I'm sorry, I don't understand the question (immediately above). I don't know what is meant by a 4-d sensor in this context. A 6-d sensor would detect acceleration as well as rotation, in all 3 axes. We can also sense the direction of the earth's magnetic field in all 3 axes after the manner of the "Bohli compass" which has been used as blind flying instrument long before these solid-state sensors existed, so perhaps we should speak of a 9-d sensor?
To be frank though, I find it more interesting to know just how much can be done with very little. I find it interesting how very much can be accomplished by reference to a simple one-axis rotation rate sensor-- particularly when it is optimized by tilting the sensing axis for mixed yaw / roll sensing.
The piezoelectric turn indicator is really just an electronic analog of a conventional turn rate indicator or turn coordinator (depending on how the gyro is canted.) It's interesting to compare the performance of the piezoelectric and conventional devices, to see what aspects of the observed behavior of the mechanical turn coordinator derive directly from the simple fact that we are sensing yaw as well as roll because we have canted the gyro axis, and what aspects of the observed behavior of the mechanical turn coordinator are due to other specific details in the way it is constructed, and likewise to see what aspects of the observed behavior of the mechanical turn rate indicator are due to specific details in the way it is constructed rather than the fundamental dynamics of flight.
I'm just interested in learning more about how all these devices work-- and in learning the best techniques for partial-panel recovery from unusual attitudes with each of these different devices.
S
Last edited by flyer101flyer; 20th Feb 2014 at 21:34.