All Activity

To answer my own question a bit, a paper by D. Juknelevicius et. al tested various AP / TMAN blue strobes and used AP/MgAl 40-80 mesh/BaSO4/Potassium Dichromate (60/25/15/5) as a reference. Magnalium wasn't treated, the dichromate was just part of the mixture where it could treat the MgAl in-situ to some degree if the mix got wet but acts as a catalyst regardless. They consolidated pellets from 1g of comp, 13mm in diameter, 4-4.5mm high, with a dead weight of ~4500lb (2000kg). No binder was mentioned / used for most of them. They age tested them in a humid environment at 32-46F for 30 days... it wasn't mentioned whether this was because the temps in Lithuania are fairly cold for the majority of the year (although they rarely reach midwest US levels lol) The reference MgAl mix showed near zero degradation after a month. The mixes using copper oxide, which was the majority, developed blue spots on the pellet surface. The mix using copper metal turned completely blue. Usually those changes are related to formation of copper complexes, apparently. The mix with basic copper carbonate didn't have a change in color mentioned. The color changes were only cosmetic (complex formation doesn't really change the elemental makeup after all) and all of them still strobed. Anyway, it's comforting to know that it probably takes a good amount of time before anything really stupid happens. I'd expect rockets to last longer given the lower surface area-> size ratio unless the tubes themselves have a really high moisture content. While I was looking, I found a 1930s German strobe / falling leaves type effect (although Germany loves strike-on-box firecrackers so it might have just been that type of thing) in a 70s Wasmann presentation that might be one of the most horrifying mixtures I've ever seen... I don't know which territory Germany occupied in 1930 but Martinikas doesn't translate from German, and it just translates to Martinis from Lithuanian according to google, which seems wrong too: "Martinikas" For preparation cardboard was coated with a dispersion of this composition in water, and dried. The substance is ignitable by friction and burns with a rattling noise. The frequencies measured were 2 - 3 cps. 34.7% Bole white (This is a type of clay) 31.4% Water 12.9% Gum arabic 9.6% Calcium carbonate 6.6% Potassium chlorate 4.8% White Phosphorous Because of the toxicity of white phosphorous it was banned almost immediately after it showed up. I'd bet that a box of these suckers is worth a fortune, it'd be a miracle if any exist that haven't caught on fire on their own yet. Anyway the rest is a light read of a 3 page section but has some odd & interesting formulas and more importantly some refs and information on tuning the strobe frequency within huge ranges. Red, green, and white that are all 7% AP or less as written with strontium / barium nitrate and potassium perchlorate as oxidizers with a note that seems to indicate the AP can be wholly replaced by one of several other gas generating oxidizers / additives... nice since AP is expensive compared to almost everything else in a strobe mix, and a mention that they're tunable from 0.5Hz to 50Hz by varying a copper chromite catalyst from 0.03% to 0.1%. There's also a set of "acoustic strobe" formulas designed purely for loudness that don't use ammonium perchlorate at all, but they do need a weird resin binding system with PEDN (di-nitrate), dinitroglycerin, or meso-erithritol converted into acrylates, and the oxidizers are barium / strontium perchlorate which don't run cheap. These can be tuned by changing ratios from 0.1Hz to 1000Hz.

No problem, thanks for engaging with this thread. I’ve also reached out to Florida Pyro, another esteemed strobe maker, to see what his thoughts are regarding core geometry and also loading pressure. I’ll continue to share any noteworthy information here. Hoping to begin my own experimentation when I’m back home to the lab this winter, even if it’s with a smaller “suboptimal” diameter. Florida Pyro has roaring 4 oz strobes so it certainly can be done…

I tried to register on the forum, but I don't think there are any active moderators. The shop looks like it's open, but there was no reply from the sales team.

Thanks for sharing. It's a logical explanation, and his strobe rockets are second to none!

Yes it is up and running bit it is almost only Richard that is posting anything.

pyro-gear.co.uk Anybody here know if this site and forum is still up and running?

