1lb Rockets Failing - I Need Help

[joeyz]

Need some help for i cannot see where i went wrong in my first batch of rockets.

 

Here are my steps...

 

Making BP Rocket Formula. 70/20/10 made 1 lb of this mix.

1. Grinded pottasium nitrate in coffee blender until airfloat.

2. Grinded spruce homemade charcoal of home depot lumber I had laying around.

3. sulfer was already air float.

placed mixture amounts in ball mill with 3/4" lead balls for 4 hours.

poured into container and spritzed about 2 tablespoons water, shaked into all desolved, powder is somewhat a little dusty but not much. a technic I saw Ned Gorski do.

 

Making test rockets, I made 3 each to test.

Rocket 1 - 1lb end burner with nozzle. standard end burner tool

Rocket 2 - 1lb end burner without nozzle. standard end burner tool.

Rocket 3 - 1lb core burner using hybrid / universal rocket tool from woodysrock. and i added 5 small stars as the header with no delay.

 

Test firing the 3 rockets.

Rocket 1 - never left the stand, i went fooooop in a flash and fell to the ground. lol

Rocekt 2 - took off real slow as if it was carrying 50 pounds, and flew in a curve of just 75' and crashed to the ground. lol

Rocekt 3 - it went foooooop in flash and the stars ejected immediately. as i was examining the launch site area after the smoke cleared to find out what happend, 30 seconds later i heard a big thump in the ground about 50' away and went to look. discovered it was the rocket that i was looking for, stuck in dirt with the stick standing straight up like an arrow in the ground, holy cow, hard impact. this rocket burned so fast and took off so fast that there was no trail in the sky.

 

trying to figure out went wrong on these 3 rockets. i assume it has to do with the fuel because a dozen of my previous end burner with nozzle flew perfect follow the instructions of Ned Gorski 1lb 70/20/10 BP, except i used air float commercial charcoal and i did not ball mill. i simply made the batch before in a container and shaked mixed all ingredients and spritzed water, shaked again and started pressing rockets like Ned Gorski steps in video.

 

So, it must be something to to with spruce chocoal or balling milling. are there rules in making BP motors when ball milling BP, milling too long making it more explosive which i don't want. i want it to fly, not blow up lol

 

joe

Edited August 15, 2016 by joeyz

[NeighborJ]

It makes things hard to diagnose when more than one thing is changed in your process at one time. The spruce is a lot more reactive then regular airfloat. It was also ball milled which made it faster.

Did you inspect what was left of the motors for cause of failure? It sounds like a bulkhead failure on the endburner. The nozzleless end burner will not work even with the very hottest bp. The core burner was definitely a bulkhead failure if it ejected it's stars.

Are these perhaps waxed tubes? If so you may need to clean off some wax near the top of the motor so the bulkhead can get a purchase on the tube. If no wax then I'd suspect a problem with grain compaction. Do you use a tube support?

A standard endburner tooling is a 1-4 ratio of tube id, this can usually withstand much hotter fuels than what you are using. So if you are having bulkhead issues it's usually a lack of compaction.

[DavidF]

My least favorite thing is to make rockets with straight mill dust. It never compacts as nicely as anything else. It drives me nuts if I can't find the carcass of a rocket. It sounds like you have all 3. Tell us about them, please!

[joeyz]

thanks for your response.

 

i was using no case clamp around the tube. the tubes were 7" long and 1/4" thick and strong enough to where i didnt need the clamp.

 

i think your right, spruce charcoal and ball milling it made my mixture to powerful.

 

3 weeks ago, i followed step by step instructions of Ned Gorski video of making the rocket bp 70/20/10 and then pressed 12 each 1lb end burner (with nozzle) rockets with my 1 ton press. every single one flew like a charm. i ran out of BP fuel to make more rockets, so i recently made a pound of BP but this time i decided to use spruce charcoal and ball mill everything for about 4-5 hours.

 

it seemed like the end burner (with nozzle) and the core burner rockets burned up within seconds, fooooop! and the end burner without the nozzle slowly took off like it was too heavy. so im think like you, the mixture is too powerful for both end burner and core burner nozzle rockets and too weak for end burner rockets. i know it wasnt a pressing issue, i pressed 12 rockets weeks ago with same press. but the nozzle rockets did poooooof in 1 second flat like i disnt press the poweder at all. weird.

 

what are your thoughts? shit can this BP fuel and use it for shells....lift, break, or prime cold stars as meal powder and just make another BP rocket fuel batch but with commercial airfloat charcoal and no ball milling?

