Hello All,

While I'm not advocating the use of fuses to launch model rockets, I've noticed that it's a fairly common practice in Europe, and it doesn't seem to be condemned there. Over the years I've seen several YouTube videos of model rocket launches in Europe that used fuse ignition. In these two recent ones (see: https://www.youtube.com/watch?v=KKiI5wo3br0 and https://www.youtube.com/watch?v=yC9tHx7dNbA ), a space modeler (model rocketeer) in Stegersbach, Austria flew his SpaceX Falcon 9 and Fairing model with an onboard keychain video & still camera with audio. The fuse can be clearly seen and heard in the camera views. Also:

The location where he flew his model (a very large and open farm area with no buildings, vehicles, or other people nearby--I was half-expecting to see Lipizzaner horses grazing in a nearby field... :-) ) looks like a place where fuse ignition would not pose any safety problems (provided that the launch pad was stable, the conditions weren't tinder-dry, and the wind wasn't gusting very high, all three of which appear to have been the case in the above-linked videos). Model rocketry safety codes in European countries do prescribe electrical ignition (and it is used in contests and other group launches there), yet using fuses instead doesn't appear to call down condemnation on people who use them when flying model rockets alone, or with family and/or friends. In addition:

To me, this is a perfectly sensible, non-uptight attitude that makes the hobby more enjoyable, without increasing the risks. I would not criticize any model rocketeer who kept a roll of green cannon fuse in his or her range box, for use in non-club flying sessions (provided that the conditions I listed above--and which appeared to be in place in the above-linked videos--were satisfied) if his/her launch controller became faulty or damaged (or its batteries died), or if s/he ran out of extra igniters. Over the years such things have happened to me a few times, and on the private land where I flew models either alone or with family (in northern Georgia and Alaska--I wouldn't have contravened the safety code at Tamiami Park, a public park where I flew rockets in Miami), I would have used fuses if I had brought any along with me, because I never flew in conditions in which fuses would have been any less safe than electrical ignition.

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Black Shire--Draft horse in human form, model rocketeer, occasional mystic, and writer, see:
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NAR #54895 SR

My first six years of model rocketry, I used nothing but M-80 fuses to launch my rockets until I built my first electric powered launch system in 8th grade as a school project.

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If it flies, I can crash it!

Fire hazard from fuses is only one reason not to use them.

A BIG reason not to use fuses is that once lit, there is no "abort". If you have electrical ignition, you count down and if something goes wrong you simply stop and do not hit the launch button. This could be the pad tipping over, an aircraft suddenly entering the airspace or a person not connected to or aware of the launch suddenly entering the area on foot, bicycle or whatever.

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-Fred Shecter NAR 20117 (L2)
Southern California Rocket Association, NAR Section 430

I had a "pad tipped over after the fuse was lit" incident, around 1972. It was a shabby old Estes tripod with a rusty loose adjustment screw. My Alpha flew into the chain-link fence surrounding an in-use tennis court. I remember the cone splitting neatly, not quite in even halves.

I remember realizing at the time that I'd probably better get a working electrical controller together.

* * *
Data Point: The comedy-drama "Bye Bye Lenin" is set in East Germany just before and after the fall of the wall. Worth seeing. The narrator / main character has a big home-made model rocket. He recalls launching it as a kid in a flashback (to celebrate the first East German cosmonaut), and later launches it again . . . I won't give away the occasion.

In both cases, he uses a fuse for ignition.

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NAR #27085 - Oregon Rocketry - SAM

When I first starting flying rockets in the 60s, a hobby store stocked Jetex fuse in the rocketry section of the store. We often used it, especially if we were riding our bikes to a nearby field, and we just pushed a launch rod into the ground instead of trying to carry a pad and launch controller.

I still have a couple of the little round tins and a small piece of the Jetex fuse.

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Lee Reep
NAR 55948

Projects: Semroc Saturn 1B, Ken Foss Designs Mini Satellite Interceptor
In the Paint Shop: Nothing! Too cold!
Launch-Ready: Farside-X, Maxi Honest John, Super Scamp

I thank you all very much for your replies! Jetex wick was quite commonly used in the old days (and it was later used as the pyrogen in Centuri's Sure-Shot igniters, of course). Green cannon fuse has also been utilized with nichrome hot-wire igniters as the pyrogen. Also:

*If* I had used fuse ignition (it wouldn’t have been my first choice, just a back-up option in the event my launch controller died or I ran out of igniters), I wouldn’t have done it anywhere where it would have made a difference, regardless of which ignition method was used. In northern Georgia, and at my now-unavailable flying site here in Alaska (the family foundation that owns it locked the gate, after its tenant user died last year), there was no one around and no dry foliage (I didn’t fly models in “Red Flag” [tinder-dry] conditions, period), and the skies at both sites were open to full scrutiny in all directions (audibly as well as visually, because both sites were virtually silent). At Tamiami Park in Miami, I would never have considered fuse ignition because there were always people and vehicles within range (not to mention R/C model airplanes flying around—I once unintentionally made an R/C pilot there gasp in horror when one of my rockets *appeared* to be intercepting his plane, due to his line of sight with respect to both models).

