First Fire Junior igniters

[cwbullet]

eMatch type heads might plug your nozzle and could be too tight of a fit. I would be concerned about a CATO in a 29mm.

[CarVac]

Yeah I'll probably use those to (ground) ignite 54mm non-Medusa nozzle AeroTech motors. I saw a technique online involving folding the shooter's wire for getting two ematch heads on one igniter that I will have to try.

[jsargevt]

Another trick for cluster success is to take a bit of pyrogen and "paint" the top of the upper grain. Effectively the same as re-dipping an igniter but if you are looking to get something lit reliably it can help. I have had to do this for a couple of AT smoky motors that were being difficult and it "resolved the issue". Also handy for those smaller motors where having a fat dip on an igniter is a pain to get through the nozzle.

[stealth6]

Some bits from my own (limited) experience.

I play around with small motor clusters a fair bit. One of my favorite rockets flys on three canted 24mm motors - either black powder or 24/40 RMS. When I fly BP, I generally use Q2G2s and have had good success.
With reloadables it's trickier. I started using FF Jr's with decent results, but then I started making/dipping my own igniters using Cat5 or shooter's wire, 32g nichrome (wrapped, not soldered) and Quickburst pyrogen. These have worked excellent for almost all my flying (generally F/G/H 29mm motors), but they're usually a bit too fat to fit well in the 24/40 motors. So, I honed my wrapping/dipping skills a bit in order to make them smaller/thinner. This worked well, for the most part - they fit those smaller nozzles, fire just fine, and have "always" lit the motors they're supposed to.

However, I had an odd experience this past weekend at Hellfire17. I prepped and loaded the aforementioned rocket with 3 E18s (24/40) and my thin homemade igniters. But when the launch button was pushed, my rocket just sat on the pad. Hmmmm. When I retrieved it, I found that all three igniters lit (and had NOT been pushed out of the motors), but NONE of the motors fired. Double hmmm. It's quite strange that all three motors failed to ignite.
So, I went back to my prep area, and decided to try again - this time loading with three FF Jr's that I happened to have.
Brought it back out to the pad, and crossed my fingers. This time - perfect ignition, launch, and flight.

But now I was faced with a dilemna. The next rocket I wanted to launch was more complicated. It also launches off of three clustered E18s, but then it uses a timer to stage to another motor, from which it motor ejects at apogee. That cluster HAD to light properly. I REALLY needed to be confident.
But.....I had no more FF Jr's, and at the moment I didn't trust my own igniters. I went searching at the vendors and along the flight line to find three more FF Jr's, but came up empty. In fact the ONLY thing I could find that would fit, and that SHOULD work well, were some commercial made igniters that looked exactly like my own that Joe at Giant Leap dug out of the bottom of a box. He had only the three, but he gave them to me and wished me luck.
I was nervous but decided to go for it. I loaded them up, and headed back out to the pad. 5, 4, 3, 2, 1 and..........they worked just fine. Second stage also fired (a CTI with it's own igniter) for a successful flight.

The moral of this story? First Fire Jr's have worked well for me a lot of the time, but I have had a few misfire problems in the past. On this occasion they worked great. If they were all I had available, I would use them again.
My own igniters have worked great every time but once. And on that occasion all three failed together. I'm a bit perplexed by this, and really don't know what to make of it. But I will take it as an anomaly for now, and continue to use them whenever I can.

Your mileage may vary, s6

[CarVac]

My interest in this is that I want to stage to a G138, and a Raven can't handle enough voltage to light a FirstFire. In lieu of ematch chips, is there a way to wrap nichrome bridgewire to make it light on lower voltages? Fewer wraps, and two of them in parallel for more active area? The Raven can supply plenty of current.

[Stewart]

One of these will solve your problem -- http://www.whooshtronics.com/product...t-o-matic.aspx

[awseiger]

As for the ematch heads plugging the nozzle, I know that CTI uses standard Ematch heads in their motors (and they work incredibly well). I have used the E-matches available from Animal Motor works to ignite around 4 or 5 SU AT motors without failure (F50's and a G80 out-of-bag in humidity for over 2 months)

I do, however, understand where the concern lies.

[CarVac]

In the 3-grain 29mm line, I do know that the White Thunder and Vmax use normal ematch heads, but in the G54 Red Lightning I flew, it had a really tiny (skinny) ematch head, perhaps to fit through the smaller nozzle (or is it that much smaller? I didn't really examine the nozzles except on the Vmax because the throat diameter was just nuts). Can I maybe trim the back side (the wide part) of an ematch head to make it smaller?

[cwbullet]

Usually not that common, but if your get a Cato, that might change you mind.

[llobdelljr]

That's not quite true. I put a Triple7 50cal. pellet in the top grain af AT reloads. Lights just fine, and fast, with an e-match, either on the pad or with a timer (altimeter) for staging.
Larry Lobdell Jr.

[QUOTE]You really ought to dip your own igniters if interested in staging, unless you put a CTI motor in the sustainer.

[cwbullet]

[QUOTE=llobdelljr;376477]That's not quite true. I put a Triple7 50cal. pellet in the top grain af AT reloads. Lights just fine, and fast, with an e-match, either on the pad or with a timer (altimeter) for staging.
Larry Lobdell Jr.

You really ought to dip your own igniters if interested in staging, unless you put a CTI motor in the sustainer.

I don't think you read the whole thread. I was referring to small slot CATOs. They do occur if the nozzle is plugged. You have to watch you igniter size and the chip size on an match.

I have seen CATOs and have had 2 myself until I learned that igniters can cause them.

As I said it is not that common, I was just warning to be careful with the size.

Dipping your own igniters is a great way to go if you plan on staging. Your odds of success go up greatly over a simple match with an AT motor. A Magnelite burns much hotter.

[Wayco]

I put a Triple7 50cal. pellet in the top grain af AT reloads.
Larry Lobdell Jr.

Never heard of this, would you elaborate?

[cwbullet]

I wrap my own igniters and use my own pyrogen recipe. The hardest ones to get right are the ones for the smaller motors. I cluster a pair of 29/40-120 in various propellant types. I've never had a time when one didn't light, although I had a pair of G64Ws where the rocket was 50 feet up before the second motor came up to pressure.

I always use a old analog multimeter to get accurate ohm reading on the igniters and try to match them within about 1/4 ohm. I'm not sure that is really necessary, but with homemade igniters I think it's good practice since the resistance will usually vary much more then commercial.

This is the key. Redip a very small ematch or make your own. You will need a small igniter for most small AT motors. The slot if brutal on igniters that are marginal or too large. It is easy to make your own.

I guess that's unfortunate since I probably won't be clustering anything else but 29/40-120 cases; everything else is much more expensive.

Can you use the ematch style heads in them without the ematch plugging the nozzle on ignition?

Yes, as I said before, just watch the ematch size, use CTI motors (they come with an match), or make and dip you own. If you use magnelite, it will light just about anything. You home made igniter size will go down as your skill goes up.

[WilliamD]

Success guys! I finally launched the Titan- twice with paired F23's. The First Fire Jr.'s did very well- simultaneous ignition both times, as far as we could tell.

[qquake2k]

Beautiful!

[cwbullet]

I have never had a problem with first fires. They work. Congrats on the successful flight.