What Ematches do you use ?? ?

I to am inclined to agree with Jeff on this issue. My question is, Where does personal responsibility fall into place. The user, is that person. IF the unit was to be proven defective and had been used in a way as it has been designed or described by the manual then the Manufacture would be at fault. BUT what I believe is trying to be said (as is with the testing that has been done as well) is that under normal operation as it is "supposed" to be run and if you the user neglect to pay attention to the current capabilities of your ematches/Ignitors and chose whatever option you have for ANY altimeter and ematch combo and it does not work and an incident happens (or even if an incident doesn't and it just destroys you rocket and such) it is you the end user that has to accept the responsibility of causing such by not heeding what is written nor by doing a the job of making sure that all the requirements for all the components were met.



Conway

UhClem said:

This will produce the wrong result for the simple reason that a test at a current too low to activate an e-match can heat it sufficiently to alter the properties of the bridgewire or pyrotechnic compound.

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Good catch!

I agree with Conway. It is the fliers responsibility to test the e-matches they plan on using with the electronics they plan on using with the configuration they plan on using the electronics in. It's that simple, and why you always hear folks say "ground test, ground test, ground test!"

I personally love my ARTS 2. I like that it is multi-functional and have had no problems with it at all.

Given the fact that the ARTS have such nice programming options - one that would be helpful would be a repeat fire for an ematch that failed to ignite. Simple continuity test should help. If the match failed to fire then it could be re-fired under the assumption that repeated fire attempts may cause it to fire. There should also be a limit to the max number of tries and something tied to a minimum altitude to avoid causing more harm than good.

This would still provide a way to avoid brownout - but maybe fire matches just on the verge - so that if you ground tested and it looked ok but you had a match just a bit lower than normal it might still fire on the repeat option even when it takes a little more current in the single fire mode.

Am I making any sense here?

uncle_vanya said:

Given the fact that the ARTS have such nice programming options - one that would be helpful would be a repeat fire for an ematch that failed to ignite. Simple continuity test should help. If the match failed to fire then it could be re-fired under the assumption that repeated fire attempts may cause it to fire. There should also be a limit to the max number of tries and something tied to a minimum altitude to avoid causing more harm than good.

This would still provide a way to avoid brownout - but maybe fire matches just on the verge - so that if you ground tested and it looked ok but you had a match just a bit lower than normal it might still fire on the repeat option even when it takes a little more current in the single fire mode.

Am I making any sense here?

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I would think this would be more taxing on the Altimeter and the battery. I myself dont thing firing a match over and over is going to make the difference. Its about the max delivered current for a specific duration that will get the job done. If a match dosent fire at that specific current or is bad firing it repatably will do nothing.

Forgive me if this sounds like a dumb question, but what is the time it could take for a "marginal" ematch to light, under worst case conditions - i.e. weak battery, high altitude, cold temperature? 1 second? 2 seconds? 3?
Since they will inevitably burn open anyways (is that a safe assumption? ) why not double that number, and just leave the pyro output active that long?
it seem to me the simplest way to give your ematch the best hope of firing under adverse conditions. If it fires in the usual time (i.e. 1/4 second or so) then there's probably no harm in leaving the leads hot the extra few seconds.
IF your circuit can monitor continuity WHILE firing (not that hard to do), then you could be really smart and watch the resistance, to turn off the power ONLY when you KNOW it has fired. And if that fails, you know it, and try to fire the main output early as a result (if its the apogee that failed).

Jeff

In this legalese society I'm more inclined to follow your lead. If, after the manufacturer makes a statement as such " Not reading the documentation and using the ARTS as recommended is CRIMINAL NEGLIGENCE."

Chuck

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Firstly, nothing wrong with disclaimers. However, putting an intentional false statement in the attempt to add some added horns to the disclaimer is not right. If you want to do it correctly, i would advise speaking with your lawyer and having them draft a proper disclaimer.

Even then both disclaimers and SIGNED waivers really don't hold any water when it comes to liability in court. They're pretty much useless.

I to am inclined to agree with Jeff on this issue. My question is, Where does personal responsibility fall into place. The user, is that person. IF the unit was to be proven defective and had been used in a way as it has been designed or described by the manual then the Manufacture would be at fault. BUT what I believe is trying to be said (as is with the testing that has been done as well) is that under normal operation as it is "supposed" to be run and if you the user neglect to pay attention to the current capabilities of your ematches/Ignitors and chose whatever option you have for ANY altimeter and ematch combo and it does not work and an incident happens (or even if an incident doesn't and it just destroys you rocket and such) it is you the end user that has to accept the responsibility of causing such by not heeding what is written nor by doing a the job of making sure that all the requirements for all the components were met.

