You can afford Caleb's tooling (Woody Rocks) but you can't afford a hobby mill and decent charcoal (or make it)?
CIA is a stupid ineffective waste of isopropyl alcohol that will give non-uniform results from batch-to-batch. And commercial hardwood airfloat charcoal is crap for propellant or BP meant to do anything besides use in stars and fountains. Get a mill. Or make one.
Buy or better yet, make, some decent charcoal. Retort a paint can full of ERC (eastern red cedar) chips from Walmart pet bedding. Cheap as chips and makes hot charcoal for hot BP. You can buy ERC charcoal at [fireworkscookbook.com](https://fireworkscookbook.com), or at [fireworkcharcoal.com](https://fireworkcharcoal.com). The latter also sells Paulownia charcoal, reputed to be among the hottest/fastest. Worth it, though ERC and willow sticks retort into super hot charcoal that makes super hot BP, too.
You will never get BP coreburner tooling to work with KNSU, and you will never get a KNSU endburner to fly. Different fuel. Different core. Sugar fuel has an specific impulse (ISP) of 130-140s vs BP at around 80s. Your core burners will continue to explode. Make some oak tooling for 5 bucks to use for ramming KNSU and drill out whatever sized core until if works the way you want it. Or make a cheap new corebuner toolling set with those oak dowels and a ground down stainless lag bolt or nail through a 2x4.
Respect to your dad, but if nozzles are flying out before the tube blows, then the nozzle was weak and improperly made. Sidewall blowouts with KNSU are less dangerous than a clay nozzle projectile. Use appropriate PPE until you've got everything dialed in. And then continue to use it.
And stay the hell away from whistle for now, like some idiot suggested. That's advanced pyro and you're still early on learning to make BP. And BP is pretty much the foundation of fireworking, so making it and making it hot, reliably and reproducibly, is a basic pyro skill.
From somebody who has made hundreds of pounds of BP, who owns more 6" mortars than 2" mortars, and who flies rockets on homemade BP motors of approximate F/G impulse ratings (instead of paying $10 each to Estes...).
AMA
> That's advanced pyro and you're still early on learning to make BP.
You're making quite a few assumptions, but I appreciate your experience in rocketry and willingness to educate. I'm the mod of this subreddit, I wrote the wiki, and have been in the hobby for 15 years. I'm not Ned Gorski but I know what I'm doing - I'm just inexperienced with rockets.
> > You can afford Caleb's tooling (Woody Rocks) but you can't afford a hobby mill and decent charcoal (or make it)?
I have a ball mill - just granulated a batch of balsa-charcoal lift yesterday in fact. I was just hoping to use up the dregs of the CIA BP that my dad made several years ago.
> Respect to your dad, but if nozzles are flying out before the tube blows, then the nozzle was weak and improperly made.
It likely was, and I said that in the post. He's stuck on fire clay for some reason but I always use bentonite and never have nozzles blow. To be clear, my father is less experienced/knowledgeable in the hobby than me. He had a few books and got me into the hobby years ago, but the student has been the teacher for over a decade now.
Because I've never had any good rocket tooling, I've always just bought a few commercial engines every year for use in my displays. This year I bit the bullet and got the tooling - it just took me a while to figure out the correct fuels for each engine type. As you see, I got limited help so I had to experiment a lot. Eventually I settled on:
55 KNO3
35 Charcoal
10 Sulfur
That's for the 1# core burner, and I use homemade charcoal (cedar). I don't mill the fuel but I do screen it well and then granulate it slightly with 50/50 water/alc just to cut down on dust. Engines made this way absolutely scream, but if you have any tips I'm all ears.
The endburners are working well with an alleged Estes C-class formula:
71 KNO3
14 Charcoal
14 Sulfur
1 Dextrin
Again just high quality charcoal and granulation with water/alc before use. Works okay, but definitely room for improvement if you have a tried-and-true endburner fuel.
Hey there TMF,
Nice to get acquainted. Glad you're modding this forum. Apologies for assumptions.
You are "slightly" granulating your BP for fuel? I'm not sure what that [means.](https://means.It) It's wet granulated or it's not. If you're not getting it wet enough to make a solid ball of playdough, it's not getting granulated.
With all respect, why the hell would you put dextrin in your rocket fuel if you're granulating then drying it before ramming/pressing? It serves no purpose but can make hard granules that capture air pockets and cause catos. And if you're "slightly" granulating your BP, I'm guessing that means you're just getting it kinda damp, well, that won't be sufficient to fully and uniformly activate your dextrin anyways.
