[sugpro] Re: Intrimidator 5 - Flight IV - KILO 6G KNSU PG reload

  • From: Kenneth Irving <kenneth.irving@xxxxxxxxx>
  • To: sugpro@xxxxxxxxxxxxx
  • Date: Thu, 15 Oct 2015 17:41:31 -0200

Richard: sorry ¿which one was 4?
best regards
Kenneth

2015-10-15 14:37 GMT-03:00 Richard Nakka <richard.rocketry@xxxxxxxxx>:

Thanks for the interesting update. Sounds like propylene glycol
isn't the greatest for viscocity reduction.
From my own experience, the most effective ways of reducing viscocity
of the slurry (to make the propellant pourable) are:

1) larger KN particle size (e.g. granular)
2) use lower fraction of oxidizer (e.g. 60/40 instead of 65/35)
2) residual water
3) use of surfactant such as sodium laureth sulfate

Comments on these:
1) quite effective in making pourable slurry. Drawbacks are reduced
burn rate and lower performance
2) quite effective, same drawbacks as (1)
3) very effective. I find that sorbitol contains a fair amount of
residual moisture. Drawbacks are slower burn rate, reduced performance
and slower setting grains.
4) extremely effective, works best with sorbitol, works ok with dextrose.

cheers
Richard


On 10/14/15, Vertical Limits <sugpro@xxxxxxxxxxxxxxxxx> wrote:
Hi List,



Just a small update on the 4th flight with my Intimidator 5 rocket on an
experimental baby M-class sugar motor. This time on a KNSU PG reload.
https://youtu.be/cIde00cdRBE



For this flight I tried the KNSU + 1,9% propylene glycol mixture (1,9% is
nett added mass) as I was looking for higher thrust and a shorter burn
so I
can use the same motor as a booster in a 2-stage configuration – as well
as
the interesting outcome what different candy propellants do in the same
motor / rocket. Propylene glycol was tried to improve pourability /
casting
and only added just prior to pouring. After simulating in SRM 2014 and
reading up on KNSU on Scott Fintel’s site I got a little concerned on
KNSU
MEOP even boosted when using KNSUI icw RIO so I conservatively tried
KNSU +
PG. Supposedly making no little to no difference in burn rate. SRM
indicated a burn time of 1,6seconds for straight up KNSU.



Some notes:



· Attached the outcome of this flight on KNSU 1,9% PG. It is
almost
the same as straight up KNDX with a 3s burn time but much more tedious to
melt / cast and lower desity. It requires continuous stirring to prevent
caramelisation and I can only melt one grain / 850gr batch at a time in a
electric pan. I ruined a perfectly good dedicated pressure cooker due to
this.

· Isp is good and considerably higher than KNSB reloads.

· The propylene glycol used was 99,5+% pure and indeed is makes
the
propellant better pourable but did not have a noticeable effect on
density
– it sure fumes though.

· I also tried straight up KNSU as a test grain which actually
gave
a slightly better density. 80% of the batch could be poured in the
casting
tube and the remaining KNSU required scooping.

· In all cases the propellant was not vacuum cast due to the
hazard
of carmelisation but did used a spring loaded compression mould.

· Average KNSU PG density was steady 95,3% of ideal. Test grain of
plain KNSU gave 96,3%.



Most likely I will not use this propellant in a future motor again. PI
pefer casting KNDX with better density any time for an equivalent thrust
curve. The addition of propylne glycol improves pourability but the added
benefit is questionable and likely surpressing the burn rate of KNSU a
bit
(although I haven’t valided this with a KNSU reload).



Regards,

VL.



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