Checking e-match before installing.

[rocketcharlie]

Hello, I have had some issues with e-matches I have used to deploy parachutes. The issue has been them not firing, so the dual deploy rocket comes down on the drogue only or worse yet, no drogue chute. I'm wondering is there a way to make it more certain they will fire? If i determine the resistance is within certain values will this help? I fully realize it wouldn't be a good idea to test the resistance while the e-match is in the deployment charge.

Thanks in advance-

 

[rharshberger]

What altimeter, what ematches (commercial or homemade). Resistance is ALWAYS checked prior to loading it with the charge. What setup are you using terminal blocks etc, pictures would be good.

 

[TimothyG]

Check continuity and resistance of the entire batch when you either purchase or make a new batch of e-matchs. And vacuum test all your altimeters. If you don't have a vacuum tester you can use a mason jar and a syringe style turkey baster to create enough of a vacuum change to effect a flight simulation. And I never do the vacuum test with lightbulbs and the like. Don't care if my altimeter can turn on a lightbulb or not, so I test my altimeters using live igniters. A couple igniters is cheap testing expense compared to lawndarting a few rockets.

 

[tim cubbedge]

I always check continuity for all e-matches used in deployment. Should be somewhere between 1.2-1.8 ohms.

 

[tfish]

Do your rockets beep out the correct continuity beeps on the pad prior to you launching them? And they come back with un-fired charges? What altimeter(s) are you using?

Tony

 

[Handeman]

Always measure the resistance of the matches before you use them to make sure they are good. Make sure your altimeter is beeping the correct sequence when it's powered up on the pad.

Sometimes things go wrong against all odds and there is nothing you can do. I had a flight where I checked the resistance of both matches, they were both about 0.8 ohms. Neither charge fired and fortunately it was before I add a little nose weight and the rocket was marginally stable. It tipped over and fell flat from 4000 ft into the middle of a corn field. I had a pretty good line on where it landed and after going 150 yards into the corn I almost stepped on it as I stepped through a row of corn. It turned out both ematches had fired. They both showed open when resistance was checked after the flight so the altimeter did fire the matches. The altimeter was also beeping out altitude like a normal flight. Neither match burned the pyrogen so neither charge went off.
Both the ematches were commercial ematches but from different manufacturers. Considering the reliability of commercial matches, the odds of having two fail in that way was very small. Probably as small as the odds the rocket would fall flat the whole way down.

Some days, the rocket gods just need a laugh!

 

[rocketcharlie]

OP here.
Rich, I have been using a perfectflight stratologger. The ematches I'm talking about have been homemade. They were from a company that provides a fuel-oxidizer dip to apply to a bridge wire The bridge wire blanks were purchased from another company.

Tony thanks for the comment about checking continuity beeps on the altimeter. I knew that there was a series of beeps that did that, but had forgotten it at that time.

Tim, I will certainly check resistance of my ematches. from now on.

Timothy, I do check my altimeters with a vacuum. I do get what you are saying about testing them with a light bulb being penny wise & pound foolish.

Handeman, I think we all have had issues that make no sense at all, hopefully that doesn't mean that we are doomed for them to happen again.


Thanks guys-

 

[tim cubbedge]

Since you say they are home made, have you ground tested any? What battery are you using in altimeter. Not all home made e-matches are created equal. Like motor starters, some can get by with low voltage (less than 9 volts), others need 12 volts.

 

[rharshberger]

OP here.
Rich, I have been using a perfectflight stratologger. The ematches I'm talking about have been homemade. They were from a company that provides a fuel-oxidizer dip to apply to a bridge wire The bridge wire blanks were purchased from another company.

Tony thanks for the comment about checking continuity beeps on the altimeter. I knew that there was a series of beeps that did that, but had forgotten it at that time.

Tim, I will certainly check resistance of my ematches. from now on.

Timothy, I do check my altimeters with a vacuum. I do get what you are saying about testing them with a light bulb being penny wise & pound foolish.

Handeman, I think we all have had issues that make no sense at all, hopefully that doesn't mean that we are doomed for them to happen again.


Thanks guys-

@ksaves2 , Kurt has made some really good statements in the past about homemade e-matchs. My first assumption when you made the original post was either a homemade altimeter or ematch. Commercial ematches are cheap and one of the areas that buying a premade is better than making them. I get that some people have a desire to make everything and there is nothing wrong with it, but it takes a lot of practice to make consistently reliable ematches. As for testing with light bulbs vs ematch, I do both, ematches to verify that the altimeter will fire them, and light bulbs to check my programming or to learn how to use the altimeter, my RRC3 probably had a few ematch tests then 20-30 simulation flights in the vac chamber with christmas tree bulbs, the "flights" were then downloaded to verify that "events" were happening at the right "altitude".

 

[rocketcharlie]

Hello again, I have used both 9V batteries and 2 cell 7.4V lipo batteries. The reason I asked about testing the rematches is that when one has failed in flight I have taken it out and haven't been able to
make it fire no matter what battery I use on it.

I have been making my own ematches and I admit to being my own demon when it comes to trying to make everything myself. I now am convinced that the right approach is to buy commercial ematches. Another flier has had good results from some he got off of ebay.

 

[rharshberger]

Hello again, I have used both 9V batteries and 2 cell 7.4V lipo batteries. The reason I asked about testing the rematches is that when one has failed in flight I have taken it out and haven't been able to
make it fire no matter what battery I use on it.

I have been making my own ematches and I admit to being my own demon when it comes to trying to make everything myself. I now am convinced that the right approach is to buy commercial ematches. Another flier has had good results from some he got off of ebay.

