how do you get it onto the inside of the fuel grain? i struggled with that.
ps i bought some isopropyl alcohol at the pharmacy and it gave me a
headache when i used it so i imagine ill have to use a respirator next time
Nikolai Nielsen
On Mon, Sep 25, 2017 at 3:58 PM, Richard Nakka <richard.rocketry@xxxxxxxxx>
wrote:
I use 70% isopropyl alcohol ("rubbing alcohol") because it is ready
available, inexpensive and contains just the right amount of water to
provide for good adhesion of the primer.
I would imagine you could use any alcohol as long as it it diluted with
water to 70%. Don't use acetone or other such solvents.
Richard
On Mon, Sep 25, 2017 at 5:03 AM, Nikolai Nielsen <
nielsen.nikolai86@xxxxxxxxx> wrote:
is it important that isopropyl alcohol is used and not something like
ethanol, methanol or acetone(i have all 3)
Nikolai Nielsen
On Fri, Sep 22, 2017 at 9:43 PM, Rick Maschek <
dmarc-noreply@xxxxxxxxxxxxx> wrote:
I am wondering if some of your problem might also be humidity. I live in
the desert and we generally have no problem igniting our motors, even in
the winter when temps are in the 30-40s F.
I have noticed motors are harder to start when either the humidity is
high (rare here) or it is raining.
Here's an example: at 8:50 the SpaceX interns launching with my 75mm
sugar had no problems with ignition before the rains came but at 11:10 in
the video, the same motor reloaded but out in the rain on the test stand
was a different story, took 3 tries (two shown in video).
Friends of Amateur Rocketry May 7, 2016 rocket launches and tests
<https://www.youtube.com/watch?v=Pf8OKQOYfTA&t=1s>
Friends of Amateur Rocketry May 7, 2016 rocket launches and tests
These are most of the flights and static tests conducted at the Friends
of Amateur Rocketry (aka the FAR site) o...
<https://www.youtube.com/watch?v=Pf8OKQOYfTA&t=1s>
We now generally don't use any primer to start our motors 'slowly' to
avoid cracking grains. The first attempt failed, there was rain water on/in
the nozzle, and so we beefed up the second igniter with some additional
APCP shavings attached to it and it 'fired' though not the best.
I might be worth while to thoroughly document the humidity conditions
from casting day to firing day and what steps are taken to protect the
propellant from moisture.
Rick
On Friday, September 22, 2017 10:12 AM, Richard Nakka <
richard.rocketry@xxxxxxxxx> wrote:
The Primer is described here:
http://www.nakka-rocketry.net/ignexp.html
Consists of 80/20 mix of potassium nitrate and charcoal mixed with 70%
isopropyl alchohol. Painted on all exposed grain surfaces.
On Fri, Sep 22, 2017 at 11:11 AM, Bdale Garbee <bdale@xxxxxxx> wrote:
Richard, what do you use as a primer? My sorbitol formula with a little
RIO lights easily, but I'm still struggling with erythritol...
Bdale
On Sep 22, 2017 7:35 AM, Richard Nakka <richard.rocketry@xxxxxxxxx>
wrote:
Nikolai,
I've only recently begun using xylitol based propellant, but have had no
problems with igniteability. However I always prime the surface (I mainly
use it for a smoke tracking charge). As with sorbitol, xylitol does not
caramelize when heated, and this likely is what makes these more difficult
to ignite. Adding a primer makes a huge difference as the primer material
readily absorbs heat and quickly heats the underlying propellant to
ignition temperature.
I also prime my KNDX grains, even if it is strictly speaking not
necessary, as dextrose does caramelize.
Richard
On Fri, Sep 22, 2017 at 8:18 AM, Nikolai Nielsen <
nielsen.nikolai86@xxxxxxxxx> wrote:
i made a small motor yesterday using xylitol and when the motor started
up it looked like it was going to burn nicely with the fuel being burned in
a short amount of time(it was a core burner) but when it lit, i could see
that it was building up pressure but then it suddenly slowed down and
proceeded to burn for another 20 seconds or so. this is what i imagined
what happened(see picture) and then today i remembered that when i lit
some of the left over fuel, it took a lot longer to ignite than my other
fuels and i then realised that unlike the KNSU motors, the KNXY motor
wasn't burning all the available surface up, just the surface that was
currently burning and i believe this is due to the difficulty of igniting
the fuel so maybe the heat inside the motor isnt igniting the rest of the
fuel as it does in other motors(i think this is also what happened to my
rocket launch day 2 video). this then made me remember this video at 0:29
https://www.youtube.com/w
atch?v=BmhnronPiYE <https://www.youtube.com/watch?v=BmhnronPiYE> and i
saw he had a black fuel grain which he said in the comments was KNSB that
was primed. I found a page on Richards website that details this so im
going to try that next time i use xylitol fuel, hope it will work.
this is the video of the burn https://youtu.be/xPuqFZ0k T_Q
<https://youtu.be/xPuqFZ0kT_Q>
[image: Inline image 1]
Nikolai Nielsen
