A kite stability index curve

In Damian Sailors paper this graph is used to compare kite aspect ratio with stability and wind speed:Damian Sailors GraphIt’s quite a confusing graph to read as it seems to have 3 axes: stability, aspect ratio and wind speed. The 2 kites compared are traditional Pacific peoples designs Lupe La (Sun kite) and Lupe Maoli (Native kite). Optimum wind-range for them is given as Bft 3 to 5. The graph indicates greatest stability for kites of aspect 1.00 to 1:2.

The KAP wind band. To see if comparable results are possible for my KAP kites it is useful to consider the wind speed as a band in which all the kites fly, some with better adaption for high speeds others with lower. Bft 3 to 5 is a good starting point, few kites excel in less than Bft3 most are useless in Bft 5.

If I plot my current favorite kites by stability against windspeed I get something like this:

BBHDs Graph 2This is based on a descriptive stability score adapted from Damian Sailors’:

1 .0 stable
0.9 yaw/rocking ameliorated by tail/drogue.
0.8 tracks to left or right, returns to apex
0.7 Heels to one side in gust without toppling
0.6 big movements across centre of wind in gust with predictable recovery
0.5 erratic movements across face of wind
0.4 needs constant attention to remain airborne
0.3 tendency to spin/top or tip
0.2 Kite unable to rise to apex
0.1 takes maximum effort to fly
0.0  un-flyable

The first pass is a bit crude, the data needs a bit of refinement but the correlation between windspeed and stability is clear- ask any kite flier and they will confirm this!

B

About billboyheritagesurvey

Heritage worker
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