What are some ideas to make tethers more noticable in the day, and especially at night?

[Windy_Skies]

What are some specific products or product categories that could be used for example?

[Tom]

@Kitepower have lit theirs up:

Windvogel by Studio Roosegaarde | Dezeen Awards

I believe this is done via photophorescent tether strands

[tallakt]

This is an interesting topic.

Some starting points would be:

a - emitting light
b - reflecting light
c - adding visible elements
d - ground based light
e - kite based light

I think all might be infeasible, in part to the small size of the tether and the nature of seeing things from a distance.

So we should also consider if we can do without, perpaps relying on fixed warnings on maps and in computer systems

[Windy_Skies]

@tallakt

I think all might be infeasible, in part to the small size of the tether and the nature of seeing things from a distance.

The link @Tom gave shows nighttime visibility is not impossible. So then daytime visibility remains - if you choose to fly in the daytime.

Only your point “c” would work in the daytime, and maybe point “b” if it reflected the sun.

Some more brainstorming:

f - bird of prey shapes to scare off birds
g - reflect the sun or shine a powerful light from an element on the kite towards anything flying
h - rapid changes in color, from movement or rotation of the tether
i - additional kites in the air with the only purpose of raising highly visible tethers, maybe demarcating the danger zone

@tallakt

perpaps relying on fixed warnings on maps and in computer systems

That then has to be a no-fly zone because of pilots flying under visual flight rules?

Worst case scenario: tether is in the clouds. Then the system should be grounded?

[tallakt]

I think fog, clouds, twilight etc means that even if you choose light or color to mark the kite and tether, there will always be times when those elements are less visible

[Rodread]

Shoot them with Freekin LASERS.
Then you can get good data back from them as well.

I’ve put bike spoke reflectors on the lines of a Daisy I lent to the scouts. They left it tied up permanently for a few days and nights at camp. They tell me that nobody was beheaded by kite lines at that camp.

But do we need to show the lines if they are only short sections between active rigid parts?
Certainly any fast moving rigid wing part can have a RAT onboard gen to power light.

[tallakt]

I believe pointing lasers upwards is a no-go for aviation

[Windy_Skies]

@tallakt

I think fog, clouds, twilight etc means that even if you choose light or color to mark the kite and tether, there will always be times when those elements are less visible

Yes. And rain and snow and hail. Fog and wind often exclude each other though. And I think clouds rarely are low enough to be a problem.

j - elastic tethers, to lessen the impact of an impact
k - slow moving tethers, to lessen the impact of an impact

So we now can make the reasonable assumption that an airborne system should be grounded some of the time, in most places where people fly. Let’s try to brainstorm specific solutions that could be used in the 2 best case scenarios: good visibility during the day, and good visibility during the night.

[Rodread]

For lighting sakes this may be problematic true!
However, an amount of laser can be pointed skyward safely.
Utilities like LIDAR are common enough now.
Low power room mapping lasers, I don’t don’t see a huge problem with them outdoor, given the separation from a rotor kite 200m to your aircraft. Laser mapping of an expected set of live scenes can be tightly focused.
Whether or not combined laser mapping and reflective patch spotting could be considered bright enough, Well yes, like the lighting rig on Strictly Come Dancing.

[Rodread]

If a couplet or set of kites is stricktly bound in a reel dance they could easily target each other with small laser. Attenuation of the laser by cloud / hail / other would be illuminated to nearby traffic.

[kitefreak]

Lasers aimed at the sky are forbidden by FAA. They alarm pilots. Laser-show pros know this and work accordingly.

“Conspicuity” lighting to FAA spec (“FAA Red”, so many lumens, etc.) every 50ft along any main tether have current FARs (Federal Airspace Regulations). Anyone who can show equivalent function can get a waiver from a local FSDO (flight standards district office). See TACO 1.0 for details-

http://www.energykitesystems.net/CoopIP/TetheredAviationConOps.html

Further reason to light up AWES colorfully is Wubbo’s AWEfest concept, to popularize AWE.

