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Help me black powder core rocket fail and end burner fail


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#1 Josh1986

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Posted 10 September 2017 - 07:07 PM

Hi everyone I just bought woodys pyro starter kit first I made my core burner rocket with 70-20-10 air float charcoal hardwood my first launch at CATO about 15 feet in the air my second on I switched up the bentonite Clay and it flew like a bat out of hell but really was not going the way I wanted it to go the third time it made it about 10 feet in the air and Cato then I switched to the end burner and I don't know if I used the gerb nipple but the one I used was the skinnier one and it went up about 15 feet in the ail then shot straight to the ground I don't now if the second core burner messed up because I drilled pass fire hole in center of the bulk head thanks everyone

#2 NeighborJ

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Posted 10 September 2017 - 07:29 PM

I think we will need some more info here.
1)the core burners are nozzles?
2)is the fuel mix milled?
3)how long is the coreburner delay, and how deep was the passfire hole?

I can say that the endburner fuel will need to be a hotter mix( a more reactive charcoal). The skinny spindle is the correct one for rocket motors.

Jason

#3 greenlight

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Posted 10 September 2017 - 08:26 PM

Are you compacting the fuel well in small increments? CATO could be from crack in the fuel grain.

Did the end burner have a stick the right size that the rocket was balanced?

#4 Josh1986

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Posted 11 September 2017 - 05:53 AM

The core burner did have a nozzle on it my bp was riced (air float hard wood) I did not have delayed comp I just drilled (in middle) of the Clay I used cat litter with oil. My stick was 36 inches long I just used the sticks for my cohete rockets how long should a stick be for a 1 lbs rocket? How do u make time delay for my bp rockets? And I was doing small increments of bp my last question is and please don't make fun of me lol is what nipple is used for end burners because I bought the woodys pyro starter kit and I got all the stuff for rockets Gerbs and stars and both look alike but one is fat and the other one is skinny. Thank you guys for your help

#5 NeighborJ

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Posted 11 September 2017 - 11:35 AM

Hi Josh, the clay with oil is a new one for me. It sounds suspect, but maybe it is used by others successfully IDK. Mine have always been pressed or rammed dry.

I'll start with the endburner, the smaller spindle is for the endburner, it should have a measurement of 3/16" at the choke point. I assume from your description above that the motor didn't have enough power and the issue wasn't caused by a blown out nozzle or a sidewall burnthru. Endburners require the hottest BP you can make but then some coarser charcoal is added to create a tail. I take 75-15-10 meal D and add 5% -30mesh charcoal then screen granulate (without dextrin). This will create the hottest fuel while still having a tail. The motor likely lifted off then quickly lost thrust because of the tip of the spindle creates a small core, after the fuel is consumed beyond it, surface area drops and so does thrust. The delay portion of an endburner is usually made by adding a few percent of sodium bicarbonate to the last 3/4-1" of comp. This will ensure that the motor stops pushing a few seconds before the header is ignited. Delays are not exclusively made with baking soda, really anything which is going to limit the burn rate will work, even nozzled coreburner fuel.

I know I didn't answer all your questions but it is easier to concentrate on one type of motor at a time.

Jason

#6 Mortartube

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Posted 11 September 2017 - 12:37 PM

You should be able to make some nozzleless BP rockets with the core burner tooling. Use a hot milled BP (75 - 10 - 15) and make sure you ram or press it well. To make a delay put the last couple of increments using a slow burning powder. I usually use tiger tail mix. 

 

This won't solve your CATO problems but you can get a few flying before you fine tune motors with nozzles.



#7 dagabu

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Posted 15 September 2017 - 10:54 AM

Jason, why do you want the endburner to coast before the heading goes off? You're only lifting more weight with no thrust, seems pretty counterproductive to me in an end burner that already struggles to lift its load to a usable height. In model rocketry, I can definitely see its purpose but certainly not in fireworks.
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#8 NeighborJ

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Posted 15 September 2017 - 03:11 PM

Hi Dave, I haven't heard from you in a while. IDK, my core burners are tuned to pop at apogee so I rigged the endburner to do the same. No one ever said that I should not use a delay after the thrust so it's just what I thought should be done. I don't like bursting headers at speed, they can horsetail with a weaker burst charge.

#9 dagabu

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Posted 15 September 2017 - 04:55 PM

Yup, lots of stuff going on in our lives this year, I come and go a lot.

 

I think you should try two rockets side by side, one that bursts the shell at apogee and a second that is still screaming as the shell is lit. I think you will find that the appearance is nearly identical for the shell burst. 


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#10 NeighborJ

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Posted 16 September 2017 - 06:02 PM

Dave I'll take your word for it. I have used endburners without delays for salute headers and they work fine. My shell building has come a long way so I think it will be just fine. I tried it early on and had a series of horsetail breaks so I added the delay and never looked back.

There are quite a few things which I did wrong and Jerry rigged a solution for without fixing the actual issue. As time goes on I've been correcting these mistakes.

It's nice to hear from you again.
Jason

#11 dagabu

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Posted 17 September 2017 - 08:23 AM

The only reason I mentioned it is to save people weight because the delay an extra tube will take away from how much shell you can lift with an endburner, which ain't much to begin
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#12 Baldor

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Posted 17 September 2017 - 01:34 PM

Why not add the delay to the shell? (time fuse or espolete)






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