I have a fixed wing aircraft and a MEMS IMU, but I am uncertain of the exact orientation between the IMU and aircraft. In the manual for the IMU, it recommends undergoing an alignment procedure prior to flight where position (obtained from GPS) and heading are required, while the aircraft remains stationary. This IMU does not have a native magnetometer, nor are we able to supply auxiliary magnetometer measurements to it, for the purposes of calculating heading.
My question is this: The manual states:
The initial position should be valid to within about 100 miles, and the initial heading should be good to within about 10 degrees
The heading of what? The vehicle? If I place the IMU at some unknown, random orientation inside the vehicle, does the IMU still only want to know in what direction the aircraft is pointing? Wouldn't it matter how the IMU is oriented relative to the aircraft? Or is it somehow able to back that out given that the aircraft will be flying in the direction it is pointing?
Note: this IMU will just be collecting data, not controlling the aircraft in any way.