Actually it does so less rapidly as one could think. L/D value 8 from the graph is at 14 degrees and under 2 degrees, peaking at 5 degrees.Regis-de-giens wrote:- L/D ratio decreases rapidly when AoA increases (of course after a minimum AoA otherwise lift is zero, hence L/D poor)
If kiter can not take power without losing the edge, he must sheet out. If he can keep his edge, he goes faster upwind at higher AoA, even though kite's pull is not optimal directed. Forward driving component of the pull is still bigger. I have tested this a lot in the winter, when conditions are much more uniform than in the water.Regis-de-giens wrote:the rider shall find the optimum balance between pure traction value (high AoA) but better upwind traction angle (low AoA) ; this explains why it may sometimes be beneficial to sheet-out to save some upwind angle (depending on your support : TT , hydrofoil ...).
For example Speed3 goes fastest upwind fully sheeted in, when adjusted for no backstalling of course. If the wind is not too strong kiter can use this force - it is hard work though. Higher wind doesn't make kite worse upwind, but kiter is just not strong enough anymore. So, he sheets out and gets his maximal pull at lower AoA.
For sure there is considerable differencies between different kites. My experiences are mainly with Speeds.
This is true and tested observation. To go fast upwind bigger kite is better.Regis-de-giens wrote:Consequence in HF foil race : for speed and upwind, it should be better to have a larger kite a bit sheeted-out rather than a smaller kite more sheeted-in.
It is very hard to believe that distorting kite to lower camber could increase L/D ratio. If you test some airfoils with some virtual wind tunnel, higher camber means higher L/D. When camber is increased, lift increases more than drag - within reasonable limits.Regis-de-giens wrote:for the opposite tuning (flatter camber = shorten B and C) as it should increase L/D ratio
Possibility to depower gives kiter a choice to control the pull he can handle without losing the upwind course.Regis-de-giens wrote:this is why the speed system not only allows to depower the kite ..., but it also allows a better upwind ride.
Going fastest upwind is one of the main challenges of kiting. Kite with highest L/D is best for that purpose, like modern race foil kites. Airfoils for these kites are compromises between efficiency and stability/depowering. Used airfoils have positive camber and reflex (I'm not sure if always) and they are quite thick.