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Again, nothing wrong with this statement. However, there is a big difference between "criminal negligence" and negligence. Even the best lawyer would have an extremely difficult time proving criminal negligence on the basis of someone not reading a manual and using a product as it was stated in the manual. There are specific criteria which need to be met to be grounds of criminal negligence.

Now if you took your HPR rocket and launched from your backyard in the middle of the city and it came down and injured someone, then yes, that could be grounds for "criminal negligence."

eastvolt said:

Firstly, nothing wrong with disclaimers. However, putting an intentional false statement in the attempt to add some added horns to the disclaimer is not right. If you want to do it correctly, i would advise speaking with your lawyer and having them draft a proper disclaimer.

Even then both disclaimers and SIGNED waivers really don't hold any water when it comes to liability in court. They're pretty much useless.

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Your right, There is nothing wrong with disclaimers.And again your right that they also dont amount to much. So why have them other then to have a fuzzy feeling of false security. But that just shows that even when a lawyer drafts them they still dont mean squat. In the end its all about personal responsibility. As well as who will pass the buck. As far as I am concerned if a product when used as it should be under the correct direction and conditions of the manufacture should fail then it comes upon the manufactures responsibility. If the user Fails to correctly do as they are supposed to then they are at fault regardless.

eastvolt said:

Again, nothing wrong with this statement. However, there is a big difference between "criminal negligence" and negligence. Even the best lawyer would have an extremely difficult time proving criminal negligence on the basis of someone not reading a manual and using a product as it was stated in the manual. There are specific criteria which need to be met to be grounds of criminal negligence.

Now if you took your HPR rocket and launched from your backyard in the middle of the city and it came down and injured someone, then yes, that could be grounds for "criminal negligence."

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Actually launching a HPR rocket from a backyard is far worse then criminal negligence. Its flat out stupidity and it should be just considered Endangering and careless with intent and Criminal with out anything negligent about it.

As far as a person launching a rocket that doesn't work right and it comes back in hot and hits someone again as if it is by fault of their own and nothing in actually defective issues they are being negligent and thus committing a crime and it can be quite easily a Criminal Negligent situation. Ive seen this happen in lots of other things in the same scenarios.

constevens said:

Actually launching a HPR rocket from a backyard is far worse then criminal negligence. Its flat out stupidity and it should be just considered Endangering and careless with intent and Criminal with out anything negligent about it.

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There seems to be lots of confusion here about what "criminal negligence" is. Please read up on the subject. What you are saying above is basically criminal negligence.

As far as a person launching a rocket that doesn't work right and it comes back in hot and hits someone again as if it is by fault of their own and nothing in actually defective issues they are being negligent and thus committing a crime and it can be quite easily a Criminal Negligent situation.

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Absolutely not. That does not fit the bill for criminally negligent. Again, please familiarize yourself with the actual definition of "criminally negligent" (per your state) and what criteria has to be met to be charged as such.

Ive seen this happen in lots of other things in the same scenarios.

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Please list some examples and references.

I've seen some statements about trying to fire an e-match more then one time.

Lets not forget most shooters e-matches are made to be shorted out after firing.

The reason is shooters use them in series, so they indeed need to fire short not open.

So you can't like just check continuity and assume the e-match did'nt fire.

Art Upton said:

I've seen some statements about trying to fire an e-match more then one time.

Lets not forget most shooters e-matches are made to be shorted out after firing.

The reason is shooters use them in series, so they indeed need to fire short not open.

So you can't like just check continuity and assume the e-match did'nt fire.

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Ematches open when fired. That is easily verified.

I still have three burnt J-Tek e-matches from a previous flight. They measure approximately 60 kOhm, 600 kOhm, and 2 MOhm.

An unfired e-match from https://www.electricmatch.com/ should measure about 1 Ohm.

Different vendors may provide different results...

WillMarchant said:

I still have three burnt J-Tek e-matches from a previous flight. They measure approximately 60 kOhm, 600 kOhm, and 2 MOhm.

An unfired e-match from https://www.electricmatch.com/ should measure about 1 Ohm.

