Reinhard Rath <[email protected]> writes: > Hi all, > > for a group project I'm looking for a backup altimeter for drogue > deployment. Preferably, it should be small enough to be mounted > horizontally within 68mm diameter. It also shouldn'trequire a vertical > orientation for operation - which, If I understand this correctly, is > the case for the bigger, accelerometer based, Altus Metrum devices. > > If the rocket performs as hoped, the upper stage's altitude will exceed > the maximum altitude where the MS5607 is usable, so I thought about > using timer based deployment. On the other hand, if the upper stage > doesn't ignite, apogee detection would be desirable. > > I thought about configuring it as follows (two ematches, same charge) > Channel 1: altitude > some_threshold && time > xx > Channel 2: altitude < some_threshold && descending > > The plan is to select some_threshold slightly above the expected > altitude in case of a non-ignition of the the upper stage motor and well > below were we'd expect sensor noise to be significant in relation to > static pressure. > > Does this approach seem viable? Is there something that we'd need to be > aware of with regards to the behavior of the sensor or Kalman filter > when flying beyond ~100kft?
I really haven't thought much about flying EasyMini above 100k' -- lacking any additional sensors, you're essentially flying a timer. As you say, you might be able to get it to also perform recovery if the flight didn't go as expected. EasyMega, with its ability to detect rotation, would be a far better choice as you could program it to fire the apogee event when the airframe tilted over by more than 90 degrees. This is a very reliable indication of apogee, and fails only when the rocket back-slides. -- -keith
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