Strobe rocket fuel
Posted 05 October 2020 - 05:52 PM
Magnalium, 100 Mesh...............................18
If not is there another strobe rocket fuel without ammonium perchlorate??
Also how would I prepare the strobe rocket fuel?
Posted 05 October 2020 - 10:33 PM
That's an interesting question. I assumed it might not work, because if it did, nobody would have to mess with AP. I happened to have some TR's White Strobe powder for rolling cores, so I pressed up an 8oz. rocket on universal tooling- no booster, all strobe. In my static test, the flashes were plenty bright, but inconsistent. They also didn't 'pop' like AP strobe. The burn time was exceedingly long in my quick and dirty test.
OTOH, the mix pressed beautifully. I've had bad luck cutting these crumbly stars, and OK luck rolling cores. Maybe pressing baby cores is a better way to go than rolling or cutting for this formula.
Posted 05 October 2020 - 11:04 PM
The inconsistency tends to be the issue with nitrate strobes. They're a little too random, and you wont get that same pop or helicopter sound that a lot of people like. That said, it should work as a delay element. It probably wont be quite the same, and probably need a little different ratios or geometry, but it probably will be a cool effect if it works out.
- Bigfatorange likes this
The sky is my canvas, and I have 2,113 pounds of powdered paint in the workshop.
Posted 06 October 2020 - 01:08 AM
The AP-based strobe does provide some thrust - not much but it's there; most of the thrust is provided by the whistle momentum.
So all in all, the strobe fuel is an energetic delay that pops nicely.
Posted 06 October 2020 - 11:23 AM
Bigfatorange, just an FYI on strobe rockets. They are the most difficult rockets to get 'just right'. The materials can be difficult to obtain and are not always conducive for making good strobe rockets. They are also the most dangerous rockets that we commonly make. Caleb from Woodysrocks.com makes very good strobe rockets, sells supplies, and is often willing to give advice as time allows.
Posted 06 October 2020 - 01:10 PM
No reason to reinvent the wheel. With strobe rockets (especially), use proven formulae and techniques and then dial them in to your liking from there. Chemicals can be found here:
Here's a link to tutorials I put together that will walk you through the entire process
Posted 06 October 2020 - 11:13 PM
I respectfully disagree with Bensmith. The original strobe rockets have been credited to Doc Barr. In those days, strobing meant 'exhibiting flashes of light upon ascension'. That didn't last long. Steve Laduke did extensive work to turn the original 'farting' strobe rockets into what is now recognized as a good strobe rocket.
A good strobe rocket has even spaces between flashes. The flashes are not poofs, they are bangs. The strobing does not fade away to poofing, it transitions to 'whistle. A well-made strobe rocket is impressive, even in the 5/8" (8oz.) size. In my opinion, a good strobe rocket has a sound like a helicopter.
Many experiments have been done with spindles, and it's generally accepted that strobe spindles are shorter than black powder spindles. It's generally accepted that hot salicylate whistle 'booster' is used to propel the rockets. In a typical strobe rocket as defined by most, the propellant column is between an inch and an inch and a half, on a 3lb rocket. The majority of the grain is made up of strobe fuel, finished off with whistle above the spindle.
The strobe rockets Bensmith describes are not typical. I've not known them to behave like the strobe rockets I describe. Their propellant is different, the tooling is different, and the performance is VERY different. I think it's important for a rocket maker to know which type of strobe rocket he/she wants to make. I want mine to be like the ones Caleb (Woody) makes, not like the original ones.
This would be the minimum level of performance I'd accept in a 'good' strobe rocket.
- a_bab likes this
Posted 07 October 2020 - 06:50 AM
Posted 07 October 2020 - 09:53 AM
As with everything pyro, personal preferences come into play. Ask 10 pyro's the same question and you'll likely have 12 different answers. As long as you're getting the results you like (and achieving these results safely), that's what is important.
In regards to the strobe rockets in my tutorial and those in the videos, the primary difference is the whistle fuel used as the booster to get the rocket flying. I've always had an affinity for benzoate whistle fuels. I like the sound, reliability, consistency and lifting power. I've just never really cared much for the salicylate whistle fuels. No real reason other than personal preference. As such, I build my strobes using benzoate whistle fuels for the booster. These fuels work much better on taller, core-burn type spindles as depicted in the tutorial. Strobe rockets built using salicylate whistle fuel as the booster tend to use much shorter spindles. Outside of that, you're still using the same strobe comps and construction techniques to build either type of strobe rocket. A bit of whistle fuel to get the rocket flying and a bunch of strobe around the spindle to make the popping sound.
