We flew two kites of the same design on Silecroft beach near Millom. The one in the bottom left hand corner is about twice the size of the higher one. So what has affected the balance of forces? Three forces act: weight, lift and tension. The wind was almost horizontal. Is it just the greater weight of the bigger kite? But it has a bigger area and so catches more wind. Perhaps the weight pulls it down so much that the kite is almost vertical so the wind pushes it sideways rather than acting as lift.
