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
|
|
|
| | |
|
|
|
| |
UCLA Rocket Project avionics & recovery flight test
|
|
|
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
