End burner vs Core burner

[pyrokid]

Will two 12" sticks function exactly the same as one 24" stick? I doubt it. Will the rocket still fly? I think there is a reasonable chance. It sounds like a test is in order. I have flown 3/4" x 2" motors with 10" long 1/2" square dowel sticks successfully. With shorter sticks the fuel must be faster so there is enough velocity for the stick to do its job.

[mx5kevin]

Nozzleless classic 75/15/10 BP core burners are the best for beginners. They can be made with simple, cheap straight rocket tooling. Factory made 75mm with 160cm stick rockets are using this simple setup. A simple absolute straight rocket tooling and maximum 3-4mm clay, and the fuse in the middle nothing extra. No need for expensive complicated rocket toolings. And don't have to experiment much.

 

End burners are not easy they often don't take off. Users can suffer a lot with them. Core burners with noozle cato are frequent. And it requires specially turned costly tooling. Many beginners buyed under the influence of others unnecessary costly tools. Users can be made for a few dollars these toolings.

 

For a 75mm rocket head with 160cm 10x10 stick, 100mm long and ID 20mm tube used with 5mm absolute straight rocket tooling and normal BP and only 3-4mm (betonite+wax) clay, and visco in the middle of the rocket hole what glued with BP paste. All the factory rockets of this type that I have seen are made this way. They are not used deep nozzle clay, or special costly toolings which narrowed towards the top. The other is a big favorite are whistle rockets, they are much more difficult but they can be done cheaply with homemade toolings.

[justvisiting]

Did you break apart the commercial rocket motors to verify that the core had no taper? I find that very unlikely, but I'm willing to be wrong on that point. I made a few feeble attempts at making my own rocket tools, and it made me appreciate my tooling made by machinists I think the easiest rockets for beginners to make are 'traditional' nozzled black powder rockets. There's no need to ball mill, and the weakness of the propellant makes CATO less likely if they are made by hand ramming, because a beginner probably won't have a press.

[mx5kevin]

Did you break apart the commercial rocket motors to verify that the core had no taper? I find that very unlikely, but I'm willing to be wrong on that point. I made a few feeble attempts at making my own rocket tools, and it made me appreciate my tooling made by machinists I think the easiest rockets for beginners to make are 'traditional' nozzled black powder rockets. There's no need to ball mill, and the weakness of the propellant makes CATO less likely if they are made by hand ramming, because a beginner probably won't have a press.

 

Yes breaked apart the 75mm, 40mm shell commercial rocket motor. All these rocket was simple Nozzleless rockets. A completely straight hole went through the middle of the rocket black powder block. And only 3-4mm (betonite+wax 9:1) clay, and visco in the middle of the rocket hole what glued with BP paste. The black powder had a hard structure. Contained minimal additives (like paraffin, vaseline). There was nothing complicated about it. This is how I make it at home too, it's simple and works well. For beginners, quick success is guaranteed. Perfect for firework rockets where more weight is used, and adding some titanium or other metallic effect for the BP.

[justvisiting]

It would be nice to see some pics to see how they do it. We can't buy commercially made rockets (other than Estes motors) here. I wonder how the propellant grain comes off the spindle, with no taper. Are you hand-ramming or pressing?

 

I press mine to 3000-4000psi. They are nozzleless BP too. I press the powder slightly damp, and that makes a very hard grain. I could never get a straight spindle out in the few times I tried, but I never waxed the spindle either, which is quite helpful. We used to use Vise-grips to grab the end of the finished motor with a rammer in the tube to prevent crushing, and twist it off the spindle. The spindle base was in a vise. Now, the tooling comes with a small tool that screws into the spindle and pulls it straight out of the motor when it's done.

 

When pressing with such low loading pressure, it's easy to get away with a cheap 'tube support','made' by wrapping a long piece of mylar around the motor and holding it with tape when pressing. You might want to try that where you are, since tube supports are very expensive and hard to come by in some places. I use Dur-a-lar that I buy on Amazon.

