First look at boundary mouse data
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j...@oxaero.com
Oct 2, 2012, 6:49:48 PM10/2/12
to Jari Hyvärinen, Deturbulator Participants, Roy Arnold, George Bennett, Nathan Murray
Jari,
Here is the first look at the boundary probe data that I took Saturday. The first image is in English units, the the second in Metric. Mt ASI reads knots, so I use English units.
First, note that the glider speeds are indicated speeds. Also, I have yet to calibrate boundary mouse/DAQ system, so the boundary flow speeds are uncalibrated values that appear to run 5-8 knots high. Also, the ID of the Pitot tubes is .055" and the center-to-center spacing between tubes is .050", so there is .005" overlap of the swaths being measured. The heights plotted are to the centers of the tubes.
1. There is only slight change in the speed values for first three levels, whereas the fourth level shows double the value. The probe is at .125 chord, where the surface angled upward, so speeds far enough away from the surface will exceed the glider speed. But, double the speed? I can verify that there is not a sensor error by swapping tube connections on my next flight. A nearly constant speed from .0325" to .1325" with a doubling of the speed from .1325" to .1825" doesn't seem right to me. I need Thomas' CFD model results.
2. I measured speeds one knot apart on each side of 0 KIAS. To avoid the clutter, I plotted only the ones 2 kts on each side of 50 kts. 48 and 52 kts are speeds where the top surface tape produces large performance improvements, with a notch (performance loss from baseline) near 50 kts. It is interesting that, over the first three levels, there are nonlinearities for speeds in that area. I will expand that area, add the 49 and 51 kt speeds and connect the points with lines to make these distortions more obvious.
3. Clearly, I need to build probes with smaller tubes and different spacings, but first, I need to know if these course measurements are true.
Comments appreciated.
Jim
Here is the first look at the boundary probe data that I took Saturday. The first image is in English units, the the second in Metric. Mt ASI reads knots, so I use English units.
First, note that the glider speeds are indicated speeds. Also, I have yet to calibrate boundary mouse/DAQ system, so the boundary flow speeds are uncalibrated values that appear to run 5-8 knots high. Also, the ID of the Pitot tubes is .055" and the center-to-center spacing between tubes is .050", so there is .005" overlap of the swaths being measured. The heights plotted are to the centers of the tubes.
1. There is only slight change in the speed values for first three levels, whereas the fourth level shows double the value. The probe is at .125 chord, where the surface angled upward, so speeds far enough away from the surface will exceed the glider speed. But, double the speed? I can verify that there is not a sensor error by swapping tube connections on my next flight. A nearly constant speed from .0325" to .1325" with a doubling of the speed from .1325" to .1825" doesn't seem right to me. I need Thomas' CFD model results.
2. I measured speeds one knot apart on each side of 0 KIAS. To avoid the clutter, I plotted only the ones 2 kts on each side of 50 kts. 48 and 52 kts are speeds where the top surface tape produces large performance improvements, with a notch (performance loss from baseline) near 50 kts. It is interesting that, over the first three levels, there are nonlinearities for speeds in that area. I will expand that area, add the 49 and 51 kt speeds and connect the points with lines to make these distortions more obvious.
3. Clearly, I need to build probes with smaller tubes and different spacings, but first, I need to know if these course measurements are true.
Comments appreciated.
Jim
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