BP power trying to make estes E motors

[RocketTony]

I am trying to make estes type e motors for some rockets i have built. I seem to be having trouble producing the needed power to lift the rocket. The rocket is roughly 6 oz. Here is the process flow i am using. 75/15/10 kno3/air-float/sulfur ball milled for 3 hours, screened through a 100 mesh screen. I then add 10% water to the mix, and the bp is screened through a 30 mesh screen and left to dry for several hours. i then pack the tube with bentonite clay and add 24Grams of bp while using an end burner tool from wolter pyro tools . when i ignite the rocket it only wants to lift about 6 inches i am using 3/4 id Convoluted Tubing along with the 3/4 inch tooling. Any help on this matter would be appericiated.

Thank You

Edited June 16, 2011 by RocketTony

[Blackthumb]

Inadequate slow burning BP........

 

Short core......

 

Too large diameter nozle.....

 

I would try lengthening the core first........

 

Check burn rate of BP...

 

There are a lot of 'givens' in rockets but there is also a lot of trial and error.....keep on experimenting...at least you get to smell smoke!

[dagabu]

Same answer on the other thread...

 

I think you hit on your own answer there Tony. I can get some endburners to work very well and lift a very meager payload but at 170g, your rocket motor is really heavy.

 

*Convolute wound tube, convoluted means hard to understand

 

With a dead weight of 146g in a 3/4" tube, I am not surprised that you dont get lift off. Also, let the BP dry longer, several hours is not nearly enough time to let it dry. Depending on the humidity, it can take three days to get dry BP. The only real way to tell is to weigh the comp before you add the water and weigh the comp as it is drying. A few percentages of water can actually make BP faster but just one percent more can make a good powder slow.

 

In a rocket like this, the length of the nozzle throat only needs to be 1/2 ID so dont add any more clay then you need to and dont even bother to add a bulkhead, its a waste in and end burner.

 

You are looking for a nozzle of .188" and no bigger so if you got a gerb set instead, it will be about .25" and as BT says, it may just be too big for good thrust.

 

-dag

Edited June 16, 2011 by dagabu

[RocketTony]

I tried to lengthen the core with mixed results. 1 1/2 inches caused an initial lift but flattened shortly after take off, anything longer than that caused catos. the nozzle bore is 3/16. is there a method to get more power out of the bp?

[dagabu]

I tried to lengthen the core with mixed results. 1 1/2 inches caused an initial lift but flattened shortly after take off, anything longer than that caused catos. the nozzle bore is 3/16. is there a method to get more power out of the bp?

 

Sorry Tony, you didn't address the issues I brought up in the reply so the question about more powerful BP is moot.

 

-The motor is to heavy.

-The BP may not be dry.

 

-dag

Edited June 16, 2011 by dagabu

[RocketTony]

I don't know of a way to decrease the motor weight, without eliminating the bp altogether, any suggestions? a far as the bp being damp i have let it dry for days with the same results, i live in California, in the desert, humidity is not an issue here.

[DeepOvertone]

Tony, What type of mill are you milling with? If it's not a very efficient mill, try milling for much much longer. Maybe on the order of 12 hrs. After that try again. Secondly, end burners need extremely fast BP. It's been tested time and time again, you need some better charcoal. Try willow and a longer mill time. You will get more power. I had the same exact issue. I was using air float that was milled for about 4 hrs. My end burners would barely leave the launch tube. One of the forum members here suggested that I try milling for much longer. I didn't think it would make any difference whatsoever. I was very wrong. After that much time they would leave the tube with no problem. However they still weren't as powerful as I wanted due to the junk charcoal I was using. Hope this helps.

[RocketTony]

it a little cheap 3 lb mill, i am using commercial air float, i will try milling for longer. thanks for the input. one more question is processing with red gum / alcohol better than using just water?

Tony

Tony, What type of mill are you milling with? If it's not a very efficient mill, try milling for much much longer. Maybe on the order of 12 hrs. After that try again. Secondly, end burners need extremely fast BP. It's been tested time and time again, you need some better charcoal. Try willow and a longer mill time. You will get more power. I had the same exact issue. I was using air float that was milled for about 4 hrs. My end burners would barely leave the launch tube. One of the forum members here suggested that I try milling for much longer. I didn't think it would make any difference whatsoever. I was very wrong. After that much time they would leave the tube with no problem. However they still weren't as powerful as I wanted due to the junk charcoal I was using. Hope this helps.

