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First 1 lb rocket and 3inch ball shell :fail


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#1 fr3dopyrox

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Posted 08 April 2018 - 12:11 PM

Hello today i launch my first 1 lb rocket with 3# ball shell, the balls weight was 120 g , total weight 220g ,with winokur 20 ,with corn cob coated bp ,with 2,5 g flash, the rocket took off, was not very high... the heads burst down !!! , with a nice big loud, my rocket fuel ,no ball milled :60/30/10, the delay was the same with 15% féti, the motor is hand rammed with one 2 lb dead blow hammer,the stick was 1cm/1cm /1,20 meter pine stick, maybe not enough delay? Maybe one pro can tell me how make dummy heading for trials and errors ? Thanks a lot..,
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#2 Baldor

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Posted 08 April 2018 - 02:09 PM

There are a lot of variables here.

 

What is the geometry of the rocket? Nozled coreburner?

 

How fast is the fuel?

 

If your rocket make a good tail, the first aproximation should be to launch it without any shell, an eyeball the timing. Timing should be the same regardless of height achieved. If something is wrong with your rocket, you will see it.

 

Or you can go the obsessive way, and make a test stand. It's easy, it's cheap, and will give you a lot of information.

 

https://www.amateurp...rototype-ver10/

 

https://www.amateurp...s-with-rockets/

 

Once you have your results, you can use this to make some estimations and calculating how much delay you need: http://www.unm.edu/~...eFixedSize.html


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#3 fr3dopyrox

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Posted 08 April 2018 - 03:55 PM

There are a lot of variables here.

 

What is the geometry of the rocket? Nozled coreburner?

 

How fast is the fuel?

 

If your rocket make a good tail, the first aproximation should be to launch it without any shell, an eyeball the timing. Timing should be the same regardless of height achieved. If something is wrong with your rocket, you will see it.

 

Or you can go the obsessive way, and make a test stand. It's easy, it's cheap, and will give you a lot of information.

 

https://www.amateurp...rototype-ver10/

 

https://www.amateurp...s-with-rockets/

 

Once you have your results, you can use this to make some estimations and calculating how much delay you need: http://www.unm.edu/~...eFixedSize.html

hello i have 1 lb coreburner tooling,my fuel is 60/30/10  : kno3 grinded witth coffee grinder,pine charcoal airfloat, sulfur screened. my rocket without heading flying high, my rocket is nozzled.

what is  the geometry of rocket?



#4 Baldor

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Posted 08 April 2018 - 05:07 PM

I made some calculations with the app linked above. Since we don't have data from your motor, I used data from a good performer 15mmID, nozzled, core burner, 60/30/10 milled. 18.2Ns total impulse, 0.5s burn time, and using your weight, a drag coeficient of 1.2, and a frontal area of 44cm^2.

 

Probably the motor used is a little small compared to yours. It give a peak altitude of 83m, and a coast time of 3.1s. This time is what is of interest to you, to adjust the delay.

 

BTW, by geometry I was referring to what you described.

 

About the dummy shell....(Disclaimer, I have zero experience with shells). Depends if you want them expendable or reusable. If expendable, you just need something capable of withstanding the launch. Any ball the right size, filled with cat litter, rice, or whatever give you the desired weight. If you want reusable, you want something more sturdy and properly packed. Just use a set of hemispheres, properly packed so the weight doesn't move around, and "paste" with duct tape or something resistant.



#5 fr3dopyrox

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Posted 09 April 2018 - 02:26 AM

I made some calculations with the app linked above. Since we don't have data from your motor, I used data from a good performer 15mmID, nozzled, core burner, 60/30/10 milled. 18.2Ns total impulse, 0.5s burn time, and using your weight, a drag coeficient of 1.2, and a frontal area of 44cm^2.

 

Probably the motor used is a little small compared to yours. It give a peak altitude of 83m, and a coast time of 3.1s. This time is what is of interest to you, to adjust the delay.

 

BTW, by geometry I was referring to what you described.

 

About the dummy shell....(Disclaimer, I have zero experience with shells). Depends if you want them expendable or reusable. If expendable, you just need something capable of withstanding the launch. Any ball the right size, filled with cat litter, rice, or whatever give you the desired weight. If you want reusable, you want something more sturdy and properly packed. Just use a set of hemispheres, properly packed so the weight doesn't move around, and "paste" with duct tape or something resistant.

hello , thank you baldor , you help me a lot!!!, now i can working with that !.....



#6 CrossOut

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Posted 11 April 2018 - 04:31 AM

hello i have 1 lb coreburner tooling,my fuel is 60/30/10  : kno3 grinded witth coffee grinder,pine charcoal airfloat, sulfur screened. my rocket without heading flying high, my rocket is nozzled.

what is  the geometry of rocket?

 

what your have there is not milled powder just green mix or screened powder.   by"milled" we usually mean that in addition to screening it, you put it in a ball mill for a few hours to further grind the powder down and mix it.   milling your powder will give you a tremendous boost in power.    since your aren't milling this is probably why your rocket are a little on the week side.

 

if you don't have a mill yet i highly recommend investing in one. totally worth the money. 

 

in the mean time, if your are going to forego milling and want to continue screening, you could try straight 75 15 10 air milled separately and screened together. i know several people who had success with this on their 1#ers.


