Kite Trim question

[themacu]

Would it be possible to trim a ram kite more on water or on shore?
For example flatten the shape or move the bow more to the front when flattened. Like trimming an olympic class boats sail for example. Or reversely changing the shape more at the beginning of downwind or acceleration during start?
This could help reach higher speeds when already on maximun velocity and hitting high apparent winds. The kite drag could be decreased, more wind could more smoothly pass through the kite and therefore lighter but more efficient pull force from the kite?

Thanks in advance for your answers

[AndersDenmark]

This i what the Z/Brake-line does.
When sheeted all the way in, the camber of the kite changes.

[themacu]

I understand the break Line purpose and function, but imagine having more control over changing the shape (more precisely), more experimenting and more possibilities at different angles to the wind and with different speeds.

Formula hydro foiling has come to a level where speeds exceed the athletes abilities to keep the stability and momentum but I'm wondering what could be done to increase the speeds even more in a controllable level. Is this maybe more about the foil and the athlete rather than the kite? Wheres the future heading right now in the tech?

[tkaraszewski]

Lots of things could be possible. There are two rigid spars and six different adjustable lines to control mainsail shape on my boat. There are no rigid spars and two adjustable lines on a foil kite. If you want to start adding more controls then the kite is going to get heavier, so they'd have to make a big enough difference to compensate for the weight.

[AndersP]

You can trim the profile of a foilkite on shore with the bridle lines. The brake/steering lines are connected to the bridles and change the profile of the kite when you use them as Andersdenmark says

The angle of attack changes with the depower line.

On a lei kite the brake/steering lines change the angle of attack but not the profile (much). Same with adjusting the the depower. That's not the case on a foilkite.

The hydrofoil can only be changed on shore with the angle of the stab and with shims.

[foilholio]

You can make the camber adjustable at the bar by adding 2 extra front lines with extra trimmer and connect them to the front of the C pulley lines. You will obviously have to disconnect the front of the C pulley lines from the front main/ A main. You could maybe reduce the original front lines diameter to optimize this. Depending how you arrange the trimmers changing either may effect depower and camber. If you have them in serial then one will control depower and the other camber. You would need maybe a race setup with long rope to operate it like that.

You could do things to use a trimmer to flatten or make the kite more C shape. If you want to discuss ideas then post about it. Flysurfer has a system that dynamically changes the AOA, camber and PA with the bar sheeting. It did this the most on the Pyscho4. I would say it detracts from the highest realms of performance but opens massive range on the kites. So it is more of a opening more use possibilities but not for race performance etc.

If you are chasing more performance from your kites or just what to change them, there is mods you can do with the bridles. One example is to flatten Z even disconnect it at the tips which will improve L/D.

[Regis-de-giens]

I think Paraavis had implemented this kind of things on their race kite, quite recently; I would say 3 years ago ; 2 lines coming from the B or C Pulleys, that were tremble from the bar ; certainly useful but in detriment of simplicity ( and what happens during or after loops or kite passed into the front lines after a crash in the water ... ?)

[foilholio]

Yes I think I remember it being mentioned on the Paraavis GVX not sure if it is exactly the same, I remember it maybe being different.

You could connected the extra lines to B or B and C pulley line, but it will work best connected just to the C pulley line. There it will adjust C for 2 of B being the correct ratio to keep the canopy shape nicer. Adding anything of course will make it less simple, if you use 2 lines like the low V front lines then you could uninvert from the bar and the lines shouldn't wrap the kite like a fifth line. The kite should behave the same as a low V 4 line but with 6 lines. You could how ever reduce the front lines to 1 and the extra lines to 1, maybe for drag it's better but would cause problems for general things like inversions, rolling the kite etc.

Apart from the drag of extra line, which could be some what mitigated with thinner lines, I see large advantages particularly for racing. There using high camber downwind and for takeoff and then low camber for upwind would I think give a large advantage. I am surprised this system has not been adopted yet. But then having not tried it I could be blind to some deficit.

[Armin Harich]

Maybe our old Mixer App Tool helps a bit for understanding, what happens if you trimm it a bit different.

Just download, unzip and click mixer.htm. Adobe Flash is needed:
https://www.dropbox.com/s/srlmlk90mmc9t ... p.zip?dl=1

There is always a best compromiose and tuning is mainly to adjust it like it fly's perfect. To tune it for my Upwind/Downwind/Turning is just a little possible without killing other things like stability, backstall, ...

Cheers, Armin.