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The main question is here. Other related question here.

When rising a kite even a few tens of meters, some danger might exist: low flying helicopters, utility planes, hang gliders etc. might hit or get tangled into the rope.

As the height increases, the length of the rope increases (duh!), and thus the risk of accidents.

How can I make the rope visible, or at least "warn" intelligent fliers that something is there to be avoided?

I think of attaching something visible to the rope every XYZ meters, so anyone could understand easily the "trajectory" of the rope and avoid it. What should I use? How should it be attached?

I thought of attaching some ribbons to the rope (similar to the "tails" of the kite), every maybe 50 meters. But they will make rising and lowering the kite difficult, and they would add greatly to the volume and length of the rope.


Note: I did not even take birds into account.


Update: As a result of the answers posted, I understood that a better solution might be to apply on the line (every X meters) something highly reflexive (maybe even fluorescent / phosphorescent): paint, silicone... So the line would look like a necklace, with the beads spaced a lot.

There should be no problem for me to mix sone transparent silicone with some reflective dust. What should that dust be?

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  • I have a slight issue with the appropriateness of this question on A&C: even though the solution might be, the problem here is not one based on craft or art, but purely on safety.
    – Joachim
    Sep 24 '20 at 20:11
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    @joachim: I agree with you, these questions are somewhere between Crafts, Hacks and Engineering. There are pro's and con's for either place.
    – virolino
    Sep 28 '20 at 6:54
  • re: last edit, I doubt glitter paint would work. You'd lose a lot of light going through the binder in both directions, and there would probably be much less than full coverage of glitter. You might be able to adhering a complete coating of glitter to the line, but it wouldn't hold up to handling. The line needs to be visible from at least two city blocks away. Experiment with the amount of reflective surface needed to see it that far away. Fluorescent or phosphorescent paint doesn't put out useful amounts of light for this. (cont'd)
    – fixer1234
    Sep 28 '20 at 10:09
  • You need very intense light. The line is too thin to see. You're relying on getting enough light on the person's retina to register, even though they can't actually distinguish the source.
    – fixer1234
    Sep 28 '20 at 10:09
  • I think the easiest way to solve the problem would be not to fly a kite near airplanes and helicopters. Oct 6 '20 at 15:22
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You will find a number of kite forums on the internet. Common to many is the consideration that one does not fly in areas known to have substantial air traffic.

This includes airports and hang gliding (and paragliding) sites.

Adding tails/ribbons to the line will not increase appreciably the visibility of the kite line to pilots, but it will increase the drag both for gaining altitude and for retrieving the line. Birds may be the only entity that would benefit from flagging the line. In the past years of kite flying, I've only had line contact one time, at the beach, by a seagull and it tumbled a bit and continued on its way.

You may want to consider to ask a moderator to migrate your three questions to the engineering SE as it appears to fit that category better than Arts & Crafts.

Per the suggestion of another answer-poster-person, my comment to attach a battery operated/powered emergency strobe (typically 360° visibility) will improve the visibility of a kite. Aircraft have beacons for this reason and pilots will react more effectively to such a lighting device.

Image from Amazon:

emergency strobe light

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  • The kite itself might not pose a real threat, unless seen from the side. The line is the one which can be very difficult to spot, until it is too late. I do not really understand why all 3 questions fit better in Engineering.I suspect only one to need it.
    – virolino
    Sep 25 '20 at 5:22
  • Additionally, the tails of the kite can be made reflective and omnidirectional with an acceptable level of success, quite cheaply I guess. Thus, the kite itself is not not the main matter of concern.
    – virolino
    Sep 28 '20 at 6:58
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Limitations

If you're talking about any kind of piloted aircraft, the human eye is pretty limited in seeing small/thin objects from a distance, especially while moving and focusing on more distant objects, like the ground, or huge structures like mountains, roads, or buildings. Moving at high speed, the aircraft also can't turn on a dime to avoid a line when it suddenly becomes visible. As fred_dot_u describes, the practical solution is to avoid areas where any form of aircraft could be.

As the question acknowledges, any form of fluttering ribbon will add drag and complicate management of the line (and unless they are large, won't add much benefit in visibility).

