Regis-de-giens wrote: ↑
Thu Oct 05, 2017 12:17 am
Some of your analysis need correction. It is not linked to this topic so sorry for the disgretion. But among errors the main one is that inertia and weight have no direct impact on L/D ratio. It will rather decrease agility (but can increase stability in drift or light wind) . Hence saying that a low AR LEI has same drag or performance than higher AR foilite is just non-sens.
Higher AR of foilkite is more linked to history and demand : before hydrofoil , Ram air where mainly interesting in lighter winds, where high AR was needed to stay upwind (Very important before hydrofoil). Then Hydrofoilers "Re-discovered " foilkite advantages for their better speed : they gained precious seconds in competition. Now that hydrofoil practices evolve , mid or low AR foilkites allows to combined low end, stability and drift for wave surfers, while upwind is not an issue anymore on Hydrofoil. But believe it or not the very low end (In the sense of riding just upwind) is lower with a middle AR kite, folkite a-fortiori. And Stephane will tell you that relaunch is often easier and quicker in wave (for simiar low AR kites).
With all the respect I can have for you, i wonder how you could have the pleasure to develop your own low ratio foik kite , with so much negative aprioris on ram air kites !
Just look at the video from Stephane Goffinet above in this post (From 1 : 30 approx) and you will notice what is the incredible level of stability at drift with slack lines. Struted LEI will not offer that I'm affraid. Regarding the agility, it seems to be sufficienty quick turning !
Just as reminder : I use (and like) both LEI and foilkites, so no religion to defend on my side.
Me too like both kite types and use them, but nowadays I use foil kites almost only in the winter. I have huge amount of all kinds of kites and I've tested much over 100, perhaps 200 different kite models through the years. I'm familiar to every kite type, from C-kites to strutless kites, from arcs to high end foil kites. I also know single skin kites (Peaks) and I have made them also as well as arcs. BTW these two are much more difficult concepts than foil kites, which always work better or worse.
I wrote "you can consider..." meaning added weight is a kind of drag. I'm a bit surprised it was you Regis who picked this up, because you have praised the light weight of the kite so much. Added weight has quite similar effects to kite than added drag, but not exactly same of course.
I would have liked to give two different L/D ratios, one for dynamic and one for static flight. But I felt it difficult to describe better so I didn't.
In Pulsion line drag is compromised for light weight. For light wind use I see it a good compromise, because then airspeeds are low and excessive line drag is not so bad thing. Added drag keeps kite also further from the edge of WW, this limits how easily it overflies and then collapses.
I have longer experience than anyone with hydrofoils in extreme low end kiting, I mean kiting in the winter. Then conditions are also more uniform than with hf and kiter skills/weight are of lesser importance. Order of efficiency and how low it is possible to go is very much in line how high AR kite has. What I have seen/used, in order of efficiency: russian extreme high AR experimental foils (AR 9 to 10)>Ozone Chrono, Sonics>Speeds>race LEI's>Peak, mid AR foils>low AR foils, most LEI's>beginner foils, arcs.
Worth noting is that extreme high AR kites are much superior, they can go upwind when everything else is struggling to keep in the air. Second point is how good performance Peak has, except for performance to jump which isn't there. Most LEI's are roughly in par with Frenzy type kites, but their feel and handling is more dynamic. Arcs are worst, they are a bit like C-kites but with less dynamic performance - although I haven't use high AR versions of them which of course have higher performance.
I don't see my views for ram air kites "apriori", because I've been using them last 15 years and more than other kite types. Personally I don't see developing low ratio foil kite very interesting, but I can still try to find out what there is to do.
I see you Regis understand quite a lot how kites are. However I woudn't say it is nonsense to say (low AR) LEI has same performance than higher AR foil kite. Performance is not easily defined, for example LEI having faster turning and acceleration it jumps more easily and higher than a foil kite with higher AR.
Finally a youtube video showing modern high AR foil kite performance in very low winds.