Characterizing Black Powder.

[anapogeetoofar]

In my never ending quest to bring rocket science to rocket art, I have decided to characterize black powder. Several obvious problems pop up, the most important of which is that black powder is the least consistent rocket propellant since brimstone nitre and coal shoved into bamboo was the best rocket available.

So, I have decided to characterize a quasi standardized BP, which is hot 75/15/10. In my case, white pine/black willow based.

 

Thus far, the results have been quite good, I can simulate an end burner with very good accuracy, a nozzleless with "in the ballpark" accuracy (more on that later), and core burners with perfect accuracy (CATO imminent).

In any case, here are the numbers I came up with (no, it isn't metric, forgive me):

 

Characteristic ISP: 75

C* 2509

Burn rate coefficient 0.4

Burn rate exponent 0.164

Gamma: 1.22

Density: 0.062 lb/in^3

 

Now I need YOUR help fellow rocketmen, what I want from you is any data you have on your endburners, nozzleless, and coreburners if the didn't CATO that you made with your standard hot 75/1510.

Hot 75/15/10 ONLY please! No airfloat, briquette, fuse powder, RP, or whatever, ONLY good and hot 75/15/10, let me know the type of charcoal and any binders you used if possible.

 

The data I need is the specifications of the motor (tubing ID, nozzle dia, core dia, length of core/fuel grain) and the BURN DURATION, thrust would be nice, and would make things more accurate but is not needed.

 

After this is done I will be doing whistle, BP comes first though.

 

Thanks for any help, it is appreciated, feel free to try the numbers out and let me know if you think some things need adjusting.

Edited August 7, 2011 by anapogeetoofar

[dan999ification]

my endburners have:

10mm id tube home rolled from 95 gsm recycled kraft 3mm walls,

standard 75 15 10 now milled for one hour, used to be three, im still pushing the motors to lift more than 35g the one hour milled is slightly slower than the three but you can follow them up easy.

i use crack willow for charcoal, makes very hot powder.

2mm nozzle in a .75g clay plug gives 10-12mm.

i use 9 .5g increments for a fuel grain just shy of two inches that burns for 2 secs i will be testing with more fuel soon.

no binder just good ole force

no top bulkhead.

 

dan.

 

 

[allrocketspsl]

In my never ending quest to bring rocket science to rocket art, I have decided to characterize black powder. Several obvious problems pop up, the most important of which is that black powder is the least consistent rocket propellant since brimstone nitre and coal shoved into bamboo was the best rocket available.

So, I have decided to characterize a quasi standardized BP, which is hot 75/15/10. In my case, white pine/black willow based.

 

Thus far, the results have been quite good, I can simulate an end burner with very good accuracy, a nozzleless with "in the ballpark" accuracy (more on that later), and core burners with perfect accuracy (CATO imminent).

In any case, here are the numbers I came up with (no, it isn't metric, forgive me):

 

Characteristic ISP: 75

C* 2509

Burn rate coefficient 0.4

Burn rate exponent 0.164

Gamma: 1.22

Density: 0.062 lb/in^3

 

Now I need YOUR help fellow rocketmen, what I want from you is any data you have on your endburners, nozzleless, and coreburners if the didn't CATO that you made with your standard hot 75/1510.

Hot 75/15/10 ONLY please! No airfloat, briquette, fuse powder, RP, or whatever, ONLY good and hot 75/15/10, let me know the type of charcoal and any binders you used if possible.

 

The data I need is the specifications of the motor (tubing ID, nozzle dia, core dia, length of core/fuel grain) and the BURN DURATION, thrust would be nice, and would make things more accurate but is not needed.

 

After this is done I will be doing whistle, BP comes first though.

 

Thanks for any help, it is appreciated, feel free to try the numbers out and let me know if you think some things need adjusting.

 

all my rockets 1,2,3 pounds use 57/34/09 makes nice long tails

[Blackthumb]

I shoot a lot of 5/8 x 3" motors...can't go too large in my area. I use a standard 75/15/10 mix, milled and then cut it 7.5 : 1 bp:cedar sawdust. Nice steady lift and good tail....and that ratio gives me almost twice the fuel!

They lift film cans, eggs, or 2" paper spheres well....

Edited August 8, 2011 by Blackthumb

[Col]

I did a primitive test using a kitchen scale for a 75/15/10 fuelled rocket motor. The bp was willow based, milled for 3 hours with a little mineral oil added and hydraulically pressed. The core was drilled by hand.

Rocket dimensions as per the pic..its a very low tech design I grabbed some video footage of the test and analysed it frame by frame afterwards, the thrust data (such as it is) is included in the description here

The burn duration was 0.771seconds

http://i770.photobucket.com/albums/xx341/colinspyro/hotfuelrocket.jpg

Edited August 26, 2011 by Col

[shockie]

The major problem with characterizing BP is that BP has charcoal in it......it's the charcoal that determines agreat deal of its final properties. If one was to make bp wit 10 different charcoal types, you would get 10 different characterizations.....Estes has had to deal with this very specific problem over the last 50 years as its BP has become weaker over time. At different time periods they have used Dupont, CIL, Goex, KIK, Goex/KIK,etc There are several excellent papers out on the effect charcoal plays in BP.

[anapogeetoofar]

Thanks for the help y'all!

 

Based On what you gave me and some more testing on my part, the original #'s posted are what I'm sticking to. So, If you have simulation software and want to get a ballpark estimate for hot BP rockets; use those numbers.

 

I'm serious about the "ballpark" thing.

And to reiterate: this is for HOT BP, IE: nozzleless and endburner grade BP.

[Algenco]

my Paulownia BP works great for nozzleless, haven't played with nozzles