Possible Approach

All that said, if you want to make the line more visible, I can think of an approach that could help. Eyes can see points of light that are smaller than the minimum visual angle normally required to detect an object (it's why we can see stars in the night sky or detect sunlight reflecting off a tiny, distant shiny object). Eyes also detect patterns even when the elements of the pattern are tiny and would be ignored if they were random.

You can capitalize on these effects. Wrap the line with a spiral of aluminized Mylar ribbon (long strands of tinsel if you don't have a source for a spool of ribbon). On a day with bright sunlight, that would make the line detectable from a much greater distance.

The more of the line that is covered, the more visible it will be; you would need the line mostly covered to have any utility. But the windings can't create a solid tube or it won't be flexible; you need separation between adjacent strands of wrap. You would need to adhere the ribbon to the line to keep it in place during use and spooling/unspooling.

A spiral of glued-on ribbon will still be flexible, but it will affect the handling. It will add bulk and weight to the line if you're planning on kilometers of line, and would make it less flexible than a "naked" line. It would also be pretty time consuming to wrap kilometers of line. You could reduce the drawbacks by wrapping only the portion of the line that will be high enough to create a risk.

Variation

In a comment, fred_dot_u suggested a variation on this. Building on that idea, you could attach tinsel pom poms to the line near the kite rather than trying to wrap much of the line. Perhaps the first three meters or so from the kite, you could attach 30 cm tinsel pom poms at an interval of say every half meter. That would create some drag, but it would be limited to a relatively short length of line that you wouldn't worry about trying to spool.

Note that this approach (or the emergency beacon on the kite, as suggested in another answer), only mitigates risk for a pilot flying at close to the altitude of the kite. If the kite is at a kilometer or more and the pilot is flying much closer to the ground, something only on or near the kite won't provide much line protection.

Scale

For any passive measure like this, let me add some thoughts about scale. People tend to misjudge scale outdoors. If the idea is to alert a pilot to avoid the kite and line, you don't want something that will startle the pilot when it suddenly becomes visible and close. That could result in hazardous emergency maneuvers. The pilot needs to become aware of it while they are at least the equivalent of a few city blocks away.

Think of traffic signals (a three meter string of pom poms that size will be about the same scale, equivalent to three traffic signals stacked end to end). If you're driving, you know they're there and look for them (unlike flying over the great outdoors). From several blocks away, you can see a collection of traffic signals but they're pretty small. Still, something that size in the pilot's path reflecting sunlight should be spotted.

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  • I also thought about making the line shiny somehow, or attaching to it some small reflective pebbles / cylinders - every X meters. What would be such "pebbles"?
    – virolino
    Sep 24 '20 at 13:21
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    @virolino, I wouldn't count on either variation working. The kite line is vanishingly thin from a distance and reflections depend on a lot of variables. Just because you have a reflective spot doesn't mean sunlight will reflect in your direction. Cylinders of any length will interfere with line handling, and small bands every few meters aren't likely to be perceived as a pattern, so there's a good chance they wouldn't be visible. A spiral wrap would be close to complete coverage. With mid-day use when the sun is close to overhead, (cont'd)
    – fixer1234
    Sep 24 '20 at 15:27
  • some portion of the line would reflect sunlight coming from some direction. The tiny speckles of reflected light in close to a continuous line would form a pattern, making it more perceivable. To a pilot, the kite line will be competing for attention with the entirety of the great outdoors. A few bright speckles of random visual noise will get filtered out before it gets to the pilot's brain.
    – fixer1234
    Sep 24 '20 at 15:27
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    I've upvoted your answer as it is a direct reply to "how to make visible" and is certainly a great idea. Even a ton of Christmas tinsel attached every few inches should provide for reflectivity. It's not practical, I believe, due to labor, weight and drag, but still a good idea. Probably more practical would be a battery operated emergency strobe on the kite.
    – fred_dot_u
    Sep 24 '20 at 15:51
  • @fred_dot_u, an emergency strobe is a great idea. You should add that to your answer.
    – fixer1234
    Sep 24 '20 at 16:07

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