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!
TRA #7915 L3
NAR 74595 L3
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?
Didn't see your post until now, odd ;/
Well, I'm still working on my last box of Daveyfire 28B's so I'm pretty
set. That being said I used to use flash bulbs but those are VERY hard
to come by now-a-days.
Once my supply of 28B's are gone I'm going to give xmas bulbs a shot.
$1.99 gets you a whole string of them at Target. That's about the price
for one ematch, total bargain.
The way I've seen it done is to crush the tip of the bulb exposing the
insides, hot glue bulb in a crdbrd tube and fill with BP. I'm sure
google could come up with some sites.
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
Before I even think of using xmas bulbs on flights there WILL be some
serious ground testing. If that fails then it's no to xmas bulbs.
I haven't worked out all the details yet but small glow plugs could have
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.
the notorious t-e-d wrote:
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
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...)
Darrell D. Mobley wrote: