I would expect that you will want to monitor the airflow on the surface of the lee side of the wing. Maintaining attached flow to a foil is the key to lift success.

Exacly the same thing that you do with tell tales on a sail. You might use some sophistated devices or you may use tell tales. Either way, you need to monitor the airflow over the foil and your eyes can not see air molecules so you will need to depend upon a visual tansducer of some kind.

GARY
pragmatist