Why at the field and when not in use the elevator's stabs are left or put in the vertical position.

I'm not sure I completely understand your question. But if you’re talking about the stab on some jets falling back. It’s because when you power down the servos the weight of one side of the stabs drops it into that position.
Here are two photos of my SM F-22 (One was taken with power off, and the other was with power on)


Hope this helps,

Steven T.

Look at the Skymaster hawks. you will seeone of the aircrafts elevators is drooping and the other is level. the one that is level is mine, I balanced the stab. the other one is Larry's and he did not balance the stab, so when the radio is turned off, the stab droops


Mark

I only have this happen on planes that have digital servos on the elevators.

Non digitals don't seem to do this

I think it's just because it looks cool.