EggTimer Quantum Failing to Fire Deployment Charges

[NateFitzgerald_LUNAR]

Hello everyone,

My team and I have been having an issue where our EggTimer Quantum will not fire deployment charges during flight. The altimeter shows continuity in the web app, and will allow us to arm successfully, but upon landing we saw that neither charge had ignited, and the rematches were still intact.

Any ideas as to why this may happen?

Thank you,
Nate Fitzgerald

 

[MProcket]

Hi Nate, if you do a ground test with the Quantum, will it fire the charges? This will help narrow down if it is an electrical, logic, or mechanical problem.

 

[NateFitzgerald_LUNAR]

Hi Nate, if you do a ground test with the Quantum, will it fire the charges? This will help narrow down if it is an electrical, logic, or mechanical problem.

I haven’t had a chance to do so since our latest launch. I would like to note that when we put the altimeter in a vacuum chamber to test its barometer (attempting to simulate a flight), it never seemed to fire the deployment channels. The EggTimer Classic that we tested at the same time did light up the Christmas lights

 

[MProcket]

I would try to do the ground test of the Quantum first, as that will check to see if there is a short anywhere in the 'firing' path of either channel. Since both channels seem to be affected, is sounds like it is probably something else. When you did your flight or vacuum chamber test, did you download the csv file? Does the recorded data match the flight profile you observed? And it might also be an issue with the specific settings you set of when each channel meets the criteria to fire (or even global settings). Can you screenshot your settings pages for us to see?

 

[NateFitzgerald_LUNAR]

I would try to do the ground test of the Quantum first, as that will check to see if there is a short anywhere in the 'firing' path of either channel. Since both channels seem to be affected, is sounds like it is probably something else. When you did your flight or vacuum chamber test, did you download the csv file? Does the recorded data match the flight profile you observed? And it might also be an issue with the specific settings you set of when each channel meets the criteria to fire (or even global settings). Can you screenshot your settings pages for us to see?

Is there a recommended software to use to look at the csv data? We haven’t looked at it before.
I’ll update this thread tomorrow with the settings page, as the rocket is in a lab I don’t have access to today.

thank you!

 

[MProcket]

Microsoft Excel, Mac Numbers, I think OpenOffice and Google Sheet can but don't have as much experience with those last two myself. Page 32 and onwards has the guides for giving you a goldmine of data about each flight that really help with troubleshooting issues. And no problem!

http://eggtimerrocketry.com/wp-content/uploads/2019/08/Eggtimer-Quantum-1_07A-1.pdf

 

[David Schwantz]

What matches are you using? Did you try the failed matches on the ground afterward? You can just touch them to a battery, with no BP, and see if they light.

 

[cerving]

I haven’t had a chance to do so since our latest launch. I would like to note that when we put the altimeter in a vacuum chamber to test its barometer (attempting to simulate a flight), it never seemed to fire the deployment channels. The EggTimer Classic that we tested at the same time did light up the Christmas lights

If it fails a ground test, it's probably not a good idea to fly it... it doesn't matter whose altimeters they are.

95% of firing (and continuity) issues with the Quantum are due to bad solder joints on the optoisolators. (The other 5% is not providing power to the deployments.) You need to get solder UNDERNEATH the leads to get them to properly bond to the PC board pads. My recommended procedure for soldering those J-leaded SOIC parts is to hold the iron to the side of the lead, wait several seconds for it to heat-soak, then apply solder to the opposite side. You should see the solder flow underneath the lead and bond the "elbow" of the lead to the pad. This is why you need the right iron, the right tip (.032"/0.8mm conical) and the right solder (which we provide). Inspect all of your joints with a 10x jeweler's loupe... it's easy for solder to pool up on top of the J-leads and not contact the PC board pads if you don't solder them correctly.

 

[Crazyrocket]

I am assuming you are using a 2S lipo, correct? I inadvertently used a 1S battery on one of my other eggtime products, and the charges did not fire. It would start up fine, but never fired the charges. Could be a simple mistake or a solder joint like Chris mentioned above.

 

[cerving]

Quantums require a 2S LiPo, DO NOT use a 1S LiPo or a 9V battery. The former doesn't provide enough voltage for the deployments, the latter doesn't provide enough current.

 

[NateFitzgerald_LUNAR]

If it fails a ground test, it's probably not a good idea to fly it... it doesn't matter whose altimeters they are.

