Trevor,
You mentioned viscosity as a concern with dextrose. Melted paraffin seems
very thin. If you can get it to mix properly, maybe the combination would
work well.
----------
Speaking of dextrose, I wonder how the viscosity of the "melted"
monohydrate compares to that of the anhydrous form when melted.
On Fri, Mar 29, 2024 at 11:50 AM Tr Mu <tl01001101@xxxxxxxxx> wrote:
That enjoyment is why I've been happy to stay with sugar. Its very
enjoyable to get a sugar motor to perform in ways that people don't expect.
I had a flight that pulled ~30 Gs off the pad and no one expected that from
a sugar motor.
As for dextrose, it is definitely cheaper than sorbitol (nearly 1/3rd from
what I found vs what I last paid for sorbitol). I may try it once I run out
of what I currently have, but that will be a bit as I restocked a little
over a year ago. My 29mm motors don't consume much and I haven't had the
time to do much lately either.
My other motivation for wax was to make a propellant with a better shelf
life. My current storage keeps the grains plenty dry but they get even more
brittle as they age.
Trevor
On Fri, Mar 29, 2024, 11:39 AM Richard Nakka <richard.rocketry@xxxxxxxxx>
wrote:
I fully agree with Rick. I have been working with sugar propellants since
the beginning of time, and with APCP for about 5 years now. I like both
kinda equally, but its amazing how sugar propellants can develop all the
power you need. I spent the past 4 months developing an M-Class KNSB motor,
it was a labour of love (and stressful at times) but I poured all my
knowledge and experience into the project, and was recently rewarded with a
beautiful and most impressive maiden firing of the motor.
R.
On Fri, Mar 29, 2024 at 10:15 AM Rick Maschek <
dmarc-noreply@xxxxxxxxxxxxx> wrote:
When I talk with university students I work with, they like saying they
need the performance of AP and sugar won't work...then they complain they
can't afford AP and limit what they do. About 10 years ago I went head to
head with a person doing a 6" O-impulse AP against my 6" O-impulse sugar.
His reached 24,000' and I got 32,000' and Mach 2.7. He complained my rocket
was 'lighter than his...whatever. I will say that all things being equal,
KNSB doesn't compare to APCP but for most things non military or for
putting things in orbit, KNSB does pretty dam good.
I help students teams at the Spaceport competition in New Mexico with
their KNSB motors that do just as well to 10 and 30,000' as do those using
expensive AP motors.
I also provide universities free of charge KNSB motors to do actual
flight testing of their avionics and recovery systems at FAR for their
liquid bi-propellant rockets rather than just doing ground deployment tests
(better than nothing) but that isn't how NASA does testing (see Little Joe
II)
UCLA Rocket Project avionics & recovery flight test
<https://www.youtube.com/watch?v=jWspWbTCXbM>
UCLA Rocket Project avionics & recovery flight test
<https://www.youtube.com/watch?v=jWspWbTCXbM>
Don't get me wrong, I do use AP when necessary (bought $7,000 worth of
Aerotech motors this year for a project we're doing) but as I mention, I
find it amusing when people mention needing the higher performance of AP
for things that KNSB can easily do.
Rick
On Friday, March 29, 2024 at 06:42:17 AM PDT, 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
