Snip:-----
>>
>> The mechanical version depends solely on the fact that the airflow is keeping
the
>>vane raised, when the airflow ceases at the stall the vane drops and makes
>.>the switch. In effect it is a crude, but effective pressure switch. I would
............
>>
If that is the case why does the stall warning not sound when the aircraft is
stationary? I thought the vane was positioned in such a point on the leading
edge that the airflow changed direction at that point at stall and in doing so
flipped the vane up. Hence the critical positioning of such a device.
My instructor told me that with the pressure tube type, the pressure in the tube
changes from positive to negative at the point of stall and can be tested by
gently sucking the over the aperture.
Ted
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