What are the dimensions of the grains?
Sincerely,
Azadul Haq
On Sat, Mar 30, 2024 at 12:08 PM Richard Nakka <richard.rocketry@xxxxxxxxx>
wrote:
Yes, my KNSB slurry was like mashed potatoes, I had to scoop and "rap" the
mould repeatedly to load. It was not this way at 115-120C, maybe I should
cast at that temperature, I may try that next time.
My M-motor uses 6 grains, totaling a tad over 6kg propellant. The design
parameters are:
Kn (max) 385
MEOP 955 psi
Tmax 712 lbf
Burn time 3 sec.
Prior to firing this, i fired a short 2 grain version. Performance for
that short motor was nominal.
The firing of the 6 grain version seemed to be nominal. I say 'seemed'
because no thrust/pressure data was collected...the laptop "froze up"
(literally) at some point prior to firing...it was -9C at the time. Based
on forensic analysis of the motor, burn time from video, and sound
(loudness) analysis, the burn appeared to be nominal. I will refire again
later this summer or fall before the temperatures start to dip.
I am planning on offering this motor to U. teams participating in the
annual Launch Canada event.
Richard
On Sat, Mar 30, 2024 at 12:44 AM Rick Maschek <dmarc-noreply@xxxxxxxxxxxxx>
wrote:
Richard, in thinking about that first surfactant experience, that was
true. The super fine KNO3 (powder) mixture was like mash potatoes and
didn't become pourable no matter what temperature. I wonder what is going
on with the KNO3 particle size/temperature/viscosity graph.
I live in a desert with humidity generally 5-20%, I never use desiccant
and don't bag my propellant grains and they stay dry for a long time (some
at FAR are 1 year old). And occasionally, get busy with other things and
will leave the KNSB in the skillet for hours at 220F so I'm sure most of
the water is gone but it remains pourable. I will have to try oven
pre-drying the KNO3 before mixing and melting to see if that increases the
viscosity of granular melt with increasing temperature.
What are the specs of your M-impulse motor? Mine are usually 5-7 grains
and will lift a 6" rocket to about 10,000' and a 4" rocket to around
15,000'. It took a large UCLA 7.5" rocket to almost 5,000' last month
testing their new recovery system for their new larger liquid rocket. The
main failed to come out of the deployment bag on the first flight but the
second flight was nominal after addressing the issue. For the safety of
rockets using my 'testing motors' I keep the Kn low, ~300
On Friday, March 29, 2024 at 08:44:45 AM PDT, Richard Nakka <
richard.rocketry@xxxxxxxxx> wrote:
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
