Recent site activity

Navigation

    Navigation

      Navigation

        Navigation

          KAP Weather‎ > ‎

          The Beaufort Scale


          KAP works best in the gentler winds, as a smooth airflow will provide stability. Most KAPers work between Bft 2 to Bft4 and, with care, in Bft5.


           Force     
          mph
          kmh m/s ktsDescription
           Effect on kite

          0


           0-1
           
          <1
           
          <9.3
           
          0-1

          Calm
          Smoke rises vertically.Launch frustrated

          1

           
          1-3
           
          1-5

           0.3-1.5

          1-3

          Light air
          Direction of wind shown by smoke drift, but not by wind vane.
          Very large lightweight Dopero, delta,  Rokkaku etc, may fly on a light line

           2

           
          4-7
           
          6-11
           
          1.5-3.3
           
          4-6

          Light Breeze
          Wind felt on face; leaves rustle; ordinary vanes moved.
          Sutton ff30 lofts 650g at 3.5mph

           3

           
          8-12
           
          12-19
           
          3.3-5.5
           
          7-10

          Gentle Breeze
          Leaves and small twigs in constant motion; wind extends light flag.
          KAP works well with most suitably sized kites at Bft 3. Drogue needed on Flowform kites

           4

           
          13-18
           
          20-28
           
          5.5-8.0
           
          11-16

          Moderate Breeze
          Raises dust and loose paper; small branches are moved
          Reduce kite size  increase  line weight & drogue size

           5

           
          19-24
           
          29-38
           
          8.0-10.8
           
          17-21

          Fresh Breeze
          Small trees in leaf begin to sway; crested wavelets form on inland waters.
          Precautions needed against risk of gust impact on  kite stability

           6

           
          25-31
           
          39-49
           
          10.8-13.9
           
          22-27

          Strong Breeze
          Large branches in motion; whistling heard in wires.
          KAP difficult as camera stabilisation becomes problematic

           7

           
          32-38
           
          50-61
           
          13.9-17.2
           
          28-33

          Near Gale
          Whole trees in motion;inconvenieance felt when walking.
          KAP not possible..

           8

           
          39-46
           
          62-74
           
          17.2-20.7
           
          34-40

          Gale
          Breaks twigs off trees;generally impedes progress.
          ..without severe risk of injury...

           9

           
          47-54
           
          75-88
           
          20.7-24.5
           
          41-47

          Severe Gale
          Slight structural damage occurs (chimney pots and slates removed).
           ...to operator and equipment!

           10

           
          55-63

          89-102
           
          24.5-28.4
           
          48-55

          Storm
          Seldom experienced inland;trees uprooted;considerable stuctural damage occurs.
           

           11

           
          64-72
           
          103-117
           
          28.4-32.6
           
          56-63

          Violent Storm
          Very rarely experienced;
           

           12

           
          73-83

           >118

           >32.6
           
          64-71

          Hurricane
          accompanied by widespread damage. 

          Note:

          Low wind speed
          : Bft 1-2
          A mix of a large sail area, light line and light rig is required to lift a camera in light winds.
          Caution is needed to be able to keep aloft during lulls, and be ready for any rise in wind speed which will make a large kite a risky platform for a camera!

          High wind speed: Bft 4-5
          Short gusts of 25mph may be survivable by a robust kite (such as the PFK Nighthawk) but if the wind is steady at these speeds the turbulence in the KAP flying zone of 30-60m AGL (above ground level) is usually such that photography is pointless.

          Adding a drogue or tail will help the stability of most kites in winds over Bft 3 (about 12 mph).

          It is worth bearing in mind that gusts are often double or more the average wind speed so a survivable gust is often a warning of a rising wind. Flying a large kite in a strong wind is not for the faint hearted, and can be downright dangerous.


          Č
          ċ
          ď
          BEAUFORTSCALE04.pdf
          (75k)
          Bill Blake,
          Jan 18, 2012, 1:12 PM
          Comments