per CTI's FAQ...Tony
Can I use a different igniter?
Theoretically yes, but… why? You will not add any reliability with another igniter, but you certainly may lose some. The ignition system on Pro38 and Pro54 motors is exactly that - a system, and it works. Commercial electric matches are very reliable, and there is more than enough output from the pyrogen to ignite the igniter pellet contained in the top of the motor core.
Some time ago we experimented on the test stand with progressively larger and larger gaps between the electric match and the igniter pellet. The final test was successfully igniting a 6 grain Pro38 with the electric match head inserted only 1" into the motor. This is not recommended! It merely demonstrated that it was not critical to have the match head in tight contact with the igniter pellet.
If you insist on using a homemade pyrogen-dipped igniter, think about this first: we recently precisely reproduced an unusual failure of a Pro38® J class reload. The flier reported that at ignition, his motor ignited with a small flame and no thrust, and continued to burn for over a minute, with the rear end of the motor case melting and dripping into a puddle of aluminum. The rocket was destroyed. We asked the usual questions, including asking if the stock igniter was used, and if the flier made sure it was all the way up the motor core. Both answers were "yes".
This left us baffled for a while, until eventually we decided that the only way this could happen is for ignition to have occurred near the nozzle of the motor. We also knew that the stock match would not ignite the propellant directly, so how could this happen? We took a few reloads out to the test stand with some electric matches, plus a couple of pyrogen-dipped igniters.
The electric match would not ignite the propellant by itself, as we already knew. We then installed a dipped igniter a short way inside the motor, and pressed the button. Bingo! The motor burned like a road flare for about 90 seconds, and the rear of the motor case melted into a puddle of aluminum just like the failed reload. In fact, we couldn't tell the remains apart. Hmmm…
When asked again, the flier sheepishly admitted he had indeed used a homemade dipped igniter, and we figured it must have caught in the core and felt like it was properly installed, or else slipped out of place. All was forgiven, and we actually learned valuable information from the tests. The flier also said he would stick with the stock igniter from now on!