Edited by CrossOut, 11 April 2018 - 04:33 AM.


#7 Baldor

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Posted 11 April 2018 - 07:04 AM

Actually, I'm using milled 75/15/10 in my nozled core burners. I think my problem is the charcoal, pine charcoal sold as pigment. this is why I'm building a tlud.



#8 WonderBoy

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Posted 12 April 2018 - 04:30 PM

I have always favored screen mixed rocket comp, ball milling just felt like a waste, but I rarely ball mill anything. 60-30-10 may work if it is milled, but I found it to be too slow when just screen mixed. Like some have mentioned, screen mixed 75-15-10 may work, depending on how hot the mix is with your pine charcoal. I'd also recommend adding some coarser charcoal to add a tail, something like 75-15-10 +5 coarse charcoal. If that's too hot, then you could back the nitrate down to 70%.

 

Are you planning to test in the daytime? If so, a simple dummy shell can be made by rolling a mock cylinder shell, for a 1lb motor just use a soda can as your former. Then put a small flash bag inside attached to quickmatch as the fuse, and fill around the flash bag with talcum powder or a colored chalk until you have the weight you want. Attach that to the top of the motor like you would a shell, and it'll make it easier to see when your shell would have burst.

 

 

WB



#9 CrossOut

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Posted 13 April 2018 - 04:05 AM

i generally mill everything.   it's easy enough when you can do 1kg batches at a time. 

any way, i was about to get away with 60 30 10 milled hot paulownia for my 4 oz rockets. the moment i put them in my 1# they catoed. pine might be slow enough.. worth a try.  i can't explain why yours aren't lifting well if you are milling tho. usually milled is on the hot end.  perhaps bad charcoal?



#10 Baldor

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Posted 13 April 2018 - 01:30 PM

Mine definitively are due to poor charcoal. I bought it as pine charcoal pigment. Working on making a tlud. My 15mm rockets work well with 75/15/10, but should not, they should cato.



#11 justvisiting

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Posted 18 April 2018 - 10:50 PM

It just kills me how rarely it is ever mentioned that the potassium nitrate has to be milled for rockets, considering how uncommon it is that it is supplied that way.

 

Don't feel bad. For my first 'black powder' rockets, I used black powder! And of course, if you don't know what you are doing, it's always best to start big;) And don't just make one, make a few!

 

I now know that black powder rockets use powder that is black- but not black powder. We live, we learn :)



#12 CaptKen

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Posted 01 July 2018 - 05:05 PM

Hello today i launch my first 1 lb rocket with 3# ball shell, the balls weight was 120 g , total weight 220g ,with winokur 20 ,with corn cob coated bp ,with 2,5 g flash, the rocket took off, was not very high... the heads burst down !!! , with a nice big loud, my rocket fuel ,no ball milled :60/30/10, the delay was the same with 15% féti, the motor is hand rammed with one 2 lb dead blow hammer,the stick was 1cm/1cm /1,20 meter pine stick, maybe not enough delay? Maybe one pro can tell me how make dummy heading for trials and errors ? Thanks a lot..,

I AM A NEW GUY! 

 

Just got my 1Lb rocket tool set. I mixed BP rocket fuel called  "Charcoal-tailed Rocket Mill Batch" from Fireworks Cookbook webpage (83.3,  5.5 and 11.1) but hand mixed it then screened (40 mesh) 3 times. Then granulated using alcohol  and screened it 3 more times at 40 mesh.  

I think the granulation and screening was more than sufficient.  Anybody think other wise or have other or better information or receipts?????

I would be very grateful to hear your thoughts and opinions.

 

RIGHT NOW  I am only experimenting with lift powders and have yet to fire my first rocket. When I figure I've got the mix right, I"ll start adding canister shells/ My thought was to use 'heads' with 4-6

 

oz  of sand (112-158h) to approximate flight time to apex and lift capacity of this fuel; then start with 1/4 stars & take it from there!

 

ANYBODY HAVE ANY COMMENTS or observations or advice- I'D BE VERY HAPPY TO LISTED

 

THANK YOU FOR YOUR TIME AND CONSIDERATION

 

STRAYIN' SAFE

 

CaptKen

 

 

 



#13 Baldor

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Posted 02 July 2018 - 12:22 AM

No need to granulate for rockets.  Just dampen the screened BP with a little bit of water or mineral oil (about 1.5%) to avoid dust and you are done. I put the BP and the liquid in a zip bag and work it manually until it's uniformly mixed. Then screen again and the BP is ready for pressing.

 

If using mineral oil, use some paint thinner or Coleman fuel to dilute it, and work the comp until the solvent has evaporated. I learned this from OldMarine in the APC discord.



#14 CrossOut

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Posted 10 July 2018 - 12:45 PM

I usually granulate w.o dextrin to prevent dust.. Pressing slightly wet with water sounds interesting,   does your rocket need to dry at all?   Are you able to launch that night?



#15 Baldor

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Posted 10 July 2018 - 01:45 PM

With so little water, there is no need to dry. The water is just there to prevent the dust. The same if you use mineral oil.

 

I tested rockets just after pressing, only the time to fuse them and put in the test stand, without any problem. For long term storage, seems mineral oil is better.






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