That's a cool idea. Going to file that away for another time. I imagine you'd maybe run your phantom voltage a little higher to overcome the ESD diode drop?

This is a big enough package that it has a lead frame, and same, I would have been using mechanical removal processes to gain access to it.

The red line is axial acceleration. The rocket rapidly slows to terminal velocity, reaching it at about 25 sec., then continues to slowly decelerate as t.v. decreases as the air gets thicker. [edit: *] The black line is estimated velocity, as integration of the acceleration. It gives up trying to calculate that at about 45 sec. Based on the barometer readings, it looks like it was going about 650 fps at impact.

What I find interesting is the 4-second delay before igniting the second stage. This is very inefficient compared to immediately igniting it when the first stage burns out. Max-Q (airspeed pressure) issues? 30,000 ft permit ceiling?

Edit: * At 25 sec. it's still going up, so the velocity is decreasing due mainly to gravity, but the rocket is ballistic so the accelerometer is slightly negative due to air friction adding to the gravity deceleration. At about 40 sec. it has reached max altitude and velocity is zero. Accelerometer is still close to zero. Velocity picks up, as shown by barometric altitude curve. Eyeballing it, at about 65 sec. its reached terminal velocity, as shown by barometer curve being pretty flat. Decrease after that is due to decreasing t.v.