One pyro device for two pyro channels on TeleMega/EasyMega

[voyager14]

I'd like to have two pyro channels run to the same e-match for my TeleMega and redundant EasyMega.

From the manual, it seems to say I can simply solder the wires running into the positive terminals together, and the two wires running into the negative terminals together. Resulting in a sort of Y shape.

I'll of course test this on the ground soon, but I'm curious if others have done the same and have any advice or can confirm what works best/is the most reliable.

Thanks.

 

[Voyager1]

Why would you want to do this? Just to save one extra ematch? That’s not sensible redundancy. If the primary altimeter ignites the ematch, but that deployment isn’t successful, then you have no secondary ematch to ignite a separate redundant charge. Don’t do it!

On a positive note - cool forum name!

 

[voyager14]

Why would you want to do this? Just to save one extra ematch? That’s not sensible redundancy. If the primary altimeter ignites the ematch, but that deployment isn’t successful, then you have no secondary ematch to ignite a separate redundant charge. Don’t do it!

On a positive note - cool forum name!

Haha, greetings fellow voyager!

The area I want to apply this most is for a high altitude apogee/drogue charge. I’ve got a two stager and my plan is to do a timer (time since launch, based off sims) if the sustainer motor successfully ignites. If it doesn’t, I’d like to use the built in apogee detection plus a short delay.

Hope that makes sense.

Edit: I would still have redundancy, as the same system would be set up on both a Tele and Easy mega.

 

[Voyhager3]

Well well well, I guess I should join in.

I do see where you’re coming from with this, however I think the main purpose of a backup is incase you have a bad e-Match, so sending it to the same one just would nullify that redundancy.

Best of luck you whatever this project is!

 

[OverTheTop]

I have done this with a TeleMega, for second stage ignition. The two channels are indeed just wired in parallel, and whichever channel fires first triggered the igniter. I had one set on a timer after booster burnout, and the second to start it earlier if it was getting too far off vertical too early.

Just really think about if you have enough redundancy and, more importantly, design the system to cope with off-nominal situations.

 

[voyager14]

Well well well, I guess I should join in.

I do see where you’re coming from with this, however I think the main purpose of a backup is incase you have a bad e-Match, so sending it to the same one just would nullify that redundancy.

Best of luck you whatever this project is!

Thanks, and makes sense. What we’ll likely end up doing for that event is having four total ematches, two per canister. As we want them pointing down into the canister, so all the black powder gets burnt.

We could technically do the same for other events, but don’t want to over complicate the wiring

 

[waltr]

I feel that it is the e-match that has the least reliability therefore you want to have redundant e-matches.
Same with air-starting 2nd stage. All my air-start failures were due the igniter failures.
However, the deployment of chutes in the sustainer always fired for successful recovery.

 

[voyager14]

I feel that it is the e-match that has the least reliability therefore you want to have redundant e-matches.
Same with air-starting 2nd stage. All my air-start failures were due the igniter failures.
However, the deployment of chutes in the sustainer always fired for successful recovery.

We will definitely experiment with separate e-matches. There’s really no drawback we can think of. As long as it doesnt complicate our wiring too much, we will go that route.

 

[Voyager1]

What we’ll likely end up doing for that event is having four total ematches, two per canister.

Two ematches per canister? That’s not true redundancy.

Your primary ematch might ignite the BP in the canister, but you might not get a successful deployment. At the same time you’ve just trashed your secondary ematch and have no secondary BP charge to complete the deployment.

I know some people do this, but I’ve never seen the logic behind it, particularly if you have the room for 2 extra canisters. The wiring is already there. I do understand that if the primary ematch fails to ignite, then you do have the secondary ematch that hopefully will ignite.

 

[Banzai88]

Two ematches per canister? That’s not true redundancy.

Your primary ematch might ignite the BP in the canister, but you might not get a successful deployment. At the same time you’ve just trashed your secondary ematch and have no secondary BP charge to complete the deployment.

I know some people do this, but I’ve never seen the logic behind it. I do understand that if the primary ematch fails to ignite, then you do have the secondary ematch that hopefully will ignite.

I've found that you usually get less than what you pay for, seldom good value, and rarely do you get more value than expected. That's especially true of the ematches and various other ignition devices that rocketeers like to use.

The ONLY ematches that I've ever had NOT ignite were those cheap orange wire ematches from China, available thorugh various sources, that were all the rage several years ago (and maybe now, too). I bought several lots of 100 units and did pre screenings on them, as any competent rocketeer should.
I noted on initial screening that many did not pass an initial ohms check, and of those, most simply failed to ignite when hooked directly to a new battery. As for the units that I had fail in flight, they passed an initial ohms check, passed an ohms check when hot glued into vials, passed a continuity check with beeps in the rocket......failed to light in flight, failed to light when directly wired to a battery upon post mortem.

Since this happened on two launches, with two crashed rockets, I ONLY fly MJG firewires, and in several hundred burned, have NEVER had a single one fail.

That orange wire junk, well, I relegated those to ground tests only, and still have a greater than 10% failure rate. Luckily I'm on my last batch of 100. I'll never waste my money on those things again.

 

[voyager14]

Two ematches per canister? That’s not true redundancy.

Your primary ematch might ignite the BP in the canister, but you might not get a successful deployment. At the same time you’ve just trashed your secondary ematch and have no secondary BP charge to complete the deployment.

I know some people do this, but I’ve never seen the logic behind it, particularly if you have the room for 2 extra canisters. The wiring is already there. I do understand that if the primary ematch fails to ignite, then you do have the secondary ematch that hopefully will ignite.

The EasyMega is our redundant computer. We currently have two canisters per bulkhead, and will do two ematches per canister. That way we can account for a scenario where the sustainer doesn’t light.

Adding a third canister could be possible, but would be a tight fit. But I’ll definitely bring it up to the rest of my team. Triple redundancy for the win.

 

[voyager14]

I've found that you usually get less than what you pay for, seldom good value, and rarely do you get more value than expected. That's especially true of the ematches and various other ignition devices that rocketeers like to use.

The ONLY ematches that I've ever had NOT ignite were those cheap orange wire ematches from China, available thorugh various sources, that were all the rage several years ago (and maybe now, too). I bought several lots of 100 units and did pre screenings on them, as any competent rocketeer should.
I noted on initial screening that many did not pass an initial ohms check, and of those, most simply failed to ignite when hooked directly to a new battery. As for the units that I had fail in flight, they passed an initial ohms check, passed an ohms check when hot glued into vials, passed a continuity check with beeps in the rocket......failed to light in flight, failed to light when directly wired to a battery upon post mortem.

Since this happened on two launches, with two crashed rockets, I ONLY fly MJG firewires, and in several hundred burned, have NEVER had a single one fail.

That orange wire junk, well, I relegated those to ground tests only, and still have a greater than 10% failure rate. Luckily I'm on my last batch of 100. I'll never waste my money on those things again.

Likewise. The main reason for us having two canisters per event is so we can make the backup charge larger. Never had an MJG match fail.