people commonly talk about a 6 axis inertial measurement unit. Roll, pitch,
and yaw gyros to measure rotational rates, and x, y and z axis accelerometers
to measure accelerations. You need them all to figure out where you were, or
are, or want to go. At any rate, no matter where you go, there you are.
happy trails - Rob Glover
The definition of an axis is "a straight line about which a body or a
geometric figure rotates or may be supposed to rotate"
From this it would be clear that the only basic axes we are dealing with in
aircraft are 3 - yaw, pitch and roll.
Any movement, up-down (as in collective on helicopters), side to side or
front to back is not rotation about an axis and therefore
cannot be regarded as an axis
--
John O'Sullivan
Nova Scotia
