Close Encounters - Kite vs. Drone - What Happens When a Drone Hits a Kite Line

What happens when a drone hits a kite line? ….Or even a drone hitting a kite….?

As a frequent kite flier and Kite Aerial Photographer (KAP) these questions have come up over time …. And with the rapid increase in the number drones in the skies above….it was time to get some answers (or at least some data) to understand the risks and most likely outcomes of a drone striking a kite line….or even a kite!

Drone drivers also have similar concerns….getting tangled with kite lines….where in certain regions of the world…. young children …. chase drones with their small kites….

Kite vs. Drone

Purpose:
Test what happens when a drone strikes a kite line. Observe what happens when a drone flies into a kite line. Test three different types of kite line. Will the drone:
• Cut the kite line?
• Get tangled in the kite line?
• Bounce off the kite line?
• Have no impact?

Unplanned purpose.
• What happens when a drone directly collides with a kite?

Kite vs. Drone


Experimental Conditions:
• DJ Phantom 2 drone
- Camera and gimbal mounts were removed to reduce potential damage to this equipment
- Intermittent error messages with GPS sync that caused some initial flight control issues

• A 9-foot delta kite (ITW Levitation Delta kite) attached to a 20-foot aluminum pole (to hold a fixed position in the sky…simulating a kite in the sky)

• Kite Line (three different line materials used):
- Braided Dacron 1.4mm 150 lbs.
- Braided Polyamide 1.5mm 150 lbs.
- Braided Dyneema 0.8mm 150 lbs.

• Kite line was attached with simple larks head slip knot to the Levitation delta kite

• Tension on the kite line was simulated by hanging a 2.5 lbs. weight on the other end of the kite line after passing through a Harken pulley that was attached to a fence rail.

• Line angle from the ground to the kite was approximately 30-45 degrees (started testing at 30 degrees, moved to steeper angle of 45% halfway through the testing).

• Foam padding and a foam swimming noodle was wrapped around the lower end of the kite line to protect the drone from striking the fence.

• The planned contact point between the drone and the kite line was intentionally placed low to the ground for two reasons: a) reduce damage to the drone and b) keep the contact point close to the video cameras that were used to document the experiment.

• Documentation of the Kite vs. Drone experiment was collected via multiple video cameras each capturing different points of views. Cameras used included:
- Gro Pro Hero3 shoot 2.7 K video
- Canon S100 shooting HD Video
- Apple iPhone 6 Plus shooting HD video and slow motion HD video 240fps
- Samsung Galaxy Note 4 shooting HD video and stills

• Safety glasses were used to protect eyes

• Location – Wind Watcher proving grounds Chester Springs, PA

• Test date: 16 December 2015

• Weather: Light wind out of the North West at 5-10 mph, temperature 50-55 degrees F with cloudy overcast skies.

The following photo shows the rough test conditions with the Levitation delta kite suspended on a pole with a kite line attached to the kite on one end and attached to the fence with a 2.5 lbs weight providing a constant pull. You can see the kite line (Dyneema) wrapped around the pool noodle.

Kite vs Drone


Test Sequence:
• First test sequence employed the braided Dacron 1.4mm 150 lbs. Kite line and 2.5 lbs line tension.
- Piloted line contacts (3)
- Hand held drone with line cut attempts (4)
• Second test sequence employed the braided Polyamide 1.5mm 150 lbs. kite line and 2.5 lbs line tension.
- Piloted line contacts (2)
- Hand held drone with line cut attempts (4)
• Third test sequence employed the braided Dyneema 0.8mm 150 lbs. kite line and 2.5 lbs line tension.
- Piloted line contacts (2)
- Hand held drone with line cut attempts (5)

Data:
Test data was captured using video, slow motion video (240 fps) and still photography. A total of 4 individual cameras were used to record each drone – kite line contact point attempt. Observations were also recorded on paper notes. A total of 77 data files (mix of video, slow motion video and still images) were collected totaling 1.8 GB data.

Test Results – Kite vs. Drone
First Test Sequence: Drone vs. Kite with braided Dacron 1.4mm 150 lbs. kite line with 2.5 lbs line tension.

Driving the drone into the kite line proved a bit difficult as the GPS stabilization mode was acting a bit flakey making it hard to hit the thin kite line. Two attempts were needed to hit the kite line using a slow forward motion of the drone.

