Shadow Blasted ... Flying In Dirty Air

[ricki]

How far away from the obstruction to you have to be to avoid excessive rotor? I recall something from hang gliding, from Pagen's "Understanding the Sky" perhaps, of distances of 10 to 20 times the height of the obstruction as a rule of thumb, perhaps further. I think higher wind velocities will also stretch this distance out. Horizontal gaps play into this as well. Sometimes they can really boost winds and maintain them and in others make the wind too erratic.

Been a long time since Fluid Mechanics, boundary flow separation just came to mind and from that found some interesting diagrams:


The chaotic separation of blobs of color simulates rotor. Imagine trying to keep a kite flying in one direction and above stall speed in that mess. That block could simulate a tree line or building in near side upwind conditions.
From: https://www.arl.psu.edu/capabilities...sim.html#images

Rotor can be a bear. In lesser cases it can simply stall your kite in a lull cause it to Hindenberg to the beach, clotheslining anyone standing in the way. How many times have you seen that happen? Pays to keep your kite aloft in clean air, free of much rotor.