I thought the Roosegaarde show used light-pumped fiber-optic polymer. kPower Austin co-tested electroluminescent kite line for show at Ambient Camping Paint-the-Sky, in shorter section than the Dutch case, but earlier.

[Windy_Skies]

Related:

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Selected comments:

For the Birds: AWE-Avian CoExistence

APPENDIX to the AWEIA TACO (Tethered Aviation ConOps)-

Birds (and bats*) have a primordial right to airspace, but can present a hazard to human aviation and are themselves put at risk by activities like conventional wind power generation and night-lit towers. The problems are increasingly well known and mitigation is an ongoing process. AWE can mostly build on existing bird management practices, adding new protocols as needed.

Migratory species in transit are most vulnerable to disturbances, but follow fairly predictable seasonal patterns, helping risk mitigation. Conventional windfarms can cause wholesale slaughter of flocks, so regulations are emerging to curb seasonal risk. Sense-and-Avoid capability of AWE systems might serve to give clearance to migrating formations. Sense-and-Warn might also work, but is an open study.

The presence of endangered bird species or high bird populations raise the urgency of bird issues. Nesting birds can be stressed by looming kites, acting out predator response behaviors. In extreme cases birds will abandon active nests, but in other cases birds adapt to kites and even seem to exploit some operations as defensive cover. Generally year-around birds exposed to kite operations adapt well, fully habituating, showing no stress response. Birds that first encounter kites can react by fight-or-flight response. Hawk kites scare birds away and might be a useful management tool, but birds are intelligent and often learn to ignore an empty threat. Young birds can act quite different to the same cues than their more experienced parents.

Flying birds are most common near the surface and become rare with altitude, with few exceptions (like migrating snow geese over high mountains). AWE at higher altitude therefore seems potentially far more bird friendly that wind towers. An exception is the tendency for birds to shun a looming flying object, while relaxing if overflying, a predation response. Its probable that wind energy operations change bird species distribution of their area. Towers are known useful to raptors, and turbine killed birds can attract scavengers. AWE has the potential to reduce such changes. AWECS and other aerial structure should be minimally visible to birds even at night, by white markings. Black or dark red markings by day usually give the farthest warning to air traffic for easy avoidance.

Visibility reduces air hazards. FAA nav markings intended to warn pilots of close proximity also serve to clue birds. Turbines that make noise and have red painted tips to delineate the disk area probably better warn birds. Fast-moving lines are a special hazard, potentially acting as a saw. Painting alternate black (or red) and white marking on moving line could help by making the motion visible. Fog has disoriented migrating birds, which in some cases cue in on artificial lights like radio mast warning lights. We should anticipate these rare events and find solutions proactively. A proposed method is to radar detect airtraffic and only then activate mast and tower warning signals. Another idea is to create clear migration corridors, well chosen gaps in the wind farm pattern, for birds to follow.

The design of an AWECS can range from benign to deadly to birds. Where bird issues are most sensitive, the slower, softer, more visible systems are favored. Although direct data is scant, its probable that fast moving kiteplanes flying ae constitute the same sort of hazard to birds as large conventional turbines. Many birds seem to have a hard time detecting or understanding the threat of a large fast-moving object on a highly curved trajectory, but do better avoiding an aircraft on a set course.

Birds easily see and avoid large slow moving tethers and kites, with no known mortality factor. Birds often do not see the fine lines on toy kites and collide with them, usually with no bad effect, although a small potential for injury exists. Classic kiting is bird friendly, with the exception of fighter kites with cutting line. Some South Asian traditions even regulate the kite-fighting season based on bird presence. Fallen line should always be collected to avoid snaring wildlife.