Update: I just spoke with Caleb and got some info around the differences between tooling, for strobe specifically. From what I heard, there’s no real benefit to having a core depth beyond 2-2.5” extending into the strobe fuel itself. The effect is produced from the fuel burning radially from the core to the tube wall (makes sense). This determines duration. Longer spindles are intended to make room for more whistle for stronger lift, that’s it. There is apparently a trade-off between thinner and thicker spindles, with thinner allowing more fuel between the core and the tube wall but with the risk of the core clogging up from “foaming up” of smoldering debris. Thicker spindles reduce clogging but at the expense of strobe duration. For this reason, Caleb warned that strobes are very finicky below 3/4” ID, and perform optimally around 2 lb or larger, where there is plenty of room for lots of fuel around the spindle but also enough clearance for debris. Caleb, if you ever read this, I hope I relayed everything accurately. Thanks for the advice.

Thats true what you have heard about glitter and water relationship, too much water kills the effect but here the author of topic and his posts are unreliable.

I don't think so. They're just parallel wound tubes that come as 50cm long tubes which I cut to length. ID is 1/2 inch/12.7mm.

Nice set up, yes the tape does the job for protecting the sequence. Those tubes look good, are those rocket tubes?

Thank you for the reply Zumber, I've been watching winokur's 40 glitter composition and there you can see some formulations that actually recommend certain wáter percentajes in order to preserve the effect. So that is why i was asking about this formulation. Thanks

Tubes are drilled with 4mm holes to take 3mm diameter fuse. I use a simple chaining of one tube to the next and have never had problems with launch pressures. However, the fuses need to be secured with tape to stop them blowing out prematurely. Here's a three-tube "cake" post-firing

Fair 'nuff

That's just where my whistle motors stopped failing. Lots of theories on taking the elasticity out of the tube wall, harder grains, etc. I'm a student of Duke's methods (if it CATOs, press it harder).

After the first increment of clay, the tooling is shaken in order to settle down the clay, after thisyou can add the moist color comp, shake again, add the priming + bp grains, tap it with the pressing plate to keep all tight and then press. A simillar process as what i mentioned is shown at 7:38 but in the video is used for adding delay composition + priming for small salutes.

You are probably right on the polycarbonate vs. plexiglass, since i believe the military makes "bullet proof" or ballistic glass from laminated layers of glass and polycarbonate. I'd still argue that plexiglass is better than nothing at all, and a thick plywood or layered plywood shield with a small window covered with polycarbonate would be affordable option. Thanks, good catch!

You can watch it by yourself at 8:48, they show the tooling with the fuses, they add clay, then the tail powder + some bp and then press the tubes. Look at the finished inserts at 9:19. Watching firework factories is a great chance to learn first hand how other`s pyro think and how they work, making the process more faster and effective is also a good improve to learn.

Wow was I confused about grain Direction and how it behaves and how to apply it to get the most out of whatever you are doing. Everything just fell into place once a friend pointed a couple things out to me.

Before i begin i really loved rockets and shells, also im a big fan of candles and fountains but cakes its a chance to somehow create a more stunning display. Also you can play a lot with timming, rythm, show design and so on. Making small shells that look good is a real challenge, this seems a great discipline. Im glad you liked this thread, really apreciated.

So far I've tried the Catalpa BP only on end burners. It has not gone well. The first tries at standard 75:15:10 all CATOed, even with different nozzle diameters. At 70:20:10, all CATOed. At 65:25:10, the CATOes ended, now I'm just getting RUDs at about 10 feet (actually checked the video on the last one and the RUD happened about 5 feet) off the ground. And the 10 feet is achieved quite expeditiously. I'll have to mill a batch of 60:30:10 and see what that does. On another note, pine cones make really poor rocket fuel. Pretty tail though.

Not to be pedantic, but speaking of blast shields of various sorts, my understanding is that if you go the transparent route, plexiglass (which is acrylic), should be avoided in favor of the significantly more impact resistant polycarbonate options (lexan etc). Please correct me if I'm wrong, as I'm actually wanting to build a blast shield myself right now & have a bunch of thick plexiglass I'd love to use if the community consensus is that it's safe enough...

Thank you so much

Glitter and firedust are great. It may be a cold day in... (eh,hem) before I exhaust those options! 🙂

Can ask for you right now. There any comp. Can by compresed, glitter or firedust, color to ,but for color is to expensive. For color beter add few drops color composition slury, anyway for color need hot prime slury ontop of the color and dip in bp grains to got ignition.

I want to make sure i have this straight. In the first Pic, that's the layer of pulverone and dextrin which is pressed underneath the clay plug w fuse. It could be pulverone or star comp which ignites upon lift and who's purpose is to leave a trail to apogee lighting the visco to the bombette payload. Yes? Great stuff here!