If you have crashed the Stratologger its a good idea to test it in a vacuum chamber (bounced under drogue type crash not ballistic entry type crash) just to verify it is functioning like it should. As for the ebay ematches many fliers have used those without issue, but please consider using MJG Firewires, a bit more expensive but there is absolutely no issue with legality.

 

[Buckeye]

The ematches I'm talking about have been homemade.

This is the problem.

Even the cheap, Chinese ematches are far more reliable than anything you solder yourself.

 

[CalebJ]

As for the ebay ematches many fliers have used those without issue, but please consider using MJG Firewires, a bit more expensive but there is absolutely no issue with legality.

What are the legal concerns with eBay ematches?

 

[rharshberger]

I'm not the best one to ask, but afaik the only legal to purchase without a LEUP is the MJG Firewires, or you can also make them yourself.

 

[Handeman]

Hello again, I have used both 9V batteries and 2 cell 7.4V lipo batteries. The reason I asked about testing the rematches is that when one has failed in flight I have taken it out and haven't been able to
make it fire no matter what battery I use on it.

Sounds like the bridge wire burned through but didn't ignite the pyrogen.
To much current can do that, it burns through the bridge wire before it can give off enough heat to ignite the pyrogen. A smaller weaker battery might work better in that case or more sensitive pyrogen.

 

[rharshberger]

Sounds like the bridge wire burned through but didn't ignite the pyrogen.
To much current can do that, it burns through the bridge wire before it can give off enough heat to ignite the pyrogen. A smaller weaker battery might work better in that case or more sensitive pyrogen.

Should be easy to check that, dip the suspect igniter into lacquer thinner and wait for the pyrogen to dissolve.

 

[OverTheTop]

I went through a phase of making igniters with Christmas tree lights. Got over that idea pretty fast. Far easier and more reliable to just buy igniters. Have not had a commercial one misfire yet.

 

[Bat-mite]

What are the legal concerns with eBay ematches?

I use them exclusively, and have for years. So far, I have had no visits from any law enforcement agency. One time I got pulled over for speeding by the State Police. My stuff was lying about in the back of my vehicle in plain sight. The officer did not ask me where I got my e-matches or how they were shipped.

Also, I ground test in my front yard, and so far, no neighbors have called the ATF and asked them to inspect my e-match situation.

YMMV

 

[tim cubbedge]

Should be easy to check that, dip the suspect igniter into lacquer thinner and wait for the pyrogen to dissolve.

Probably just as easy to check with an ohm meter.

 

[CalebJ]

I use them exclusively, and have for years. So far, I have had no visits from any law enforcement agency. One time I got pulled over for speeding by the State Police. My stuff was lying about in the back of my vehicle in plain sight. The officer did not ask me where I got my e-matches or how they were shipped.

Also, I ground test in my front yard, and so far, no neighbors have called the ATF and asked them to inspect my e-match situation.

YMMV

That's encouraging, as I have my first set out for delivery today from an eBay purchase.

 

[rharshberger]

Probably just as easy to check with an ohm meter.

An ohm meter is just going to say "yep no continuity", removing the pyrogen is going to allow you to see the failure mode.

 

[Handeman]

I went through a phase of making igniters with Christmas tree lights. Got over that idea pretty fast. Far easier and more reliable to just buy igniters. Have not had a commercial one misfire yet.

I did the same thing. I always pulled the wire off the filament wires first, check continuity and used two in parallel. Soldered all connections and hot glued into the bottom of a tube made of a few wraps of craft paper. Made it nice, just pour in the powder, fold over the tube, tape and go.

The down side, about +15 minutes per tube to build. They worked very well.

 

[rocketcharlie]

As always I thank everyone for there response to my original post. I have looked on Ebay for ematches and there are several under the search item of "fireworks igniters". Can anyone recommend which emstches to use?

 

[CalebJ]

I'm in no position to give an educated recommendation, but this is what I ordered the other day.
https://www.ebay.com/itm/Ship-from-...Wire-For-Fireworks-firing-system/133196978575
It's the bilusocn branding mentioned elsewhere on this forum. I lit one off and it produced a small and instant fireball. More than I'd expected to be honest.

 

[Bat-mite]

DELETE: These are the typical Chinese ones. I usually buy one-foot lengths, because I cut them down to a few inches long for use.

CalebJ nailed it.

 

[CalebJ]

A lot of the eBay options seem to ship from China, but there are a few exceptions. The ones I linked above arrived in about three days.

 

[Kelly]

BTW, and perhaps this is obvious to most, there's two kinds of chinese 'igniters' commonly sold on ebay etc. One is the kind pictured by CalebJ above, which (IME) are great igniters. But I'm seeing less and less of these advertised, being replaced by a type that I think it just a little clip with a piece of nichrome acros the leads. The idea is that you can clip a piece of safety fuse into the end, and the nichrome will ignite the fuse. These are NOT what you want:

 

[electricmatch]

As always I thank everyone for there response to my original post. I have looked on Ebay for ematches and there are several under the search item of "fireworks igniters". Can anyone recommend which emstches to use?

We have a list of rocketry products. https://electricmatch.com/rocketry

In regards to the ATF or IATA/DOT(if you get them in 3 days from china, they are flying them unmarked), I would just watch what you use at group launches or shows, as if they are going to pop up anywhere, it would be there.

 

[g.pitts]

We have a list of rocketry products. https://electricmatch.com/rocketry

In regards to the ATF or IATA/DOT(if you get them in 3 days from china, they are flying them unmarked), I would just watch what you use at group launches or shows, as if they are going to pop up anywhere, it would be there.

I've used the MJG Firewire Initiators and had zero issues. I'm sold on them for life.