of the round trips.

Both changes to try and get rid of the last few fails. Other then that, exactly according to his specs. Exotic experiments haven't yet started.

 

Anyway, still haven't confirmed that this is still my issue. Intend to try and disassemble the upcoming weekend.

 

On the topic of time fuse... I actually prefer the spolette, it's cheaper for one. It just has to work 99.99% of the time, rather then 99% of the time.

[MrB]

Generally i would just edit my post, but it seams that option is gone, so there is a time limit on that.

Also, i suppose a new post makes it ring all the bells for people still subscribed here.

 

Dissected the shells today. Much as expected, the spolette had burnt through cleanly, and even left some white residue on the black match. But there was no igniting of the match. And yet is near instantly lit on fire from a lighter. I'm going to try with just a slightly pointier final rammer, and see if that can cause the flame to generate enough heat to make it more reliable. Stupid issue to have.

 

The rockets. (3 that didn't ignite from the visco) I decided to just make them new fuses, the "right" way, and light them on fire. So, more of the same old Visco, bent it at the end, dipped it in BP/NC slurry, and then in BP dust from corning NP, and stuck it up the throat as far as it would go.

 

Half an hour later i had my self a bit of a late pyro show.Took of like nobody's business. Or like rockets. Go figure.

I "usually" do like this, but my paint supply, and my pyro isn't next doors to one and other, and i ran out of NC for pyro... Which puts the blame squarely on me, just as it should be.

[Mixer]

Dissected the shells today. Much as expected, the spolette had burnt through cleanly, and even left some white residue on the black match. But there was no igniting of the match. And yet is near instantly lit on fire from a lighter. I'm going to try with just a slightly pointier final rammer, and see if that can cause the flame to generate enough heat to make it more reliable. Stupid issue to have.

 

You need a cavity - the answer is here.......

 

*ED. NOTE: Practices and feelings about this problem vary from country to country, and from pyrotechnist to pyrotechnist; Rev. Ronald Lancaster (private communication, 1983) claims that "the shaped rammer is essential and should be 1/4" deep at least ... I have often met failure in its absence." Lancaster reports that most Europeans now press fuses which include a recess in the powder charge.

Edited January 8, 2018 by Mixer

[calebkessinger]

It happens.. It's nice to know it's something simple that can be easily fixed.

That rammer with a tit is popular. I make em right around 1/8 x 1/4in. long.

If you load a little extra comp you can drill them back to perfection leaving a nice big ring of fire throwing bp in there.

[MrB]

You need a cavity - the answer is here.......

 

*ED. NOTE: Practices and feelings about this problem vary from country to country, and from pyrotechnist to pyrotechnist; Rev. Ronald Lancaster (private communication, 1983) claims that "the shaped rammer is essential and should be 1/4" deep at least ... I have often met failure in its absence." Lancaster reports that most Europeans now press fuses which include a recess in the powder charge.

 

I'm that far already. Now i'm just trying to figure out how pointy i need to make it. And i do want a conical shape, it should be the easiest to make, and direct the flames towards the match nicely.

 

@calebkessinger: Both the quote above, and you site 1/4", bot not siting a diameter for the spolette it self. But regardless, it seems a lot more pointy then my current, so, i'll make another one and aim for 5-6mm. My tooling is 8mm, so that is a lot more pointy then i expected it to need to be, but i'll give it a try.

I'd prefer not having to drill them. Mostly since it adds a step. But yes. You could add a lot more then needed, and have a bunch of cored material up top which would set anything on fire.

 

Thanks to both of ya for pushing in the same direction. Helps me not to go insane.

Edited January 8, 2018 by MrB

[kaotch]

MrB,

I know how frustrating such situations can be. When using spolettes , finish off hand pressing a small increment of slow flash booster. This way your black match

will ignite .

[NeighborJ]

Slow flash booster? Most people just put a pinch of granulated BP in the fire giving side of the spollette, then BM. I've never yet had one fail to give fire when fused this way. Edited January 8, 2018 by NeighborJ

[dynomike1]

Read it wrong

Edited January 8, 2018 by dynomike1