The risks are two-way. A bird strike can bring down almost any airplane by varied damage. Engines can be damaged enough to stop. Control surfaces, windscreens, pitot tubes, antennas, radardomes, etc. can be made inoperable. A kiteplane is subject to bird-strike risk, it can be blinded, brought down or breakaway, creating risk off-field. Birds can create a nuisance to ground equipment, nesting in cavities and fouling surfaces with droppings.

Bird study is a part of AWE site assessment. Baseline bird presence should be determined before a kite farm is established and bird presence tracked for ongoing impact detection and mitigation. Qualified independent biologists should be relied on to develop flexible management plans to meet high standards.

In conclusion, AWE and birds can seemingly coexist well, but its up to designers and operators to make sure adverse impacts are minimal.

*Bats are presumed to resemble birds in their general relation to AWE, but with a more nocturnal presence.

Hello,

at TU Delft we have been testing now perhaps 30 days (each day perhaps 6 hours) with
the current team, so perhaps 180 hours.

During this time we once observed a bird, that had a collision with the tether. It survived and
continued to fly, but was a little bit dizzy.

This is not an objective, statistically representative observation, just my current knowledge.

The risk for birds, to collide with a fast moving tether can be mitigated, if a dancing (or balanced)
pair of kites is used. In this case the length of the tether, that is moving fast through the air
is reduced a lot.

[kitefreak]

Thanks to TUDelft for the report. Their bird strike event is consistent with broad kite hobby and sport experience, where strikes are fairly common, but birds are generally unharmed. KiteLabs and kPower have also reported seemingly harmless bird strikes.

The reality is that higher-velocity AWES architectures (rigid wings) will pose a far greater risk to birds and bats, but no specific reports yet. AWE professional practice will surely come to include incident reporting, like most wind farms and aviation do. Its known and regretted some stealth ventures have chosen not to report mishaps, under weaker ethics.

We are supposed to self-regulate in aviation R&D, or we become regulated as failures occur.

[Windy_Skies]

@Tom

phosphorescent tether strands

Didn’t find those yet, or didn’t search yet.

Phosphorescence | Materials

Strontium aluminate

DIY project:

DIY project : Glowing bike with ultraviolet LEDS

[Windy_Skies]

Flying at night has many advantages:

• If you illuminate the system, you will be visible from very far away.
• Less activity in birds and so lower chance of collisions with them.
• There is no UV damage to line and kite. UV damage is the most important factor by far in the longevity of polymer materials out in the sun I think.
• Some countries do not allow flying at night under visual flying rules.

Night VFR

It also has possible disadvantages:

• Light pollution.
• Possibly stricter regulation, maybe or probably overlapping with night visual flying rules.
• Bats more active and so higher chance of collisions with them.

Ecological light pollution

What are some more advantages and disadvantages of flying during the day or night? Can you elaborate on or correct an advantage or disadvantage I already mentioned?

[Rodread]

The advantage of flying an AWES at night is
The sun ain’t shining - people want to charge their e-car at night - solar ain’t working - perfect time to get flying because your kite isn’t going to get any UV damage.

and you can take cool pictures too

[Rodread]

The Lidar system used by Waymo cars is being offered for testing in projects. https://waymo.com/lidar
As mentioned previously. Lidar is extensively used already in wind field analysis without problems.
Anyone still harbouring objections that Lidar can be useful without presenting a risk to aviation?

[Tom]

When the aviation industry will use lidar, they will have to assess the risk and then we’ll have definite answers.
I’d bet there won’t be an issue and one can include lidar in awes.

[Windy_Skies]

Linking two related topics:

Flying advertising

With all this talk about how hard it is to get economically viable awes, I thought I’d share another niche idea: One can use Kites as flying advertisement. Moving or stationary. There are two ways this intersects with awes: One can light the kite up with flygen It has to be automatically launched, landed and flown.

[kitefreak]

There will continue to be Airspace conspicuity standards defined by FAA-ICAO criteria independent of advertising-based conspicuity, which would be harder to validate.