So I feel the main point we disagree on is the kite with a faster speed or more L/D won't have as much pull as some potential lower L/D one, I guess like pulsion, below some wind. This I strongly disagree in that it couldn't go faster if it didn't create more pull. And all of my experience with faster vs slower kites too disagrees. Where you are likely right is the heavier kite with better L/D at some point the weight creates too much disadvantage for it and so it loses. I think it could be argued that the weight would somehow diminish the L/D.
you can obtain better upwind with a bigger lower L/D kite
So we should have to keep a constant comparing kites or their principles. Upwind depends on many things especially and most importantly the board. If we took at a high L/D kite and say increased the drag to reduce the L/D, say by adding a fifth line, or using thicker lines or even just running streamers off it, do you think now that kite with lower L/D would go upwind better? I think no, and my experience says no. Do you as well think that that kite would pull more flying in the window? I say no, my experience says no. So you could then argue that no it is some other special kite that has lower L/D but won't suffer the same consequence as to the kite we just tampered with. Well what other principles other than L/D do we have? Weight yes I will concede that is a factor and then total lift that is another factor. So lets tamper with the same kite, add 2kg to it. Is it worse in every possible way? yes. I am sure we agree on that. Now lets tamper another way with the same kite, we add some camber to increase the lift. This is an interesting point, the L/D is now maybe lower but does it go upwind better? My experience is usually no but maybe in some case yes and to that I would say you have likely increased the L/D. This is on kites where I have increased the camber and too seen a speed increase in the kite, but that is only a slight camber.
But if we look at info on paragliders with regard to sink rate. Lower sink rate equals more lift or pull. So for a paraglider the slight application of the brakes or Z lines results in the highest pull. It is only a slight change in sink rate 1m/s with brakes vs 1.1m/s without. The information for aircraft in general is the minimum sink rate is always slightly below the speed for maximum L/D. Now it is hard to find this info for many planes because they are only interested in maximum L/D or maximum glide ratio. But for gliders you can find this info, and the name of the graph of speed changing the sink rate is the "Polar curve". So lets look at some polar curves and more.
https://aviation.stackexchange.com/que ... s-related
So from that link this is the L/D graph and Polar curve for an aircraft caller the dg1000, a sailplane.
So both L/D and Lift(minimum sink rate) increase with speed and then drop off. You will note that peak L/D is about 10kph after peak lift or about 10% after. Then another interesting thing about these graphs is the effect of weight which would simulate changes in wind speed. So as weight or wind speed goes up, the speed for peak L/D increase which we already knew, but the total L/D increases too but only slightly, but even more interesting the peak lift speed increases, but also the peak lift seems to change with there being a higher peak in less wind speed but a quicker drop off and then a lower peak in higher wind speed but a slower drop off. But if we do some basic math and compare the wing loadings of 28kg/m2 vs 42.8kg/m2 we have 53% increase in wing loading, so if the sink rate was to remain constant there would have to be a 53% increase in lift. If we compare lift respectively we have about 0.5m/s vs 0.6m/s so a 20% increase in sink rate. So we increase the lift needed by 53% but only saw a effect of 20%. Without doing the math to resolve the actual change in lift I would say the lift has increased but not linearly with the speed increase or change in wind.
So the L/D or glide ratio for the DG1000 is 46.5 which is pretty high compared to kites, so lets compare different polars at different L/D.
So this is the ASK 21 glider a sailplane. It has a L/D of 34.5
https://aviation.stackexchange.com/ques ... ts-related
If you look the lower wing loading graph is cut off so we don't the early change we would expect and the wing loadings are not exact to compare between the ASK21 and the dg1000. If we look at the 28kg/m2 on the dg1000 at L/D of 46.5 its 0.5m/s sink at 80kph, wheres at 26.1kg/m2 on the ASK21 at L/D of 34.5 its 0.7m/s sink at 75kph. So its lower lift and lower speed with a lower L/D. But lets look at one more.
Boy it is hard to find this data on paragliders.
So the Agera RS L/D has no data but if we guess it from the below graph would be about 11.1 , 40kph is 11.1m/s divide 1m/s.
http://www.iparaglide.com/swing-paragli ... -en-c.html
So the wing used is likely the L at 29m2 wing area, it says "RS/L" but also from the weight specs. The weight is 122kg/29 is a wing loading of 4kg/m2.
It achieves a lowest sink rate of 1m/s at a speed of 35kph with a L/D of 11.1 compared to the dg1000 at L/D of 46.5 with its 0.5m/s sink at 80kph. The wing loading is drastically different though, 4kg/m2 vs 28kg/m2. We do know that increasing wing loading will increase sink rate but also increase speed. Should the paraglider have the same wing load the pattern is clear it would have a vastly worse sink rate. So we see a pattern that lower L/D makes less lift and at a lower speed.
So I hold the point that a faster kite has more pull, always
Thankyou for reading