 

i know i have a great ball mill. the longer i ball mill BP powder the faster it becomes almost like a flash powder effect.

 

could it also be the amount of water i used, not enough? does water effect how fast BP will burn in rocket fuel? i used very little water, almost none on that last BP batch.

[joeyz]

tell yout what, pictures have a thousand words. i am going to video the BP mix, press 1 end burner rocket, fire the rocket and post it so you can analyze.

 

David speaks of a good point, this new BP batch is alot more powdery then the first batch i made. it makes sense that mill dust will compact but maybe exands again? causing my rockets to burn up in 1 second lol.

[joeyz]

here is a video of the bp rocket fuel i made, maybe you can see something wrong.

tomorrow will do a video on burn rate dime test and actual rocket taking off.

 

thanks

 

[dagabu]

What tubes are you using? That makes a huge difference.

[NeighborJ]

You can make this work with what you have.

The endburner likes hot fuel and mine can take the hottest bp with a smaller nozzle then you are using. The fuel is not the problem. The problem is compaction.

Sometimes when I wet bp too much then press, it will dry out in storage and cause the grain to shrink. This causes bulkhead and nozzle failures. To fix this problem I just don't wet the comp or I rice the comp and dry it before pressing.

It sounded like you had a tube support for the 1/8" wall tubes, if so try pressing it again with increased pressure on nozzles and bulkheads. If this does not fix the problem as a final resort I run a bead of CA glue along the bulkhead and nozzle so it can grab the tube a little better.

Is your core burner nozzleless? Your fuel is a good choice for nozzleless motors. But if you try to use it in a nozzled motor it will likely be to hot. Those tubes are overkill and I can see your concern. I'd save them for making fountains and try to locate some1/8" wall tubes for rockets. They will still lawn dart but the kinetic energy involved will be a lot less. They are stronger than you think.

[dagabu]

Yupper, those tubes are Marshall's. They have a tendency to crack the inner paper when pressed but when hand rammed, seem to hold better. I have hundreds of them from a group purchase some years back and I made BOS' for years with them and have realized that they are all but worthless for good rockets.

 

The NEPT tubes for sale now are very expensive but Phil's General Store carries an anomaly of a spiral wound tube that seems to be as good as the NEPT most of the time. They are also made to the same specifications as the NEPT tube so the same supports and tooling work with them.

 

I made my VERY hot end burners with NEPT tubes for my dolas and will make next years dolas with Phil's tubes.

 

Frankly, if super glue fixes your problems, you are not using enough pressure, the nozzle should "bell" the tube and grab it. Failure means tube failure, not nozzle failure. I also agree with many, many here in that ricing the fuel is vital and with 2% of dextrin, you get mush better compaction and a grain that is literally glued together.

 

Forgot to say: Waxing the pulpy tubes helps as does controlling the humidity, very dry tubes crackvery easily as well. I found that whetting a rag with water (and 10% benzoate), ringing it out really well, throwing it into a 2 gallon bag full of cut tubes allows for a good amount of moisture to be present in the paper though the tubes touching the rag do get too wet and have to dry some.

Edited August 15, 2016 by dagabu

[joeyz]

okay thanks. i think my powder is too dry and its not compacting correctly. this batch compared to the other, when i add a teaspoon of bp and insert the rammer, dust poofs out. i didnt have that with my last batch. never riced rocket bp before and willing to give that a shot. any postings on how to do that or do i just moist the bp and push through a tea strainer. or do like i make my other bp for lift, wet, knead into ball, rub through a screen. i guess the last batch was small and easy to moist and shake whereas now i made a large 1 pound batch of this stuff and hard to make it consistant throughout which might still be too dry and powdery. i apply the same pressure as the other rockets before, if its too powdery (dusty) is that my issue, wont compact no matter how much pressure? by the way, the nozzles did not blow out of the rocket test i mentioned above and yes, i used a clamp if that helps you assess my problem.

 

- thank you for your comments on tube sizes, i like the 1/8" and will use the other 1/4" tubes thickness for gerbs, fountains and hummers.

Edited August 15, 2016 by joeyz

[joeyz]

Made a video of the 70/20/10 BP fuel test so you can see if too hot or too cold. i think its just right. just too dusty.

 

Edited August 15, 2016 by joeyz

[joeyz]

here you go guys. VIDEO, same bp fuel and pressed it harder. i think cause its so dusty and fine that im not getting it to compact. this time the end burner nozzle rocket left the ground but sputtered like a strobe rocket without the flashes, hahaha

 

your analysis...

