First you need to answer a fundamental question:
Must the proposed stall warning device actually provide a consistent
warning of impending stall, or only satisfy a "paper" regulatory
requirement (as you mentioned in your message--Beamtenmentalitaet!).
In the latter case, a calibrated pressure switch in the pitot, as you
also mentioned, is ideal. Note that the pressures involved are quite
low, and may be tricky to adjust--but you might find an appropriate
switch in catalogs for HVAC (Heating, Ventilation, Air Conditioning)
contractors and supplies. Also, check scientific equipment supply
houses, etc.
Of course, in the real world, stall is related to angle of attack
(Anstellwinkel), not directly to airspeed. Traditional stall warning
switches a` la Cessna, etc., use a little metal tab to measure the
displacement of the stagnation point on the wing leading edge; more
sophisticated ones use a little vane to drive a potentiometer for an
actual angle of attack indication on the instrument panel. On Europa,
you'd have to get this outboard of the propeller stream. The easiest
way, given construction constraints, might be to build a little "fin"
sticking down from the bottom of the wing a few inches, with the a/a
sensor mounted on it. If you combine it with the pitot, you already
have a hardpoint and (hopefully) a conduit through which to run the
wires. If you don't have a conduit, since there'e no significant power
involved, you might be able to run _very fine_ wires right through the
plastic tube for the pitot itself.
Viel vergneugen!
Peter Lert
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