dracop wrote:2.5mm line vs 1.6mm
well if you do the full calculation, say you have 22 meter lines, 5 lines, lets include the kite for drag, the cross section of the leading edge of the kite is around 1 or 2 square meters on a 12 meter kite, depending on lots of factors (lets call it 1 square meter that's a worst case scenario) then you have 1.6mm diameter line with the 2.2mm Y part, so the total area of the lines is 0.0016 * 22 * 3 (rear lines + 5th line) plus 12 * 2 * 0.0016 for the Y part near the kite then 10 * 1 * 0.0022 for the thin Y segment you are buying for a total of 0.166 drag for the lines that a significant amount of drag, something like 15% of the total drag here is in the lines. Now I'm not doing the coefficient of drag obviously you need to calculate it for the the kite and for the long cylinder lets just leave that for now and continue see what we get. With the 3mm line you get a number of 0.174 for the surface area for the thicker 3mm line and a total of 1.174. Let's see what the difference is: 1.174 - 1.166 = 0.008. 0.008 / 1.166 = 0.7% more drag in the 3mm line. I suppose you might notice it but it would be difficult. Like I said I would just go with the 3mm. For differences this small it's hard to really tell by flying the kite. That's just doing your 2.2mm line vs my idea of a 3mm line. Should have run the numbers for 2.5mm oh well, anyway it's less than that.
You can do this other calculation of the 2.2 vs the 1.6 m line for the 2 front lines the same way if you feel like running your entire power lines 2.2mm both below and above hmmm lets see, 0.20 area so if you run this 2.2mm line both below the Y and above the Y on your lines you should see something like 3% more drag. You'll probably notice it if you run the 2.2mm the entire way.
What do you weigh, 100kg or a bit more? I bet you are pulling 3g in those loops, so you kind of want those center lines to be able to handle 3 * 100kg and then double that for a safety factor. If I were you, I would want my single center line (below the Y) to take 600kg and above the Y where it splits for each line to take 300kg. You can go above 600kg but above that it's more about getting some abrasion resistance because once you go above that the attachments on your kite rip off.
Or you could give up kiteloops, then you'll be fine with the original lines