Originally Posted by Bavafa
Does anyone know if they can be calibrated for accuracy?
If by they you mean the vane type stall warning?
Yes, they can.
The way they work is that the switch trips when the stagnation point on the leading edge of the wing switches from hitting the leading edge at a point above the vane to hitting a point just below the vane.
Or in simpler terms, when the relative wind transitions through the point where the relative wind switches between hitting the top side of the vane (and holding it in the down position) at a particular angle of attack, to hitting the bottom side of the vane and causing it to lift.
So if you adjust the bend angle of the vane, the switch will occur at a different angle of attack.
If you need the warning to come on at a slower speed (higher angle of attack), you need to bend the vane downward.
If you need the warning to come on at a higher speed, you need to bend the vane upward.
In most airplanes, it should actually be referred to as a pre-stall warning. There is no point in warning you that you are stalled.... you probably would already know at that point.
The typical setting is for it to activate at 5 - 7 kts above stall AOA.