Homemade igniter? If so it might have popped and fractured the nichrome wire. Was it ematch/pyrodex or a dipped ematch augmented pyrogen or did you have sufficient battery juice to use a standard nichrome dipped pyrogen igniter. Kurt -------------------------------------------- On Sun, 6/28/15, Casey Barker <[email protected]> wrote:
Subject: [altusmetrum] Update and Questions about TeleMega on 100K Attempt To: "Altus Metrum" <[email protected]> Date: Sunday, June 28, 2015, 7:58 PM We launched a two-stage flight last weekend attempting to break 100K again. The sustainer ignitor failed (incomplete pyrogen burn), but the recovery was mostly successful, and we'll try again next month. In the updated design, we've got one TeleMega and one EasyMega each, for both booster and sustainer. All four units worked great. Having a common programming interface and terminal block across everything has really simplified our lives! We had a couple of questions arise out of the flight. They're all about sustainer ignition. To be clear, the TeleMega clearly fired it because the igniter was partly burnt. I'm just trying to understand the data a bit better. Here's the .eeprom file: https://drive.google.com/file/d/0Bw8Fmi_7rzqMVnBLN2pjZFloUDA/view?usp=sharing 1) We used the tilt angle lockout on the sustainer ignition. I can see this is the tilt relative to the pad orientation immediately before liftoff (ao_ground_roll/pitch/yaw). I see the derived ao_sample_orient goes in the OTA telemetry, but not the eeprom log, which instead gets the ground values stored in the header along with raw r/p/y. Presumably, that's enough data to reproduce the same math. Unfortunately, I'm not good enough at java to discern how these get plotted in the UI. When looking at the .eeprom graph, is the "tilt angle" still the angle vs. pad orientation? (Or is that a silly question, because the gyros only give rates not absolutes?) I'm interested because the tilt angle graph seems to start at a flat, non-zero value, roughly 3.7. We did launch at about 2 degrees off vertical to compensate for wind, but I wouldn't expect that to show up in the plot if it were relative to pad. 2) We also set a time window of >17 seconds and <19 seconds on the sustainer ignition. (Really, we want it to fire at 17 seconds, but we learned last year that we needed to close the window in the event the sustainer was off-angle to prevent a misfire during recovery.) In the eeprom file, the "Ignitor A" event shows up at ~17.2 seconds. However the "Ignitor A Voltage" shows a brief drop around 15.5 seconds, and no sign of a drop at the actual event. The other ignitor voltage drops line up with their events, or immediately after. It seems strange that this one was over a second early. I can't explain that... We know it burned. Did our wiring briefly glitch right before? Also, possibly a minor bug: I don't see the ground r/p/y and aux ignitor voltages in the csv export. (I should learn java...) Casey PS: I made the new avionics bays on a 3D printer. The bay models themselves probably aren't useful to others, but I do have basic solid-body STL models of both computers for evaluating fit and screw posts. I'll share those when I get a chance. -----Inline Attachment Follows----- _______________________________________________ altusmetrum mailing list [email protected] http://lists.gag.com/mailman/listinfo/altusmetrum _______________________________________________ altusmetrum mailing list [email protected] http://lists.gag.com/mailman/listinfo/altusmetrum