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Black Shire--Draft horse in human form, model rocketeer, occasional mystic, and writer, see:
http://www.lulu.com/content/paperba...an-form/8075185
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http://www.lulu.com/product/cd/what...of-2%29/6126511
All of my book proceeds go to the Northcote Heavy Horse Centre www.northcotehorses.com.
NAR #54895 SR

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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When in doubt, WHACK the GAS and DITCH the brake !!!

Yes, there is such a thing as NORMAL, if you have to ask what is "NORMAL" , you probably aren't !
Failure may not be an OPTION, but it is ALWAYS a POSSIBILITY.
ALL systems are GO for MAYHEM, CHAOS, and HAVOC !

International competition events use electrical ignition for all rockets, but fuse still has a number of uses in those events.

Fuse ignition of upper stages in Scale and Scale Altitude if often used. The electrical ignition of the booster simultaneously ignites a fuse, precisely timed to ignite the upper stage. The U.S. team used this very successfully on their Bumper Wac models at the last several championships. This is easy to do, but extremely difficult to do well. Lots of important design considerations and tons of practice are required.

Fuses are also used, with varying degrees of success, to delay ignition of upper stages in altitude models which use direct motor staging (similar to using Estes booster motors). Euro motors have VERY tiny nozzles. A piece of fuse stuck in the nozzle of a sustainer engine can provide delayed ignition by completely occluding the nozzle. Instead, the booster motor ejects flame which gap stages to the short piece of fuse in the sustainer, short delay while the fuse burns and then ignites the sustainer motor. Lots of debate as to whether this really helps, also very difficult to get precise delays.

A third, and more common use of fuses in international competition is for dethermalizers (similar to free-flight glider events here in the U.S.). The FAI timed rocketry events all have maximum times. FAI events also require 3 rounds and you must fly 3 rounds with two rockets. This means you must get at least one back to have all 3 flights. The max in parachute duration for example, on A motors, is 5 minutes. In order to get 5 minutes you have to catch a thermal but it is very common to just have your model thermal away after the 5 minutes. So a dethermalizer of some sort that deflates your parachute at 5 minutes is very helpful. A number of teams use a piece of fuse connected to a parachute riser line which holds half the shroud lines. The fuse extends out through the side of the model (often through the lower edge of the nosecone). As soon as they get the launch command from the RSO they ignite the fuse, then push their electrical launch button. This is a simple and effective method but requires you have a parachute folding technique that is guaranteed to open even if the parachute has been packed a day or week before (you can't really do the precise packing with dethermalizer out on a windy launch field). The U.S. does not use this techinique because of the difficulty of practicing here in the U.S. (we're just all way too nervous about attaching long burning things to our parachutes).

So although I've never seen a booster ignited directly by fuse in an international event, I have seen the very effective use of fuses in a number of circumstances.

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.

__________________
Black Shire--Draft horse in human form, model rocketeer, occasional mystic, and writer, see:
http://www.lulu.com/content/paperba...an-form/8075185
http://www.lulu.com/product/cd/what...of-2%29/6122050
http://www.lulu.com/product/cd/what...of-2%29/6126511
All of my book proceeds go to the Northcote Heavy Horse Centre www.northcotehorses.com.
NAR #54895 SR

Well, if one is foolish enough to try and launch with silly "AA" battery launch controllers on a snowy day one deserves whatever they get IMHO...

There are FAR better battery choices that will operate model rocket ignitors perfectly well in conditions too cold to fly in for a sustained period. One need not resort to fuse ignition because stupid "AA" batteries are an extremely poor choice for the job.

As for the other uses, I don't have a problem with that, but in some cases the MRSC does, and ultimately, if you're flying outside the dictates of the MRSC, and if something happens that results in injury or property damage, that is grounds for denying the claim and refusing any insurance payouts by the company, leaving it all ultimately on the flyer himself to bear the burden of liability.

I know, as a landowner, that if something happened due to another's stupidity or lack of sense or good judgment, *I* would be PO'd and *we* would have a problem that they would have to make right. As a landowner, knowing the MRSC and the provisions of the insurance that state that flight activities MUST be conducted within the MRSC to be covered by the insurance, I would not be particularly amenable to simply "doing away with it" whenever someone got a wild hair to fly something not in accordance with the MRSC which would void the insurance on that flight. Not saying *I* would categorically refuse, but they'd "have to convince me" that it was safe and an acceptable risk.

Some landowners probably would not be so amenable, and *if* something happened, and the insurance didn't cover it, the club would probably be looking for a new field-- it's happened before and it'll surely happen again at some point, but there needs to be some serious consideration of the risk/reward ratio.

Something to keep in mind.

Later! OL J R : )

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