58 replies to this topic

[donperry]

kn/sui with 1.5% red iron oxide for end burners.

[Bilbobaker]

kn/sui with 1.5% red iron oxide for end burners.

Why red iron oxide and not black?
Just curious

[dagabu]

Why red iron oxide and not black?
Just curious

Brown, yellow, red and black all work as a catalyst with brown *reportedly out performing the others.

*DC

-dag

P.S. Don, please dont use acronyms that are cryptic or ambiguous. "kn/sui with 1.5% red iron oxide for end burners."

[dagabu]

I have been doing HP rocketry since the 1980s but I have to say, I have never made en end burner! Sugar, RC-Candy, AP, BP, all core burners. I launched a bunch of 3# two stage rockets at PGI this year and I have one 3#er lift a 5" ball to 300'. It broke well and all the stars went out before landing. It was a prefab shell but it did work.

I am having pianomistro make me a set so I can see what all the fuss is about end burners.

Dave

 

 

Talk about a necro-post!

 

13 years have passed since I wrote the above post and I have shot about 2000 since that time. For those just learning to make rockets, I am using ball-milled BP using the 75:15:10 Sir Francis Bacon formula using Humphry's airfloat charcoal and 2% white dextrin liquor (137.5g of water and 20g of white dex in a 1 kilo batch of BP). 

 

I am also pressing them to 6500PSI in small increments in order to control the burn rate and slow the burn some. Most of the motors I make nowadays are being used to power Girandolas so I am using 6-18 motors each launch and I have them dialed in pretty good!

 

Interestingly enough, I am making a bunch of 5/8" ID motors to launch 8" dolas as of late. They scratch the itch but take just a small amount of powder (21g each) to make. 

[nordicwolf]

So about the 75:15:10 described just above ... is that what you use in the end-burner set you got 13+ years ago?

 

What is your mix for core burners?  Do you add dextrin to that?  Does the dextrin reduce risk of CATO?

 

I have 1/2" tooling for end burner and core burner.  I have a press, ball mill and ERC charcoal.  I am considering 6:3:1 (or just 6:3) for the core burner, and 75:15:10 for end burner.  Hopefully the ERC is not too hot for the tooling ... it seems most of the posts I have read suggest commercial hardwood which I understand is slower.

 

I also have 3/4" universal tooling (and something called Econo Tooling for 3.75" x 3/4" tubes, spindle shape looks like universal, fatter than core burn and a bit shorter).  Anyway for the Universal and Econo Tooling I am considering 75:15:10 with ball milled ERC.

 

If I were to try the Steve Laduke formula 60:30:10, I would ball mill 60:15:10 to get the fine meal, then add in 15 of 80-Mesh.  Except I do not have commercial hardwood charcoal.

 

Oh!  one last question...where do you fuse the core burn motors?  I have been told that if you use quickmatch to get ignition at the top of the core, the motors take off like a bat out of hell.  If you fuse it so the ignition is at the bottom of the nozzle, the power is greatly reduced but still functional.  In other words, another way to control thrust is where you fuse the motor.

 

So many variables!

 

Thanks.

[nordicwolf]

and thanks for posting about Humphrey's charcoal.  I may order a 20# bag of the hardwood lump charcoal to try it out as a source for, um, hardwood charcoal.  Hopefully shipping is not a killer.  I guess I should look locally as well to see what sort of similar charcoal may be available at retail.

[dagabu]

So about the 75:15:10 described just above ... is that what you use in the end-burner set you got 13+ years ago?

 

What is your mix for core burners?  Do you add dextrin to that?  Does the dextrin reduce risk of CATO?

 

My mix is always the same for BP, 75:15:10 plus 2% white dextrin liquor (137.5g of water and 20g of white dex in a 1 kilo batch of BP).  I use the same BP for core burners, end burners, zips, girandola drivers, monocopter drivers and Z-bombs. Dextrin MAY reduce the RUDs but I dont see a difference with my rockets. 

 

I have 1/2" tooling for end burner and core burner.  I have a press, ball mill and ERC charcoal.  I am considering 6:3:1 (or just 6:3) for the core burner, and 75:15:10 for end burner.  Hopefully the ERC is not too hot for the tooling ... it seems most of the posts I have read suggest commercial hardwood which I understand is slower.

 

​I made a LOT or ERC charcoal years back, I had a truck full of bales from the pet store and sold a bit of it to make money to attend convention one year. It was fantastic and had a lot of power but now I just want it to be reliable 100% of the time.  

 

I also have 3/4" universal tooling (and something called Econo Tooling for 3.75" x 3/4" tubes, spindle shape looks like universal, fatter than core burn and a bit shorter).  Anyway for the Universal and Econo Tooling I am considering 75:15:10 with ball milled ERC.

