Yes it is much easier to develop smaller kite than bigger.
Foilholio, you should give a general description from what you have done and what are the goals and what is the reasoning behind your modifications. And a bit more specific level than "to make kite turn better", "to have better high end" or what ever nice wishes.
This has been said before, but I guess it has been lost in many posts. Changes now from stock I have are 3:1 mixer, no C bridles, move and shortened 2 tip B bridles to C (yes technically some of C then still exists lol), shorten Z. Previously I had just shortened Z and used a WAC line. That large previous post was just a reply to someone explaining how I went about my latest changes, so they could too.
Intention is simply to improve the kite for my riding style. Over stock I have observed a faster kite, tighter easier turning, shorter bar throw, easier relaunch, moderate( for foil user not tube) bar pressure. One of the main objectives was to improve bar throw, and it achieves that thoroughly. Turning and response I would view as coming mainly from that. Speed increase from loosing the C bridles, I observed in the exact same wind, C bridles on the kite but disabled then 2 mins later no C bridles at all, speed increase was definitely observable but not massive. A speed gun, or something to measure speed on the kite would have been helpful if I did this for work.
I don't think any 9m kite owner will make similar mods as yours based on 18m kite, even if there is a "bridle size conversion table" available.
This is a silly assertion you make. I have used bridle conversion before and it works quite well. This mod deals mainly with the mixer. Most likely all A15 Pansh mixers are the same. But even if they are not then careful restoration, of the AB limit and the mixer setting will have the kite close to as before. Then Merely adjusting Z and tip C will get things right. Sure a 9m and 18m are quite different but, the adjust between won't be that great.
The funny thing as well you design in kite CAD and that only uses bridle conversion to make different sizes. You are basically saying your design process doesn't work!
Best is if you could show a drawing using original line plan picture of A15, it really is too arduous to dig what you are suggesting from your long posts.
Pictures would be much easier, but if a person wants to do the mod they can from what I wrote. To me it is quite simple, but I have much more experience than most. Aswell what I wrote is more help than I have ever received!
One problem is when whole line row is taken away loads for the rest attachment points increase and something can fail.
Well observed by C before going slack, plus understanding of low wing loading at that area and B and Z are already close, then we can very reasonably make the guess C had very low loading. Loading is then passed to B and Z, which are of the same construction of A and A will still have higher loading. Z is also particularly low loading and can take more. There are LCLs, and I don't have much reason to think a structural failure will be a problem. A main which was a problem is now doubled as well!
So there is no more C line row, then how much B is pulled?
Yes amazing C is gone and my original thoughts when I first saw the kite that it could go are proven correct! I believe I have used the same B(Z) setting as before, but will have to check. I did change it around a bit while testing things. AB limit is the same, I tried longer originally but I was trying to get WAC working and with the reduced mixer travel I had trouble. I gave up on WAC with this mixer it is not really compatible.