I think a big difference in whether folks experience positive results has to do with the modes they fly in.
Accel-based modes are VERY sensitive to even small changes (Like 50-100mm) in location of the MPU from COG / Center of rotor plane, while gyro-based flight modes are mostly immune. This has to do with what is measured... the accelerometer measures relative acceleration and direction, while a gyro is much simpler; it measures changes in angle in 3 planes.
However in real life, the quads we fly are small enough that it is hard to move the MPU very far from the center of the craft. They are also agile and generally pretty symmetrical in terms of thrust points and distribution of mass... our modern, more powerful FCs are capable of making the changes needed more than fast enough to account for any imbalance we could reasonably inflict upon them by dint of poor design.
Cheers!
mnem
Wait... I just saw an answer here somewhere; not sure it's a right answer, but an answer...
Yeah that's a valid point, I sometimes forget people still fly in stabilized modes :D Typically I think by the time they're comfortable enough to calculate a custom motor mix, they should be comfortable enough to fly acro. I actually for FPV would recommend never starting in stabilized modes. That's what I did, straight to acro. Never had a problem with it.
Yeah your last paragraph is pretty much what I was pointing out here. If you look deeper into the way the motor mix is being applied anyway, it doesn't really do what people think it does. An interesting conversation to have with Boris if you ever get the chance :D
mnementh:
Aug 27, 2016 at 09:00 PM
Hey Ryan...
I think a big difference in whether folks experience positive results has to do with the modes they fly in.
Accel-based modes are VERY sensitive to even small changes (Like 50-100mm) in location of the MPU from COG / Center of rotor plane, while gyro-based flight modes are mostly immune. This has to do with what is measured... the accelerometer measures relative acceleration and direction, while a gyro is much simpler; it measures changes in angle in 3 planes.
However in real life, the quads we fly are small enough that it is hard to move the MPU very far from the center of the craft. They are also agile and generally pretty symmetrical in terms of thrust points and distribution of mass... our modern, more powerful FCs are capable of making the changes needed more than fast enough to account for any imbalance we could reasonably inflict upon them by dint of poor design.
Cheers!
mnem
Wait... I just saw an answer here somewhere; not sure it's a right answer, but an answer...
quadmcfly:
Aug 27, 2016 at 09:08 PM
Yeah that's a valid point, I sometimes forget people still fly in stabilized modes :D Typically I think by the time they're comfortable enough to calculate a custom motor mix, they should be comfortable enough to fly acro. I actually for FPV would recommend never starting in stabilized modes. That's what I did, straight to acro. Never had a problem with it.
Yeah your last paragraph is pretty much what I was pointing out here. If you look deeper into the way the motor mix is being applied anyway, it doesn't really do what people think it does. An interesting conversation to have with Boris if you ever get the chance :D