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Old Mar 20, 2012, 09:37 AM
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The Netherlands, OV, Almelo
Joined Nov 2010
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pchewn, hi

For the ACE Thermal Sniffer it is more likely two (self heating) thermistors were used, but not to confuse with "hot wire".
This "thermistor principle" also was used by Moore and other brands in variometers in the 1:1 gliders.
The thermistors I did use myself in the past were much smaller than the head of a pin and connection wires as thin as a hair.

We also can write, it's a pneumatic way of differentiating, compare the new value of altitude pressure with the old pressure in the chamber, which of course is following the ambient pressure with use of a restriction.

All varios we can buy these days indeed are based on the technical possibility of measure the flight altitude with high accuracy and solution. Problem can be damping of the differentiating and I think that's why the sensitivity normaly is reduced to plus or minus 0,25 m/sec.

The chamber methodes don't need that damping, to show in my video in post 49 and that's the reason I think these methodes can be about twice as sensitive.
It can be an important fact with very weak thermals (of trees?). The "chamber" method does need more attention for calibrating and that makes it less interesting for manufacturers.

Signal processing of all "new" variometers of course is the modern way, show a lot but without telling us the important information, "speed to fly", which is of highest importancy in 1:1 contest glider.
I am kind of surprized I don't hear anything of that in XC gliding and also not in the "poll".
Still interesting to hear of experiences with variometers and airspeed measurement.

I myself do some research for measuring of low airspeed with hot wire sensors as a backup method, see the picture of one of the prototypes for the ASK18.

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Last edited by Taurus Flyer; Mar 20, 2012 at 09:45 AM.
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