Power Kite Forum

Depower Guide for Dummies

Brandon Phillips - 13-1-2013 at 05:48 PM

Hey everyone! Hoping to get some help from you guys!!!
So i flew my new to me 10m Flysufer Psycho today (my first depower), over all it went well and i got a pretty decent feel for flying it. Few questions though.......

1. Could someone explain the situational/ practical usage of the trim strap
2. How to shorten the range of motion of the depower bar.....im a little guy with short arms lol
3. Is it normal to only beable to turn the kite with the bar all the way pulled towards me? It seems like i should be able to turn fully depowered am i right? If thats the case what would be the easiest way to shorten my outside lines and would my center lines be affected by this?!

Thanks guys!
-a new kite freak
:thumbup:

joedy - 13-1-2013 at 06:24 PM

If you pull the trim strap all the way in, you'll notice that the bar can no longer power the kite with the bar. What you want is a good balance of bar power from full powered to fully depowered and the trim strap is how you accomplish this.

The Flysurfer instruction manual shows how to shorten the length of the depower line if your arms are short. There's a procedure of doing this while keeping your lines the correct length once you're done. The manual has some pretty good photos that illustrate the steps. If the Psycho manual doesn't have this information, download the Speed3 manual since I know that it is in that manual.

My Pulse and Speed will fly and turn while depowered with the trim strap and bar. Were you flying in very light winds?

-joedy

Brandon Phillips - 13-1-2013 at 06:30 PM

Thanks joedy, it was probably 12mph or so constant on the beach, you wouldnt happen to have a link to that pdf? Previous owner didnt send the psycho manual!

-dj

joedy - 13-1-2013 at 07:19 PM

It's on the Flysurfer.com website. I can't seem to log into it at the moment, but you'll want to search for Product and Technical Data. You'll see the PDF instruction manual available for download.

-joedy

ps. Welcome to Flysurfer Land.

markite - 13-1-2013 at 08:50 PM

some basic concepts might help you understand a bit more. There are two line foils that simply turn left and right and then 3 and 4 line foils. When you have a 4 line foil the top lines are power lines and bottom lines work for braking and extra steering input. You can take the bottom two lines off of a four line foil and the kite will still turn flying it like a two line kite pulling on one line or the other.

Now if you take that four line kite and put it on a bar and run the top power lines to the centre of the bar, that is the pivot point on the bar when you turn the bar left and right so no matter how much you turn the bar the kite won't steer. This is like flying as a two line foil but keeping the lines stuck together at the end so no pulling or pushing. The kite needs the bottom lines to steer and these are on the outside of the bar.

The bottom lines not only are essential to steering but also used to change the angle of attack on the kite to produce more power when pulling in on the bar.

When a kite is de-powered you are pulling in the front lines shorter which effectively lengthens the back lines. So with the back lines extra slack, even when pulling in the bar you will not be able to pull them in enough to tighten and add power to the kite - so the kite is de-powered. The other side of this de-powering is your steering gets loose and the kite less responsive. You then need to adjust the trim to let out the front lines which now starts to tighten the back lines up. When set properly the the kite will fly and steer and produce power. Fine tuning your set up on the trim will give you the right place where the kite will give you a burst of power and keep moving without stalling. Some people may want the kite set up so trimmed out and the bar pulled in will stall the kite to back down and then adjust trim to keep it just above the stall point and use that extra amount for landing some kites. All personal preference but you do need to get it within a certain working range of steering and power.

Some kites have a longer throw than others giving you a broad power range available within the amount you move the bar. Reducing the length of throw can reduce the power range available in arm movement. For example (these are just numbers for illustrating the point) lets say a kite has a range of power from 0-10 and if you had a throw distance of 10 inches every inch you move the bar is going up or down that range of power from 0-10. Now if your throw was only 6 inches of movement all you would get it a range of 6 power levels. When your kite trim is set to less power that would mean your bar movement would give you power from 0-6. As you adjust the trim to add more power to the kite you are moving that range of 6 available up the scale. So more power, then you now have 1-7, add more power and the bar movement is now minimum 2 to max 8, more power etc until your range of 6 in bar movement is at the max 4 to 10. So a longer throw might give you that full range available 0-10 and shortening the throw will give you a smaller available range with the main thing being if you are set at full power and push the bar out the kite will only power down a certain amount and not the max available if you had longer arms.

