I previously posted that there were a discrepancy between our old analog airspeed indicator and the DYNON at the low end that seemed large (> 10 kts). I have since used a water manometer as suggested by other posters to measure both instruments. Turns out that the analog instrument was indicating significantly too fast at the low end and the DYNON was a little too slow, so both errors added yielding the large discrepancy. The DYNON was the more accurate instrument however, being essentially dead-on down to approx. 65 knots and then only off by a few knots at 60kts and 50kts, which are already below the stall speed. Just like DYNON says, they are checked at the factory and very accurate. Here are the results.
These results are ground testing, and don't take into account any pitot tube errors due to angle of attack, etc., in flight.
Reference Analog Dynon
Manometer
200 200 202
190 193 193
180 182 180
170 171 170
160 161 161
150 151 150
140 142 141
130 132 129
120 126 119
110 116 109
100 106 100
90 96 89
80 87 80
70 79 70
60 68 58
50 59 47
These results are ground testing, and don't take into account any pitot tube errors due to angle of attack, etc., in flight.
Reference Analog Dynon
Manometer
200 200 202
190 193 193
180 182 180
170 171 170
160 161 161
150 151 150
140 142 141
130 132 129
120 126 119
110 116 109
100 106 100
90 96 89
80 87 80
70 79 70
60 68 58
50 59 47