 

The Econo Tooling is the result of a collaboration between caleb and I when I started the Cohete flights a few years back. I had asked Cal for tooling for the 5/8" tubes 3.75" long as well as the tooling for the 3/4" tubes. My wife uses the 5/8" tubes on her 3 ton arbor press and I use the hydraulic press on my 3/4" Cohetes. We alway make them without nozzles or bulkheads and fill them to the top of the 4" tube! They easily lift a 3 inch ball shell to an acceptable height but a 10g report is the most pleasing to most. 

 

If I were to try the Steve Laduke formula 60:30:10, I would ball mill 60:15:10 to get the fine meal, then add in 15 of 80-Mesh.  Except I do not have commercial hardwood charcoal.

 

If you make ERC charcoal, hardwood charcoal is just as easy to make. I also add 5-8% coarse charcoal to my fuel for a bushy tail and it eliminates the thrust drop when homogeneously mixed before corning. 

 

Oh!  one last question...where do you fuse the core burn motors?  I have been told that if you use quickmatch to get ignition at the top of the core, the motors take off like a bat out of hell.  If you fuse it so the ignition is at the bottom of the nozzle, the power is greatly reduced but still functional.  In other words, another way to control thrust is where you fuse the motor.

 

Sorry, there is no free lunch in physics. You will get the same useable thrust measured as total impulse. The total impulse (I) of a rocket is defined as the average thrust times the total time of firing. So measure the thrust and the total time of firing for each example. 

 

Personally, I J-hook my core burners with Chinese visco and insert a flared end of Chinese visco into the nozzles of my end burners and use 4 strands of commercial Chinese quickmatch in the nozzles of drivers. 

 

So many variables!

 

Thanks.

Edited by dagabu, 01 September 2022 - 03:36 PM.

[nordicwolf]

So much good info. Thank you. And thanks for the info on the cohete tooling.  I have a few more questions specific to that.

 

1.  what is "RUD"?

2.  for the 3/4"x3.75" tubes, how do you attach your stick?  a single 36"x1/4x1/4?  Or do you break it, say, 26" on one side and 10" on the other side?  When I got the tooling from woody, I also got some 36x1/4x14 sticks

3.  Is it the same "stick strategy" if no header, 3" ball shell header, or 10g report header?

4.  how did you attach the 10g report?  Was it a 1" ID tube slid over the end of the motor?

5.  do you wax tubes, cores, or anything special when using the 3/4"x3.75" tooling?

6.  do you press 75:15:10 the entire length of the tube?  Or do you go to something slower for delay once you switch to the flat rammer?

7.  finally regarding your comment: I also add 5-8% coarse charcoal to my fuel for a bushy tail and it eliminates the thrust drop when homogeneously mixed before corning."  how does corning enter into this?  I thought corning was the breaking up of a pressed puck of BP, so I do not understand the comment.

 

Thanks again very much!

[dagabu]

So much good info. Thank you. And thanks for the info on the cohete tooling.  I have a few more questions specific to that.

 

1.  what is "RUD"? Sorry, RUD = Rapid Unplanned Disassembly

2.  for the 3/4"x3.75" tubes, how do you attach your stick?  a single 36"x1/4x1/4?  Or do you break it, say, 26" on one side and 10" on the other side?  When I got the tooling from woody, I also got some 36x1/4x14 sticks Naw, those motors just get one stick, about 24" long, 1/4" X 1/4". We use tarred string to attach sticks to the Cohetes. They stay tighter that any other method, period!

3.  Is it the same "stick strategy" if no header, 3" ball shell header, or 10g report header? Yes sir 

4.  how did you attach the 10g report?  Was it a 1" ID tube slid over the end of the motor? Yes

5.  do you wax tubes, cores, or anything special when using the 3/4"x3.75" tooling? Nope, I tried all that stuff with absolutely no difference found in the end, dry tubes, dry spindle. 

6.  do you press 75:15:10 the entire length of the tube?  Or do you go to something slower for delay once you switch to the flat rammer? 75:15:10 all the up, including the delay of 1 ID above the spindle, adjust as necessary.

7.  finally regarding your comment: I also add 5-8% coarse charcoal to my fuel for a bushy tail and it eliminates the thrust drop when homogeneously mixed before corning."  how does corning enter into this?  I thought corning was the breaking up of a pressed puck of BP, so I do not understand the comment. Corning is my word for making grains by pushing the whetted BP ball through the 1/4" mesh. Not sure what the right word is. 

 

Thanks again very much!

[nordicwolf]

I have a bunch of 1/4" x 36" square dowel sticks.  If I were to use 24" lengths with 3/4"x3.75" cohete tubes, what can I do with the 12" left over?

 

Can I glue and tape two 12" lengths together and use that as a "24 inch" stick on another cohete rocket?  Thank you.

[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 by justvisiting, 16 September 2022 - 10:32 PM.

[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.wichitabu...nozzleless.html

or

http://creagan.net/f...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.