Different vendors may provide different results...

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Were those blown up by BP or do you have ones that you just fired in a test to measure ?

You sure would not want to series wire your shoot with those at that ohm-age :surprised:

Art Upton said:

Were those blown up by BP or do you have ones that you just fired in a test to measure ?

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The one that ended up at about 600k was used in flight and exposed to BP. The other two were burned in the open to see if electronics would fire them.

WillMarchant said:

The one that ended up at about 600k was used in flight and exposed to BP. The other two were burned in the open to see if electronics would fire them.

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Humm....

Oxrals are designed to "burn short" so they can be wired in series.

Now I need to see if that "burn short" is only during the several second "Burn Time" the match seems to have, and then if they fail open.

Preparing to test.......

Please stand by........

.......

Well, the famed Oxral burn short does fail to open (500K ohms) after the burn.

I learn something new every day.

Another fun fact about initiators is that the plasma ball that surrounds the ignition can cause a short, though for a very short time. You can see this effect in some of the plots from the oft-cited Robert Briody report. So the resistance you measure after the event doesn't always tell the whole story.

Art Upton said:

Humm....

Oxrals are designed to "burn short" so they can be wired in series.

Now I need to see if that "burn short" is only during the several second "Burn Time" the match seems to have, and then if they fail open.

Preparing to test.......Please stand by........

Well, the famed Oxral burn short does fail to open (500K ohms) after the burn.

I learn something new every day.

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I haven't needed to purchase MJG with daveychips available, but had recalled that testing a ways back showed daveyfire (and I thought Oxral) were always open.

I don't see how they would short when the pyrogen is consumed. I notice the single bridgewire is visible on J-tek photo on their site just like the bare chips.

From the parallel versus series wire instructions I've read explain that using matches from same manufacturer (same batches even), results in an all fire in the brief window the nichrome is heating up. They are consistent enough to fire prior to the wire breaking.

But back to the original point of testing them, one of the reasons for wiring series is to test that cue prior to the show. Parallel could miss an open.

For the record.

Things change.

I have e-matches and can ship them. A Permit is required along with HazMat Fees.

The Hot Coils have been discontinued. I would make them on request (e-mail request please).

The E-Match kit:
1.) Does not require a permit to purchase.
2.) Federal requirements for storage apply after the mix is made by the consumer.
3.) The above statement is true for all binary explosives, even Magnelite and QuickDip. A BATFE LEUP is required to manufacture these items and there are shipping restraints. Dropping these items in the mail with out proper labeling is illegal. Most of the time items like these can go ORM-D as long as the requirements are met (including proper labeling).
4.) I was never "raided". The ATF actually called and made an appointment to "do the deed". Which consisted of telling me to stop manufacturing, until I was granted the proper permit. The LEMP permit was granted to me by the ATF after 90 days had passed. This is the normal processing time for permit applications. I was pretty upset about it, but there was no one to blame but me.
5.) Now other manufacturers are allowed to do what I am not allowed to do. Go figure?


If you are permit challenged use the e-match kit. You will be making e-matches comparable to the commercial offerings; and yes, the ArtsII will fire them, as well as all other altimeters that I know of.

The Federal requirements for proper storage of items like QuickDip or Magnelite are not enforced by the ATF. I'm not sure which alphabet soup branch does and I doubt seriously if the Feds know. I really don't see that it matters, as soon as you place the e-match in an ejection charge you have violated another law.

Or use Christmas tree light bulbs, seems to work, I don't think I'd bet my Bird on them. It's your bird, do as you think best.

I'm not convinced that using Pyrodex or any other Smokeless Powder for ejection charges is legal, but this seems to be the accepted practice. I also doubt seriously if the ATF would show up at a launch or your house and arrest you for possessing or using BP, Pyrodex or any smokeless powder. They have much bigger fish to fry. Many of these laws are never enforced, unless you do something really stupid, then they will all be used against you.

Good enough for me.

I use the Quickburst E-Match Kit, Those David CAN ship No problem, The Kit is VERY easy to use and I have NEVER had a failure.

As long as you read and follow the directions, you should never have a failure.

Fact:
E-Matches fail.

It doesn't happen very often.

Checking resistance/continuity prior to flight will identify most duds.

