Judging wind-speed in the window compared to the ground

[Materdaddy]

I'm a newb.  I've not flown a lot, but I bought some used kites including a Prism Quantum which I took out today.   A small storm is blowing through right now so the wind is stronger than usual, but based on an AFUNTA GM816 wind-meter I have, there was a wind-speed of about 8-11mph.  I held the meter at eye level.

I adjusted the bridal of the Quantum all the way to the "strong wind" tabs on the bridle and laid out my lines.  I only have braided polyester 50# lines.

Almost instantaneously after launch, both lines snapped.  I was flying where there's a lagoon, 4-lane road, then the sand I was flying on.  The kite went across all 4 lanes and I almost had to take a swim in the lagoon, but luckily it didn't quite reach the water!

All of that back story is to setup the question.  How do I determine what line material and strength I need for a given wind/kite combination?

Also, based on the short amount of pull I felt on the lines when the kite shot upward, I presume the wind at ground level is lower than the power point of the wind window.  Is there any way of judging the wind speed in the window vs. ground level?

[makatakam]

Hi, Materdaddy. Welcome to the forum. 

50# lines? The Quantum comes from the factory with 150# lines. The Quantum is rated at medium to heavy pull. If you were using 50# lines they would probably have snapped at 6mph. The wind at ground level can be significantly less than it is further up in the window, although ground level is usually below eye level. The lower speed caused by ground turbulence is generally below six feet, and even lower as wind speed increases. Usually, the difference is less than 20%. How much depends on the type of "turf" present, i.e. sand, grass, rocks, etc. Wind is also choppy and gusty on occasion, especially inland, and unpredictable most of the time.

For the Quantum, 8-11mph wind should not require moving the bridle adjustment all the way to the high wind tabs, maybe only slightly below center at most.

However, I can relate to both lines snapping together. Happened to me while flying a Thunderfoil 2.4 in 25+, gusting to 35. The foil ended up about 70' up in a tree. I did get the kite back using a slingshot to shoot a lead fishing weight with paracord attached to it at it until I could snag it and pull it down. Only one 3" tear. I got lucky, it could have been worse.

There is no fast rule regarding line weight/kite/wind speed. It depends on variables that can be changed dramatically by making adjustments to the bridle. A small kite can have twice the pull of a kite twice its size depending on the sail design, and how the wind spills off the sail, the type of fabric used for the sail, ........ after a while you just develop an instinct for what you can get away with in certain conditions.

[Materdaddy]

The "used" part was the catch... I got 2 line-sets for the 4 kites, neither appear to be the ones that came with the kites.

Crazy story about your Thunderfoil!  Glad you got it back with minimal damage.

I have 110# line I got from Klig's with a purchase that I'll have to see about measuring out and equalizing tomorrow before taking off another flight (it's still supposed to be pretty windy tomorrow).  I've also ordered some 150# lines as well, but they won't be here for a few days.

[RobB]

The Quantum has a pretty strong pull, stronger than the average kite. Don't buy into this 'high wind' and 'low wind' settings thing... adjust the bridle to 'low wind' (all the way towards the nose) and leave it. It will fly in low wind, and have less pull in high wind. Unless you're trying to do tricks, there's no reason to venture towards the 'high wind' setting. I never venture below half way, I would fly power kites more if I liked to get tugged around.

The Quantum came with 150# lines, and could probably break those if the wind approaches 20mph. I broke so many sets of 50# line that I all but swore it off, I only fly 50# lines in near zero conditions. Hopefully you have enough of the 50# lines left to make up a light wind (no wind) set and they won't be a total loss.

[Wayne Dowler]

When I flew dualies a lot - I used 3 sets between 3 sails - 50# for my light wind Prism Ozone, 150# for my Flexifoil Stranger, and 90# for my Prism Alien, The weight lines wasn't so much a matter of wind speed as it was the characteristics of the individual kite. My medium condition Stranger required heavier weight line than the higher wind Alien! Design, weight of kite, size, amount of stress, all play into the equation. I, like Rob, only used 50# on my very lightest wind (pulling) sails. 

I found a sweet spot on my bridle settings on each kite and really didn't feel much need to change them. But I am a sail switcher, more than willing to pull off 1 sail to put on another if conditions dictate.

Now I do pretty much the same thing with my Revs, but not as much. 90# will do in almost every situation, but I also use 50# in extremely light wind. The little less weight and wind resistance all help in really light wind flying. I even use 50# on my Zen when the winds are down! But I also carry a set of 150# if there is a near hurricane blowing and I need to fly!

Learning to match up wind speed, proper line, and proper sail all come with more experience on the lines!!

PS: you do have a built in wind gauge - the hair on the back of your neck!!

[cerfvoliste]

13 MPH exceeds the (flying is fun) wind range of the Quantum. #50lb lines are for light wind kites. If you're going to fly your Quantum over 9 MPH, I suggest 150lb. Lines. Otherwise #90lb should be fine. The sweet spot for your Quantum is 6-8 MPH on #90lb lines.

No Matter Where You Go, There You Are.

[Materdaddy]

Is there any "range" for light wind or "low pull" kites?  I guess what I'm asking is more details to quantum being a "strong pull" kite vs. another "light pull" kite.  Most kite manufacturers publish the wind speed they should fly in, but don't talk about pull.

I now have a few sets of different strength lines for different conditions to help combat breaking lines like I did, but is there any way to easily tell which way to go?  If it's blowing a certain speed and I'm flying a certain kite, I don't want to break lines.  I also don't want to have too heavy of lines? Or do I?  What's the negative effect of having too heavy of lines?  Just more drag creating slower movement of the kite, or slower reactions to my inputs?

[cerfvoliste]

For me, most dual line kites 1-3 MPH 50lb lines, 4-9 MPH 90lb lines.

10+ fly a Rev.

No Matter Where You Go, There You Are.