I like your solution Johhnn, simple and effective.
That said all other things are relevant. The PA change effect is dependent on bridle shape, bridle placement and canopy shape. Changing any will have an effect, as you have seen by altering the bridle shape by changing the lengths of Z and B. Not to be underestimated is the canopy shape or inflated shape, the C shape of the kite is highly dependent on it. Ideally I think the tips sit neutral going neither in or out, sort of bouncing around a bit(well on the P4 they do but the speed4 is a little more solid). Problem I think is that point of flight is very sensitive to going either way, so the tips may fold in. The problem is the dimensions of a thin piece of fabric are hardly static as neither are lines or ropes even thick ones. So what may have been designed and made to be mere millmeters within a workable area can soon find itself outside that workable area.
I'll also add a bit of my albeit limited and possible a little wrong understanding why altering Z such that it is flatter or longer in the tips will reduce tip collapse. You have the 2d view which I must have explained many times, the camber at the tips is altered (reduced) and such it has less of a pitching moment forward. You then also have the 3d view where air is rotated by the wing. By pulling more in the middle there is then more air rotating out to support the tips or perhaps it is rotating at a better angle to support them.
Speed 4 is way lower in power and upwind compared to the lotus and it has much more active wingtips. Also theserves kites door seem to turn off below a certain wind speed. I like my 8 in surf at 20 kts plus, preferably 25.
People have described very poor turning with new speed 4 dlx kites possibly a problem that resolves as the kite beds in? There was talk on foil zone of lengthening the front lines to fix very poor turning while depower Ed.
My problem I think was frontstall in the tips with the bar pulled in. So riding along powered and suddenly the kite would fold up. I fixed by lengthening Z with a pigtails between Z main and the first cascade. The pigtails are set so the inner and outer cascades length can be adjusted independently. The solution surprised me because it it counterintuitive.
Start by checking line lengths. Then mixer test. Then long mixer test.
If you find yourself in Corpus I would be happy to look at it and let you fly mine for comparison.
I improved it be extending the front lines by 6-7 inches (which shortens the back lines in comparison), so the kite will then steer properly. You may need to adjust a bit to your kite. But you want it so that in light winds, with the trim strap fully out and the bar fully in (max power) the kite just starts to back stall.
The kites angle of attack can be set on the bar exactly at two points without any additional special tweaking.
1. Most Flysurfer bar has 3 attachment points right at the bar ends under the floater. If you shorten the back lines you raise the angle of attack of the kite so you will get more back line tension and better turning,
2. The depower rope lenght is also adjustable and by making it longer you will also raise the kite angle of attack.
These two technique should be enough to set the correct angle of attack on any Flysurfer kite which is correctly trimmed. Good to know these settings on other kites as well, as I found also some tube kites pretty out of trimm since the above mentined settings were fucked ( for eg. North bars has +-10cm at the bar ends). Also the bar position and lenght of bar travel is pretty much of a riders preference, but it can actualy change plus or minus 5-10 cm based on the rider height, arm lenght, and especially if the rider is using a low hook in point seat harness or a waist harness.
coleman wrote:...Wing tips would fold easily while riding, trailing edge looks crimped and kind of flat (not full of air like rest of cells). And the kite had a real on off feel at the bar. Basically had to ride with the bar pulled in to at least halfway at all times. Kite won't turn when sheeted out past 75-80%....
I own a 10m Speed4 Standard and it's a great kite. I love battens on the LE, love simplified bridles. It works so well for me.
Contact John Elkins at Powerzone - he's great in fixing up and tuning foils.