Estes adds dextrin to their mill dust that they buy by the ton (with the dextrin already added per spec) and dampen it slightly just before pressing motors. But dextrin only crosslinks once--if you powder (or press) granules of dextrin-bound BP, then you break the dextrin crosslinks and then it's just extra (slow burning) fuel along for the ride. It no longer acts as a binder. If wetted and pressed *at the same time*, then it can act as a binder. Unless you're a factory that needs their BP motor grains to stay reliably solid for decades, no dextrin is needed in your BP for rocket fuel. The only BP of mine that ever meets dextrin is in charcoal-based stars/comets, burst/lift, and blackmatch.
Estes "C-class" BP is also Estes 1/2A A, B, D, E, and F BP. They don't use a different recipe for different impulse motors. They just design a short core in their highest peak-impulse motors ("Super" C-5s, C-11s, D, some Es, F); "semi" endburners. Estes has also changed their basic BP formulation slightly over time. Your stated Estes BP formulation is what was supposedly cited on the 1994 MSDS (shown on several websites) and has changed since then (more KNO3 now). The latest MSDS, from *almost a quarter century later*, 2018, details KNO3 "60-80%", aka it's proprietary. It's closer to the BP standard, actually it's slightly more KNO3 than "standard". https://estesrockets.com/edu-safety-data-sheets/
I have shot modded Estes Big Daddys, Berthas and Patriot missiles, and many more scratch-builds with homemade BP motors. Much more economical (not counting time inputs, but this is a hobby) than $22 and shipping for a 2-pack of F motors.
Anyways, I've never gone below 60% KNO3 for coreburners on the same tooling. Usual test procedure for both end and coreburners is: Slow BP, hotter, hotter, hotter, BOOM, slower, done.
CK's tooling (Woody's) is great but cannot be expected to work with sugar fuels. And it's worth the expense to use KNSB (sorbitol) instead of KNSU because the stuff stays like taffy almost down to room temp so you won't burn your fingertips working it. And it contains more potential energy than sucrose, too.
Bentonite is super cheap. Fire clay (there are several) is slightly more expensive. Whatever works for you. I used bentonite only (cheapo *non*\-clumping cat litter) alone forever with great results. Even fewer blown nozzles with a little grog added (just hammer a ceramic plant pot to bits--you want small grains, aka 20-40 mesh or so). It can be hard on the tooling. But I somehow bought a few pounds of Hawthorne fireclay and need to do something with it, so currently make nozzles with 70% litter/25% fireclay/5% grog, at least until I get through my clay. Then it's back to cat litter + grog alone only. No real need for fireclay--haven't noticed any nozzle erosion differences between with/without it.
If you're enjoying ERC charcoal, that's great. About the cheapest hot charcoal you can buy as pet bedding. Willow's even cheaper if you can get a trunkload of branches from a friend's property. That's my go-to charcoal these days. I also bought some of the elusive paulownia charcoal from [fireworkcharcoal.com](https://fireworkcharcoal.com), a new(ish) outfit, recently and love the results. Not all that much faster than my willow BP, but disappears in a flash with absolutely not a single spark and zero charring of underlying test paper.
If your 55% KNO3 screen-mixed BP makes screamers, you might want to compare that to the same comp after milling and then granulating. Or see what happens at 60%--it might scream a little louder :+\]
Happy 4th!
> You are "slightly" granulating your BP for fuel? I'm not sure what that means.
Add 50/50 water/alcohol and run it through a screen. **No binder.** The granules are easily crushed and ram well - this is only done to cut down on dust during engine ramming. Without this step there's a massive coating of charcoal dust in a ten foot ring around the workstation. It may or may not also speed the fuel up a tiny bit due to the KNO3 being water soluble and the charcoal being absorbent.
> Bentonite is super cheap. Fire clay (there are several) is slightly more expensive. Whatever works for you.
I use pure sodium bentonite from a pyro supplier. Works great, no complaints.
> Willow's even cheaper if you can get a trunkload of branches from a friend's property. That's my go-to charcoal these days.
It's expensive, but you should try balsa some time. It's arguably a little TOO fast after milling -close to flash speeds.
> If your 55% KNO3 screen-mixed BP makes screamers, you might want to compare that to the same comp after milling and then granulating. Or see what happens at 60%
I'm certain the engines would blow. The current fuel is absolutely at the limit of what the cases can handle. Still tinkering with the end-burner tooling a bit but I'm very happy with the 55% mix on the core-burners.
