Colored Rocket Fuel Problems

[Guest PyroManiac1]

I used the Ruby Red Formula from this article https://www.skylighter.com/blogs/how-to-make-fireworks/colored-rockets and mixed by shaking (like sugar fuel).

 

My tubes are a little less than 1cm ID and about 2 inches long. I made a clay end capping and a mini clay nozzle. I cored it about 2.5cm into the clay and rammed fuel. I balanced a thin bamboo stick and hot glued the fuse into the cored cavity just to keep it in place.

 

It flew, but went up about 4 feet and flew right back at me. Anyone know what I am doing wrong?

Edited April 13, 2020 by PyroManiac1

[Mumbles]

I would look into how fine your chemicals are first. Secondly, try screening the mixture together. You'll get a better mixing than just by shaking.

[SharkWhisperer]

Oven dry your strontium nitrate. Put it through the coffee/spice grinder first. You want dust. Like Mumbles said, sort it through a 40-mesh (or 60, or 100) screen 3x (not once, not twice) instead of shaking, which is guaranteed to settle your heavier ingredients to the bottom of your container. If you don't have sufficient screens, then get some, or make them. Safely (stainless steel mesh).

 

What kinda charcoal are you using. Critical factor here. You're mix is already oxidizer poor, even for a semi-core-burner, so your fuel better make up for it. How fine is it? How wet is it? Charcoal loves atmospheric water. Oven dry that, too, after it's truly airfloat. If you're making it from Kingsford briquettes or using "commercial hardwood airfloat", you're using a sissy slow-burn charcoal. Same for a kit from Skylighter or anybody else. Kit's generally suck.

 

You "cored it about 2.5 cm into the clay" in a 5-cm tube??? Uh, this sounds like your nozzle mix (heavy) is taking up half your tube; I hope that's not the case. 1/4" nozzle length should be fine. 3/8" max (one ID) for these dinky motors. Your problem is not blowing out nozzles.

 

Just looked at skylighter's formula. Looks like an oxidizer-restricted star or gerb formula repurposed for rocket fuel. Do not add dextrin. You do not need a binder and it is a shitty rocket fuel that will slow things down. Red gum is a little hotter fuel, but at 2%, again you do not need a binder, it is probably not an essential fuel. Drop the dextrin before anything. Then swap the red gum for more oxidizer. Do one thing at a time.

 

Parlon frequently has small chunks in it--don't bother trying more than casually to break em up on the screen; just dump em.

 

And you don't need a clay endcap if you're shooting them right away. Cardboard disc is sufficient. And light. You might clay cap them if you're storing them because the strontium nitrate will want to suck up atmospheric water with the quickness, rendering them inert firepit enhancers within a few weeks or months (or days if in tropics). But it'll come in the fuse hole, too, and through cardboard walls eventually, so if stored keep some desiccant in with them. And in your airtight jar of milled/baked strontium nitrate. And in an airtight jar containing your milled/baked high-quality charcoal. And in the airtight container containing any finished comp.

[Guest PyroManiac1]

I am using the same ERC charcoal I use for my black powder. I don't have any screens, so I guess I'll ball mill the comp. I cored 2.5 cm into the 1/4" clay nozzle and the fuel. I forgot to mention that after the flight I found the remnants and saw the nozzle was completely gone. I substituted the Red Gum in the formula with 1.7 grams of Phenolic Resin. I will have to mix it again without dextrin. What do you mean substitute my red gum (my case Phenolic resin) with more oxidizer?

[Mumbles]

Absolutely do NOT ball that composition. That's a very dangerous idea. I wouldn't even ram it as you've been doing.

[SharkWhisperer]

I am using the same ERC charcoal I use for my black powder. I don't have any screens, so I guess I'll ball mill the comp. I cored 2.5 cm into the 1/4" clay nozzle and the fuel. I forgot to mention that after the flight I found the remnants and saw the nozzle was completely gone. I substituted the Red Gum in the formula with 1.7 grams of Phenolic Resin. I will have to mix it again without dextrin. What do you mean substitute my red gum (my case Phenolic resin) with more oxidizer?

Mumbles is SO right. Amigo, you're considering milling a comp with Perc, another nitrate, MgAl, and sulfur??? Are you suicidal. You're blowing nozzles? Your nozzles suck. Fix that first. You don't have screens? Go to the dollar store and get a bacon grease pan-top screen. For a buck. It's about 30-40 mesh. Phenolic resin? Wtf? WHY???? You do not need a binder. Period. And there's much better fuels.

 

Amigo, with all due respect, you are taking poorly-thought out shortcuts, contemplating dangerous actions without even realizing it, arbitrarily changing a comp recipe with clearly little knowledge of how each component functions and why it's there.

 

Do this: Build a simple black powder rocket. Then make another 100 or them. When you get to 100 without a nozzle blow-out or other tube explosion, then consider yourself a beginning rocketeer and move on to other comps. AFTER you read, read, read, and actually gain some working knowledge of pyro ingredients. You'd doing the cookbook approach instead of the scientific approach and it is very likely to get you hurt or worse.

 

I have no further advice to offer you, except that you seem to be getting waaaaaay ahead of your abilities and knowledge base, and that is not a good place to be.

[Guest PyroManiac1]

I have already mastered black powder rockets in that same tube. I have never had a black powder rocket CATO. You are under estimating my friend. Yes I was stupid to even suggest ball milling, I apologize, I probably wouldn't have done it anyway, I like to save the ball mill for strictly black powder. I bought a strainer of unknown mesh size from Walmart,(looks small enough to mix a comp). I never had a nozzle blow out in any of my black powder rockets, maybe it crumbled when it flew into the wall and hit the ground. In all of my stars I substitute Red Gum with .85% Phenolic resin. Again, I was following Skylighters recipe which never excluded a binder. I thought that since Phenolic resin was a hotter fuel it might aid the composition. I'll leave it out along with the dextrin. So to sum up, I will use the same recipe just leave out the binder, correct? If you want to suggest another red rocket fuel that will work better, be my guest.

[Arthur]

Ball milling clean ingredients can be very good, ball milling mixtures can be very BAD. BP is probably the only comp I'd mill.

 

Have you retrieved the motor casing? Change of direction is usually due to change of thrust. either as the nozzle blows out or as the cored portion is finished and the coreless part continues at lower thrust

[Guest PyroManiac1]

Arthur I did retrieve it and I believe the nozzle blew out. So I will try again with my fuel, no binders, screen mixed and maybe score the tube with a slightly thicker plug.

[Mumbles]

The other thing to take into consideration is that there comps burn hotter. It may be eroding the nozzle or tube, weakening the bond. You may want to consider selling if you can add a convergence to the inside of your nozzle. You can get more surface area against the tube, and help funnel the hot gases out more efficiently.