Recovery Node Behavior
- detect launch
- detect apogee
- has a timer in case everything else fails
Recovery Node Hardware
It needs an accelerometer for launch detect. We may also want it for apogee detect.
Accelerometer Debate
Do we want a 3-axis or a single axis accelerometer? We want to pick one before we design the board because laying out with options is hard.
Pressure Sensor
We want a pressure sensor for apogee detect.
MPX500A was the old pressure chip. It was only guaranteed up to about 20,000ft-ish. It needs to work down to a vacuum.
Tim wrote a paper on conversion of units to altitude. posted on RocketScience wiki page under atmosphere. Pressure sensor output changes depending on humidity, temperature, etc. To calibrate them at our previous launches, we called the local weather station and asked for humity. We might want to add humidity sensor to ground station.
2-meter Radios
We may want a 2 meter radio. We made our own one-way radio last time, but we may want to buy a 2-way radio this time. It would have its own battery, but may run off high reliable battery system.
Do we want a radio if we have 802.11? Represents low bandwidth channel to rocket.
Old Software Behavior
Last launch, we blew the parachutes when the IMU was in the coast stage and (either the pressure sensors or the GPS said we were at apogee).
Critical Path
We need the airframe team to choose an ignitor so we can design the High Voltage (HV) system. We can't design recovery node until we know this.
Ignitors
Ordered Quest ignitors; we need to characterize them as soon as they arrive. Old ignitors used in LV2 (Axril) are still available, but can't buy through their website.