A failure can still happen if testing passes with flying colors. This could be caused by a number of things. Including battery failure, avionics burps, or something as simple as a bubble in the match head. For example, if a match has a bubble over the bridge wire, the match will pass all testing and fail due to the bubble not allowing the bridge wire to contact the pyrogen. I suspect this happens in many of the reported failures.

Murphy finds a way.

I've been having good results with Pyrodex and Estes ignitors potted into cardboard tubes with epoxy:

(Click to enlarge)


The tubes come from 1/4" launch lugs from Apogee. For larger charges, you could substitute 13mm body tubes to keep them shorter. I haven't tried that myself, yet, because all of my rockets are small. The charges in the picture were tested as follows:

1/2" charge in a Blue Ninja with a piston and a sealed bulkhead: perfect ground test
1/2" charge in the same Blue Ninja with a hole in the bulkhead and another in the piston: Partial ejection (lesson learned: Pay attention to pressure leaks)
3/4" charge in a Thunderbolt 38 with a piston: partial ejection in ground test
1" long charge in a Thunderbolt 38 ground test: adequate ejection, but a little wimpy.

All tests and flights burned the pyrodex completely.

Then I made a second batch, with one launch lug yielding two 1.25" charges and one 1/2" charge. Two of the 1.25" charges worked perfectly yesterday in my level 1 and level 2 cert flights, in glorious mid-70's weather. Today it's 50 degrees colder, snowing, and blowing like crazy, so it must be springtime in the Rockies.

In case the construction method isn't self-explanatory from the pictures, here are some details:

1. Cut your tubes in lengths appropriate for your rocket(s) based on ground tests
2. Carefully bend up the tips of the ignitors so that the ignitor head will be in the middle of the tube while the rest of the ignitor is laying flat
3. Mix up some 5-minute Epoxy and glop some onto some plastic or waxed paper. Set the ignitors into the epoxy, making sure that the leads are completely embedded and the head stays dry. To make them easier to separate later, keep them in a line, and some distance apart from each other.
4. Put the cardboard tubes over the ignitor heads, doing a little twist to make sure the epoxy adheres to the edge of the tubes all the way around. Wait for the epoxy to cure.
5. Fill up the tubes with Pyrodex or BP. Tamp down gently so the powder leaves the top edge exposed all the way around.
6. Mix up another batch of epoxy and cover the ends of the tubes, making sure that the epoxy adheres to the sides of the tube all the way around the top.

Time to make a batch of 6 charges: 10 minutes + waiting for cure + 5 minutes

Cost: $5.00 for 6 ignitors + $0.10 for powder + ~$1 Epoxy

QuickBurst said:

As long as you read and follow the directions, you should never have a failure.

Fact: E-Matches fail.

It doesn't happen very often.

Checking resistance/continuity prior to flight will identify most duds.

A failure can still happen if testing passes with flying colors. This could be caused by a number of things. Including battery failure, avionics burps, or something as simple as a bubble in the match head. For example, if a match has a bubble over the bridge wire, the match will pass all testing and fail due to the bubble not allowing the bridge wire to contact the pyrogen. I suspect this happens in many of the reported failures.

Murphy finds a way.

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I have ground tested dozens of the Quickburst "Kit" E-matches and I have to agree with Gary T, they have proved to me to be very reliable and I have not experienced a single failure.

As David mentions above, I have routinely checked for resistance/continuity when making the ematch and again before testing. I also check the battery power, wiring and such.

While admittedly I have not flown a Quickburst e-match, I will not hesitate to do so, it is very good product. If anyone is hesitant about the reliability of ANY ematch, then consider using two connected to the pyro channel. As always, ground test, Ground Test and GROUND TEST. Checking something one time is great, do it several times and have a repeatable result.

IMO
John

I'm one of the three that voted "Skylighter Kit" cuz that's what I have sitting in an unopened box downstairs.

Do the Skylighter kits have some kind of "Suck Factor" or other quality issue that I'm not aware of? Or are they just not as popular in rocketry as the QuickBurst kit is?

Scott

I am using the skylighter kit and have made over eighty ematches. Prior to use, I always check continuity and resistance. They are always very consistent (~1.5 ohms if I remember right). I have had a few failures, but I think it is an air bubble on the end as Quickburst stated. I may have put on the pyrogen too thick (thickness and viscosity, not sure which). I now use 2 ematches per charge (when using only 1 altimeter), just in case. I have had great success with Newtons3rd charge holders (no failures), so I may use them more. I may also try Quickbursts ematch kit as well.