[NightHawkInLight]

If you're trying to copy the engine performance exactly this might help:

 

ESTES C-class rocket engine propellant

Source: rec.pyrotechnics, Composition from 1994 US Dept. of Labour Material Safety Data Sheet.

 

Potassium nitrate.................................71.79

Sulfur............................................13.45

Charcoal..........................................13.81

Dextrin...........................................0.95

 

 

You'll still have trouble if you're not using the exact same charcoal, but it's a start. I would guess that Estes presses their rockets to 1.7g/cc more or less to get the fastest burn possible. I've broken up the grains before to check out the comp and it's very fast stuff.

[DeepOvertone]

Tony, thats the same mill I use. It needs more than 4 hrs to really get it where it should be. And definitely try out some willow charcoal. You will be amazed at the difference in power. Airfloat is fine for core burners but end burners need the hottest stuff you can make. As far as the alcohol/red gum goes, you dont need to add any additional fuel or binder. Doing so will just slow down your BP and not provide any additional benefit as far as binding. I'd also try using your powder straight out of the mill jar. I've heard of people adding water and it was having the effect of re-crystalizing the kno3 into larger particles that aren't as reactive as after its been milled properly. You just have to experiment with all of these variables untill you get a super hot BP. I Wouldnt waste time on bulding motors to test your powder either. When I was experimenting with how much time my mill needed to make my BP as fast as it could be, I just poured a small line out on a piece of paper and lit it off. The first powder which was milled for only a few hours or so burned slowly enough to light the paper on fire. After milling for a much longer time, the powder line burned so quickly that it barely scorched the paper. Have fun experimenting!

[RocketTony]

I will try milling through the night. Thanks for the info. I hope to get these things off the ground soon.

Tony, thats the same mill I use. It needs more than 4 hrs to really get it where it should be. And definitely try out some willow charcoal. You will be amazed at the difference in power. Airfloat is fine for core burners but end burners need the hottest stuff you can make. As far as the alcohol/red gum goes, you dont need to add any additional fuel or binder. Doing so will just slow down your BP and not provide any additional benefit as far as binding. I'd also try using your powder straight out of the mill jar. I've heard of people adding water and it was having the effect of re-crystalizing the kno3 into larger particles that aren't as reactive as after its been milled properly. You just have to experiment with all of these variables untill you get a super hot BP. I Wouldnt waste time on bulding motors to test your powder either. When I was experimenting with how much time my mill needed to make my BP as fast as it could be, I just poured a small line out on a piece of paper and lit it off. The first powder which was milled for only a few hours or so burned slowly enough to light the paper on fire. After milling for a much longer time, the powder line burned so quickly that it barely scorched the paper. Have fun experimenting!

[RocketTony]

Thanks I'll give it a try.

If you're trying to copy the engine performance exactly this might help:

 

ESTES C-class rocket engine propellant

Source: rec.pyrotechnics, Composition from 1994 US Dept. of Labour Material Safety Data Sheet.

 

Potassium nitrate.................................71.79

Sulfur............................................13.45

Charcoal..........................................13.81

Dextrin...........................................0.95

 

 

You'll still have trouble if you're not using the exact same charcoal, but it's a start. I would guess that Estes presses their rockets to 1.7g/cc more or less to get the fastest burn possible. I've broken up the grains before to check out the comp and it's very fast stuff.

[dagabu]

Tony,

 

This is what I was talking about, this motor is a core burner so the weight is about 20g shy of an endburners weight but you get the point that your motor weight seems to be way off.

 

BTW- the little rubber jar ballmills need about 24 hours to properly mill good BP... But watch out, the powder will consolidate and you will get one big ball of media and BP if you dont listen for the change in sound from milling to clumping.

 

http://www.pyrobin.com/files/100_2349.jpg

 

http://www.pyrobin.com/files/100_2350.jpg

 

http://www.pyrobin.com/files/100_2351.jpg

 

-dag

Edited June 17, 2011 by dagabu

[RocketTony]

I am not launching fireworks I am flying model rockets. I have some restraints in which I have to work, ID .75 OD 1 inch and a length of 3.75 inches, which leaves room for 20-22 grams of fuel plus delay charge and ejection charge. the original question was the power of the BP and if there was a way to achieve a more powerful fuel, a question which has since been answered, though the slide show was interesting it was of no use to me. the motor in the configuration i have described, either an end burner or a core burner should, with the right mix of BP be more than capable of lifting a 6oz rocket, without problem.

