I didn't go back and look, but iirc, psas flight data has the same
pressure glitch at motor burn-out. Previously we have attributed the
glitch to changes in the pressure field over the vehicle surface due to
the presence or absence of motor plume.

This explanation may be wrong. In particular at supersonic velocities
motor plume cannot effect the pressure field on the forward part of the
vehicle. Perhaps motor exhaust is somehow leaking into the interior of
the airframe and pressurizing the entire structure? If that were the
case then running a hunk of tubing from the pressure sensor directly to
the outside would eliminate the effect.


The (calibrated) pressure sensor is probably more accurate in
determining altitude at apogee than the accelerometer. You could rescale
the filtered accelerometer data to match the pressure determined apogee.
That should provide a better calibrated view of the burn-out pressure


I'm a little confused as to why all the accelerations are positive. Even
accepting that the acceleration on the pad reads as +1 gee it really
seems like the initial post-burn-out acceleration should be negative.

(2009.04.22) kei...@keithp.com:
> [..] 
> Taking a look at the results, you'll see that the speed computed from
> both pressure sensor and altimeter track very closely, except where the
> pressure sensor saw some noise during motor burn-out. The cause of this
> is as yet unknown.

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