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Kite Line Strength vs Cost and Line Drag

Reels Spools Safety

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#1 Frank Crane

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Posted 16 June 2014 - 02:00 PM

I have designed and tested my spools and reels for a couple of years and think my system would be ideal for KAP.  But none of my family have gotten into this photo game and we've only been flying deltas and regular kites.  So I don't know much about the line strength and equipment you generally need for photography.


Here are my questions:  How much line pull do you encounter under what wind conditions?  Do you have a method of testing the pounds of pull?  How much line do you usually play out?  During recovery or if the wind dies, how quickly do you need you get your kite back in hand?  What are the requirements for line strength?


In my kite flying I have rarely had more than 18 pounds pull, as tested using my fishing scales.  I try to fly with the smallest Spectra appropriate for the conditions.  So if I don't need 200 # line I find the 60 # line has less drag, especially when I have a half mile out.  I think that 60 # line would be a lot safer for the environment if my kite ever got away from me than would 200 # line.  Costs less, too. 


In a wind over 20 MPH and a large delta of 9 feet, I will exceed the 18 # pull, and I use my 100 # line.  With a half-mile of line to reel in, the spool gets literally tons of compressive force and never a problem.  I will soon need to satisfy myself that a camera up there would yield spectacular results but I must not get in trouble with FAA regulations so I will limit it to 1,000 feet.


By using a really good reel system, I never have to lay my line on the ground.  No tangles, no leaves and grass, no nicks.  Any of which could weaken my line.


I always wear one or two gloves because there is no safe way to hold Spectra with bare hand.


As soon as I have satisfied myself that I have good answers to all this I will be ready to set up a web site and photos of my stuff for you to take a look at.


Like to hear from you KAP veterans.  I am Frank Crane.

#2 About Kites

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Posted 26 July 2014 - 10:43 PM

The FAA rules state that you have a 300 ft limit and less if your near an airport. Gomberg kites has the rules available so that you can review them.

#3 About Kites

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Posted 26 July 2014 - 10:58 PM

Most people like yourself figure the line needed is determined by the kite alone. The other factors also need to be considered. When you are using the line ratings you first have to understand how they were determined. Suggested working load, Max working load, and other points on the scale come up with a number that's advertisied. Using a digital scale several years ago and a hydraulic press rigged to pull like was stressed to the breaking point. All of the line exceeded the rating and some by a large factor. The problem is a fishing scale in not going to show large momentary loads. the shock load is where the problem lies. Other factors to contend with is the larger line being easier to handle. I have seen large foils that exert less than 200 pounds of stress flying on 500 pound line that parts under a gust. Its also easy to cut the big line when it comes in contact with any other line or object. If I was flying a kite that I cared about much less the camera combo I would want to be far from the max ratings and know it was all under complete control.


Each time you fly with a lineset you put stress on the line hundreds or thousands of cycles. The fibers are rubbing each time the line is pulled and relaxed. So a used line is not the same strength as a new line. Add environmental issues like salt air and pollution and you further degrage the line. Then you have the dust and dirt blowing in the wind not to mention if it does actually touch the ground. To take it to the extreme you also have the material the gloves are made of and everything they have come in contact with.


With that in mind I fly kites with a few hundred pound max wind load on #750 or better yet #1000 pound line. I have had the line sag from the weight as I work the kite into the air and then 30 min later its whistling from the vibrations over the tight line. I like my kites too much to risk flying on light line as an every day activity. The record holders for highest kites for the most part used wire and they had special approved locations and permits with strict requirements.

#4 Todd Copeland

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Posted 28 July 2014 - 07:18 AM

Spectra is not a good choice for single line kites. It's know for its very low stretch. If a strong wind comes up, all of that force is excerted on the line and very quickly. Using line with a little more stretch and it acts like a rubber band and much of the force is absorbed. Also, as you mention, Spectra is thin and slick. It's very difficult to Gold onto and requires much more special attention. Dacron would be a much better choice. Also, one nick in Spectra and it will easily break. A thicker line is more resistant to abrasion.

Strong winds really don't have much pull on something like a large delta. However, what needs to be considered is that the line is not always in perfect condition and you also want a large margin of over kill for safety.

Several people post that they let their kites out past a few thousand feet. To each their own but you then have the FAA issues and truth is, you can't see a kite that far away anyway.
Todd Copeland
Utah Kite Fliers - http://www.utahkitefliers.org
Treasure Island Sport Kite Klub - http://www.tiskk.org

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