Discussion:
Igniting sugar rocket propellant
(too old to reply)
Ignigena
2007-06-04 07:07:10 UTC
Permalink
I'm kind of new to this group, but I've been reading posts by you guys
for a while. This is sort of off the topic of pyrotechnics, but
ignition is an issue for any sort of pyro creation. My friend and I
recently launched a rocket on a 6 grain K motor we cast out of a KNO3/
sugar mix. The exact comp was 65% KNO3 and 35% erythritol. When we
were trying to launch, we burned through a couple e-matchs that did
not ignite the motors. We decided to try coating an e-match with a
thick layer of pyrodex, which eventually did the trick. After the e-
match went off the rocket smoked on the pad for about 7 seconds before
it finally built up enough pressure and heat to launch. Once it was
going the motor burned great, it was about a 5 second burn and sent
the rocket to 5400 feet, and got close to Mach. We'd hoped to get
higher, but I wouldn't be surprised if we burnt through an entire
grain while sitting on the pad. The only issue we had with the launch
was with the igniting of the motor. As a rocket propellant, the sugar
mixture we used has been relatively untested. As far as I know only 2
other people have launched rockets on this mixture, and we're trying
to work out the kinks. It seems like the regular e-matches did not get
hot enough to ignite the motor, and even the e-match in pyrodex was
barely able to start it. An alternative we were considering was a
thermite ignitor, but I know very little about the production and
usage of thermite. I'm sure the temperatures produced in a thermite
reaction would be more than enough to get that motor going. So my
question,

can thermite be used in an electric ignitor, and can an e-match start
a thermite reaction? Also from the research I've done, iron oxide and
aluminum metal powder make the best thermite. Is this true?

All advice and input is greatly appreciated!

-Malek
Lloyd E. Sponenburgh
2007-06-04 11:56:26 UTC
Permalink
Post by Ignigena
After the e-
match went off the rocket smoked on the pad for about 7 seconds before
it finally built up enough pressure and heat to launch. Once it was
going the motor burned great, it was about a 5 second burn and sent
the rocket to 5400 feet, and got close to Mach. We'd hoped to get
higher, but I wouldn't be surprised if we burnt through an entire
grain while sitting on the pad.
So.... you're into really high-performance engines (for candy), and you
don't know about burst diaphrams and ignition primers?

LLoyd
c***@yahoo.com
2007-06-04 14:44:00 UTC
Permalink
Post by Lloyd E. Sponenburgh
So.... you're into really high-performance engines (for candy), and you
don't know about burst diaphrams and ignition primers?
LLoyd
Burst diaphrams seem awful tricky for beginner stuff, that is the only
reason I have not done some high powered rocketry myself. I have the
lathe though and I guess all I really need is some block graphite. And
a WASP....
Lloyd E. Sponenburgh
2007-06-04 16:29:05 UTC
Permalink
Post by c***@yahoo.com
Post by Lloyd E. Sponenburgh
So.... you're into really high-performance engines (for candy), and you
don't know about burst diaphrams and ignition primers?
LLoyd
Burst diaphrams seem awful tricky for beginner stuff, that is the only
reason I have not done some high powered rocketry myself. I have the
lathe though and I guess all I really need is some block graphite. And
a WASP....
BAck in the day, I used to cast my diaphrams from plaster. A tissue paper
"straw" filled with black powder formed the "booster" for the ematch.

LLoyd
Rocketflite
2007-06-04 16:45:01 UTC
Permalink
Post by Ignigena
to work out the kinks. It seems like the regular e-matches did not get
hot enough to ignite the motor, and even the e-match in pyrodex was
barely able to start it. An alternative we were considering was a
thermite ignitor, but I know very little about the production and
usage of thermite. I'm sure the temperatures produced in a thermite
reaction would be more than enough to get that motor going. So my
question,
can thermite be used in an electric ignitor, and can an e-match start
a thermite reaction? Also from the research I've done, iron oxide and
aluminum metal powder make the best thermite. Is this true?
All advice and input is greatly appreciated!
-Malek
There is a company that makes a kit for building your own very
reliable high temp (magnesium) rocket motor igniters. I have no idea
who they are but I have heard wonderful things about them ;)

Igniter placement on a cored rocket motor design can make a huge
difference on how fast the motor comes up to pressure. The closer you
place it to the nozzle the longer it will take to come up to pressure.

