Testing in flight but not testing

[gdjsky01]

I build Eggtimer products and I love them. But I have had some fails. Even AFTER I test them on the ground. Let us not quibble about that. Instead... do you all have a way of testing in flight where you are sure it was the altimeter that set off the charge, not the heat from the motor ejection charge? Think of it this way. I use a little plastic capsule with an ematch. It goes down into the body tube. Then the chute/protector. And then the chute.

How would you make sure the ematch went off BECAUSE of the altimeter and not because of it getting fried by the motor's ejection charge?

Thing is I can't tell. I use motor backup. What I guess I mean is what is a good way to simply carry the ematch up making sure it, if it goes off, it was the altimeter that set it off, not an aggressive BP charge? Hope that makes sense. I mean I can not wrap it in aluminum foil!! Don't say "Ground Test" as that is not under the conditions the electronics are dealing with.

 

[GalantVR41062]

Use a ohm meter on the ematch post flight. If the altimeter electricly fired the ematch it would no longer have continuity.

 

[waltr]

If ematch and BP is inside a vial then it is very unlikely the motor ejection will ignite the BP.

You could test this by placing a vial of BP in the BT without an ematch connected. Then can see if the BP ignited.

Not sure if Galant's idea will be conclusive: If the BP ignites it will ignite the pyrogen on the ematch would will probably break the bridge wire.


Which Eggtimer?
The Quantum and up do log status including firing of channels (outputs). This tells you if the Eggtimer commanded an ematch to fire.

 

[cerving]

I tested this once by putting a BP charge in a charge well, with no ematch, and a few pieces of masking tape over it. No ignition... in fact, the masking tape wasn't even charred. I would be pretty confident that if the charge fires, it was your altimeter that did it.

 

[StevenM]

I agree with the other replies and offer an additional thought. Presuming the Eggtimer initiated event (at apogee) is separated in time by a few seconds from the motor backup event, obtaining good video (and audio) from either/both the ground and an onboard video camera (on outside of airframe) of the deployment sequences could provide the clues needed to answer the question of "did both charges go off independently".

 

[Handeman]

Use a ohm meter on the ematch post flight. If the altimeter electricly fired the ematch it would no longer have continuity.

That is seldom true.
I've found that most of the time my matches that were fired by an altimeter do NOT open when they fire.

 

[gdjsky01]

Thank you all. I think I'll add the charge to the little plastic vials I use, and wrap it in foil. Or heck, if I am just testing, don't bother with the BP. If the charge is blown or the e-match burnt, the altimeter did it. If not, then I know something is not right.

BTW: I can not be SURE, but I think I had my first Shurtler switch failure. The Stratologger gave me it's "I got nothing" for altitude sound. And the cable cutter charge did not fire. I HAD 3 beeps on the pad (drogue and main). When I did a post mortem I turned on the switch. Nothing. Then I jiggled it back and forth and the Stratologger turn on. HOWEVER that could have been because of the faster impact of the switch upon touch down. No way to know...
But it has me wondering, "Twist and Tape"? Instead? I have use those switches many time as never had one fail. But... it was a K695...

 

[Handeman]

Thank you all. I think I'll add the charge to the little plastic vials I use, and wrap it in foil. Or heck, if I am just testing, don't bother with the BP. If the charge is blown or the e-match burnt, the altimeter did it. If not, then I know something is not right.

BTW: I can not be SURE, but I think I had my first Shurtler switch failure. The Stratologger gave me it's "I got nothing" for altitude sound. And the cable cutter charge did not fire. I HAD 3 beeps on the pad (drogue and main). When I did a post mortem I turned on the switch. Nothing. Then I jiggled it back and forth and the Stratologger turn on. HOWEVER that could have been because of the faster impact of the switch upon touch down. No way to know...
But it has me wondering, "Twist and Tape"? Instead? I have use those switches many time as never had one fail. But... it was a K695...

I've never trusted those switches. They are designed to select input voltage, 120 VAC - 220 VAC or 50Hz - 60Hz, for a computer or similar equipment. Set once and forget. They are NOT designed for a lot of switch cycles which means to me, they are not durable. I wouldn't be surprised at all if they fail after little use.
Just my opinion. YMMV

 

[Worsaer]

I've never trusted those switches. They are designed to select input voltage, 120 VAC - 220 VAC or 50Hz - 60Hz, for a computer or similar equipment. Set once and forget. They are NOT designed for a lot of switch cycles which means to me, they are not durable. I wouldn't be surprised at all if they fail after little use.
Just my opinion. YMMV

I have used those switches, and stopped for that very reason. I've had some fail - iterally fall apart. I realize someone else will say they have used them for years. I only bring this up because failure of these is not theoretical - it happens.

 

[David Schwantz]

Send the alt up in question in rocket with only ematch and no BP. This is of course in a rocket with a completely different deployment system, one that you know works. When alt in question comes down and if the ematch was fired, all is good.

 

[Voyager1]

Send the alt up in question in rocket with only ematch and no BP. This is of course in a rocket with a completely different deployment system, one that you know works. When alt in question comes down and if the ematch was fired, all is good.

Or just prep it as a backup altimeter with BP.

 

[gdjsky01]

Or just prep it as a backup altimeter with BP.

Thanks... too much work... yeah maybe not.... I have a Quark (with mini-wifi switch) and an Apogee prepped with just a chinese match (or matches). I powered on and made sure I am getting the "Eggtimer patented annoying sound"... we'll see tomorrow how it goes. Motor eject in both is the way the chute will get deployed. All I want to do is prove (ish) that under Gs I have built them to work. They already work in my vacuum chamber (aka Food Saver Can). But so did the Apogee that never armed after 200'. Or the Stratologger whose switch MAY have failed. I want to try and test under real conditions. Tho that may seem a little over the top. (ok worse pun evah)

 

[cerving]

Thank you all. I think I'll add the charge to the little plastic vials I use, and wrap it in foil. Or heck, if I am just testing, don't bother with the BP. If the charge is blown or the e-match burnt, the altimeter did it. If not, then I know something is not right.

BTW: I can not be SURE, but I think I had my first Shurtler switch failure. The Stratologger gave me it's "I got nothing" for altitude sound. And the cable cutter charge did not fire. I HAD 3 beeps on the pad (drogue and main). When I did a post mortem I turned on the switch. Nothing. Then I jiggled it back and forth and the Stratologger turn on. HOWEVER that could have been because of the faster impact of the switch upon touch down. No way to know...
But it has me wondering, "Twist and Tape"? Instead? I have use those switches many time as never had one fail. But... it was a K695...

I gave up on Schurter rotary switches when I had one fall apart in my hands. Screw switches or pull-pin microswitches with real spec sheets to prove that they won't vibrate open. Most of my builds have Quantums/Protons/Quasars and/or WiFi Switches and don't have any mechanical switches at all...

BTW, that annoying "chirp" that we use makes it REALLY easy to tell if our altimeters are armed... without having to count beeps and hope that you got it right. It's even easier if you have the telemetry/voice option... your receiver will say ALTIMETER READY FOR LAUNCH. Not much mistaking that...