Every kite is different some you can do adjustments here and there. And again, don't take those numbers as gospel - they are just to help you understand the relationship

joedy - 14-1-2013 at 05:55 AM

Here's the link for the Flysurfer Psycho 4 manual in PDF format:

http://www.flysurfer.com/wp-content/plugins/download-monitor...

-joedy

Brandon Phillips - 14-1-2013 at 04:42 PM

Thanks guys, markite- great info, helped me visualize alot more of the concept

Im going to start by playing with the trim strap, hopefully that will fix the amount of slack on my outside lines

Also found and read through the flysurfer manuals, little free time and i should beable to get working!
:thumbup:
-dj

Proletariat - 21-1-2013 at 01:37 AM

Nice questions... I have the same questions about my Waroo. In lower winds, I have to use the full throw in order to turn as fast as I want. I assume that's get better when a)moving and b) higher winds.

Tht being said, I enjoyed reading markite's 'splanation. I always learn something from that guy.

Kamikuza - 21-1-2013 at 05:39 AM

The trim strap and the bar do the same thing - alter the relative lengths of the front and rear lines to alter the Angle of Attack of the kite; the former more permanently than the latter. Technically, it's not taking power out of the kite so calling it a "depower system" is a misnomer...

The whole idea of the system is to properly trim the kite for the given conditions for maximum lift efficiency... and annoyingly feels like it makes the most power :lol:

Think of it like this: an aircraft wing doesn't make or lose power - it can't generate thrust like engines do - it generates lift. By altering the trim (ailerons etc) you alter the Angle of Attack and how much lift the system makes for given airspeeds. More AoA = more lift... until you stall the wing, of course. What we're doing with kites is trading lift for ground speed - or altitude :D - at a given angle to the wind.

At least I think so :lol: coastalwindsports.com has some good technical stuff on buggies that applies to all kite traction systems. It's all about the vectors - not the throttle ;) say "depower" but think "trim" :D

Markite covered the important stuff - bar movement and trim strap range of travel vary between kites and systems. Long throw isn't always a good idea... neither is being trimmed a lot.

1. When you're riding, you want to use the trim strap to keep the bar in the range where you can hold it comfortably and still hold a good posture, without wearing your arms out.

2. With the Flysurfers you can shorten the "depower" line (FSer calls it the Slver Line) by undoing the knot at the bottom of the trim strap and shortening it.*

3. You're having problems turning the kite cos there's not enough tension in the lines. That could be bad trim or lack of wind.

* Before you do that - 'tune' the front & rear lines. They should be the same length (at the ELCs at the kite) with the bar fully in.
a. Check the length of the depower line. My method: push the bar up hard against the trim-strap and measure from the CL T-bar thing to the bottom of the bar - should be 40cm.
b. First time you're doing this - take the lines off the kite. Attach them to something solid. Walk them out, pull the bar in.
c. You'll know if the lines are the same length :) center or outer lines will be saggy if they're not equal.
d. Above the trim strap is the "Black Rope". It should be attached to the trim strap by a figure-8 knot. Undo that and, if the center lines are saggy, shorten it. Loosen it if the rears are saggy.

Personally, I wouldn't recommend meddling with depower line lengths... leave it all stock for now.

Aw man there has to be a YouTube of this somewhere...

joedy - 21-1-2013 at 05:49 AM

Quote:
Originally posted by Kamikuza
The trim strap and the bar do the same thing - alter the relative lengths of the front and rear lines to alter the Angle of Attack of the kite; the former more permanently than the latter. Technically, it's not taking power out of the kite so calling it a "depower system" is a misnomer...

The whole idea of the system is to properly trim the kite for the given conditions for maximum lift efficiency... and annoyingly feels like it makes the most power :lol:

Think of it like this: an aircraft wing doesn't make or lose power - it can't generate thrust like engines do - it generates lift. By altering the trim (ailerons etc) you alter the Angle of Attack and how much lift the system makes for given airspeeds. More AoA = more lift... until you stall the wing, of course. What we're doing with kites is trading lift for ground speed - or altitude :D - at a given angle to the wind.

...

1. When you're riding, you want to use the trim strap to keep the bar in the range where you can hold it comfortably and still hold a good posture, without wearing your arms out.

2. With the Flysurfers you can shorten the "depower" line (FSer calls it the Slver Line) by undoing the knot at the bottom of the trim strap and shortening it.*

3. You're having problems turning the kite cos there's not enough tension in the lines. That could be bad trim or lack of wind.


Excellent explanation, Kami.

I think that this is one of the best descriptions of how the trim system works and why it's important to understand the concepts of it.

-joedy