I loved the NWI-1 igniters. They came in at least two versions.

The original was around 30 ga with a smashed section that was coated with the blue flexible pyrogen. you bent it at the smashed spot and that spot had higher resistance and heated a bit faster than the rest of the wire.

The later version was 31 ga and had no smashed section.

The original solar igniters were not so great and would break apart - even when new. They improved the tape strip and the weld of the bridge wire to the lead wires and they got better. Except for a bad period with the reddish pyrogen that would corrode the lead wires after sitting around. I think the lead wires are more of an iron-based wire and they would rust if exposed to the elements, but that red pyrogen would just decompose itself and the lead wires.

The last 20+ years of black tipped solar igniters were superior - especially when used with the plugs.

but I still love nichrome wire with a little loop formed around a straightened paper clip. I pre-load hundreds of motors a year with those so we can have faster club launches. The newbies alos love the demo I do where the loop of nichrome turns to molten metal when I hit the launch button.

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

I'm glad to see I'm not the only one that does that. School launches were painful at best when I let the classroom teachers and students try to prep motors.

As for melting the nichrome, I used to take spent solar igniters and melt the heavier leads with my 12v relay system just for fun.


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I love sanding.

The answer you seek was right there in what you quoted from me