Casey Barker <[email protected]> writes: > 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?)
The computed tilt angle is always supposed to be absolute, not relative to the pad launch angle. That does depend on the calibration of the three-axis accelerometer data to initialize the launch angle. > 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. Sounds like the calibration is pretty close (1.7 degrees off); more careful calibration might lead to more accurate computation of the pad angle. > 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... Yeah, that's weird. Can't say I can explain it either. Your igniter configuration looks fine too. Looks like it was also ignited for about 300ms, which is well over the selected ignition time. I need to finish up the on-board flight replay code so you can validate the firmware more easily. > We know it burned. Did our wiring > briefly glitch right before? Sure seems unlikely. > 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...) Yeah, should add those. -- -keith
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