This race foil advantage certainly does not show when flying kites through the wind window, especially if kite is bigger. Foils are so heavy (have so much inertia) that with normal line lenghts there is not enough time/space to accelerate, and longer lines would increase the drag considerably. That is why how much lesser L/D ratio LEI's are better in active flying, they turn and accelerate faster.Regis-de-giens wrote:So your 5+ is reasonnable for a standard tube kite, while a foil race kite could even reach 10+.
Inertia explains (partly) how foils and LEI's produce their power. LEI gives more constant pull which is quicker available, race foil gives much more pull when given time to gain speed - before that its pull is quite weak.
Small race foils don't suffer very much inertia, because their volume is relatively small. If you double the area of foil kite its volume gets almost three times as big. This is true with LEI's too, but their volume is always quite small.
I don't know exactly how high race foils L/D is. Value 10+ sounds a bit too much, kites don't fly over 50kn speed through the wind window in 5knots. Nor is gliding from 2m height over 20m long, there is however drag of the kiter included in that example. Third method to measure L/D is to observe how high kite climbs, but this angle is difficult to measure exactly enough. Comparing different kites it is ok method.
I appreciate how you try to explain the basics - and you do it well, Regis. I see you understand the physics of flying, unlike certain overenthusiastic foilfanatic...