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!
Chuck Neff
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.
Ted Novak
TRA#5512
IEAS#75
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.
Ted Novak
TRA#5512
IEAS#75
http://www.perfectflite.com/Downloads/Ejection.pdf
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!
I was on vacation recently and stopped by a fireworks showroom. They had
refill fuse "e-matches" for an inexpensive fireworks firing console they
also sold. After seeing them, I went ahead and bought two boxes (25
e-matches ea.) for $9.95 each thinking I may be able to use them. They're
basically a little plastic closepin with a filament inside notched to hold
on a fuse attached to 5' leads. I did some bench testing with them on an
RRC2 and every one fired. I added some black powder and tested a few more.
Again, every one fired. I was very pleased with the results and the cost of
about 40 cents each. The other good thing was that I can order more and
have them shipped to me with no problems.
Anybody else seen these?
Care to share your source? I need a new source as I'm down to only 4
Oraxals (SP?) left in my stock. Each flight of my 1/2 scale Patriot
uses 4 matches (2 per altimeter)
-Aaron
Chuck Neff wrote:
Interesting.. How do you mount these? Have any pics closer up of what
these things look like?
These almost seem like the blank chips that you can get from firefox.
Chuck Neff wrote:
What's the secret to using the Firefox chips? I made up some and one
burned out my MAD unit. Richard Galejs sent me a power chip to fix it
though.
When I connected up one of the "ematches" to a plain battery it fired
but like
I said, it burned out my previously functioning MAD unit.
I'm sticking to ematches for now. M-teks work good in all my tests
and are still available.
Kurt
The IRF 7101 used in the output of this and other units is somewhat
fragile. The AltAcc uses it and I have used mine since 1999 without any
trouble. The secret I think is that the e-match opens up quickly. If you
look at the data sheet for the IRF7101 you will see that it is very
limited by heat dissipation. It is so small that any significant current
for more than a few tenths of a second will kill it.
From what I have seen of the MAD units, they use a capacitive discharge
system. This limits the energy and you shouldn't have had any trouble
even with a dead short on the output. Unless the series resistor to the
capacitor were something like a 0R0.
--
David W. Schultz
http://home.earthlink.net/~david.schultz /
Hey Chuck,
I bought a box and testfired two. Even put cannon fuse in one with
no ignition. Did you pry the chip out of that plastic carrier in order
to put it in a canister? Does this thing need something of a booster to
get to work?
Kurt Savegnago
Chuck Neff wrote:
Hey Kurt,
No, I did not pry the chip out. I separated the two pieces of the clip
(removed the small rubber band and lifted the top off). The breakdown of
the tests I performed are as follows:
Test #1 - (5) E-matches
1. Separated the "bundle" into individual twin lead e-matches.
2. Disassembled the clips by removing the rubber band and lifting the top
off.
3. Attached lead ends (stripped) to my RRC2 outputs (I did double the lead
end and twist to give it a larger surface area).
4. Turned on my RRC2 and activated the output test.
5. E-match connected to Apogee/Drogue outputs fired after 10 seconds
followed by the Main (by firing, I mean I can visibly see the filament
burn/flash).
Test #2 - (5) E-matches
1. Separated the "bundle" into individual twin lead e-matches.
2. Disassembled the clips by removing the rubber band and lifting the top
off.
3. Attached lead ends (stripped) to my RRC2 outputs (I did double the lead
end and twist to give it a larger surface area).
4. Placed the e-match end in a WD-40 cap.
4. Poured a small amount of black powder in the cap until about 1/2 the clip
body was covered.
5. Turned on my RRC2 and activated the output test.
6. E-match connected to Apogee/Drogue outputs fired after 10 seconds
followed by the Main.
I also tested (2) with a PML Co-Pilot altimeter (same basic design as the
RRC2) with the exact same results.
What are you testing them with? I assume you can see the small spring
shaped filament in the clip? Did you check for continuity before testing?
Chuck
Thanks for the specifics Chuck. Always good to have some alternatives
on hand.
I tested only two using a 12v. battery and I was able to do a continuity
check with one of them. I think I'll just open one of them and pour a
little 4F on it and repeat the test at a distance.
I was expecting a visible flash but didn't notice anything.
Kurt
Chuck Neff wrote:
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
some promise.
Ted Novak
TRA#5512
IEAS#75
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
same reason.
Kevin
Have you ever actually seen the filament break in flight conditions? I've
flown christmas bulb charges with over 200 flights, including a K1275 and
M4000, and only had 2 failures, both of which I figured out the cause and
neither was due to the filament breaking. On one, I had left too much air
in the charge and the BP wasn't touching the filament when the current
flowed. Now I always pack a bit of flameproof wadding in the end before
taping. On the other, the leads of the bulb had corroded enough to inhibit
the current and prevent firing. Now I lightly rough up the leads with
sandpaper if the bulbs have been stored for a while. I have had no failures
since instituting those changes. Contrary to what others say, I also have
had success with up to 5g charges (in a 7.5" rocket with shear pins). The
size of the shrink-wrap tubing needs to be increased significantly the more
BP you plan to put in. If you use a long thin tube of BP, the BP furthest
from the filament will be blasted away without burning.
Don't let people tell you that christmas bulbs won't work. Try it, and
think carefully about the failure modes, and you should have great success.
-- David
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