I left off using dissolved ping pong balls when I found I could buy
nitrocellulose laquer in pints at Ace hardware. It has been used for many,
many years as THE finish for fine musical instruments (violins). It isn't
clearly worded on the front, but on the back label it says, "nitrocellulose
laquer" as the main ingredient with a few solvents added. I brush it inside
the nozzles of BP motors with a small paintbrush and then quickly cover
with fine 4F black powder. Shake out the excess, and after it dries, if the
igniter lights -the motor lights. Every time. Clusters need that extra
insurance. I think since there is no water involved it might be good for
sugar motors. Comments?
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On Fri, Sep 22, 2017 at 12:20 PM, Dave Barr <dhbarr@xxxxxxxxx> wrote:
Fintel mentioned several types of pyrogen, one of which was given as
follows:
"10 grams of Red Dot smokeless powder (for a binder) dissolved in a few
ounces of acetone, 95 grams of black powder green meal, 5 grams of
magnesium shavings (sieved at about 15 mesh), then added acetone to bring
the liquid volume to 8 fluid ounces."
Obviously most of us don't need 90g of primer, but there's also several
ping pong recipes out there as well.
On Fri, Sep 22, 2017 at 12:11 PM, 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/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/xPuqFZ0kT_Q
[image: Inline image 1]
Nikolai Nielsen
