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Originally Posted by ghrocketman
Many years ago I almost always used green visco cannon fuse.
My 8th grade science teacher switched to fuse for the rocketry segment of class every year after I introduced him to it. He was very frustrated with the failure rate of Solar igntiters installed by his 8th grade students.
I almost never use it any more as I have a launch system that is all but fool-proof even using bare nichrome.
I don't think it's a big deal and dont even think it should be in the safety code. So what, no abort.
We are not talking J-class motors here.
The first model rocketry safety code had NO provision against fuses and HAD provisions for MAKING one's OWN BP motors. THAT code is PLENTY.
First model rocketry used FUSE ignition as NORMAL and STANDARD !
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I think the reason (or *a* reason) why model rocketry was moved away from fuses was to distance it from fireworks in the minds of officials and legislators; plus, electrical ignition is more realistic for our miniature astronautics activity, and electrical ignition definitely provides complete control over when--or if--a motor is ignited. Igniter plugs have also greatly increased the reliability of igniters and starters (including plain, constant-gauge hot-wire nichrome igniters), by ensuring physical contact between the igniter and the propellant. And:
I also think that home-made motors (particularly the small, sugar propellant ones that can be made in quantity safely, on a kitchen table, see:
http://home.alphalink.com.au/~brucej/nickle.htm ) should be allowed and encouraged in model rocketry. (I don't feel the same way about home-made black powder motors. While they *can* be made safely by individuals [Orville Carlisle made the first black powder model rocket motors--as well as his own firework pieces--by hand, after all], it's very easy to kill or maim oneself while making them--the first instructions in the Teleflite BP motor-making book are for making an explosion shield, for when things go wrong...) Also:
I have no objections to fuse ignition as long as it's used in places and circumstances in which its control limitations (as compared with electrical ignition) are of no account. For example, there are many fine, calm, and clear winter days with a light snow cover that are perfect for rocket flying (many R/C glider pilots also like such days--even thermal flying is possible on such days, since thermals are caused by ^differences^ in air temperature, even when the "baseline temperature" is cold). But even when one is dressed comfortably for the conditions, the batteries in self-contained hand-held launch controllers become weak as they cool down, and stuffing a launch controller under an armpit to keep it warm between launches is an uncomfortable hassle. In such circumstances, fuse ignition is an ideal alternative. In addition:
Even in a group launch setting in such circumstances, I see no reason why fuse ignition couldn't be used with a level of safety equal to that of electrical ignition. To eliminate the necessity of moving away from the launch pad quickly after lighting a fuse (or having to use longer lengths of fuse, which is another--although more expensive--alternative), a short length of fuse in the motor could be lit by a glowing "punk" (it looks just like an incense stick), which would be affixed to one end of a long but stiff stick. (My father used a punk on the end of a ~5' long stick for lighting firework pieces on New Years' Eve and Independence Day.) Using a stick of that length, one would just reach out and light the model rocket's fuse with the punk, step back 10 feet (to the 15' minimum safe radius) in a leisurely fashion, then lay the stick down with the punk propped up on a rock or a brick (so that the punk's glowing tip wouldn't touch the snow and be extinguished). As well:
The specialty uses of fuses in model rocketry that Gus described are all legitimate and useful, too. (As well as DT [Dethermalizer Timer] fuses, European competition space modelers also sometimes use black powder-powered "staging funnels" and reusable "squib" igniter tubes that are loaded with loose black powder.) Apogee Components' 10.5 mm diameter, European-style black powder Micro Motors, which powered their "Centrix" family (see:
http://www.rocketreviews.com/centri...components.html ) of single-stage and two-stage rockets (they'd fly nicely on the two new types of Quest's MicroMaxx motors, too) had tiny nozzles of the kind that Gus mentioned. The two-stage Centrix--which also had a nifty Aerobee-like, three-dowel "open-air" interstage structure--used what Apogee called a "staging igniter" (which was a length of fuse) to ignite the second stage's motor.