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  1. #151
    Join Date
    31st August 2016
    Posts
    242
    Quote Originally Posted by cerving View Post
    Unless you completely sealed up the little hole in the pressure sensor (which would be very hard to do) it's unlikely that your plastic shield had anything to do with it. I'm assuming that the battery/switch/ematches were the same as your previous flight and your ground test, so they should have been adequate. Since your wires were soldered to the board that leaves either the battery or switch disconnecting in flight as the likely culprit. What did you do to keep the battery wires and connectors from flopping around and becoming disconnected in flight?
    Thanks for the great questions, I really appreciate it. Keep 'em coming :-)

    All battery connections (JST) were taped based on advice from your manuals :-). I taped the JST connection, and then taped the battery wires with gaffers tape to the underside of the board.

    Battery, switch, ematches are identical to previous flight. Battery and ematches are identical to what I've used successfully many times in another rocket (and where I used less care in preventing floppiness).

    You can see in the picture above in post #146 - almost all wires pass through precisely fit holes in the mounting board so that there is little slack on the parts leading up to solder joints. This was a pretty low stress flight too - 6Gs of acceleration, max speed 620fps. It seems very unlikely to have both circuits disabled under such a flight by failed solder joints.

    There are plug connections that connect the switches to the board, and connect the drogue charges to the board (the main charges are hard wired from altimeter to charge with only soldered connections). The plugs are mounted orthogonal to the flight direction though, and are a highly recommended type (anderson powerpole) by folks on this board including bob krech, and they take a fair bit of force (12lbs by spec the way I used them) to unplug. Further, the plugs are physically separate for each circuit, so they would both have to unplug independently to disable both circuits.


  2. #152
    Join Date
    13th February 2016
    Location
    Gilroy, CA
    Posts
    567
    Good find that the sound at 28 seconds is from your ground video. "Great" timing for that noise I must say.

    Thinking about this, I remembered something I'd witness earlier this year...
    I witnessed a Madcow 4" Fiberglass Tomach come in ballistic after failing to deploy the drogue. This rocket is very similar to the Frenzy XL... same Av bay etc. I watched the flight, and noticed no deployment using my Binoculars.. but I lost sight of it as in came in ballistic. Before it hit the ground I heard a ripping/tearing noise for a split second.. then saw a limp floating 84" Top flight parachute in the sky, at perhaps 300 ft or so. I later talked to the owner, and he had his main charges set to something like 1000 or 1300 ft AGL. However, at the speed it was traveling, the rocket had traveled hundreds, likely over 700 ft before the main charges fired. The takeaway point to consider is that even if the main charges were operable on your Frenzy, if it were coming in ballistic, it's quite possible that the charges weren't fired before impact if they were set to 600 and 500' AGL. What is a typical ballistic velocity for a similar heavy 4" fiberglass rocket? I'm guessing it's on the order of 500 to 700 ft/sec.

    I think you and I used the same Turnigy Nanotech 2S 460mAh LiPo for our Quantum installations. At a draw of 85mA for the Quantums, it should have lasted over 5 hours... so that's likely not the issue.

    It looks like you configured the deployment battery option rather than use a single battery. I found myself wondering if the Quantum status page checks that both the altimeter and deployment batteries are connected and that there is continuity across the deployment channels. Reporting a single voltage suggests that its just looking at battery connected to the altimeter side. Perhaps Chris can answer that.


  3. #153
    Join Date
    31st August 2016
    Posts
    242
    Quote Originally Posted by kevinkal View Post
    Good find that the sound at 28 seconds is from your ground video. "Great" timing for that noise I must say.

    Thinking about this, I remembered something I'd witness earlier this year...
    I witnessed a Madcow 4" Fiberglass Tomach come in ballistic after failing to deploy the drogue. This rocket is very similar to the Frenzy XL... same Av bay etc. I watched the flight, and noticed no deployment using my Binoculars.. but I lost sight of it as in came in ballistic. Before it hit the ground I heard a ripping/tearing noise for a split second.. then saw a limp floating 84" Top flight parachute in the sky, at perhaps 300 ft or so. I later talked to the owner, and he had his main charges set to something like 1000 or 1300 ft AGL. However, at the speed it was traveling, the rocket had traveled hundreds, likely over 700 ft before the main charges fired. The takeaway point to consider is that even if the main charges were operable on your Frenzy, if it were coming in ballistic, it's quite possible that the charges weren't fired before impact if they were set to 600 and 500' AGL. What is a typical ballistic velocity for a similar heavy 4" fiberglass rocket? I'm guessing it's on the order of 500 to 700 ft/sec.
    Yup. I think it's quite likely I wouldn't know if the main charge(s) had fired. However, the quantum's were *both* configured to fire the main if they detected the rocket falling at 125fps or more for a second. I am 95% sure that would have happened early enough (~5s after true apogee) that we would have seen it happen, and further I would have expected the tracker to survive that event, whereas in practice the tracker signal was completely lost. I designed the recovery components (aka calculated the load it would experience) to survive deployment in the failsafe mode as well, so I would have expected to see the rocket come down (and float a very long way, but float back towards the field) under the main. I guess it is possible that the failsafe mode triggered but the tracker didn't survive the event, and then the rocket floated back over us (wind was coming directly at us from where the rocket was) without anyone seeing it. That feels pretty unlikely though, and people claimed to have seen it fall all the way down. I know I heard it whistling on the way down for some time. When I get home tonight I'll simulate how it would have drifted under this scenario, though the error range will be pretty large.

