Is my understanding correct that in order to obtain/possess e-matches (such as Davyfires, Oxrals, M-TEK's, etc.) that you must have a LEUP? If so, what are most of the non-LEUP holders using for ejection charge firing? I'm aware of flash-bulbs but would care not to go that route. Any input would be greatly appreciated. Thanks!
Why won't anyone respond? I realize that I'm not a regular poster, but I do frequently visit the group. There can be good info. found here at times (as long as you can read between everything else). Please?
I used this method once for dual deploy and it worked 50%. I had continuity on the altimeter when the rocket launched, but during flight, the bulb in the drogue section wound up coming loose and didn't fire. The bulb with the main deployed perfectly though.
I haven't taken the time to really think of other ways to make this work, but I am sure there are many ways to do so. Plus they are SUPER cheap, so if you figure out a reliable way to use them, then great!
Little bit of self promotion here but take a look at Newtons3rdrocketry.com and select products. We have a ejection solution based on 48 gauge Nichrome bridge wire on a PCB substrate. Much like an ematch without the pyrogen. Come in a prepackaged ecan with either a 2 or 5 gram capacity. Very robust and the small ones are ~ $1.00
Ground testing isn't really gonna help with Christmas Bulbs because ground testing isn't representative of flight contitions. The filament on the christmas bulb is pretty weak and not soldered on, so that is one place where the stress of flight can cause a failure. Another is the bulb coming un-seated. Ground testing, while smart if you are trying to figure out how much BP to use, isn't going to be able to account for those things. And the one I used on my 3" Thor failed on an I211. I imagine it would have failed on a J350 or 570 as well.
Your best bet is to test the charges in flight as a backup to whatever e-matches you have installed. Really, you just want to make sure that you get them to fire with a high rate of success, so maybe stick 1/2 gram or 1 gram of powder in them or something.
I've used Christmas bulbs with great success. The key is to use more than one for each ejection charge. I normally use 2 bulbs per charge for redundancy, but based on the canister size, one could use 3 or 4. It's not much more work to add more if desired. It's much less work and costly than replacing a rocket.
I also use ematches, and I always use at least 2 for each charge for the same reason.
What size flashbulbs do you typically use? It's been years since I've used any, and I don't remember the size designations (last time I used them was in the early seventies along with some Centuri Sure-Shot igniters -- this was my cluster ignition method of preference...)