Now I have to disagree with you, Rick, a qualified disagreement. For my new
M-motor, I ground the KN very fine. The heated slurry was viscous, but
nearly pourable at 120C. So I heated it to 130-135C thinking it would get
more fluid - no, the opposite, it became even more viscous. This was the
case with all 11 grains I cast for that project.
Possible explanations for our discrepant observations:
1) my KN is very fine, yours is granular
2) my products are quite dry to start with, heating drives out what little
moisture is present (residual water is known to make a slurry more fluid)
R.
On Fri, Mar 29, 2024 at 10:36 AM Rick Maschek <dmarc-noreply@xxxxxxxxxxxxx>
wrote:
Richard, I've seen that video using surfactants a few times and this time
I converted the 119 C you begin with (unpourable) and the 130 C with
surfactant that you do the pour. 119 C = 245 F and 130 C = 266 F. The
hotter the KNSB the less viscous it is. I'm not denying surfactants don't
work; I remember years ago when we had a batch of KNO3 that was super
powdery and the melt was like mash potatoes and we tried Scott Jolley's
surfactant method.
surfactant <http://www.ajolleyplace.com/surfactant.html>
surfactant
Surfactants
<http://www.ajolleyplace.com/surfactant.html>
It made the otherwise unpourable pourable.
I don't grind my KNO3 super fine and in motors 4" and above, I don't grind
any and am able to pour my KNSB at 220 F ( 105 C ). When you are making
KNSB motors with 70 to 650 pounds of propellant, grinding the KNO3 to a
powder isn't an option.
Rick
On Friday, March 29, 2024 at 08:16:35 AM PDT, Richard Nakka <
richard.rocketry@xxxxxxxxx> wrote:
Sodium Laureth Sulfate works very well.
https://www.nakka-rocketry.net/sorb.html#Casting
Have you seen my video?
https://www.youtube.com/watch?v=hcUBmzIBSjc
R
On Fri, Mar 29, 2024 at 10:11 AM Tr Mu <tl01001101@xxxxxxxxx> wrote:
What surfactants would you recommend? I'm adding Bi2O3, Mg, & Ferrocene
and so anything I add needs to be compatible with everything at casting
temps. I'd still test it by heating to +100°F over casting temp. But
currently my sorbitol is plenty liquid at temp and so I do not see a reason
to add a surfactant.
Trevor
On Fri, Mar 29, 2024, 11:06 AM Richard Nakka <richard.rocketry@xxxxxxxxx>
wrote:
Adding surfactant to KNSB or KNDX reduces the viscosity of the slurry to
make it easily pourable. If only a tiny amount is added (0.1% or so)
performance is not affected.
R.
On Fri, Mar 29, 2024 at 8:42 AM Tr Mu <tl01001101@xxxxxxxxx> wrote:
My main reason for not wanting to go to dextrose is the viscosity.
Sorbitol is quite thin and thus I can load it up pretty high with KNO3, Mg,
& other things. My current formula for a fast propellant is only 30%
sorbitol and still can pour easily into my 29mm casting setup (with coring
rod already in place). Paraffin was a thought because it is even thinner
when melted and I was hoping it would allow me to go higher on the KNO3
percentage. This is why I started up in the 80%s. Mainly I'm looking for
things that are different to do. Eventually I'll be able to do APCP and get
all of the performance I want, but for now it is fun to see how much I can
get out of cheaper ingredients.
Trevor
On Thu, Mar 28, 2024 at 11:07 PM Lincoln Ross <lr21643@xxxxxxxxx> wrote:
BTW, Trevor, if you're trying to save money, you might consider dextrose.
I think Baker's Authority has it at something like $79 for 50 lbs. As
usual, Richard Nakka has quite a bit of info about using it in fuel grains:
https://www.nakka-rocketry.net/dex.html Note that the hydrated form
melts at a low temperature and doesn't give up all that much specific
impulse.
On Thu, Mar 28, 2024 at 8:21 PM Lincoln Ross <lr21643@xxxxxxxxx> wrote:
There is also something called Gulfwax, commonly found at supermarkets. I
think mine might be from the previous millennium, though. Unless there was
some kind of aging over that time, I bet it is about the same stuff. In
bulk, of course, the stuff is cheaper.
On Thu, Mar 28, 2024 at 5:36 AM Tr Mu <tl01001101@xxxxxxxxx> wrote:
I just used some I found at Hobby Lobby. It was labeled as being pure
paraffin for candle making.
Trevor
On Thu, Mar 28, 2024, 12:56 AM Lincoln Ross <lr21643@xxxxxxxxx> wrote:
Any specifics or does the paraffin just end up covered with tiny bite
marks? ;-)
On Thu, Mar 28, 2024 at 12:53 AM Bruce Beck <bbeck7@xxxxxxxxx> wrote:
Nitrates are lousy oxidizers for paraffin.AP works well but chuffs at low
pressure.
On Wed, Mar 27, 2024 at 4:16 PM Tr Mu <tl01001101@xxxxxxxxx> wrote:
This past weekend I had the idea of trying a paraffin based propellant.
Has anyone tried this? It melts at a lower temp than sorbitol and based on
the prices I found, it would end up cheaper than my current sorbitol motors.
I tried some small 10 gram batches of 80:20, 85:15, & 90:10 KNO3:paraffin.
These were based around 85:15 being an "ideal" ratio as per ProPep3 None of
them would sustain combustion. I want to try it again this weekend with
finer ground KNO3, but I wanted to see if anyone else has tried it.
Trevor