95% of firing (and continuity) issues with the Quantum are due to bad solder joints on the optoisolators. (The other 5% is not providing power to the deployments.) You need to get solder UNDERNEATH the leads to get them to properly bond to the PC board pads. My recommended procedure for soldering those J-leaded SOIC parts is to hold the iron to the side of the lead, wait several seconds for it to heat-soak, then apply solder to the opposite side. You should see the solder flow underneath the lead and bond the "elbow" of the lead to the pad. This is why you need the right iron, the right tip (.032"/0.8mm conical) and the right solder (which we provide). Inspect all of your joints with a 10x jeweler's loupe... it's easy for solder to pool up on top of the J-leads and not contact the PC board pads if you don't solder them correctly.

I suppose I should have clarified that we have ground tested the altimeter very thoroughly in the past (30+ successful tests), but it’s certainly possible that a solder joint has broken over time. We did have a particularly rough landing a couple weeks ago due to a catastrophic motor failure. I did check for deployment continuity after this event, but I don’t recall if I actually tested for deployment ignition since the crash.

 

[NateFitzgerald_LUNAR]

Quantums require a 2S LiPo, DO NOT use a 1S LiPo or a 9V battery. The former doesn't provide enough voltage for the deployments, the latter doesn't provide enough current.

We are using 2S 450mAh Tattu batteries for all of our electronics besides our ION

 

[NateFitzgerald_LUNAR]

I am assuming you are using a 2S lipo, correct? I inadvertently used a 1S battery on one of my other eggtime products, and the charges did not fire. It would start up fine, but never fired the charges. Could be a simple mistake or a solder joint like Chris mentioned above.

Correct

 

[NateFitzgerald_LUNAR]

What matches are you using? Did you try the failed matches on the ground afterward? You can just touch them to a battery, with no BP, and see if they light.

I did not test the matches that flew, but we are using FireWire Ematches from Chris’ rocket supplies, and we haven’t ever had one fail in 30+ tests

 

[Kelly]

I'm confused - you wrote

I would like to note that when we put the altimeter in a vacuum chamber to test its barometer (attempting to simulate a flight), it never seemed to fire the deployment channels.

but also

I suppose I should have clarified that we have ground tested the altimeter very thoroughly in the past (30+ successful tests)

If you put the device in a vacuum chamber and the pressure goes down and then up but the charges don'f fire, that is a failed test. When you say 30+ successful tests, exactly how were they tested? Or were these 30 tests all prior to the failed vacuum chamber test?

 

[NateFitzgerald_LUNAR]

I'm confused - you wrote



but also



If you put the device in a vacuum chamber and the pressure goes down and then up but the charges don'f fire, that is a failed test. When you say 30+ successful tests, exactly how were they tested? Or were these 30 tests all prior to the failed vacuum chamber test?

That was confusing indeed, my apologies.

We have done 30+ deployment tests on the ground, the vacuum tests were performed with Christmas lights as dummy loads to simulate a flight, which it never illuminated.

At the time, I figured that the quantum was too smart to be tricked by a vacuum chamber, but now I’m starting to think there was actually an issue there.

EDIT: So when we used the remote pyro testing feature of the quantum to force the deployment channels to fire, they worked.

 

[David Schwantz]

So my next question is, "you flew an alt that you knew did not work?" I really hope it had a backup deployment alt!!

 

[NateFitzgerald_LUNAR]

So my next question is, "you flew an alt that you knew did not work?" I really hope it had a backup deployment alt!!

We did have a backup, but at the time we were highly confident that it was functioning properly

 

[cerving]

A vacuum test will show you that the outputs are working, but it's not a qualitative test. The reason for that is because the vacuum generally is pulled and dropped too quickly, and it may be difficult to maintain a stable vacuum for "apogee" detection. You may see the outputs firing immediately after you drop the vacuum and they may appear to fire at the same time if the "apogee" and the main altitude happen in rapid succession. If you graph the detail you'll see why.

 

[NateFitzgerald_LUNAR]

A vacuum test will show you that the outputs are working, but it's not a qualitative test. The reason for that is because the vacuum generally is pulled and dropped too quickly, and it may be difficult to maintain a stable vacuum for "apogee" detection. You may see the outputs firing immediately after you drop the vacuum and they may appear to fire at the same time if the "apogee" and the main altitude happen in rapid succession. If you graph the detail you'll see why.

We had our Eggtimer Classic in the chamber at the same time as our Quantum, and it did light the Christmas lights. Should the quantum have done similarly?

 

[cerving]

They use very similar logic, you should have seen both of them light time at nearly the same time. Look at the flight summary and detail data... if it shows that it fired, then you have a hardware issue somewhere.

 

[NateFitzgerald_LUNAR]

They use very similar logic, you should have seen both of them light time at nearly the same time. Look at the flight summary and detail data... if it shows that it fired, then you have a hardware issue somewhere.

Duly noted, thank you very much!