From: cdt@sw.stratus.com (C. D. Tavares)
Newsgroups: rec.models.rockets
Subject: Re: Fuse
Date: 10 Apr 92 17:21:04 GMT
Organization: Stratus Computer, Inc.

In article <1992Apr10.034541.5390@usenet.ins.cwru.edu>, ah157@cleveland.Freenet.Edu (Rob Henry) writes:
> I guess everyone has their own preferences,I've never seen anyone get hurt
> from using fuse.

As Gardner Hendrie used to say, there are three types of engineers.
The first type learns only from his own mistakes.  The second type 
learns from everybody else's mistakes.  The third type never learns.

> You can't tell me it's any different than an igniter in that it
> takes a long time to burn and in case of a misfire you can't be sure.

Oh, can't I.  Read on.

> A fuse just won't sit there and smoulder for 5 minutes if it does not ignite
> the engine

False.  A defective fuse can sit for a long, long time -- sometimes
over five minutes -- smouldering invisibly and internally before finally 
re-catching and igniting your motor at the worst possible time.

> simply wait until
> you see no smoke,then wait 3 or so minutes before going near the pad.

Don't bet anything you value on this.

At the 1980 World Spacemodeling Championships, the world champion for
R/C Rocket/Glider entered a model that used an FSI F7, outfitted with what
was at the time FSI's standard electrical igniter.  This was a piece of
slow Thermalite with nichrome wires attached.  The champ loaded up and
walked 100' away onto a slight hill to man his transmitter.  The launch
control officer gave the countdown and pushed the button -- nothing
happened.  He tried once more, gave the countdown and pushed the button,
and still nothing happened.  The champ put down his transmitter and ambled
back to the pad.  The LCO went on to service the next contestant in the
firing order.  Just as the champ got back to his pad, the engine ignited.  
NOBODY had seen the igniter burning, despite the fact that four teammates, 
four world-class modelers, were staring at the engine from the 15' rope.  
Without guidance, the engine pod separated and flew around the range
for a full 10 seconds.  It burned a fist-sized hole in the shirt yoke
of one Canadian timer, bruised his shoulder, and missed burning it only 
by some miracle.  Everybody else hit the dirt or ducked behind cover.

This accident caused the NAR to take up the safety question of what was 
essentially electrically-operated fuse.  The Safety Code was amended to 
allow only igniters that would ignite engines WITHIN ONE SECOND of pushing 
the launch button.  The manufacturer was forced to modify his cheap igniters.

The other result was that the heavy hand of the state of New Jersey came
down upon model rocketry, due to the fact that there was a state fire 
safety official who had come by to observe the event.  Rocketry permits
were enforced, along with age limits and engine purchase restrictions.
It took NAR modelers in New Jersey 12 years to reverse the prohibitions
that resulted from that ten-second disaster.  In this instance, several 
THOUSAND people were hurt by the use of fuse.

> I wouldn't reccomend fuse for children in the hobby,let them have the joy :)
> of pressing the button and going ooh ahh.They don't know how to figure the 
> seconds etc that have to do with fuse.

And you do.  OK, be a "man."  Every product you've ever bought has always 
worked properly 100% of the time, so why hesitate now?

> As for the law,I've never seen or heard of any law like this

Unless you're a lawyer, a rocket manufacturer, or have worked in the
area of state model rocketry regulations, what does that really prove?
You can take my word for it that this is what the regulations in your
state say.  Ohio is a strong NFPA state.

> although other stupid laws exist so I guess this one could also.

Unfortunately, stupid laws serve a ready-made constituency.
-- 

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