From: "Bill D"

The electronics look clever but putting a vane on a fin-mounted TE
probe isn't going to work for anything but measuring the wing's
down-wash angle.

Trust me, this position works fine for a glider, the only reason to
change it would be a retractable engine. The vane is of course
affected by down-wash, but as an approximation, down-wash angle is
proportional [1] to the angle of attack. This means an angle measured
in this position is not really the angle of attack, but an angle
proportional to AoA. With proper calibration this is just as fine for
the purpose of a stall warning.

The sensor itself could be placed in any position (remember, it´s
wireless), but for a glider stall warning device the TE probe is a
reasonable compromise.

Michael

[1] Down-wash is not proportional to AoA anymore close to the critical
AoA, but it still works.