As the drone slowly approached the kite line the props were slightly above the kite line. The lower body (legs) of the drone contacted the kite line causing the drone to rotate as it pulled against the kite line. The drone tipped up a bit and the back left prop hit the kite line with multiple strikes prior to the prop wrapping up the kite line and flipping over. The drone then ran into the safety foam noodle that was wrapped around the kite line. The foam noodle did sustain several deep cuts from the high speed drone props as it tumbled to the ground.

The following photos show a typical drone encounter with a kite line:
Kite vs. Drone
Kite vs. Drone
Kite vs. Drone


The kite line did not get cut by the drone high speed props.


The drone electronics seemed to detected the contact with the kite line and depowered the prop with the line contact. This caused the lift to drop under that prop. The drone rolled to over and crashed to the grassy ground below. No damaged was sustained to the drone from the short 4 foot drop to the ground (soft grass).

The Dacron 1.4mm kite line remained intact with no obvious visual damage.

Multiple experiments continued with drone vs. Dacron kite line with similar results.
• Under direct pilot control the drone either wrapped up the kite line or bounced off the kite line. The wrap vs. bounce outcomes appeared to be related to the angle of first contact.

Kite vs Drone


The next phase of testing took a more direct approach to challenging the kite line with one person (kite pilot) manually holding the drone while the drone pilot accelerated the drone motors to near maximum speed with the remote control unit.

I describe the technique used as the “Chainsaw” approach where a person holds the drone firmly in two hands with the drone blades running a full speed. The drone is then tilted to a vertical orientation relative to the horizon like holding a chainsaw and slowly moved directly into the suspended kite line with the objective of cutting the kite line with the tips of the high speed props.

Multiple attempts to cut the Dacron kite line with the direct “Chainsaw” approach failed. The drone upon striking the kite line with the tip of the prop blades either bounced off or wrapped up the kite line around one of the props. Basically using the high speed drone prop blades as a high speed cutting tool.

No visual breaks or cuts were observed in the Dacron kite line. Close examination with macro photography revealed minor abrasion marks on the braided Dacron in several locations.

Kite vs. Drone


Drone Strikes Kite

During the 1st test sequence with Drone vs Dacron kite line the drone unexpectedly veered off course, rose up and struck the kite attached to the top of a 20-foot pole simulating the kite in the sky. This was not a planned test step.

The drone cut across the front of the kite with the prop blades slashing into the rip stop nylon fabric in several locations. The drone then hit the kite line flipped over and had a hard crash down on concrete below. The hard impact of the drone hitting concrete dislodged the battery and a prop from the drone. A few tense minutes passed as the drone was reassembled and checked out OK to continue the Drone vs. Kite testing. The Levitation delta kite did not fare as well with several large gashes in the light weight rip stop nylon fabric.

Kite vs Drone

Second Test Sequence: Drone vs. Kite with braided Polyamide 1.5mm 150 lbs. kite line with 2.5 lbs. line tension.

The line attached to the kite was switched to the second of three materials (Braided Polyamide 1.5mm 150 lbs.) and the drone vs. kite line challenge was resumed. The braided polyamide material has greater elasticity (~30%) and a much looser braid.


The same test techniques were employed for the Braided Polyamide kite line (piloted drone line contacts and “chainsaw” direct cut attempts).


Test results were the same as for the braided Dacron kite line.

The drone wrapped the kite line around the high speed props about half the time with both piloted and “chainsaw” techniques. The braided polyamide kite line held up the best with no visible evidence of wear or cuts upon both visual and macro photographic inspection.

The drone behavior during contact with the Polyamide 1.5mm kite line remained the same as for the Dacron kite line. Upon contact with the kite line the drone intelligent circuits appear to reduce power to the prop which causes the drone to roll over and crash to the ground. When the drone bounces off the kite line it re-establishes level flight.

Third Test Sequence: Drone vs. Kite with braided Dyneema 0.8mm 150 lbs. kite line with 2.5 lbs line tension.

The line attached to the kite was switched to the third of three materials (braided Dyneema 0.8mm 150 lbs.) and the drone vs. kite line challenge was resumed. The braided Dyneema material is very thin and slippery with a very tight braid. The drone pilot had a hard time seeing the very thin kite line.

The same test techniques were employed for the braided Dyneema kite line (piloted drone line contacts and “chainsaw” direct cut attempts).

Test results were the same as for the braided Dacron kite line.

The drone wrapped the kite line around the high speed props about half the time with both piloted and “chainsaw” techniques. The braided Dyneema kite line held up with no cuts or breaks. The braided Dyneema did have several small nicks or abrasion points visible upon inspection and with the more detailed macro photographic inspection.