 

[joeyz]

another rocket flight test video.

 

in this one, i added water to my dry fuel fuel and moistened it up a but dry enough so its not so dusty. this time i used regular pressing on the 1lb end burner with nozzle. flew great except sputtering is still there. i dont think the sputtering in flight is due to moisture. remember, the other rockets were bone dry dusty fuel and did same thing. maybe my teaspoon measurememts is too large at one time? not sure but at least my rockets aint exploding on the ground now. he was right, i had a compacting issue that resulted in all catos. which i think was because i just could not press that dusty fuel.

 

your thoughts...

 

[DavidF]

I don't thank many guys would recommend 70-20-10 for end burners. It's not strong enough, but yeah, ball milling made it stronger- well faster at least. That small end burner tube looked like a thinner than 1/8" tube, and I thought I saw a spiral in it. Those inner spirals can cause the sputtering. That's not ideal for sure. And the thick pulpy tubes aren't ideal either. Thick is not good, and either is pulpy. You have both.

 

I don't have Ned's instructions in front of me but if I contradict him, then it's me that's wrong.

 

That press is pretty small for one thing.

 

You should not be ball-milling the comp, Joe. The potassium nitrate can be milled. But you don't want to mill the charcoal. I'm talking about a core burner here. Here's why, in my opinion. Charcoal has elasticity. It can be compressed, and then re-expand to grip the tube, which is what you want. If you mill it to death, the elasticity suffers, and it doesn't pack right. If you make 70-20-10 with milled potassium nitrate, sulfur, and unmilled airfloat charcoal, you will have a nice coreburner with a decent tail. It should even work with those tubes. The nozzle and bulkhead perform another function too. They act as plugs to hold the somewhat crumbly propellant grain tightly in place. The air in the charcoal helps the propellant keep tension on the tube. If you mill the air pockets right out of it, not so much. Besides, the charcoal particles that provide a nice spark trail are now too small. And not the ideal charcoal for sparks anyhow- spruce that is.

 

You could make a bigger batch of 75-15-10 with your spruce-based stuff, and use that for end burners.

 

These are just some thoughts that pop into my head on your problem. I hope there is something of use to you. Oh, now I saw the last video! You really should run dampened BP through a screen a couple of times to evenly distribute the water. The little torches don't like the residue fro black powder. It makes the clicky igniters fail. You should try to always light from the side so the spit of fire doesn't go in the end.

 

BTW, these little youtube videos are a GREAT way to get help! Way better than typing!

[NeighborJ]

That chuffing sounds familiar, one of my posts here was about that exact same issue. And it was Dagabu who diagnosed the problem of my nozzle throat being too short. When I made my nozzle it did not have enough clay and it created eddys which made the case pressure surge and drop. Just check your throat length and make sure it is at least two diameters of the opening long this will ensure laminar airflow and steady case pressure. And I do agree with DavidF I'd be using 75-15-10 but it shouldn't be so fuel rich that it causes chuffing.

[dagabu]

The chuffing is strange, let me think on that overnight...

[joeyz]

I don't thank many guys would recommend 70-20-10 for end burners. It's not strong enough, but yeah, ball milling made it stronger- well faster at least. That small end burner tube looked like a thinner than 1/8" tube, and I thought I saw a spiral in it. Those inner spirals can cause the sputtering. That's not ideal for sure. And the thick pulpy tubes aren't ideal either. Thick is not good, and either is pulpy. You have both.

 

I don't have Ned's instructions in front of me but if I contradict him, then it's me that's wrong.

 

That press is pretty small for one thing.

 

You should not be ball-milling the comp, Joe. The potassium nitrate can be milled. But you don't want to mill the charcoal. I'm talking about a core burner here. Here's why, in my opinion. Charcoal has elasticity. It can be compressed, and then re-expand to grip the tube, which is what you want. If you mill it to death, the elasticity suffers, and it doesn't pack right. If you make 70-20-10 with milled potassium nitrate, sulfur, and unmilled airfloat charcoal, you will have a nice coreburner with a decent tail. It should even work with those tubes. The nozzle and bulkhead perform another function too. They act as plugs to hold the somewhat crumbly propellant grain tightly in place. The air in the charcoal helps the propellant keep tension on the tube. If you mill the air pockets right out of it, not so much. Besides, the charcoal particles that provide a nice spark trail are now too small. And not the ideal charcoal for sparks anyhow- spruce that is.