[dagabu]

I am not launching fireworks I am flying model rockets. I have some restraints in which I have to work, ID .75 OD 1 inch and a length of 3.75 inches, which leaves room for 20-22 grams of fuel plus delay charge and ejection charge. the original question was the power of the BP and if there was a way to achieve a more powerful fuel, a question which has since been answered, though the slide show was interesting it was of no use to me. the motor in the configuration i have described, either an end burner or a core burner should, with the right mix of BP be more than capable of lifting a 6oz rocket, without problem.

 

The name of the forum has Pyrotechnics as the middle name, if this were a model rocket question, you should have said so right away.

 

-dag

[RocketTony]

Apparently you didn't read the initial post and the topic rocketry it does not specify fireworks or rockets and since the basic idea is the same, lifting something off the ground, i assumed this to be the correct topic and area to post my question.

The name of the forum has Pyrotechnics as the middle name, if this were a model rocket question, you should have said so right away.

 

-dag

Edited June 17, 2011 by RocketTony

[dagabu]

Apparently you didn't read the initial post and the topic rocketry it does not specify fireworks or rockets and since the basic idea is the same, lifting something off the ground, i assumed this to be the correct topic and area to post my question.

 

I am trying to make estes type e motors for some rockets i have built. I seem to be having trouble producing the needed power to lift the rocket. The rocket is roughly 6 oz.

 

Well, that helped a bunch, what did I miss? Hmmmm, nope no mention of models, just rockets. Did you know that rockets were pyrotechnic first? You have model rockets we have just plain old rockets. You have it backwards.

 

It's a pyrotechnic forum and there are lots of differences between the two types of engines. In pyro, we seek most of the time to burn end burners for several seconds to lift girandolas and such which aim for a 2:1 lift and no more then 3:1. You are looking for the holy grail, the 4-5:1 thrust of the Estes rocket engine and a burn time of very few seconds, perhaps 4-5.

 

-dag

[RocketTony]

enough of you, your trying to turn this into a pissing match, the general idea is the same the lift is for a Maxim of 3 seconds anything more than that i never recover my rocket and the ratio is more like 2to1 not 3 or 4, so i wish to hear no more from you, the question has been answered by people who understood it. have you nothing better to do? Thank you and good day.

Well, that helped a bunch, what did I miss? Hmmmm, nope no mention of models, just rockets. Did you know that rockets were pyrotechnic first? You have model rockets we have just plain old rockets. You have it backwards.

 

It's a pyrotechnic forum and there are lots of differences between the two types of engines. In pyro, we seek most of the time to burn end burners for several seconds to lift girandolas and such which aim for a 2:1 lift and no more then 3:1. You are looking for the holy grail, the 4-5:1 thrust of the Estes rocket engine and a burn time of very few seconds, perhaps 4-5.

 

-dag

Edited June 17, 2011 by RocketTony

[Mumbles]

I wont comment otherwise than to say that the idea that this was a model rocket seemed fairly clear to me.

 

Should longer milling, or perhaps better charcoal still not be enough there are a few other ways to get some more thrust from the motors. Since you're contstrained with the engine size, one simple fix would be to fit more fuel in there. From the sounds of it, it seems you're ramming them by hand. A press is able to achieve higher pressures, and thus better compaction. There is yet another way to add more power, which is to augment the BP with whistle mix, but I'd treat that as a last resort, and it absolutely requires a press. Testing afterwards and before placing in a rocket is probably a good idea. It'd be a shame to have one CATO and ruin the rocket.

[dagabu]

enough of you, your trying to turn this into a pissing match, the general idea is the same the lift is for a Maxim of 3 seconds anything more than that i never recover my rocket and the ratio is more like 2to1 not 3 or 4, so i wish to hear no more from you, the question has been answered by people who understood it. have you nothing better to do? Thank you and good day.

 

That's too bad Tony, This would have been fun to work through and get your feedback on the way it worked out. Still, with under ten postings, you have shown your true colors and inability to be civil when you have opposition.

 

Good luck and post video please.

