Remember, it's not measuring air speed, but air mass, which is basically=20
speed*pressure.  And I'm sure it measures the intake temperature.

Kerry


Adam Field wrote:
>>  Michael,
>>
>>  For a no moving part anneometer, you could use a piece of technology
>> from the automotive industry.
>>  That would be the Hot Wire Mass Air Flow Sensor used on many cars and
>> trucks today.  It is basically
>>  two wires that are heated via an electric current.  One of them is
>> shielded from the airflow.
>>  The other is directly in the path of the airflow.  The air moving past
>> it cools it down.  Circuitry
>>  connected to the sensor then varies the current to bring it's
>> temperature back to where it was before
>>  the air started cooling it down.  This current then represents the mass
>> of air flowing across the wire
>>  and into the engine.
>>    =20
>
> Wandering slightly OT but still in the realm of measuring air properties.=
...
>
> That's interesting. The MAF on my newer model Nissan has a diode that
> can be plainly seen. It may have the wires you describe further into
> the sensor. The diode I assume is measuring the intake temperature.
>
> Is the two wire method assuming the reference wire is at the outside
> air ambient temperature? Otherwise, you have two unknowns cooling the
> wire, the air flow rate and the temperature (and pressure) of that
> air.
>
>  =20



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