[email protected] writes: > Hi, > I have two questions to which I wasn't able to find an answer for in > the AltusMetrum documentation. > 1. What does the "apogee lockout" mean for the main charge? I > understand it prevents the apogee charge to be fired for the preset > number of seconds.
It doesn't just prevent the apogee charge from firing; it actually prevents the unit from detecting apogee, and that means that the apogee charge *and* the main charge will not fire until this timeout has passed. Note that we do not recommend the use of this value for the usual rocket flights. > But let's say, our hybrid rocket has some kind of motor failure and > stays under the main deployment altitude. Will the main charge be > fired at apogee? Or afterwards? The apogee detection will be delayed, but once that timeout has passed, and you're heading back down, then the apogee charge will fire. If you are also below the main altitude, then two seconds later, the main charge will fire. > This is especially interesting since we have a flight safety > recommendation over here which states not to influence the stability > of the rocket as long as the motor is still running (let this be > reasonable or not, I can't change it if the flight safety board wishes > so...) One of the many reasons we discourage the use of the apogee detection delay value. > 2. Are there any informations on how TeleMega actually determines > apogee? TeleMega uses a sensor-fusing Kalman filter to compute height, speed and acceleration using both the barometric and acceleration sensors. It automatically transitions from baro+accel to accel-only when speeds are high enough that mach effects may cause the baro sensor to report inaccurate values, or when the computed height is above the range of the barometric sensor. We continue to collect and analyse GPS logs from various flights to see if there's some way we can reliably incorporate those into the Kalman filter. However, the logs we've seen have been very inconsistent, with no obvious way to discern 'good' data from 'bad' data. All of the code is available for your inspection and modification, of course. -keith
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