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Noise




In article <9304271140.AA22153@wrcd1.urz.uni-wuppertal.de>, nowak@wrcd1.urz.uni-wuppertal.de writes:
>I wrote in <9304261121.AA04803@wrcd1.urz.uni-wuppertal.de>
>something about my wish to make my noisy kite silent. I forgot to
>mention that the kite has already standoffs 
>  
>                                 /
>                                /             |  
>                                /              | 
>                              /               | 
>                             /------------#---------------
>                            /             /\  | / 
>                           /       ------   \ |/
>                          /       /          \/
>                         /  ------
>                        /-/    ^noisy part 
>
>                        ]-------- ~1m  ----[
>                                          ]---[
>                                            ~0.2m
> 
> # : position of standoff
>
> length of sails edge between stand of and wingtip 1.5 m

There are lots of things to try:

        - You can add another standoff approximately .5m from the wing
          tip. Most of the noise comes from the outer part of the
          sail.
        - You can also add a batten, or several battens along the
          trailing edge. Make the battens fairly long around .5m.
        - You can sew a pocket along the trailing edge from the
          wingtip to the standoff. Attach a line from the standoff to
          the wingtip inside of this pocket. Adjust the tension in
          this line so that it is "just taught". Overtightening will
          cause a pocket to form and performace will suffer.
          Undertightening will have no noticeable effect.
        - You can glue some semi-stiff mylar or similar plastic sheet
          to the trailing edge. Make this fairly wide as well, around
          30 cm. If you make it too narrow, the entire sheet will
          vibrate which will cause a lot of drag and kill performance.

The changes will affect tuning, so don't be afraid to do some bridle
adjustments.
--
Marty Sasaki



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