Got the SA out (finally) today for what was a perfect day for it. EXACTLY what I bought it for. No chance an arc woulda flown and I waited a bit and worked a bit and got it airborne. I had pulled in the trim strap as per what I "thought" was proper but once I got the feel for it I decided to try playing around with it. I let it all the way out and surprisingly the kite stayed flying and of course was way more powered up. (That thing is powerful to begin with.)

So here's what I "thought" prior to this season (having similar revelations on the Phantom).

I thought when the winds were light you want to pull in on the trimmer and when it picks up you can let it out. Let me tell you - the winds were LIGHT today yet when I let the strap out the kite powered up and stayed flying like a champ. Now, not knowing the SA yet I'll share my observation on the Phantom. When I powered it up despite light winds it was the same - performance I didn't expect.

Can anyone shed some light on the finer points of the trim straps for me?

I found that the best thing to think about the trim strap is that it's adjusting the relationship between front and rear lines - altering the Angle of Attack of the kite relative to the wind and direction of travel.

I used to think that it was a simple matter of more power = trim out, less power = trim in. Seems it's a bit more complex than that For my C-kite, it's pretty easy to tell when the kite is trimmed properly and that seems to be that.

My experience yesterday, playing with the Syn 19 in barely flyable wind was that the kite was more stable trimmed in more ie. it would auto-zenith and generally not stall and fall out of the sky, but trimmed out for power made more power (duh!) but was less hands off flying - had to keep an eye on it for stalls and spent more time pumping the front lines.
Now that's GOT to be related to the AoA when "at rest" and with the bar sheeted in ...! Must be a feel thing, something experience teaches you

Flysurfers though - no idea I'm bored at work and there's still an hour to go yet so I'm spouting and wasting time

couple things to add in here

line drag adds bar pressure that feeds into the light air equation esp. at idle.

more power by letting out the trim ...this is in higher winds as the stall point of the rig is higher.

understanding the "choking" point of the kite with the wind and while riding (apparent wind adds up) allows you to discover amazing power peaks at the given wind speed.

bar position is a factor for some , you can trim for feel and position and apply as you ride or trim to full out or full in (bar position)and not fiddle with holding it in. like KK said its a front line back line relationship basically it.. adding in the wind speed gives pilot feedback to trim to.

From what I''m assuming based on what I've seen/understand you want to set the strap so that you're just about at the choke point where you want to ride your bar? (I like my bar 1/3 of the way down from fully sheeted out.) I did notice yesterday and with the Phanny & Access that bar position was directly related to how the trim was set but there's a bit more I'm missing I think....or maybe I'm just getting used to the rigs enough to want to tune the sweet spot so it's where I like my bar?

you got it, bar position and working power range..

the wear spot on the line are good points of reference . as my balance has improved the less wear on the main for sure.

bar pressure and fatigue are good guides for position. flexed and comfortable .

i think at first the gear forces what we do, and as we gain smarter flying positions and knowledge of the gear it becomes the obedient slave. mastery demands time for this change to occur.

Strap in or strap out also depends on what your calling light winds. For me, light wind usually refers to winds that are so light that you need to pump the kite to launch and keep the kite moving back and forth just to keep it in the air - if you stop flying aggressively then the kite will just fall out of the sky. If the kite is able to launch ok - maybe with a tiny bit of coaxing - and actually sit at zenith without plummeting to the ground, then that is the light end of the kites wind range - not necessarily what I would call ultra light conditions.

As mentioned above, adjusting the trim strap to where the kite is barely not choking would give you maximum power output, especially if you get aggressive with flying the kite. If you want to launch the kite in winds that you know are way to light to fly in then you will want to adjust the trim strap in all the way to maximize your angle of attack so the kite will fly (fully depowered position). Then by flying the kite aggressively you can start to create apparent wind from the kite and get a little bit of power from it - even though there really isn't enough wind to actually fly. You probably wouldn't get any jumps or be able to buggy / board with it in these wind conditions, but you can at least get the beast into the air. Not the funnest type of flying but it beats sitting around waiting for something to happen.

If you have wind and are able to get the kite in the air on its own power then adjust the trim accordingly to maximize your power output. If the kite stalls out and/or doesn't want to fly, pull the strap in a bit more to get the kite to fly easier. More kite speed = more power, regardless of the trim strap.

In normal flying conditions, trim strap in = depower, trim strap extended = full power.

Hope that helps understand the trim strap a little more.

Sure you guys are sick of the aerodynamics, but...

Any kite or 3d wing will have a maximum lift-to-drag ratio that can be attained and it involves a certain configuration of angle of attack, camber, and mess of other characteristics of the wing along with apparent windspeed. Think of this as the peak of a curve - it's the position where you would get maximum power from the kite.

If the winds are light but the kite can zenith OK and reach it's max lift to drag (kite as far overhead as it can get statically) you should be able to fly it to develop apparent wind and get power from it. If the winds are super light, there may not be enough to get it to reach max lift-to-drag. You may still be able to get it to fly, but you may have to live with increased drag to get the lift you need to keep it in the air.

Think of a single line kite bridled for a pretty low angle of attack in moderately light winds. It will zenith just fine. If you lower the angle of attack further, you'll eventually hit a point where it won't move any further forward in the window. Lift-to-drag wil actually increase. If the wind is really light, with that same optimal angle of attack you had before, the kite won't make the same zenith. It may not stay in the air at all becasue lift is so low. You increase the angle of attack to increase lift just to get it in the air, but the extra drag means it sits way back in the window.

Now if you have a way to steer that single line kite, you may be able to work it to get some apparent wind and then decrease the angle of attack a bit, but park and ride will be tough. Probably be forced to keep working the kite. I that bugs ya, time for a more surface area. Kind of what Kent is saying from a different perspective.

krumly

I don't like to over think this stuff and I don't like to work the kite more than necessary to launch it so I leave the kite fully powered and only pull the trim strap in when feeling overpowered while riding. The best way to understand the impact of adjusting the trim strap is to fly untrimmed and then pull the trim strap all the way in and see how the kite stalls and falls back into the window and notice the change in power in moderate winds. Its pretty obvious how the trimmer effects the kite when you see it on a moderate to low wind day flying across the window and then falling back on itself as you pull the trim strap all the way.

So let me see if I got this right ...

Trim strap above the bar : alters the over-all AoA of the kite and adds or subtracts to how much difference sheeting in or out has on total depower.
Center trim strap : alters the "tightness" of the kite, increasing or reducing the AoA across the surface, LE to TE - tight increases the drag due to 'scooping' more air but makes more power.
Tip straps : shorten the rear lines even more, increases turning response but increasing bar pressure and decreasing depower.

Kamikuza -

Presume you are referring to a newer Arc with all three adjustments. You got it.

Adjustments to tip straps also allow you to tune the kite to keep it balanced if it favors one side or the other. FWIW, a tuning tip for older Arcs that want to drift to one side or the other is to tie a small line from the leading edge to the trailing edge across the top of the kite at the tip so you can pull in more reflex in the foil.

I think the latest Ozone Access forgoes the front line trim strap for fixed length full-throw and has the individual trimmers for the rear lines.

krumly