 

You could make a bigger batch of 75-15-10 with your spruce-based stuff, and use that for end burners.

 

These are just some thoughts that pop into my head on your problem. I hope there is something of use to you. Oh, now I saw the last video! You really should run dampened BP through a screen a couple of times to evenly distribute the water. The little torches don't like the residue fro black powder. It makes the clicky igniters fail. You should try to always light from the side so the spit of fire doesn't go in the end.

 

BTW, these little youtube videos are a GREAT way to get help! Way better than typing!

Dave, thank you so much for your response, every note taken and worth a lot to me. i have begun "backup and regroup" actions to correct my anomalies:

 

Rocket Fuel

You make logical sense in chemistry & physics. im no expert in this new rocketry hobby but ball milling the death of carbon (charcoal) seemed to change the properties of the mix that steered away of what i need to use it for, to where it came more explosive mix rather than a fuel. that seemed to be my first issue. the second issue that emerged was the bp fuel batch was too dry. i did a test a few hours ago. i pressed a end burner nozzle rocket, measured the threshold and discovered after pressure release it appeared to slowly decompress itself and as i tapped on the side of the tube to shake off excess powder along the walls. i also noticed that everytime i add a scoop of powder and insert rammer rammer, i would get puffs of dust poof out like an erupting black volcano. messy stuff. so im definately learning. logically, i think i must have enough water to moisturize the formula to allow caking and binding of the ingredients or you not going to compact moon dust. my analysis of this is in contrast to those flat paper thin sponges you see and buy at the store. to save shipping and storage cubic feet, they dampen the sponges, compact them with machines, let dry and it holds its form until a person buys the sponge, takes it home, wets it, and bring is full size again. same can be said about two peices of steel compacting a dry peice of cardboard, it wont hold its compact state (thin as paper) unless there is moisture (caking), it will slowly rise back up after release of pressure.

 

New Rocket Fuel

I made a new 70/20/10 1lb batch before i saw your post of recommending a different formula for end burner nozzle 1lb rockets. This time I simply mixed all 3 airfloat chems in 2 quart rubbermaid container, used commercial airfloat charcoal and no ball milling. shaked it vigoriously for 10 minutes then added about 10 spritz of water from sprayer. i then pressed the nozzle, fuel and added one of my homemade 3/4" red comet star in top chamber with few granuals of my super bp, capped it, added fuse, mounted 1/4" stick and balanced rocket, results, rocket soared about 17 sec, over 1,000+ feet and red comet ejected as planned. there was no sputtering, flew straight as an arrow and performance burn was smooth. my trouble is now gone thanks to you guys, tomorrow, will post of a video of another rocket using this new bp batch. it would be nice now to fine tune the fuel ratio. ie; what fuel ratio is best for 1lb end burner nozzle and which is best for 1lb unversal core burner nozzle rockets. once i graduate those areas, then i can move on to adding headers (3" shells and mines). stars, bp lift/burst, shells, cakes, mines, comets, meteors, racks, firing systems, pyromusical, firework trailers, public displays 1.4/1.3 and scripting has always been my forte', rocketry fireworks is something totally new for me and i thank all of you.

 

Rocket Press

I hear ya and thanks, i believe you that im reaching a threshold. for now, this Ned Gorski harbor frieght 1 ton version seems to do the trick up 2lb rockets. As a systems engineer, i will design and make one of those hydralic presses with gauges, push buttons, changeable rams, and other bells and whistles this winter. im pretty good with things like that. ya should see my custom built 2 man crew "Bismarck" mobile digital 324 gun fireworks trailer, weighing just 3,000 pounds, she can cruise up to 70 knots, towed by my pathfinder suv, shoots over land and sea and takes only 2-3 hours to setup any public display whereas it takes other pyros all day to setup. setting up fireworks every day at six flags and sea world can be time consuming, solution accomplished. i also engineered custom ATF approved kevlar magazine with alarm system, 4' helicopter and a rocket laucher. anything pyro and IT systems is fun stuff, so i cant wait to explore and engineer a more simple affordable universal press solution system for rockets thats safe and highly efficient, i love challenges. Right now im busy with another project, U.S.S Austin, 1,000+ gun semi truck flatbed digital fireworks trailer.

 

 

Rocket Tubes

i like what ya said, here is a photo of the rocket tubes and the tools i have.

