Flying a wind sensor

I ended up with a couple of digital wind sensors because logging the wind speed at a KAP rig seemed like a really appropriate thing to do. I connected a Modern Device Wind Sensor (Rev. P) to my SkyPod GPS logger and lofted it with a new seven foot Rokkaku. The wind data are very noisy, so I am trying to figure out why, but it looks like the sensor might be capable of returning good data. I posted some details about the flight at Public Lab.

BreadWind_20170730-0293
Above: The sensor has a somewhat delicate loop extension and it's hard to protect that without interfering with the wind readings.

LoftWindSpeedRM
Above: A 10-observation running mean (60 second averages) makes the result look really reasonable. Some more testing is needed to figure out what causes all the noise.

Wind_531_33o39sph4k
Above: While the SkyPod was logging data, the Canon EOS M was taking 900 photos, 33 of which are stitched into this spherical panorama of the Bread Loaf Campus of Middlebury College, Vermont.

Comments

  • edited August 4
    Great Chris!
    I will add a link to the Kite Aerial Remote Sensing page.
  • Like the thinking Chris.

    I too have an interest in recording wind speed.

    I have been planning on recording wind speed at the ground, the KAP rig and the kite and add in line pull to compare kites and kite line.

    I purchased a couple of small used hand held wind speed Digital Anemometer on Ebay that can be placed on the kite line. Limited time has slowed my pace with these experiments.

    We found the direction anemometers are very sensitive to angle to the wind.

    I certainly would be interested in hearing more about your experiments, wind sensors and data loggers used.

    Ken Conrad and I did a bit of testing back at the AKA Convention in Oregon last October. See Ken's wind plots here.

    WW
  • That is very convincing data about wind speed and kite pull. It would be revealing to have that kind of data about different kites.

    I didn't know there were digital anemometers which logged data. I should have one of those for calibrating the hot wire wind speed sensors. It looks like they cost >$200, (here is one used for $130). Maybe Ken figured out how to collect the data from the cheaper anemometers which don't have integrated data logging.

    I have the two Modern Device wind sensors ready for the next tests. I separated the Rev. P wind sensor from the GPS receiver and temperature sensor to see if simplifying the circuit will reduce noise. I will mount it on the Picavet cross so it does not rotate when the autoKAP rig pans. That's not very good science because I am altering two variables, but it seems that these days nobody believes in science anyway. I also changed the battery pack for the Rev. C wind sensor to add a couple of volts and learn if that makes a difference. Now I need a chance to deploy everything.

    Chris
  • The heated wire trick isn't a good way to read wind speed in such an open system... that's why you're getting such wild readings.

    Changes in ambient temperature, air pressure (elevation), and even sunlight will all invalidate the data.
  • Air temperature and barometric pressure vary predictably in this situation and are only a problem if you ignore them. Both are being measured continuously on the rig. It would be good to make better use of those data to improve the results.
  • I sent the wind speed sensor up again and got somewhat better results. At least there seems to be less noise. The general pattern of the result (winds aloft were 6-9 mph) agrees with my sense of how windy it was.

    wind_20170810-0433

    This time, the wind speed sensor was riding on the Picavet cross so it did not rotate with the autoKAP rig and stayed in unobstructed air. That is probably the primary reason for the reduction in noise.

    windElev

    A brief increase in wind speed beginning at 14:14 was the only reason the rig was able to climb to 240 m above the ground. It didn't stay that high for long.

    wind_20170810-0452

    There was not enough wind to lift the rig with the camera on it, so I removed the camera. So this flight was KA, not KAP. There is more about the flight at Public Lab: https://publiclab.org/notes/cfastie/08-12-2017/winds-aloft-less-noise

    Chris
Sign In or Register to comment.