 

http://www.pyrobin.com/files/duty_calls.png

 

-dag

Edited June 18, 2011 by dagabu

[stckmndn]

May I ask, do the fins and nose-cone club crowd frown upon making their own motors? Just curious.

[shockie]

Estes model rocket engines never had dextrin in them as a binder.......that rec.pyro posting doesn't correspond to what the Estes MSDS says are the ingredients which is Kno3,S and C. Its is probably around 75/15/10.... I think using 10% water is way too much...I would cut that back to 2-3% at most. Also Estes presses their BP grains to somewhere between 10,000 psi to 20,000 psi......You are not going to achieve that with a mallet or even an Arbor Press...a hydraulic press would be required.

 

Black powder absorbs about 1.5 its weight percent moisture under 75 percent relative humidity at a temperature of 21.1.degrees C. (70.degrees F.) over a period of 24 hours. If black powder picks up sufficient moisture, there is a possibility that the black powder will not burn as fast.

 

http://www.freepyroinfo.com/Pyrotechnic/Black_Powder/Chemical%20and%20Ballistic%20Properties%20of%20Black%20Powder.pdf

 

see page 2.

 

http://www.public.iastate.edu/~codi/PPB/bp-moisture.html

 

 

 

Have you seen this:

 

http://www.skylighter.com/skylighter_info_pages/article.asp?Item=141#art

 

Particle size of the ingredients under mallet pressure will also determine burn rate and whether the powder burns slow or fast. The smaller the particle sizes the faster the burn. 4F BP burns much faster than 1F BP does because of the particle or grain size. At the pressures that Estes presses their model rocket engines, particle size doen't really matter because the ingredients exhibit plastic flow at those pressures.

 

hth

 

Terry

[dagabu]

May I ask, do the fins and nose-cone club crowd frown upon making their own motors? Just curious.

 

There are a lot of prohibitions and lots of clubs bar their use in official shoots. The one exception I saw was motors under J class. I am sure others have experiences different then mine though...

 

-dag

[r1dermon]

the NAR does not allow motor manufacture, however, tripoli rocket association does allow it...the catch is you have to be Lvl 2 certified (which means basically you are proficient enough to build and fly and recover a rocket under power of a J class motor safely. the Lvl 2 certification covers motors in the classes J, K, and L. once you have proved you are proficient with such motors, by passing the extensive written "exam" for the Lvl 2 certification, (it aint that easy unless you've been studying FWIW) you can then build and fly motors of any size up to L. and a Lvl 3 certification covers M class and above (the sky is truly the limit...no pun intended). you can then build motors in the M class, N, O, P, Q, R, S...etc...the largest amateur rocket motor IIRC was an S motor built by CSXT in their space shot. once you start putting together APCP or PBAN in those quantities, you've got yourself one hell of an expensive hobby.

 

a model rocket is a rocket which is designed to fly under thrust of a motor, and be recovered fully in-tact. although they use the same propulsion systems in design (mostly in regards to BP motors), the difference is that a "firework" is designed to produce some sort of pyrotechnic visual, or audible effect, where a model rocket is not.

 

2 or 3:1 is not a safe thrust:weight ratio. unless your rocket is supremely stable, an errant breeze, or rod whip, or just the weight of the backend of the rocket, will send it sideways and into undesirable paths of travel. you're looking for a 5:1 initial ratio. this can be achieved by lengthening the core of the motor. a core burning motor has a higher initial thrust than average thrust, so even if your average thrust is 2-3:1, that will work to "sustain" (hence the reason an upper stage in a multistage rocket is called a sustainer) the initial momentum gained by the initial thrust provided. your initial thrust could be 5:1, 6:1, 7:1...it's all in how you design it. there's a lot more to designing a functional motor *properly* than you think. although, given what we know about the ISP of black powder in general, you know what the potential for your motor is as soon as you weight the propellent. from there you can tailor it to burn extremely slow and produce very little thrust for a very long time, or a lot of thrust for a little time. most estes motors achieve a good middle ground. the thing to realize is that 60g of propellent is 60g of propellent. you could make it lift a light rocket and go extremely high in the sky, or you could make it lift a heavy rocket and go really low...it's all in how you design the core.

[dagabu]

Dang that was a nice posting. Thanks for spelling it all our for us in easy to understand language.

 

-dag