I read these reviews on the 8m Aurora1 with the following summary of comments/fixes.
https://www.extremekites.com.au/reviews ... ra-8m-r37/
First flight, straight from the bag, didn't go as excitingly as I hoped. shortened the rear lines, several times until 150mm had been taken out. then it flew but would tuck at zenith. further adjustment and the rear lines were 200mm shorter and it would sit nicely but always on power. as soon as I touched the center line trim it would again tuck the nose and collapse. so I thought it through, looked at the speed stystem and realised that as you depower the kite, it was able to reduce the aoa too far and the wind would be ontop of the canopy and push it down. I stopped this with a small mod of a rubber grommet on the speed system. it allows the kite to be powered up, but on depowering it would only let the b lines go as far as I wanted which left the a and b line identical lengths. this maintains a positive aoa at the front of the kite keeping it steady and sitting as it should. upon further depowering it would still allow the c lines to slacken and essentially break the back of the aerofoil resulting in some reflex and loss of lift. ive used grommets so its adjustable and later I may be able to change the line length its on instead. now I have only tried the mod in low winds but did help the kite to zenith by running backwards and there was no tuck but only stalling due to low wind. infact when the wind picked up enough the kite sat what looked like past the window directly above, this made me worry but it still didn't tuck or fall. could be a good sign? we will see, as soon as I get out in decent conditions.
UPDATE!!!!! The mod on the speed system needed tweeking to make it reliable. The rubber grommets didn't work as one broke under use and allowed one edge to tuck again. I Replaced them with metal rings and tweeked it further. When fully depowered the a lines are 1/2 inch above the b lines at the gather knot. This little positive aoa keeps it flying while allowing for good depower. Tacks were a sinch and suicide gybes became sexy all the while being able to throw the bar away, depower, hold the line and not worry about the kite.
So I ordered up an Aurora2, the colors have changed and looks like the bridle attachments at the wingtips were changed in the line-plans. Took 2 weeks to arrive and looks good for a new kite. I set it up on 30m/100ft lines on a 52cm bar and single front line safety. It did fly first time out, but between 11-12-1 o’clock a gust would push it to over-fly and luff. Below 11 or 1 o’clock it flew forward in the window but not enough to luft Adjusting the bar trim it flew best when I could pull in the bar (rear lines) enough to have it stall/brake effect with the Z-Line trailing edge in. The kite makes more lift than I would have expected from an 8m depower kite, so I don’t mind loosing some lift/power to improve stability eliminating over-flying. I assume shorter lines might help by reducing the size of the window, next time out I'll try some 15m lines.
Hoping I can fix the luffing with bridle and/or mixer changes only. Before getting into the A, B, C, Z adjustment details, wanted to understand a few more whys.
If for example, a parafoil has 3 bridles per cell, (conventionally called A, B, and C), then pulling in B on one side outer cell without changing A or C will de-camber that cell and pull the kite towards that side. The reason this works is because, as from above, less camber means less lift, more drag.
So I assume the kite has too much camber when depowered and generates enough lift to fly at the edge of the window. A gust gives it a little more lift, the kite flies even further forward, then a lull and the kite leading edge is first to loose lift, it distorts or pitches down enough to then have the top pressure increase enough to stall.
Reading a bit more...
...camber is a complex property, that can be more fully characterized by an aerofoil's camber line, the curve Z(x) that is halfway between the upper and lower surfaces, and thickness function T(x), which describes the thickness of the aerofoil at any given point. An aerofoil where the camber line curves back up near the trailing edge is called a reflexed camber aerofoil. Such an aerofoil is useful in certain situations, such as with tailless aircraft, because the moment about the aerodynamic center of the aerofoil can be 0.
And for span-wise and chord-wise adjustable non-rigid wing like a kites and paragliders:
I understand some adjustments to keep the COP from moving too far forward when sheeted out are:
1. Limiting the minimum AOA by lengthening A line or shortening mixer lines. This reduces depower range of the kite.
2. Reducing the camber line by shortening the B and C line. This will reduce lift, efficiency, and wind range.
3. Reducing the camber line by adding a WAC line that limits the B and C line range. This will reduce lift, efficiency, and wind range.
4. Adding reflex mid-span by shortening B or C line. This reduces lift, efficiency, and wind range.
5. Adding drag by shortening Z line. This moves the COP rearward but will reduce efficiency, and wind range.
And probably others, suggestions welcome…