Strobe Rocket Fuel

[calebkessinger]

Just a quick vid of how I make my fuel.

 

[Col]

I only add the mgal after the AP, barium and dichromate is mixed and in a wet state. Wearing a respirator is a good idea when making the fuel and pressing the motors. .

[NeighborJ]

 

The fuel worked great, Thanks Caleb.

[calebkessinger]

Woooohooooo!

Glad they are starting to work for ya Neighbor!

 

Yeah Col,
I have worm respirators in the past for many things including pyro but I don't worry too much about it anymore, I hate them, That's one of the reasons I bound that batch with NC to help capture the dichromate better so I don't breath it as much while pressing.

[Col]

A respirator isnt the most comfortable thing to work in but when it comes to "agent orange" i dont take any chances

[dynomike1]

I like these videos a whole lot better than Neds. Just need more volume.

[willowchar]

Hey guys,

Looking for advise on strobe fuel problem.

I can get the formula to strobe pretty good, but there is no popping sound. More of a sizzle sound.

Chems are dry, fine and well blended.

using lamp oil dispersed in camp fuel.

Could the quality of the magnallium cause the problem?

I am using 50/50 magnallium

thinking of making 60/40 (mg/al) and trying that.

 

Any help would be appreciated:)

[pyrokid]

What was the context of your tests? Have you tried the composition in a rocket? I have observed ground based strobes to emit different sounds depending on the progress of the burn inside a thin casing. It may be that the strobe composition needs to be pressed inside a tube with a void length above it in order to "pop" like you want it to. In the context of pyrotechnic noise production, the tube provides confinement for the gaseous combustion products of the strobe fuel. The greater the pressure produced, the greater the sound we might expect to hear.

[willowchar]

Thanks for the reply.

 

I have noted that some members have pressed ap based strobe comp with a core (excluding whistle portion) directly in a motor and are able to get both the popping sound and thrust.

Also have seen some video of open pile burn test of strobe comp that burns with a strobing and slight popping sound (quite reactive).

Through some testing, I am starting to believe that the mgal I used (50/50) is not reactive enough?.

Perhaps a more reactive blend 60/40 or even 70/30?

 

Regards,

[BetICouldMake1]

50/50 MgAl will work just fine for strobes. You won't get much popping unless you have it pressed in a tube with a core. How loud the pops are will depend on many factors (core size, MgAl mesh size, chem particle size).

[Mumbles]

Strobe fuel can very finicky to get that primo popping. Some people resort to mixing in a little magnesium powder to get things a little hotter. It tends to be easier than trying to source different alloys of MgAl. It can be a very frustrating experience dialing them in from what I've heard. You may want to try milling some of the non-AP components to get them finer as well.

[ronmoper76]

I to have this issue right now...i lit two 3lb rockets tonight that took off like a bat out of hell,had a sweet sparkly tail,howled loud as hell The one when the delay kicked in,it accelerated out of sight over the mountain. The other went way up and then arced back down,howling as it was trucking for the earth and then it just exploded with a heck of a bang...thing is neither one had a heading on them,what blew up so loud? they were awesome but had zero popping sound......

 

[justvisiting]

The magnalium that does well in strobe rockets is the nice shiny stuff. Dull grey magnalium doesn't work as well. I've milled the dull stuff for a few minutes to 'freshen it up', but that could be dangerous, and shouldn't be done without knowing the risks.

[ronmoper76]

i just picked up 6lbs of it,its brand new i was wondering what was up. i will give that a try for sure,and will get it shined up one way or the other,i have just the idea. thanks man i will post once i get to test it again., im trying a blue strobe thats sugar based this evening when its dry,i made the doc bar white strobe which is fairly simple and hot,so i thought....it would make excellent stump remover the way it is now. it has no issues detonating.lmao

[SharkWhisperer]

i just picked up 6lbs of it,its brand new i was wondering what was up. i will give that a try for sure,and will get it shined up one way or the other,i have just the idea. thanks man i will post once i get to test it again., im trying a blue strobe thats sugar based this evening when its dry,i made the doc bar white strobe which is fairly simple and hot,so i thought....it would make excellent stump remover the way it is now. it has no issues detonating.lmao

 

 

The magnalium that does well in strobe rockets is the nice shiny stuff. Dull grey magnalium doesn't work as well. I've milled the dull stuff for a few minutes to 'freshen it up', but that could be dangerous, and shouldn't be done without knowing the risks.

I've never pressed strobe fuel, but have used plenty of MgAl in ground strobes and DEs (and a whole slew of metallic stars). I've never noticed a difference in performance according to shiny/dull status, presumably an oxide layer inhibiting ignition to some extent, but seems dialing in strobe propellant is a different beast that's a little more finicky than my MgAl comps. Have others shared your observation of the MgAl "freshening" approach improving strobe fuel? Seems even if only spinnig a few minutes (I assume with milling media?), you'd be doing as much buffing as you would low-level milling to slightly smaller grains given its brittleness?

