As I understand it, the VOR needle swings right and left. If you beyond (10?) degrees of the selected radial, the needle will always stay pegged to one side. The needle will move if you are within (10?) degrees of the selected and it will show you which side you are on and how close. It is physically impossible for the needle to point forwards or backwards, it just swings side to side.
We must be talking about two different things here because your description is so far different from my understanding/observation of a VOR needle.
Curt: he's talking about an RMI VOR indicator -- it takes the same input from the VOR receiver, but it also includes a gyro compass just like the DG (and usually an ADF needle as well), and the display is different. Instead of swinging a CDI to the left or right, it compares the inverse of the VOR radial to the plane's indicated heading (from the gyro) and points the needle to the difference between the two. For example, consider this (remember that the radial is always the FROM indication):
Inputs: VOR radial (from nav radio): 240 deg Indicated heading (from gyro): 90 deg
Calculations: Inverse Radial: 240 - 180 = 60 Needle position (north up): 60 - 90 = -30
So you swing the VOR needle 30 degrees to the left, and like magic it is very roughly pointing towards the VOR transmitter (+- 10 degrees). The card underneath rotates just like the digital gyro (it's basically the same thing, except that it's sometimes slaved so that it doesn't drift), so that 90 deg rather than 0 deg is at the top. Now the VOR needle is not just showing the relative bearing to the VOR station, but also the inverse radial (and the tail of the needle is showing the actual radial).
This is all 1960's technology (or earlier), but it's still very cool, and much easier to use than a regular left/right CDI.
All the best,
David
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