Maybe this should be a private PM for @Adrian A but then again, I wonder if anyone else has seen similar noise in their raw Blue Raven acceleration data ...
I've got six flights now with a Blue Raven -- the first four were with a Power Perch on a plank and the two most recent flights were in a Featherweight 38mm Av-Bay.
I am flying the Featherweight 38mm Av-Bay package 'Active Side Down' so that if I ever need the 4th e-match output channel, it will be easily accessible in the booster.
This means my axial accelerometer and gyro data is inverted which the Blue Raven handles automatically for event control.
My first flight with the FW Av-Bay was an AT H180W to about 3500 ft in "T'Pring's P'Toy" -- a 675 gram ( dry mass ), 1.9-inch rocket.
These are Raw Pressure Altitude, Density Altitude and Inertial Altitude -vs- time and Acceleration and Air Density -vs- Velocity for the H180W flight:
Note the very rough acceleration data in the 2nd plot.
After that first flight, I wondered if the free-end of the Blue Raven was 'ringing' like a tuning fork so I added a nylon hold-down for the top, free end before my 2nd flight in the same rocket:
My 2nd flight in T'Pring's P'Toy was on an AT I161W to about 5000 ft:
The top-end hold-down didn't seem to fix the noisy acceleration data ...
I don't think the rough acceleration is due to any real physical phenomena because I would think something would also show up in the gyro data and thereare no obvious blips in the gyro data.
These are axial inertial and 3-DoF gyro data during the thrust phase for the two flights:
I've also got four flights with the same Blue Raven in a Power Perch where I fly the Blue Raven right-side up and none of those flights exhibit the accelerometer noise !
So I finally looked at the end of the flight summary.csv files. This is the most recent I161W flight:
Direction of 1st motion | -0.9998| -0.0085| -0.0175
Gravity direction on pad | -0.9992| 0.0029| -0.0395
Low-G accel pad offset | 0.0092| -0.0000| 0.0004
Hi-G accel pad offset | -1.53| -20.45| 0.94
Pad gyro rates (deg/sec) | 0.16| -0.19| 0.47
Pad Hi-G Accel | -2.53| -20.45| 0.90
Pad low-G Accel | -0.99| 0.00| -0.04
Q1: Could the noise be due to the Blue Raven Firmware switching between the Low Range and High Range Accelerometer ?
Q2: Do I need to recalibrate my Blue Raven ?
Thanks !
-- kjh
EDIT: P.S. I have swapped out Blue Raven S/N 0236 from above with S/N 0828 which does not show the Hi-G offsets:
Direction of 1st motion |-0.9947 |-0.0157 |0.1014
Gravity direction on pad |-0.9999 |-0.0152 |0.0006
Low-G accel pad offset |0.0009 |0.0000 |-0.0000
Hi-G accel pad offset |-0.00 |0.83 |2.41
Pad gyro rates (deg/sec) |-0.89 |0.73 |0.64
Pad Hi-G Accel |-1.00 |0.81 |2.41
Pad low-G Accel |-1.00 |-0.02 |0.00
I'll try to fly an H180W in the same rocket at the next AARG launch or maybe at the TNT Seymour Launch next weekend if I can make the launch and I am feeling lucky
I've got six flights now with a Blue Raven -- the first four were with a Power Perch on a plank and the two most recent flights were in a Featherweight 38mm Av-Bay.
I am flying the Featherweight 38mm Av-Bay package 'Active Side Down' so that if I ever need the 4th e-match output channel, it will be easily accessible in the booster.
This means my axial accelerometer and gyro data is inverted which the Blue Raven handles automatically for event control.
My first flight with the FW Av-Bay was an AT H180W to about 3500 ft in "T'Pring's P'Toy" -- a 675 gram ( dry mass ), 1.9-inch rocket.
These are Raw Pressure Altitude, Density Altitude and Inertial Altitude -vs- time and Acceleration and Air Density -vs- Velocity for the H180W flight:
Note the very rough acceleration data in the 2nd plot.
After that first flight, I wondered if the free-end of the Blue Raven was 'ringing' like a tuning fork so I added a nylon hold-down for the top, free end before my 2nd flight in the same rocket:
My 2nd flight in T'Pring's P'Toy was on an AT I161W to about 5000 ft:
The top-end hold-down didn't seem to fix the noisy acceleration data ...
I don't think the rough acceleration is due to any real physical phenomena because I would think something would also show up in the gyro data and thereare no obvious blips in the gyro data.
These are axial inertial and 3-DoF gyro data during the thrust phase for the two flights:
I've also got four flights with the same Blue Raven in a Power Perch where I fly the Blue Raven right-side up and none of those flights exhibit the accelerometer noise !
So I finally looked at the end of the flight summary.csv files. This is the most recent I161W flight:
Direction of 1st motion | -0.9998| -0.0085| -0.0175
Gravity direction on pad | -0.9992| 0.0029| -0.0395
Low-G accel pad offset | 0.0092| -0.0000| 0.0004
Hi-G accel pad offset | -1.53| -20.45| 0.94
Pad gyro rates (deg/sec) | 0.16| -0.19| 0.47
Pad Hi-G Accel | -2.53| -20.45| 0.90
Pad low-G Accel | -0.99| 0.00| -0.04
Q1: Could the noise be due to the Blue Raven Firmware switching between the Low Range and High Range Accelerometer ?
Q2: Do I need to recalibrate my Blue Raven ?
Thanks !
-- kjh
EDIT: P.S. I have swapped out Blue Raven S/N 0236 from above with S/N 0828 which does not show the Hi-G offsets:
Direction of 1st motion |-0.9947 |-0.0157 |0.1014
Gravity direction on pad |-0.9999 |-0.0152 |0.0006
Low-G accel pad offset |0.0009 |0.0000 |-0.0000
Hi-G accel pad offset |-0.00 |0.83 |2.41
Pad gyro rates (deg/sec) |-0.89 |0.73 |0.64
Pad Hi-G Accel |-1.00 |0.81 |2.41
Pad low-G Accel |-1.00 |-0.02 |0.00
I'll try to fly an H180W in the same rocket at the next AARG launch or maybe at the TNT Seymour Launch next weekend if I can make the launch and I am feeling lucky
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