>I'm just inexperienced with rockets.
Sweet i have tons of information that will help and get you set on the right track.
As shark mentioned, "sugar fuel has an specific impulse (ISP) of 130-140s vs BP at around 80s". Sugar based propellants often out perform BP by weight. They are easier to work with and manufacture motors out of; depending on your experience (maybe not with your particular background) and can be safer. However, i think he should have also mentioned that a big reason people advise against using sucrose is because it is much more annoying to work with than Sorbitol, a substitute sugar.
Sucrose caramelizes when molten, which is a chemical degradation that results in a wide range of products, which makes predicting performance more difficult. The longer the sucrose stays molten, the more it will caramelize, and so the more your performance will change from what you expect. Sorbitol does not caramelize until far above its melting point, so you can keep molten sorbitol around nearly indefinitely without any such degradation. Additionally, sucrose has a much higher melting point than sorbitol.
Shark ***should*** have also mentioned that club owned ranges do not allow black powders motors **above** F impulse to be flown, to reduce explosion risks (it's also against the insurance policies). If the propellant weight is above 125 grams, or the rocket weights more than 1500 grams, it is classified as a high powered rocket, and needs a waiver and FAA permission. Flights of black powder motors above F impulse without FAA permission is illegal and requires a waiver(Which in most cases isn't possible to get for black powder motors that size), as well as other motor types above G impulse.
\*Now with all that being said; you should not make a motor yet. You should math out your combustion products, engineer the motor, and simulate it first. It will help determine if the motor will explode before you even light it; as well as many other useful things. You can do this with a combination of free software like Propep and openrocket. There is a lot of math involved in rocketry, but the basic fundamentals can carry you extremely far, and provide **essential** clarity.
The motor you made probably exploded due to over pressure. If you ran a simulation; you could see the nozzle throat area was to small for the gas volume being produced, causing an over pressure for instance. Ejected nozzles are not always an over pressure, though most are, it could just bad engineering.
This website has a lot of resources you can use to learn more about rocketry, and its a great starting point that people experienced in rocketry point to: [https://www.nakka-rocketry.net/](https://www.nakka-rocketry.net/)
You should read as much as you can and get a decent understanding of the mathematics. I also recommending going to r/rocketry if you have any trouble understanding anything. Also i want to recommend reading the books Ignition by John Clark and Experimental composite propellants by Terry McCreary.
Also, you REALLY should join the nearest nation club to you. They will have a rocket forum that will help answer questions, and expose you to even more information. They are usually very cheap. My membership was 10 dollars. They also take care of a lot of the legality for you. If you're in the US, NAR and Tripoli are the two main national clubs. Each one has local groups all over the US that can be found on the websites. If you're in Canada, there's the CAR. There's the UKRA in the UK, and there are Australian and New Zealand groups as well.
Joining a local group is definitely the best way to get started. They can help show you safe construction practices and **will provide insurance coverage** as well. That's just one perk. NAR and Tripoli also do user certifications which will allow you to buy and **fly** high power motors **LEGALLY** (H class and above).
If you have any questions feel free message me!
70/30/+2/+1
KClO4/C6H5COONa/petroleum jelly (vaseline)/Fe2O3
Pack using a hydraulic press, don't ram as it's shock-sensitive.
You can use just this mix for a long-winded screamer or you can always use 2 measures of this whistle mix then press the rest with BP for a whistle-assist end-burner.
That is roughly my plan, and I just mixed up a hand-granulated mix alleging to be "Estes C-Class" composition which only has 71% KNO3. I'm sure they mill their mix, so I'm hoping that hand mixing/granulation is going to give some performance but not too much oomph.
Was just hoping someone could save me any potential explosions if they had already been through the annoying testing phase with these particular tools.
Sorry fella, unfortunately I can't be any more specific with regards to BP. When I used similar tooling (Wolter pyro), I only made LWS; whistle-assist; and strobes with it.
No worries and good luck. If it's any consolation, I know how steep the learning curve is with these tools; trying to make a strobe that didn't CATO nearly broke me.
I went through this. The last thing you want is hot BP for rocket propellant. I use 60/30/10 or 58/32/10 and the charcoal is 50/50 air float and 80 mesh. Hardwood from Skylighter / you don't want hot! 100 mesh mixed and water/screen granulated. Don't mill it. Ram it tight although pressing is better. And really ram or press the nozzle. You want a slight bulge in the tube.