 

 

Dag was instrumental in coaching me a few weeks ago on the universal 1LB core burner, MANY different uses. its a step up from the end burner i have. tubes is a problem to find, correct length, ID and thickness. either too expensive or sold out. right now im stuck with a 3 1/2", 3/4", 1/8" thick tubes for my end burner, i prefer longer length. the swirl tube works just fine, i clamp it during pressing. i also seem to prefer the same for the core burner but stuck with these 1/4" heavy 3' tubes. i didnt know exactly what to buy. i guess i use it for hummers, gerbs, fountains.

 

sorry to get long winded, i love pyro science. Nothing can be more exciting than taking the elements produced by our wonderful universe, created through super novas, and safely recreate the same super novas but at smaller scale in our night sky that brought the elements to our wonderful earth. the universe is full of magic and you guys are the wizards

Edited August 16, 2016 by joeyz

[joeyz]

The chuffing is strange, let me think on that overnight...

 

Dag, i think it was something with the bp fuel batch. its gone now with this new bp fuel. still would be cool to know what causes that. that popping sound acted like it wanted to detonate. like a engine with bad spark plugs lol

[joeyz]

NeighborJ, Dave, thanks! switching over to 75-15-10 for 1lb end burner nozzle at soonest. will use this 70-20-10 new batch for the 1lb core burner instead. Edited August 16, 2016 by joeyz

[joeyz]

NeighborJ, roger, when i press the clay end nozzle, i do it fully and leave just 1 mm or 2 mm above the end burner spindle so my visco or ematch touches the bp fuel.

[NeighborJ]

I've slept on it and I just can't leave it alone. I've got one more thought about the chuffing. After I press a nozzle I turn the tube upside down and knock out the excess bentonite, I've noticed that if I forget this step I can hear the chunks of clay ejecting from the nozzle and it sounds like chuffing. If a large enough chunk gets lodged in the nozzle it causes a Cato, but this has only happened on 4 and 2 oz end burner.

[MrB]

You get lose chunks after pressing?

Well, you wrote it, so i shouldn't question it. I guess i should figure out a different question.

 

Does anyone else get chunks of clay that can be "knocked out" after pressing the nozzle?

B!

[NeighborJ]

MrB the chunks I'm referring to are loose bentonite along the walls of the tube, also the nozzle former gets some clay inside it, so when it is removed the clay falls out and into the convergent. This is where most of the chunks come from. It will make a chuffing sound as it gets scoured away.

In no way does the nozzle erode chunks you are reading it wrong.

Edited August 17, 2016 by NeighborJ

[joeyz]

Okay, so last night i was so excited to see my new batch of BP fuel work on my 1lb end burner (with clay nozzle) sail flawlessly and gracefully over 1,000' into the night sky with the exception of using the right mixture instead of using 70/20/10 fuel which should be for my core burner.

 

Being so happy and excited, today i presses another one and it soared to about 50' and went bananas in flight. Seems i have a new problem that i havent seen before. It burned through the side of the casing. I thought maybe the swirl seem busted but the split is not along the swirl seem at all. Maybe someone can explain this one?

 

thing i did different from last night was adding a 2" header. The rocket did take off slower. Which brings me back to what neighborj and dave said, shouldnt use 70/20/10 bp fuel on end burner. I might being already answering my own question. Im thinking because it was lifting slower with weight that gases could not escape fast enough, over heated tube and forced burn out through side. Also, my rocket rack...do you think i need to modify so rocket isnt flush at base, maybe it was a contributor?

 

I added a photo of the tube clamp, could this be the culprit?

 

In the video, i also noticed that something shot out from side of rocket? The rest of rocket fluttered upwards with hole in it lol Clearly the fluttering on this was was fuel ejecting from the side of the engine and ripped paper breaking wind.

 

SEE PICTURE & VIDEO

 

Edited August 17, 2016 by joeyz

[NeighborJ]

Yeah it is a must that you use high quality tubes on endburners. Yes you can use slower fuel but it severely compromises your payload capacity. The cheapo tubes are made from recycled paper and it could be 1/2" thick and will still burn thru. On the other hand you can use high quality tubes with virgin paper or low % of recycled paper 3/32" thick, and make a 12" long 1# motor which won't burn thru. It makes that big of a difference.

Have you ever considered making your own tubes?

Waxing can also help get enough burn time out of cheap tubes but it is not a good solution. Sometimes it will earn you enough burn time to just get thru the burn. While waxing is helpful in almost all other areas of motor construction it should not be relied upon to prevent burnthru.

Edited August 17, 2016 by NeighborJ