Uplinker- that's exactly what the likes or early Dehaviland Moths were equipped with!!
Ah, interesting, Wiz, but not what I meant. The Moth speed gauge has moving parts which could get iced up. My thought was to have a small plate about the size of a credit card sticking out at right angles to the fuselage which is fixed at the base and therefore has no moving parts or joints. This would therefore be less affected by ice. The airflow would cause the plate to bend and this could be measured by piezo electrics or resistive sensors on each surface of the plate.
Only problems I can foresee would be airflow turbulence affecting the plate and not giving a constant reading.