Week of 2018-06-11 Notes

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‘A:‘B ratio. staging site.


Should I track which type of sports field is visible on the infield, if any? Probably so.

types of visible fields:

I’ve updated all the tracks in my google sheet with apex radius measurements. Seeing some interesting configurations, clear ratio of A’ to B’ should indicate the configuration.






a:b ratios - 1.2.3b -14.10 - 1.2.3c -32.26 - 1.2.3d -17.45

difference in turn distance. actual vs simple (single radius) method - 1.2.3b -5.62% - 1.2.3c -12.50% - 1.2.3d -7.64%

anything over 3% positive a:b is almost certainly an error

double bend tracks have 5-12% less turn than their simple turn diameter would indicate. We credit too much turn distance when using a simple single radius measurement on these tracks. We should adjust.

A:B thresholds for track types

min max type

  1. based on a:b, label each track as “single radius” or “double bend”.
  2. if double bend
    1. if A:B > -20, subtract 6.5% from turn distance (1.2.3b/1.2.3d)
    2. if A:B <= -20, subtract 12.5% from turn distance (1.2.3c)

These adjustments will ripple out to speed rating. And make these tracks slower.

key to accuracy is not a perfect isosceles triangle. i’m pretty good at nailing the apex by sight. the key is getting the exact shoulder of the turn as the base of the triangle. it isn’t always at the common finish!