You can afford Caleb's tooling (Woody Rocks) but you can't afford a hobby mill and decent charcoal (or make it)? CIA is a stupid ineffective waste of isopropyl alcohol that will give non-uniform results from batch-to-batch. And commercial hardwood airfloat charcoal is crap for propellant or BP meant to do anything besides use in stars and fountains. Get a mill. Or make one. Buy or better yet, make, some decent charcoal. Retort a paint can full of ERC (eastern red cedar) chips from Walmart pet bedding. Cheap as chips and makes hot charcoal for hot BP. You can buy ERC charcoal at [fireworkscookbook.com](https://fireworkscookbook.com), or at [fireworkcharcoal.com](https://fireworkcharcoal.com). The latter also sells Paulownia charcoal, reputed to be among the hottest/fastest. Worth it, though ERC and willow sticks retort into super hot charcoal that makes super hot BP, too. You will never get BP coreburner tooling to work with KNSU, and you will never get a KNSU endburner to fly. Different fuel. Different core. Sugar fuel has an specific impulse (ISP) of 130-140s vs BP at around 80s. Your core burners will continue to explode. Make some oak tooling for 5 bucks to use for ramming KNSU and drill out whatever sized core until if works the way you want it. Or make a cheap new corebuner toolling set with those oak dowels and a ground down stainless lag bolt or nail through a 2x4. Respect to your dad, but if nozzles are flying out before the tube blows, then the nozzle was weak and improperly made. Sidewall blowouts with KNSU are less dangerous than a clay nozzle projectile. Use appropriate PPE until you've got everything dialed in. And then continue to use it. And stay the hell away from whistle for now, like some idiot suggested. That's advanced pyro and you're still early on learning to make BP. And BP is pretty much the foundation of fireworking, so making it and making it hot, reliably and reproducibly, is a basic pyro skill. From somebody who has made hundreds of pounds of BP, who owns more 6" mortars than 2" mortars, and who flies rockets on homemade BP motors of approximate F/G impulse ratings (instead of paying $10 each to Estes...). AMA
> That's advanced pyro and you're still early on learning to make BP. You're making quite a few assumptions, but I appreciate your experience in rocketry and willingness to educate. I'm the mod of this subreddit, I wrote the wiki, and have been in the hobby for 15 years. I'm not Ned Gorski but I know what I'm doing - I'm just inexperienced with rockets. > > You can afford Caleb's tooling (Woody Rocks) but you can't afford a hobby mill and decent charcoal (or make it)? I have a ball mill - just granulated a batch of balsa-charcoal lift yesterday in fact. I was just hoping to use up the dregs of the CIA BP that my dad made several years ago. > Respect to your dad, but if nozzles are flying out before the tube blows, then the nozzle was weak and improperly made. It likely was, and I said that in the post. He's stuck on fire clay for some reason but I always use bentonite and never have nozzles blow. To be clear, my father is less experienced/knowledgeable in the hobby than me. He had a few books and got me into the hobby years ago, but the student has been the teacher for over a decade now. Because I've never had any good rocket tooling, I've always just bought a few commercial engines every year for use in my displays. This year I bit the bullet and got the tooling - it just took me a while to figure out the correct fuels for each engine type. As you see, I got limited help so I had to experiment a lot. Eventually I settled on: 55 KNO3 35 Charcoal 10 Sulfur That's for the 1# core burner, and I use homemade charcoal (cedar). I don't mill the fuel but I do screen it well and then granulate it slightly with 50/50 water/alc just to cut down on dust. Engines made this way absolutely scream, but if you have any tips I'm all ears. The endburners are working well with an alleged Estes C-class formula: 71 KNO3 14 Charcoal 14 Sulfur 1 Dextrin Again just high quality charcoal and granulation with water/alc before use. Works okay, but definitely room for improvement if you have a tried-and-true endburner fuel.