[justvisiting]

The 'freshening' is a touchy subject for some. The general consensus that is spoken quietly among friends seems to be that the dull stuff doesn't make good loud pops. My theory was the oxidation that occurred because of the way the magnalium was processed. I bought a bunch of different mesh ranges of magnalium that is supposed to be 'gourmet', but it is all a dull grey color, somewhat like the old oxidized magnesium I had in jars. It works in stars, no problem. Adding milled magnalium (dangerous!) to strobe propellant speeds up the strobe rate. I bought magnalium from another guy and it was mixed mesh sizes, specifically for strobe rockets. It was (and is) perfectly shiny, with no oxidation. Maybe the dull stuff is dull due to the poor purity of the magnesium and/or the aluminum used to make it, or the impurities make it more prone to oxidation, I don't know. Caleb (Woody) agrees that the shiny magnalium makes the best strobe rockets, and he makes the best strobe rockets I know of. Caleb makes them the Steve Laduke way, with sali booster and a short fat core. The gourmet magnalium that is NOW being made is apparently made with more pure magnesium, and is said to be shiny instead of dull, like it has been all along. I don't know if the water quenching process has been abandoned, but it was my unqualified and uneducated opinion that the water quenching affected the quality of the magnalium. The magnalium from China is shiny, BTW.

 

I've found strobe rockets to be finicky as well. There's a lot of conflicting information about strobe rockets, because there are two general schools of thought on tooling and propellant that are very different. These differences are often not mentioned in the reporting, when a person has a problem. The people that most commonly report poor popping are using dull magnalium, pottery grade barium sulfate, and/or BP tooling instead of strobe tooling, and sodium benzoate whistle.

 

I was once given a bunch of old DEs, and they barely popped, and just sort of sputtered. I put it down to the oxidation of the magnalium, which rendered them useless. This is just opinion as well, with nothing to back it up.

 

Like BetICouldMake1 said, 50/50 magnalium works just fine. If my strobe pops were poor, the alloy ratios would be well down on the list of things I'd look at.

[ronmoper76]

sorry i gotta ask because im still playing around with mine. benzoate causes issues? my last two that didnt pop but flew halfway to the moon had benz in them. i dont use sali much,i doesnt agree with me much,lol Not using sali affects how it works?

Edited February 28, 2021 by ronmoper76

[justvisiting]

ronmoper76, there are 2 general ways that strobe rockets are made. I've done both, but I'm not claiming special knowledge. I'll share my observations in the hopes that they might be helpful.

 

The first guy to make strobe rockets was a fellow named Doc Barr. His rockets have been described as 'farting rockets', due to the sound of the 'pops'. I made a couple his way from an article in AFN, and they sucked. There is a school of folks that hang on to this 'original' or 'authentic' way of making strobe rockets. These farting rockets are typically made on a long BP-type spindle, and use a tall column of benzoate whistle booster, topped with strobe fuel. I've never heard one of those make loud pops- ever. I mentioned this in another thread, and a proponent of this type of strobe rocket posted a video that I felt proved my point, which is that the pops are mediocre at best. If someone tells you that they get loud pops on BP tooling, just ask to see the video and then judge for yourself if that's the kind of rocket you want to make.

 

The 'new and improved and used by all the cool kids' way of making strobe rockets is to use a short fat spindle, with a short column of hot salicylate whistle booster, topped by strobe fuel to just over the spindle tip, and finished with whistle. THESE strobe rockets are the ones that make loud pops that sound like a helicopter. Steve Laduke perfected them. Caleb (Woody) and Uncle witty are modern pyros that make excellent strobe rockets with (always) loud pops, and the occasional really loud pop

 

 

I'm not saying sodium benzoate whistle is a problem. I'm saying I have not seen it used to make a good strobe rocket. Sodium benzoate whistle requires a longer spindle so more of it can be used to get the rocket high enough, since the propellant is weak. There are VERY zippy variants of benz whistle, but I have not seen them to be used in strobe rockets. My personal theory on why the benz/BP tooling strobe rockets don't make loud pops is because the column of strobe is way up inside the tube. The heat can't get away freely enough, and the separation between the dark and flash phases is less pronounced as a result. The pops are correspondingly weak.

 

It's important to make strobe rockets in a particular way from a specific set of instructions, if repeatable results are to be obtained. If there is a problem, it's easier for others to help if they know which of the specific methods was used.

[MrBOOMbastic]

Someone please help. 3lb strobe flying great but just not getting that helicopter noise. Followed Neds formula to a t and get ingredients from Skylighter. Using a 4inch spindle 1/2 wide and tapered with 1 degree down to 1/3.

 

1 and 5/8 of (sail)whistle and rest strobe . .. tried less whistle but wasnt flying right

 

Pressed to 7500psi

 

Any suggestions?

[Wickedpyro]

Hello my fellow pyros have any of you heard of using e85 fuel to make strobe fuel??

[greenlight]

I have made a batch of strobe fuel (second attempt) using chunks of homemade magnalium in a furnace.

I have crushed it with a hammer and milled some in a grinder to get a variety of meshes from 80 to 200.  This was mixed with the required 325 mesh magnalium.

The result is a much better burning powder with slight flashing when ignited in an unconfined pile.

After the solvent was evaporated, I have pressed a small scale test sample into a tube using Caleb's whistle insert tooling.  The salicylate whistles made with it scream spectacularly 😀.

I couldn't get the pressure very high due to the tube starting to deform even with a piece of PVC pipe as a support.  So I think I only got about 2000 psi on the comp.

When initiated, I have a bright burning mix with slightl noticeable flashing and barely any popping at all.  

1.  Is the lack of pressure resulting in bad performance as the mixture is not consolidated enough in the tube (~2000psi) ?

2.  Or is it because it is a solid plug of composition and does not have a core?  I have read on here that the core is required for the popping.

Any help or advice is greatly appreciated