Model Forum / General / Rockets / January 2006

When I started in 1965 or thereabouts both Estes and Centuri gave you a
length
of #32 nichrome wire, you formed a loop in the middle using a pen
point, inserted this in the nozzle 'till it touched the propellant and
held it in place with a wad of tissue paper.It would glow red hot and
ignite the propellant if it was touching

I am told the first electric igniter MMI used was a piece of jetex wick
bent in half, you striped the ends to expose the copper wire core which
was hooked up to your clips.Push the button and several second later it
would get hot enough to ignite the pyrogen

Dale Greene
SPAAR 503

When I started in 1965 or thereabouts both Estes and Centuri gave you a
length
of #32 nichrome wire, you formed a loop in the middle using a pen
point, inserted this in the nozzle 'till it touched the propellant and
held it in place with a wad of tissue paper.It would glow red hot and
ignite the propellant if it was touching

I am told the first electric igniter MMI used was a piece of jetex wick
bent in half, you striped the ends to expose the copper wire core which
was hooked up to your clips.Push the button and several second later it
would get hot enough to ignite the pyrogen

Dale Greene
SPAAR 503

When I started in rocketry in 1965 both Estes and Centuri gave you a
piece of #32 nichrome wire, you made a loop in the middle using the
point of a pen and inserted it into the nozzle 'til it touched the
propellant, this would glow red hot to ignite the motor provided the
loop didn't short out. I think early FSI igniters were the same until
they went to thermalite, you used the nichrome wire wrapping the
outside to ignite the fuse.

I think the first MMI electric igniter was Jetex wick with the coating
stripped from the ends to expose the copper wire in the core which was
hooke to the clips. I'm told it took several seconds to heat this up to
ignite the pyrogen

Dale Greene
SPAAR 503

Nichrome wire igniters are still used today. I use hundreds a year myself and I've sold
thousands of feet of 30, 31 and 32 gauge nichrome wire on eBay (and direct e-mail sales to
TRF readers). I include a sheet that explains and shows how to roll the small loop in the
middle of the igniter by using a straightened paperclip. It is better to use a clip than a
pen tip.

Any decent 6 volt lantern battery will heat the 32 ga wire. 4 D alkalines will work as
well. For the 30 ga I suggest better batteries, like a 7.2 Volt NiCad pack or a motorcycle
or car battery. They will heat the 30 ga wire almost instantly and turn it to molten
metal. The intense heat at the looped tip is even more intense and it heats up there
faster - and that's what you want. Held into the motor with a ball of paper wadding or a
standard igniter plug with a tiny bit of wadding (tiny flat square) used to prevent the
plug from melting and falling out too fast (also, the wire is thinner than the Estes/Quest
igniter lead wires, so it needs more thickness to hold in place.

All the old catalogs online show the igniters used.

I've described the Estes "Astron" Igniters before (either here or TRF or YORS).
Originally, they were a thick (30 ga?) nichrome wire with the center portion smashed flat
with an insulating, yet flammable pyrogen painted on the center portion (and slightly
beyond the flattened area). The folding was easy since the flattened area bent first. The
insulation prevented (or reduced) shorts. the flattened area had greater resistance and
heated up first.
They switched to a nonflattened version in the mid 1970's and reduced the wire gauge to
31?

Centuri always used 32 gauge for their bare looped igniter wire or for the wires wrapped
around the Sure Shot sticks.

-Fred Shecter NAR 20117

Shockie,

 Just curious, after you finish these "investigations", where do you
publish the results?  They sound interesting.

-- David

Solar igniters first appeared in 1972.

Steve