Quest Q2 vs. Q2G2 igniters - firing current
 

I just got back from the monthly Boeing Employees Model Rocket Club launch (where we had a bunch of Scouts launching their first rockets, among other things).

I discovered the hard way the the club's large launch system is only partially safe for Quest igniters. The first time I hooked one up - a Q2 as supplied with the German-made A8-3s they are currently filling A6-4 orders with - with great care since I didn't know if the continuity light current would fire it. It didn't. I subsequently flew that one and another just fine.

I later racked up my Zenith II for its maiden launch with a German Quest B6-0 booster and Estes A8-5 sustainer. I used the supplied Q2G2 igniter in the B6-0....and the rocket took off when I flipped the toggle to check continuity. No one was too close and it was actually a nice flight, though the sustainer shed a fin somewhere - and all was recovered except that fin.

I obviously generalized too much about firing current between the two types of Quest igniters.

I subsequently flew another Q A8-3 with Q2 igniter and all worked as it was supposed to.

So....how much different is the all-fire current for the Q2G2 than the Q2?

you might find this an interesting read on the Quest Q2 igniters:

http://psas.pdx.edu/Q2IgniterEvaluation/


as for thr Q2G2 read this thread:

http://www.oldrocketforum.com/showthread.php?t=4516

both should answer all your questions concerning the Quest Q2 and Q2G2 igniters.

HTH

Terry Dean

Terry,

That helps. In working the math backward from that first link, it looks as if the Q2s take similar amounts of current to fire as do Estes igniters. They concluded it took about 1Joule, or 1 watt-second of energy. If we assume their 100 ms fire time and, say, 6V, then we get about 1.7A fire current.

That would certainly correlate with what I observed on a launch system that was pretty much designed for Estes igniters and which was running off a 12V garden tractor battery yesterday.

The specs of the Q2G2 are available and I've participated in the other thread you linked to, so it was the Q2s that I really had the question about.

I'll just have to take a meter to the launch next month and measure the continuity current on that system - and not use Q2G2s on it any more.

The Q2G2's (Quest igniter 2, generation 2) are the very first igniters that Quest has made that have a low all-fire current threshold. The previous generation Q2 igniters had firing current requirements that were similar to those of the Estes Solar igniter, as you noted. I don't know what the requirements were for the Tiger Tails (first generation igniters; hey, you might still run across them at some point - it could happen), but I suspect that they were the same as those for the Q2's and Estes igniters.

MarkII

Thanks.

I clearly misunderstood in the midst of all the info I've been absorbing since becoming BAR'd in January. Before that I wasn't even aware that Quest existed, never mind that they've had three kinds of igniters in their history, while during the 30+ years I've been out for Estes what were back then then brand-new Solar igniters are still the standard.

I will try to remember to take my good multimeter to the next BEMRC launch and actually measure the continuity current of their 5-pad setup.

According to Quest, the "No-Fire" current is 50 mA and the "All-Fire" current is 150mA.


Replace the incandescent lamp ("bulb") for continuity with an LED that allows 30 or less mA to pass. Our club replaced ours with a very high light output LED that only passes 10 mA. It is ****ED bright.

Fred,

That would be the way to go....but I need to convince them it's needed first. I'm probably the first one that's ever shown up to one of their launches with a Q2G2 (or even a Q2). In the case of this particular launch setup it will be one replacement per channel - it has 10 or 12 (I don't recall). We were using five this past Saturday. Each one has a dedicated lamp and toggle switch for continuity checking/arming.

I use Q2G2 igniters myself primarily with an Electron Beam that is modified as you suggest (though it draws 27 mA on fresh cells). I also have a Quest controller from my Micromaxx starter set and it's in my field box as well.

Definitely worth the modification.

From the Sept NAR Electronic Model Rocketeer:

The OLDER Q2's are virtually identical to the standard Estes ignitors and should have pretty much the same current requirements/continuity current limits.

The NEWER Q2G2's are much more current-sensitive and you need to be careful with those.

Always test a spare ignitor against any system you have doubts about to prevent 'continuity check launches'... :)

Later! OL JR :)

Yep.....clearly should've done that. And I would have had I not been confused about the Q2s and thinking that they and the Q2G2s had similar requirements. And even though the Q2s are "older" they are still being supplied today by Quest in two forms: undipped with Micromaxx engines and dipped with the German WECO A8-3s they are substituting for Chinese A6-4s as I've posted about in another thread.

And yes, I saw that bit in the Electronic Rocketeer. As previously noted, I was well aware of that but was mistaken about similarity between the two types.

Fortunately besides a group of startled onlookers and one lost sustainer fin, there were no real repercussions from the incident.