59 replies to this topic

[dr thrust]

yeah, more of the same im afraid, first a 1 lb perc bp motor pressed to two tonnes on my press to see if this would improve performance in a vain attempt to recreate the chuffer again, but has eluded me so far, must be a core design thing.

secondly on the vid you may of noticed Ive been testing whistle rocket at the same time but with really slow motors, i was using standard 70, 30 whistle, but after reading an article in AFN it was suggested that you could tweek this by using the sodium salicylate formula but using k benzo in the same amounts as the sodium formula

heres the tweeked formula potassium perc 64, potassium benzo 32,red iron oxide 1, petroleum jelly 3, and wow this tweek on the 70, 30 formula really wakes up the rocket, judge for yourself rocket test

[dr thrust]

well, might as well resurrect my old thread, ( i like to keep all my work together it's easier to search)
hmm potassium sorbate ehh ..well popped down to the "local home brew shop" and procured myself 100g
and proceeded to make myself a small batch of propellant , pot perc 75,pot sorbate 25, iron oxide 1, Vaseline 3 and left to dry for a week
then knocked up a little 1lb motor,with homemade tooling 9mm wide by 35mm long spindle, base 19mm dia.
the motor was 80mm long using 22grams of propellant ,total weight of finished motor 54gram,
"notes on pressing, the propellant presses extremely well with relatively no extrustion into the rammer under pressing load, unlike pot benzoate"


and finally a video of a successful rocket test, and it whistles to boot!

[digger]

Very cool. You have proved it before I had a chance. Nice to see that it whistles in a fashion too. How was it in real life? It sounded quite a bass note for a whistle.

Edited by digger, 28 April 2010 - 11:13 PM.

[dr thrust]

yep it was great "in real life" at bit short lived as i only used the minimum amount of propellant, only just covering the spindle with a clay end plug.
i didnt know if it would get off the ground or cato and wanted to keep the bang!! to a minimum lol.
lots of base in the whistle sound,very cool!
id say there's more experimentation needed yet with different fuel ratio's, tooling design, i think i'll try a 10mm longer core next

[dr thrust]

yeah me again!
for your amusement? a video for how to make copper sorbate, followed by a test motor.
the motor ,same dimensions as the last sorbate rocket, same fuel ratio, but copper oxide as a catalyst
notes on pressing, presses well
notes on fuel ,burns with blue tint, but more hygroscopic.
conclusion; the addition of copper to the fuel stops whistling,difficult to store because of moisture absorption, possible blue colored propellant,
so all in all a novelty propellant not really worth the effort! VIDEO

[digger]

Interesting stuff there Thrusty.

Just a quick question. I note you used gravity filtration. Did you wash the filter cake to remove the postassium sulphate?

The only reason I ask is because I made some copper sorbate and gave it a good wash while vacuum filtering it. I made up 10g of composition and did not note any great hyroscopic nature.

Edited by digger, 25 October 2010 - 09:17 PM.

[Vic]

so all in all a novelty propellant not really worth the effort!

I think it was worth the effort, somebody needs to test these rockets.
The best bit is you are sharing your results and that gives others something to build on.

[dr thrust]

thanx, yep there's a good chance of sulphate contamination, i washed it once, not enough i guess? but it was my first attempt, as for performance, id say the propellant particle grains where to large, fuel and perchlorate needed milling finer ( separately of course!)before combining.
it was just a basic experiment to answer a question

Edited by dr thrust, 25 October 2010 - 10:15 PM.

[digger]

thanx, yep there's a good chance of sulphate contamination, i washed it once, not enough i guess? but it was my first attempt, as for performance, id say the propellant particle grains where to large, fuel and perchlorate needed milling finer ( separately of course!)before combining.
it was just a basic experiment to answer a question

As Vic says interesting.

Do you think it is worth a try with AP or pot chlorate as a propellant? It may be bluer (if there is such a word)

[dr thrust]

i believe vaslop as tried ap/copper sorbate in the colored rocket fuel thread, in fact it was this thread that inspired me to try this k perc formula.
vaslop had a cato, probably because the copper acts as a catalyst aiding the rapid decomposition of the ap?.( im sure ive read your not supposed to mix ap with copper somewhere))
potassium chlorate's out of the running for me, because, chlorate whistles are more sensitive, so it a safety issue there.
as said before i didn't set out to make a blue propellant, i was interested in forming some hard evidence that the addition of copper killed off the whistle effect.
the propellant is lazy and the formula needs tweaking, then just add parlon? for more "bluer"? me thinks so

Edited by dr thrust, 26 October 2010 - 06:03 PM.

[digger]

i believe vaslop as tried ap/copper sorbate in the colored rocket fuel thread, in fact it was this thread that inspired me to try this k perc formula.
vaslop had a cato, probably because the copper acts as a catalyst aiding the rapid decomposition of the ap?.( im sure ive read your not supposed to mix ap with copper somewhere))
potassium chlorate's out of the running for me, because, chlorate whistles are more sensitive, so it a safety issue there.
as said before i didn't set out to make a blue propellant, i was interested in forming some hard evidence that the addition of copper killed off the whistle effect.
the propellant is lazy and the formula needs tweaking, then just add parlon? for more "bluer"? me thinks so

looks like there is some scope for sperimenting there, mmm if only the blue whistle was viable without compound motors.

Edited by digger, 26 October 2010 - 11:03 PM.

[dr thrust]

"compound motor" please elaborate ? is it a whistle sound producing unit, a fixed to the side of a colored motor or is it a multi layered composition, blue lift propellant ,then last quarter of the core and delay whistle?
maybe the sorbate isn't a good candidate for a colored whistle, i have found this on the forum as a proposed blue whistle
Potassium Perchlorate, 60
Copper Benzoate, 30
Copper Oxide, 5
PVC

Edited by dr thrust, 27 October 2010 - 07:14 PM.

[dr thrust]

i thought "dj's nozzle-less page was lost but ive found it for who ever may be interested
and with a bonus blue strobe comp blue strobe nozzle less
and the main page here
and some more garb on whats happening in a nozzle-less motor, i found on the interweb whilst researching nozzle less spindle design clicky clicky

Edited by dr thrust, 16 February 2011 - 10:59 PM.

[digger]

i thought "dj's nozzle-less page was lost but ive found it for who ever may be interested
and with a bonus blue strobe comp blue strobe nozzle less
and the main page here
and some more garb on whats happening in a nozzle-less motor, i found on the interweb whilst researching nozzle less spindle design clicky clicky

Interesting stuff there Thrusty, I would love to see a video of the blue strobe rocket.

The last link appeals to my sceintific nature, if I get a chance I will sit down and digest that one.

Cheers

[dr thrust]

yep the blue strobe does look interesting ... hmm ill put it on my "to do" list!
yes the "internal ballistics considerations of nozzle-less rocket motors" paper, is very interesting indeed
they test four motors with different cone shaped aft end geometries, and come to the conclusion that a flat ended propellant is the most favorable,and a small diameter chamber is the best performing.
now, i wonder if it was shear dumb luck that dj's tooling has these same attributes? was he just using the simplest set up he could make with-out a lathe?, the first bp nozzled tooling i made wasn't far off, just a straight rod, not the best for nozzled motors,but possibly a dream for nozzle-less motors.
one thing i did notice on my motors, as the tube id increased, performance tailed off, i wonder if a small dia chamber in a larger motor would help?
1lb motors fly well, but reducing the tube id from 3/4" to 5/8" maybe the ticket but its not a popular size

Edited by dr thrust, 17 February 2011 - 11:22 PM.