1LB core burners

[Tim1877]

I just bought a 1 LB BP core burner set from Caleb been doing some research on different rocket formulas and been noticing that a lot only have 5% sulfur in them just wondering why this is and if anyone would like to share their tried and true formulas your welcome to PM me if you dont want to share your formulas in public before I get burnt up on here I do know this hobby is about experimenting and dialing in until you find what works but some of us have less time than others to experiment I would love to spend more time in the shop just not possible at this time

[Bigmark]

If it where me I would leave out the clay nozzle. And just ram hot BP in it 75/15/10. And use 1% to2% water. Screened in the fuel.

You can fire them as fast as you can make them. At least that would get you started.

Nozzles motors are pretty reliable and fast and easy to make. Good luck.

[davidh]

60 - 30 - 10: Tried and true. Start there with a hand mix. Use finely powdered KNO3. It's hard to mess up.

[Bourbon]

So, I am completely new to black powder rockets and looking for a bit of advise from someone who doesn't mind sharing.

 

After months of reading and spending a year picking up the things I thought were necessary (work gets the way) I decided to try my luck at some stinger missiles. I picked up a set of stinger tools from Woodys and went with Skylighter instructions on their easy BP formula for their stingers. They say 75/15/10 works well without milling as long as everything will pass a 40 mesh screen and granulate with a 20. However, I made them pass a 130 mesh and then milled for 4 hours and granulated using 70% Iso through a 18 (didn't have a 20). Made 3 rockets and all popped. First 2 lost all clays and third had the nozzle left. Casings were fine. It was to my understanding the 75/15/10 would be fine because it's using commercial hardwood so it wouldn't be that hot. Maybe I shouldn't have milled it but i still didn't think it work that good. Did some open air tests before building and was amazed at the speed for poor quality charcoal.

 

I pounded the crap outta the nozzles and heads and it was like they weren't even there. So my question is, Should I try 60/30/10 or maybe another ratio before changing anything up besides fuel.

 

I have to say I'm still amazed at that crappy 75/15/10. I have FFF Goex and it's just as fast.

[SeaMonkey]

It would be interesting to see how your 75/15/10 propellant mix functions

when rammed as an end burner.

 

A screened 75/15/10 mix with relatively large particles of Potassium Nitrate

will burn more slowly. But if still too fast the 60/30/10 mix will burn more

slowly still. For the larger rockets milling isn't always necessary since milled

powder is always faster.

 

That being said, there is always a feeling of satisfaction when one sees

a core burner literally zoom into the sky like a bullet without exploding!

[davidh]

Reread my answer above. Then go to fpag.org and look at the fourth slide. That's me. It's possible that I might know what I'm talking about...

[Bourbon]

Reread my answer above. Then go to fpag.org and look at the fourth slide. That's me. It's possible that I might know what I'm talking about...

Hand mix only? No wetting, granulating or milling?

 

If that's what you're saying. Will do, and I'll report when I get a chance.

[Mumbles]

It sounds like you're doing some good processing to it. That might be the difference. Trying something in between might be the ticket. 70-20-10 should slow things down a touch. Otherwise handmixing the comp like David suggested should also work. If you want to back things off, mixing in a little charcoal will take what you already have back down a level or so.

Hand ramming can only get so good. As you progress, if you were to be able to press the nozzles and end plugs, I bet it would solve most of the problems too.

[davidh]

I usually granulate. Just add some water til slightly damp (makes an easily broken ball when squeezed), squeeze into balls, push through a screen, and dry on paper sheets. NO BINDER! You want soft grains. This is just to keep dust down and normalize volume measuring.

 

Milling makes much stronger propellant. Moving from RP proportions to BP proportions makes stronger propellant. With a decent charcoal, stingers will fly fine with normal hand-mixed RP.

 

You are blowing out nozzles, which means your propellant is too strong, your nozzle diameter is too small, or your core is too long. With a given set of tooling, the propellant is what you can change.

 

BTW, you can also use more clay in your nozzle. That effectively shortens your core.

 

When you move to end-burners, however, the rules completely change. End-burners for girandolas use the hottest BP you can get, and you make the nozzles with wire-gauge drill bits no more than a couple days before you fly them. You HAVE to extensively test on a scale to know the actual thrust and lifting capacity. Completely different.

[Bourbon]

Thanks Mumbles and David, I appreciate your reply's and insight. I'll try both when I get a chance (rained for 2 days and pesky work always in the way). I'll make sure to give a report back so I don't leave your time helping, wasted.

 

Thanks again!!

[Bourbon]

Alright, here's my report:

 

Screened no milling 130 mesh 60/30/10, granulated using 70% Isop and rammed, 1# Stingers 3/4 X 3 3/4 with Woody's tools and tubes.

 

Went out this morning with four I made yesterday. One of the four without a tangential hole or fuse because some fool forgot to drill the hole before ramming the fuel. I decided to use that one first so I taped a 36" marsh mello stick to it and just stuffed a piece of visco in laughing as I new it wasn't going to fly. Well... I was wrong. It didn't just work. It flew amazingly. So my first flyer was something I wasn't even trying to make lol. So I got out my launch pad and lit a stinger. I was blown away, It was flawless. The last two were so good my wife and I lost site. All four straight up.

 

As a noob I'm dumbfounded and giddy like a little kid. "Early 40's here" I've only made 7 rockets and I have four awesome flights. I'm glad I took yawls advise and kept it simple before making drastic changes. I'm going to try some some 60/30/10 milled next for a touch more heat and see if they still hold on my next run.

 

Anyway, sorry to burn your eyes up, just wanted to say thanks for the help, worked like a charm.

[davidh]

Things to try:

1 - Mix a pinch of Ti with the increment that goes directly above the spindle.

2 - Above the increment above the spindle, fill the remaining tube with star comp. Be careful, some star comp doesn't like to be rammed!

3 - Above the increment above the spindle, fill the remaining tube with very small stars.

4 - If they are flying out of sight, add a few parts course southern yellow pine charcoal to the comp. It really ups the sparks!

 

You can mill the comp, but it's just going to make them fly higher or blow up. Flying higher is good for rockets, because it allows a heaver heading. Problem with stingers is that they get squirrelly when you add extra weight in a header.

[Bourbon]

I'll have to try that as soon as I get my hands on more supplies. New to this, I literally only have the stuff to make RP/BP for the rockets. I have never made stars or anything for that matter.

 

With them already flying out of sight, does that mean they are already capable of lifting a few stars like you mention? I was only going to mill for more oomph to account for weight. Probably jumping the gun.

 

Can I also just use the spin stabilized tooling to make motors without the side vent like I did by accident? Or, was that just luck? I haven't learned the difference in what seams to be endless different styles of tooling yet, besides thee understandable nozzless, nozzled, end burner, cored etc.

 

Thanks again for the hints on the stingers and weight issue.

 

I probably shouldn't have picked stingers as my first rockets but turned out cool non the less.

[Bourbon]

One more question for now. When using a cored motor, should you shield fuse all the way to the top of the core? Or, just into the fuel grain? I have read mixed comments all over the net. Especially lighting delay to early and possibly your payload? So I guess question is, bottom, middle or top?

[davidh]

Different ways of fusing an RP motor make no difference. However you light it, the core acts like quickmatch and instantly lights in my experience.

This is very much NOT TRUE for other types of motors. Fusing a motor with whistle and/or strobe fuel it a bit of an art, or they WILL blow up.

[Bourbon]

Good to know.. Thanks!