I too also like my strobes to sound like an Apache helicopter flying overhead. I've had really good luck achieving that using the formula in my tutorial. Nothing better than a strobe rocket flying at night with the noise reverberating off the hillsides! The biggest issue I've seen impact those who are new to strobe rockets is the amount of strobe pressed over the spindle. Too much, and your rocket will switch from popping to just flashing as the fuel around the spindle has burned and it's just the solid plug above the spindle still burning. You're also likely to have a rocket make a nice round trip back to the ground.
Soooo... you can make great strobe rockets using salicylate whistle fuel on a shorter spindle or benzoate whistle fuel on a taller spindle. It really just depends on your own preferences. I'd estimate I see just as many benzoate strobes as I do salicylate strobes anymore. Just go with what works for you.
Posted 07 October 2020 - 02:22 PM
I don't claim any expertise with strobe rockets, but I have made quite a few. I've never seen what I would call a good strobe rocket (strong pops) made with benzoate whistle booster. I've never seen a good strobe rocket made on BP tooling. If there are lots of folks making good strobe rockets with benzoate, they aren't posting video- at least that I have seen. I don't mind being wrong, if I can be shown examples.
I've read that the barium sulfate can make or break strobe fuel. Somebody just went through that recently with Firefox barium sulfate. Myself, I've used cheap (APS) barium sulfate, pharmaceutical grade, and homemade (by me). All worked the same.
Some folks find that the blend of magnalium particle sizes is the most critical thing. Myself, I've found that the shininess of the magnalium is most important. The stuff that is dull and grey doesn't work very well if you want strong pops. A short mill cycle can shine up the magnalium and improve things. Of course, milling magnalium is potentially dangerous and shouldn't be done without foreknowledge of the dangers involved. Strobe rockets violate one safety rule that's commonly adhered to with rockets: sharp hard metallic particles are pressed with high forces, being forced against a hard metal spindle. All this is done under confinement. There are very few accidents with strobe, but the dangers should be known before making these rockets.
The potassium dichromate has been referred to as 'orange death crystals', which is somewhat of an exaggeration. However, I had an incident with it that caused me to have much more respect. I casually (without a mask) cleaned maybe 250 grams of the dichromate mix off the inside of a rubber milling jar, and off of the milling media. I had fits of sneezing, bled from the nose, and had scabs form inside my nose that took several months to heal. The mix had no perchlorate in it when it was milled.
Another thing that is a bad practice is to mix the complete strobe fuel as a dry mix, before adding solvent. Adding the solvent to the oxidizer component first, and then adding the rest of the mix is a bit safer (less dangerous) way to do it.
My unsubstantiated opinion is that strobe rockets benefit from having a high strobe to whistle ratio on the spindle, a wide core, and a short distance from strobe core to the mouth of the rocket. When the strobe is too far up inside the tube, the pops are weak. I think it may be because there is not enough difference between the light and dark reaction conditions.
The best strobe rockets I've made were on 3lb strobe tooling from Wolter. The spindle is short and fat. If I try to make the pops louder by using more strobe fuel and longer (universal) tooling, I get the opposite result- quieter pops. This seems (to me) to substantiate my theory that the light and dark reaction conditions are at the root of the 'pop' issue- for those of us that find it to be an issue.
I think if we all state our positions and why we have them, others can perhaps glean some tidbit of value that resonates with them, so I share my experiences for that reason- as a fellow student of pyro- not as an expert.
Posted 18 October 2020 - 08:11 AM
I regularly use benzoates for strobe rockets but it requires abandoning the conventional construction methods. The benzoate whistle needs to be used at the top of the spindle instead of the bottom and much less is then required. It also allows for more strobe comp in the core to displace the missing whistle comp. This also has the result of stronger pops capable of pushing the rocket on strobe fuel alone, if the strobe fuel is dialed in enough.
If you are just learning strobe rockets it is my advice to build with proven methods before attempting the method listed here.
Edited by NeighborJ, 18 October 2020 - 08:16 AM.
Posted 18 October 2020 - 02:57 PM
J, you're saying you press the rocket with strobe on the bottom of the spindle and whistle at the top? Do you then press strobe above the spindle and then more whistle? Do you use a longer spindle or still a normal strobe spindle? Any video of any of these flying?
Posted 18 October 2020 - 07:55 PM
The biggest issue i see with the traditional method of construction is incomplete ignition of the core. This is why you see so many strobes burn forever into the ground and with no thrust. Long cores work but the tip needs to be fat like the UH spindles or extreme strobe spindles to allow fire to reach the top. Thin BP spindles don't allow the entire core to ignite.
My top light ignition makes a hard popping noise all thru the burn and quickly turns off before the whistle delay. My strobes don't spudder out before the whistle.
Posted 19 October 2020 - 02:13 PM
Really impressive! Just as you said it would be. Nice "pops" or "thuds."
- NeighborJ likes this
Posted 22 October 2020 - 04:56 PM
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