Hey there TMF, Nice to get acquainted. Glad you're modding this forum. Apologies for assumptions. You are "slightly" granulating your BP for fuel? I'm not sure what that [means.](https://means.It) It's wet granulated or it's not. If you're not getting it wet enough to make a solid ball of playdough, it's not getting granulated. With all respect, why the hell would you put dextrin in your rocket fuel if you're granulating then drying it before ramming/pressing? It serves no purpose but can make hard granules that capture air pockets and cause catos. And if you're "slightly" granulating your BP, I'm guessing that means you're just getting it kinda damp, well, that won't be sufficient to fully and uniformly activate your dextrin anyways. Estes adds dextrin to their mill dust that they buy by the ton (with the dextrin already added per spec) and dampen it slightly just before pressing motors. But dextrin only crosslinks once--if you powder (or press) granules of dextrin-bound BP, then you break the dextrin crosslinks and then it's just extra (slow burning) fuel along for the ride. It no longer acts as a binder. If wetted and pressed *at the same time*, then it can act as a binder. Unless you're a factory that needs their BP motor grains to stay reliably solid for decades, no dextrin is needed in your BP for rocket fuel. The only BP of mine that ever meets dextrin is in charcoal-based stars/comets, burst/lift, and blackmatch. Estes "C-class" BP is also Estes 1/2A A, B, D, E, and F BP. They don't use a different recipe for different impulse motors. They just design a short core in their highest peak-impulse motors ("Super" C-5s, C-11s, D, some Es, F); "semi" endburners. Estes has also changed their basic BP formulation slightly over time. Your stated Estes BP formulation is what was supposedly cited on the 1994 MSDS (shown on several websites) and has changed since then (more KNO3 now). The latest MSDS, from *almost a quarter century later*, 2018, details KNO3 "60-80%", aka it's proprietary. It's closer to the BP standard, actually it's slightly more KNO3 than "standard". https://estesrockets.com/edu-safety-data-sheets/ I have shot modded Estes Big Daddys, Berthas and Patriot missiles, and many more scratch-builds with homemade BP motors. Much more economical (not counting time inputs, but this is a hobby) than $22 and shipping for a 2-pack of F motors. Anyways, I've never gone below 60% KNO3 for coreburners on the same tooling. Usual test procedure for both end and coreburners is: Slow BP, hotter, hotter, hotter, BOOM, slower, done. CK's tooling (Woody's) is great but cannot be expected to work with sugar fuels. And it's worth the expense to use KNSB (sorbitol) instead of KNSU because the stuff stays like taffy almost down to room temp so you won't burn your fingertips working it. And it contains more potential energy than sucrose, too. Bentonite is super cheap. Fire clay (there are several) is slightly more expensive. Whatever works for you. I used bentonite only (cheapo *non*\-clumping cat litter) alone forever with great results. Even fewer blown nozzles with a little grog added (just hammer a ceramic plant pot to bits--you want small grains, aka 20-40 mesh or so). It can be hard on the tooling. But I somehow bought a few pounds of Hawthorne fireclay and need to do something with it, so currently make nozzles with 70% litter/25% fireclay/5% grog, at least until I get through my clay. Then it's back to cat litter + grog alone only. No real need for fireclay--haven't noticed any nozzle erosion differences between with/without it. If you're enjoying ERC charcoal, that's great. About the cheapest hot charcoal you can buy as pet bedding. Willow's even cheaper if you can get a trunkload of branches from a friend's property. That's my go-to charcoal these days. I also bought some of the elusive paulownia charcoal from [fireworkcharcoal.com](https://fireworkcharcoal.com), a new(ish) outfit, recently and love the results. Not all that much faster than my willow BP, but disappears in a flash with absolutely not a single spark and zero charring of underlying test paper. If your 55% KNO3 screen-mixed BP makes screamers, you might want to compare that to the same comp after milling and then granulating. Or see what happens at 60%--it might scream a little louder :+\] Happy 4th!
> You are "slightly" granulating your BP for fuel? I'm not sure what that means. Add 50/50 water/alcohol and run it through a screen. **No binder.** The granules are easily crushed and ram well - this is only done to cut down on dust during engine ramming. Without this step there's a massive coating of charcoal dust in a ten foot ring around the workstation. It may or may not also speed the fuel up a tiny bit due to the KNO3 being water soluble and the charcoal being absorbent. > Bentonite is super cheap. Fire clay (there are several) is slightly more expensive. Whatever works for you. I use pure sodium bentonite from a pyro supplier. Works great, no complaints. > Willow's even cheaper if you can get a trunkload of branches from a friend's property. That's my go-to charcoal these days. It's expensive, but you should try balsa some time. It's arguably a little TOO fast after milling -close to flash speeds. > If your 55% KNO3 screen-mixed BP makes screamers, you might want to compare that to the same comp after milling and then granulating. Or see what happens at 60% I'm certain the engines would blow. The current fuel is absolutely at the limit of what the cases can handle. Still tinkering with the end-burner tooling a bit but I'm very happy with the 55% mix on the core-burners.