Here is there website: www.rocketflite.com

Greg Dyben
Rocketflite
b***@gmail.com
2007-06-04 17:12:19 UTC
Permalink
Post by Ignigena
I'm kind of new to this group, but I've been reading posts by you guys
for a while. This is sort of off the topic of pyrotechnics, but
ignition is an issue for any sort of pyro creation. My friend and I
recently launched a rocket on a 6 grain K motor we cast out of a KNO3/
sugar mix. The exact comp was 65% KNO3 and 35% erythritol. When we
were trying to launch, we burned through a couple e-matchs that did
not ignite the motors. We decided to try coating an e-match with a
thick layer of pyrodex, which eventually did the trick. After the e-
match went off the rocket smoked on the pad for about 7 seconds before
it finally built up enough pressure and heat to launch. Once it was
going the motor burned great, it was about a 5 second burn and sent
the rocket to 5400 feet, and got close to Mach. We'd hoped to get
higher, but I wouldn't be surprised if we burnt through an entire
grain while sitting on the pad. The only issue we had with the launch
was with the igniting of the motor. As a rocket propellant, the sugar
mixture we used has been relatively untested. As far as I know only 2
other people have launched rockets on this mixture, and we're trying
to work out the kinks. It seems like the regular e-matches did not get
hot enough to ignite the motor, and even the e-match in pyrodex was
barely able to start it. An alternative we were considering was a
thermite ignitor, but I know very little about the production and
usage of thermite. I'm sure the temperatures produced in a thermite
reaction would be more than enough to get that motor going. So my
question,
can thermite be used in an electric ignitor, and can an e-match start
a thermite reaction? Also from the research I've done, iron oxide and
aluminum metal powder make the best thermite. Is this true?
All advice and input is greatly appreciated!
-Malek
Find Scott Fintel's site.

Byron
h***@yahoo.com
2007-06-04 19:06:24 UTC
Permalink
You may or not find this link useful.

http://members.aol.com/ricnakk/engine1.html

This a a direct linke to Nakka's B-200 motor construction. Note the
position of the igniter in the candy grain, and the thrust time curve.

The link to his home page is:

http://www.nakka-rocketry.net/index.html

If you visit there, take a look at his A-100 motor design as well.
Particularly note the total burn time and thrust figures.

It is important that there is a vast difference between fireworks and
high powered rocketry, not only in the choice of fuels, but in
construction techniques and materials employed as well.

Not fireworks, but still Nakka's site is a fun place to visit.

Harry C.
Post by Ignigena
I'm kind of new to this group, but I've been reading posts by you guys
for a while. This is sort of off the topic of pyrotechnics, but
ignition is an issue for any sort of pyro creation. My friend and I
recently launched a rocket on a 6 grain K motor we cast out of a KNO3/
sugar mix. The exact comp was 65% KNO3 and 35% erythritol. When we
were trying to launch, we burned through a couple e-matchs that did
not ignite the motors. We decided to try coating an e-match with a
thick layer of pyrodex, which eventually did the trick. After the e-
match went off the rocket smoked on the pad for about 7 seconds before
it finally built up enough pressure and heat to launch. Once it was
going the motor burned great, it was about a 5 second burn and sent
the rocket to 5400 feet, and got close to Mach. We'd hoped to get
higher, but I wouldn't be surprised if we burnt through an entire
grain while sitting on the pad. The only issue we had with the launch
was with the igniting of the motor. As a rocket propellant, the sugar
mixture we used has been relatively untested. As far as I know only 2
other people have launched rockets on this mixture, and we're trying
to work out the kinks. It seems like the regular e-matches did not get
hot enough to ignite the motor, and even the e-match in pyrodex was
barely able to start it. An alternative we were considering was a
thermite ignitor, but I know very little about the production and
usage of thermite. I'm sure the temperatures produced in a thermite
reaction would be more than enough to get that motor going. So my
question,
can thermite be used in an electric ignitor, and can an e-match start
a thermite reaction? Also from the research I've done, iron oxide and
aluminum metal powder make the best thermite. Is this true?
All advice and input is greatly appreciated!
-Malek
yuv
2007-06-05 09:07:35 UTC
Permalink
Candy motor ignition IS tricky. The fuel itself needs lots of energy
to catch on fire, because energy is lost to melting the sugar. And in
order to get ALL the fuel surface burning, you need to have pressure
built in the motor.

Two methods work great for me:

1. make an "igniter grain": a small fuel grain partialy cored. get
your ematch in that core with some BP (or other pyrogen, but BP is
good enough for this). What you got is a small caseless motor. Placed
in the forward end of the main motor, it will give a powerfull, hot
and long jet to ignite the motor. It also rises the pressure.

2. Prime the grains with a slury of BP with alchohol. Be extra
carefull not to over prime, or you"ll get a pipe bomb. You dont need
much. Only enough to get several ignition points. A good priming
location is between the grains. You can even use a piece of black
match stuffed between them.

Yuv
Ignigena
2007-06-06 02:54:07 UTC
Permalink
Thanks for all of the info guys. We actually decided the easiest
solution would be to cast the motor with a slightly expanded core and
then fill the core with an AP mixture and redrill the motor to the
proper core size. This would leave a thin layer of AP that could
ignite much more easily and start the rest of the grains. Yuv your
idea of an igniter grain would also work quite nicely though.
Alex
2007-06-07 19:59:01 UTC
Permalink
I had same problems with my candy rockets.

The sollution that worked 100% is to put igniter right to the top of the
core inside the motor. Try it.
Post by Ignigena
Thanks for all of the info guys. We actually decided the easiest
solution would be to cast the motor with a slightly expanded core and
then fill the core with an AP mixture and redrill the motor to the
proper core size. This would leave a thin layer of AP that could
ignite much more easily and start the rest of the grains. Yuv your
idea of an igniter grain would also work quite nicely though.
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