    Quote Originally Posted by kevinkal View Post
    I think you and I used the same Turnigy Nanotech 2S 460mAh LiPo for our Quantum installations. At a draw of 85mA for the Quantums, it should have lasted over 5 hours... so that's likely not the issue.

    It looks like you configured the deployment battery option rather than use a single battery. I found myself wondering if the Quantum status page checks that both the altimeter and deployment batteries are connected and that there is continuity across the deployment channels. Reporting a single voltage suggests that its just looking at battery connected to the altimeter side. Perhaps Chris can answer that.
    Cris can confirm, but I believe the status page voltage is voltage of the main battery. You won't get continuity if the deployment battery isn't connected. I imagine you might get connectivity with a nearly dead but connected deployment battery, but I am quite sure I checked the voltage of all batteries and they were completely charged.
    [/QUOTE]

  4. #154
    Join Date
    3rd February 2012
    Location
    So Cal (ROC, TRASD, SCRA)
    Posts
    2,509
    The Quantum's battery status is the altimeter battery, however you won't get continuity (and thus it won't arm) if your deployment battery isn't connected. Now, that doesn't mean that it's good... the optoisolator that does the deployment checking only requires a few hundred uA at 2V to trigger. I think that a bad battery is highly unlikely here, however.

    Do you know what firmware version you were on?

  5. #155
    Join Date
    31st August 2016
    Posts
    242
    Quote Originally Posted by cerving View Post
    The Quantum's battery status is the altimeter battery, however you won't get continuity (and thus it won't arm) if your deployment battery isn't connected. Now, that doesn't mean that it's good... the optoisolator that does the deployment checking only requires a few hundred uA at 2V to trigger. I think that a bad battery is highly unlikely here, however.

    Do you know what firmware version you were on?
    1.06N. I was able to get screenshots (after the rocket crashed) of what the status screen had shown me since I hadn't reloaded the page. These are from the secondary altimeter, so drogue delay was 1.5s and main altitude was 400 feet. The primary had a main altitujde of 600 feet but I couldn't get back to it (obviously) since I did it before the secondary.

    This is one of the reasons I am completely 100% sure the altimeters were armed though - I literally have a screenshot of the page telling me they were armed :-)


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  6. #156
    Join Date
    31st August 2016
    Posts
    242
    Cris - how vulnerable are eggtimer quantum's to power blips? Is there a capacitor across the power input or could a vibration-induced blip cause them to power cycle? The powerpole connectors I used are supposed to be good in high vibration environments, but the frenzy is known for whistling which makes me wonder if it has more vibration than normal.

    Next time around I'm going to avoid any connectors in the power path other than the battery connectors themselves I think, and I'll just use hard-soldered magnetic switches.

  7. #157
    Join Date
    12th April 2015
    Location
    Arizona
    Posts
    268
    almost all wires pass through precisely fit holes in the mounting board so that there is little slack on the parts leading up to solder joints.
    How little slack was there? You actually want some slack for strain relief, otherwise any vibration/shifting/whatever will pull directly on the joints and connections.

    Still weird that you seemingly lost both altimeters. Do you have any ground video of this one that would verify you were still getting "ARMED" beeps from both units when the rocket actually launched?
    I aim at the stars. But sometimes I hit London.

    NAR #99868
    L1: MDRM on CTI H175, 7/26/2015 @ NARAM 57
    L2: "Flugel der Freiheit", AT J420R, 11/4/2017 @ GHS Memorial

  8. #158
    Join Date
    31st August 2016
    Posts
    242
    Quote Originally Posted by Oberon View Post
    How little slack was there? You actually want some slack for strain relief, otherwise any vibration/shifting/whatever will pull directly on the joints and connections.
    Not absurdly little. I didn't pull them tight in general, but the goal was no substantial flopping around. I'll be sure to think about this though in future builds and make sure I don't have taught wires either.

    Quote Originally Posted by Oberon View Post
    Still weird that you seemingly lost both altimeters. Do you have any ground video of this one that would verify you were still getting "ARMED" beeps from both units when the rocket actually launched?
    Yeah losing both is the weird part that makes me think a solder joint failing is unlikely to be the cause.

    There is ground video but it's from 200 feet away, people are talking, my tracker is beeping, and there are other rockets out on pads so I really can't tell from the audio. Here it is. We stopped recording at apogee because the only thing I was worried about was losing the rocket if the tracker lost signal, so I didn't want to be worrying about video and lose the rocket. Of course now I wish I had video of the whole thing...



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