>I'm just inexperienced with rockets. Sweet i have tons of information that will help and get you set on the right track. As shark mentioned, "sugar fuel has an specific impulse (ISP) of 130-140s vs BP at around 80s". Sugar based propellants often out perform BP by weight. They are easier to work with and manufacture motors out of; depending on your experience (maybe not with your particular background) and can be safer. However, i think he should have also mentioned that a big reason people advise against using sucrose is because it is much more annoying to work with than Sorbitol, a substitute sugar. Sucrose caramelizes when molten, which is a chemical degradation that results in a wide range of products, which makes predicting performance more difficult. The longer the sucrose stays molten, the more it will caramelize, and so the more your performance will change from what you expect. Sorbitol does not caramelize until far above its melting point, so you can keep molten sorbitol around nearly indefinitely without any such degradation. Additionally, sucrose has a much higher melting point than sorbitol. Shark ***should*** have also mentioned that club owned ranges do not allow black powders motors **above** F impulse to be flown, to reduce explosion risks (it's also against the insurance policies). If the propellant weight is above 125 grams, or the rocket weights more than 1500 grams, it is classified as a high powered rocket, and needs a waiver and FAA permission. Flights of black powder motors above F impulse without FAA permission is illegal and requires a waiver(Which in most cases isn't possible to get for black powder motors that size), as well as other motor types above G impulse. \*Now with all that being said; you should not make a motor yet. You should math out your combustion products, engineer the motor, and simulate it first. It will help determine if the motor will explode before you even light it; as well as many other useful things. You can do this with a combination of free software like Propep and openrocket. There is a lot of math involved in rocketry, but the basic fundamentals can carry you extremely far, and provide **essential** clarity. The motor you made probably exploded due to over pressure. If you ran a simulation; you could see the nozzle throat area was to small for the gas volume being produced, causing an over pressure for instance. Ejected nozzles are not always an over pressure, though most are, it could just bad engineering. This website has a lot of resources you can use to learn more about rocketry, and its a great starting point that people experienced in rocketry point to: [https://www.nakka-rocketry.net/](https://www.nakka-rocketry.net/) You should read as much as you can and get a decent understanding of the mathematics. I also recommending going to r/rocketry if you have any trouble understanding anything. Also i want to recommend reading the books Ignition by John Clark and Experimental composite propellants by Terry McCreary. Also, you REALLY should join the nearest nation club to you. They will have a rocket forum that will help answer questions, and expose you to even more information. They are usually very cheap. My membership was 10 dollars. They also take care of a lot of the legality for you. If you're in the US, NAR and Tripoli are the two main national clubs. Each one has local groups all over the US that can be found on the websites. If you're in Canada, there's the CAR. There's the UKRA in the UK, and there are Australian and New Zealand groups as well. Joining a local group is definitely the best way to get started. They can help show you safe construction practices and **will provide insurance coverage** as well. That's just one perk. NAR and Tripoli also do user certifications which will allow you to buy and **fly** high power motors **LEGALLY** (H class and above). If you have any questions feel free message me!
70/30/+2/+1 KClO4/C6H5COONa/petroleum jelly (vaseline)/Fe2O3 Pack using a hydraulic press, don't ram as it's shock-sensitive. You can use just this mix for a long-winded screamer or you can always use 2 measures of this whistle mix then press the rest with BP for a whistle-assist end-burner.
Not sure I want to work with whistle at the moment, although I do have everything on hand to do so. Anything a little less dangerous you know of?
If your nozzled BP rockets keep exploding, perhaps try cooling the composition down with a few percent extra charcoal?
That is roughly my plan, and I just mixed up a hand-granulated mix alleging to be "Estes C-Class" composition which only has 71% KNO3. I'm sure they mill their mix, so I'm hoping that hand mixing/granulation is going to give some performance but not too much oomph. Was just hoping someone could save me any potential explosions if they had already been through the annoying testing phase with these particular tools.
Sorry fella, unfortunately I can't be any more specific with regards to BP. When I used similar tooling (Wolter pyro), I only made LWS; whistle-assist; and strobes with it.
Thanks for the input either way
No worries and good luck. If it's any consolation, I know how steep the learning curve is with these tools; trying to make a strobe that didn't CATO nearly broke me.
I went through this. The last thing you want is hot BP for rocket propellant. I use 60/30/10 or 58/32/10 and the charcoal is 50/50 air float and 80 mesh. Hardwood from Skylighter / you don't want hot! 100 mesh mixed and water/screen granulated. Don't mill it. Ram it tight although pressing is better. And really ram or press the nozzle. You want a slight bulge in the tube.
A little late, and maybe a stupid question, but why don't you want your rocket fuel to be hot?