Launch Prep - Some Hurdles Part 3

This is another appropriate rocket for October launch, the MMX Zoom Broom.

I've been using square toothpicks to hold the small MicroMaxx igniters in the engine nozzles.
Where some use a round toothpick, I prefer the square ones.
It's like fitting a square peg into a round hole, I think it allows a little "venting" when ignition takes place.
A round toothpick seals the round nozzle on all sides and might contribute to some of the MMX engines exploding. I've never seen a MMX engine explode.

But, why take chances? This square toothpick is too wide to fit into the nozzle.


The narrower end of the toothpick was sanded even smaller on a block with 220 grit sandpaper.

This is the problem with the MMX igniters.
The thin bridge wire fits fine - but where the thin bridge is joined to the copper leads is the problem.

That bent bridge wire tip has to make contact with the propellant far up inside the nozzle. When inserting the igniter, those connecting "nubs" stop the bent tip just short of the propellant.

To insert the igniter far enough, you've got to squeeze those nubs close together - without touching each other and shorting out the igniter.


It can be done, you've just got to take a moment to be sure the nubs don't touch.

Use the toothpick to hold the igniter in place. The toothpick also separates the nubs pressed into the nozzle.

TIP: Never use force when pressing the toothpick in the MMX engine nozzle! Use just enough pressure to hold the igniter in the nozzle. Too much force and that engine might explode!