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13655Re: [GPSL] Re: Winds aloft to 15K agl

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  • Mark Conner
    Oct 30, 2013
      A theodolite and a set of pilot balloons will work fine, and there is Java software on the web where you can enter the relevant data and get a wind profile from your az/el observations.  However, you do have to have a theodolite which is a few hundred dollars at least.

      If you need all-weather capability (wind profiles into a cloud deck), an APRS payload with a cutdown on a ~100g balloon may be better.  The balloon size required will depend on total payload weight, but I would think a 100g balloon could loft what you envision to 15kft.

      To increase the accuracy, you may want to have the flight string fairly short.  Otherwise the payload swinging under the balloon changes the velocity the GPS senses away from the true wind velocity, which is especially a problem in the first couple of minutes before things stablilize.  A short string should minimize the swing velocity.  Alternatively, you can compute speed by differencing successive position reports and/or averaging more frequently-sampled velocity vectors.

      73 de Mark N9XTN

      On Wed, Oct 30, 2013 at 11:13 AM, kmcaviezel <kmcaviezel@...> wrote:

      Balloon theodolite.

      Sent from my Verizon Wireless 4G LTE Smartphone

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