This thread is when it was explained to me years ago. tridude was one of those explaining.

A couple of points that are slightly off point.

Some kites also shape shift as you " depower " . As you trim in on your front lines the kite tightens up and it's C shape has a smaller projected area.

Many bars come with an adjustable stopper on the trim . Nice for cruising because you can set it not to depower too much and relax with the bar out slightly.


Hand out the window is the perfect way to get AOA straight in your head!

Ok, so I get the whole AOA, projected area, lift and pull stuff. I was confused on my whole "triangle" point, where if you pull one leg everything else must change to keep the same total angle. Take the "hand out the window" example, which I do quite often because it is fun:D. If the person connected to the lines is the sideview mirror, and your hand is the kite, rotate your hand and imagine what the lines would have to do if they are a fixed length.

That, is my point. Now, after reading the thread that BeamerBob posted, and others pointed out, in theory, and on some kites, the bridle, attached to the front lines, can shift the shape of the kite independently of the back lines.

Now here is my big "however". Look at the picture of the bridle layout of my Apex III and the Speed4. There are mixer pulleys between the front lines and the back lines. When I look at that layout, and I imagine trimming in, I cannot see how it could do that WITHOUT the trailing lines attached. I say WITHOUT because if the back lines are supposed to be MORE slack when you trim in that would mean they are independent of the front lines and the AOA is increasing in the bridle somehow. I cannot see how this would happen with this kite.

Now that I look at the Speed4 line plan also, I am having a very hard time understanding how the AOA can increase independently of the back lines. And if it does not move independently of the back lines, how would the back lines become MORE slack when you bring the front lines closer? This goes back to my whole "triangle" theory. Look at the Speed4 line plan. The front and back lines are 21M. Now, if you were to unhook the back line the pull would be all on A-main. If you were to trim in or out the only thing happening would be the kite getting closer and further away respectively. B-main and Z-main would be too slack to do anything and, from what I can see, would do nothing to the AOA of the kite. Now, hook up the back line and now the mixer comes into play. Trim in, to increase the AOA, and you now mix between front and back lines and it goes back to the whole "triangle" theory.

I understand the "triangle" theory goes out the window a bit because of the mixer pulley but my point is that it is not independent so how can they become more slack?

Does that make any sense?

Big versions;
http://www.rx7turbo.com/images/Apex3_Bridle.jpg
http://www.rx7turbo.com/images/Speed4_Line_Plan.jpg

The back lines are involved in AOA and shape as long as they have some tension on them if they are loose (because the center trim is pulled way in) the kite is fully depowered and flying as flat as the designer designed it to fly. Let the front lines out a bit(via the center trim strap) or pull on your bar and you begin to affect AOA and shape again. Your assessment is correct. Except the part about pulling in the trim increases AOA. Have you checked to see if all your lines match the line diagrams from HQ. Your whole description of whats happening to the back lines just seems wrong.