IREC 2 Headed Motor Lighter

Our rocket took 10 seconds to get off the pad, but it did go. That happened to other teams as well. That's unnerving to say the least. I noticed you used two different brands of pellets - ours was Pyrodex, not Hodgeson. I wonder if that makes a difference?

An igniter is supposed to be touching the delay charge, but on our igniter the top pellet was about 3/8 of an inch down the dowel, preventing that contact. Normally, that's a chuff waiting to happen - and guess what? Ours apparently did chuff!

I discussed this with various folks. The contention is that the flame should propagate up & down very quickly & efficiently. I still contend the distance may make at least a little difference.

For really large motors, I question whether 2 pellets is enough. We may want to give folks the option to use three pellets.

Further, I see no value of having a space between the pellets. They should be butting up against each other. That'll make their burn more consistent & concentrated.

It may also be a good idea to put the ematches in between the two pellets, but we should test to see if a single ematch can light both pellets.

In any case, I don't see why we can't simplify the process by simply using an ematch pyrogen dipping kit with 2 ematches dunked together. Sell the kits to the teams, have a class similar to the existing motor building class, teach them how to use it, and have the igniter build supervised, and RSO'd at launch time.

One more annoying suggestion:

The wood dowels are a great idea, but they still require adjusting their length to the specific motor being used. How about making life easier for the teams by pre-measuring how much of the dowel needs to be cut for various motors? You can do this by publishing a chart, or a spreadsheet. You can also mark all the dowels with a Sharpie at manufacturing time. You can use different colors to make life easier for folks. For example, "if you're flying an O5500, cut the igniter stick at the black mark. If you're flying a M2050, use the green mark. If your motor is from Loki
Research, you're on your own... :-D"

Fun homework assignment #1:

Doug Pratt of Pratt Hobbies did a white paper on using smokeless powder (like Pyrodex) as a BP substitute for ejection charges. You may want to take a look at that & see if you can apply his results to your IREC igniters. He makes a very important discovery: getting smokeless powder to burn right requires pressure as well as an ignition source. He recommends you wrap your charges in something like thick electrical tape to insure they go off properly and don't just smolder.

That right there might solve our chuff-like behavior.

Fun homework assignment #2:

Google NASA Standard Initiator. That's NASA's standard igniter for everything, including the Shuttle SRBs. It's a redundant bridgewire lighter developed from the single bridgewire Apollo Standard Initiator.

Dig deep enough & you'll find the formula for their pyrogen equivalent is also online.

Feel free to contact me to discuss this further

Thank you,

George N. George
TRA 129
NAR 24025
[****]

Links:
https://pratt-hobbies.com/will-ejection-canisters-work-with-powder-substitute/
https://en.wikipedia.org/wiki/NASA_Standard_Initiator
https://psemc.com/products/103377-500-space-standard-initiator/
https://llis.nasa.gov/lesson/35