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.


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