 

Grafix Matte 20” x 12’ Roll 005” Dura-Lar, Economical Alternative to Drafting Film and Acetate, Translucent Drawing Surface for Lead, Ink, Charcoal, Paint and Colored Pencil, Feet : Amazon.ca: Home

Edited September 17, 2022 by justvisiting

[mx5kevin]

I'm hand-ramming BP motors but pressing with a hydraulic press are much better. They don't over complicate it the commercial rockets they put a little noozle clay a part of which in many cases comes off and the black powder block is visible. The block thus ignites inside the hollow core hole, the rocket launches more stably, and in the pressing or hand-ramming you can work more cleanly. To the BP i add 3% mineral oil. The engine is not dusty retains its shape and the block are hard. The environment is not smeared either too much this way. In the commercially made rockets before pressing the tubes they pull on it onto a mold which leaves a maximum gap of 10 mm at the end of the tube. The rocket tooling is a cheap simple straight metal rod. Before pressing first come a little clay, than the BP. What the English amateur descriptions leave out Nozleless commercial rockets include a 3-4mm little clay at the end of the rocket which burns out at the moment of launching. And that there is no need for specially designed rocket tooling, a completely straight metal rod is used. In the factory, with as few work processes as possible, as simply and made as much as possible on short time the fastest way as possible. It is perfectly suited for launching larger heavier rocket heads with little margin for error. A metal plume or other similar effect is no problem either in the motor. End burner and Core burner with noozle there is much more room for error cato, or doesn't even the rocket takes off. With beginners, many people want to sell them unnecessary and very costly tools.

This is a useful page how to build Nozzleless Rockets (and other fireworks):

http://www.wichitabuggywhip.com/fireworks/rockets/nozzleless.html

or

http://creagan.net/fireworks/rockets/nozzleless.html

 

More authentic than Skylighter tutorials, because Skylighter tutorials they are intentionally over complicated (some compositions and how to make tutorials) to sell as many chemicals and tools as possible.

[nordicwolf]

What are the advantages/disadvantages, pros and cons, of end-burners vs core-burners?

 

From my extremely limited experience and knowledge, I observe:

- core burners need "slower" fuel so as to avoid CATO (60-30-10 maybe, and screen mixed not ball-milled together)

- end burners can use hotter fuel (perhaps even 75-15-10 milled together in the ball mill) and not CATO

 

core burners may use less comp, while end burners use more comp for the same motor size.

 

Does one fly higher than the other? Is one more stable in flight than the other?

 

I guess an end burner might be slower to reach apogee?

 

Is one easier to "time" when a header might go off? Core burner would have much less delay but maybe it gets to apogee sooner?

 

Just wondering when you would use one over the other assuming you had plenty of appropriate BP comp for each style. Thank you.

[justvisiting]

My experience with rockets is strictly practical, but I'll relay a few observations I've made as a hobbyist.

 

Coreburners includes nozzleless core burners. A nozzled coreburner uses a propellant like you described, but a nozzleless coreburner uses a fast milled BP, perhaps with an additive like oil or wax or water to aid consolidation (I prefer water). A nozzled coreburner creates audible thrust for a second or two, and then coasts a bit as the delay burns. The rocket looks nice as it flies and leaves a long thick tail

 

A nozzleless coreburner zips right up there, with a thrust time of maybe .4-.7 sec. This kind coasts upwards more after the thrust stops because it's going faster- quite a bit faster. IMO, these are the best kind to reliably lift large headers, and a nice tail can be added with Feti or Ti. Charcoal can be used in small amounts for a sparser tail and slightly weaker rocket.

 

An end burner delivers the impulse over a much longer time. With a header on them, there's not much upward coast when the thrust stops. The rocket flies slowly and steadily. They are best for small headers, and not much can be done to make a decent tail. Steve Laduke is a rocket motor old timer and he uses whistle powder successfully in endburners. I've never done it, but I have used fast BP. He makes really long-burning end burners that go so high they can have a long delay (C.O.M.) that makes a big streak across the sky for seconds of burn time. I've always wanted to make those but never have. I got the most impulse in end burners by using fast BP dampened with 2% water before pressing, which was suggested by Mr. E. Brown. Since pressing (any) BP rockets with a bit of water, I've never looked back.

 

I mention the coast time because a nice shell would want to be displayed when the rocket is moving more slowly. An end burner needs no delay really, a nozzled BP rocket needs some delay, and a nozzleless coreburner needs most delay- in one guy's opinion.

[utmustang05]

 

With a good press, good powder and NEPT tubes, its pretty easy to duplicate ESTES motors. The secret was actually in the press and the nozzle, not the fuel.

 

-dag

I agree. I can get really close hand raming Estes once fired motor casings.