The drone behavior during contact with the Dyneema 0.8mm kite remained the same as for the Dacron kite line. Upon contact with the kite line the drone intelligent circuits appear to reduce power to the prop which causes the drone to roll over and crash to the ground. When the drone bounces off the kite line it re-establishes level flight.
Kite vs Drone
Kite vs Drone


Summary & Conclusions

• Kite line is tough and is not easily cut by high speed drone prop blades. The drone was unable to cut any kite line in any of the experiments conducted.

• All three kite line materials held up with the following rough ranking for least evidence of wear to most (based on macro photographic inspection see below):
- Braided Polyamide 1.5mm 150 lbs. – no evidence of wear
- Braided Dacron 1.4mm 150 lbs. – trace evidence of wear
- Braided Dyneema 0.8mm 150 lbs. – minor nicks

Kite vs Drone


• Kite fabric (light weight rip stop Nylon) is easily cut if the high speed drone prop blades directly contacting the Nylon fabric.
Kite vs Drone

• Drones (at least some) appear to have quick acting logic to de-power a prop rotor if it senses contact with an object. This preliminary observation need to be confirmed. This makes sense from a safety design point of view.

If a drone contacts a kite line the following outcomes are expected based on this limited experimental data:

• The kite line will wrap around the drone prop. The drone will stay affixed to the kite line and either stay in the sky or slowly sink to the ground depending on the pull on the kite line (from the kite in the sky) and the overall weight of the drone.

• The drone will bounce off the kite line and momentarily roll and fall from the sky (due to a power down of one or more props). Depending on the altitude it is unknown if the drone could recover orientation quickly enough to regain leveled flight. Experiments with drones hitting kite line several hundred feet up in the sky were not performed during this series of tests.

If a drone directly contacts a kite (the actual fabric that the kite is made of) the following outcomes are expected based on very limited experimental data:

• The drone high speed prop blades will cut the lightweight rip stop Nylon fabric or plastic. Depending on the extent of damage the kite most likely will become unstable and slowly fall from the sky.

• The drone may become entangled with the kite fabric, bridles and or framing and fall from the sky with the kite.

Future

Additional testing of kite vs. drone is anticipated with high speed drones passes directly contacting the kite line with the expectation that the drone prop blades would be running at near maximum rpm.


Thanks to Jon Iannacone for being the drone pilot and putting his drone at risk during these interesting Kite vs. Drone experiments over the Wind Watcher proving grounds.


Supporting Data:


High resolution images can be found here on flickr


• HD and 2.7K video with additional commentary can be accessed here on YouTube


Kite vs. Drone - Part 1 - Introduction -

Kite vs. Drone - Part 2 - Dacron -

Kite vs. Drone - Part 3 - Bottom View -

Kite vs. Drone - Part 4 - Bottom View -

Kite vs. Drone - Part 5 - Line wrap -

Kite vs. Drone - Part 6 - Drone hits kite line

Kite vs. Drone - Part 7 - Drone Hits Kite -

Kite vs. Drone - Part 8 - Summary -


Copies of the raw data sheets can be viewed here on flickr


Enjoy the video and still photographic data.

Enjoy the flying and fly safe (both drone and kite pilots)!

WW


Reference section:

Kite FAA regulations:
Kite Aerial Photography safety tips:


Drone FAA regulations:
Drone FAA regulations:
Drone safety tips:
Drone safety tips:

Comments

  • Great write-up, and thanks for taking the time and effort to test and document this.
  • A wonderful piece of work, WW, and full marks to the drone owner for being brave enough to risk his expensive machine in the cause of science.
  • A fantastic contribution to our hobby - many thanks!
  • edited January 2016
    Looks like Science!

    Have you seen the mythbuster drone mini-myth? http://www.discovery.com/tv-shows/mythbusters/videos/can-drones-kill-people/

    What I got out of the Mythbuster episode:

    1) the plastic props are somewhat flexible and bend out of the way. Carbon props are a bit scarier as they're inflexible and perhaps sharper/abrasive.
    2) props have very little inertia so it doesn't take much to slow them down. I think this is happening with your tests. Most of the damage will be from the first hit -- just from the physics of it.
    3) drones naturally take up some of the energy of an impact by bouncing off or rotating. Holding the blade in place (the chainsaw) will do more damage than you would see from a natural impact.
    4) tip speed varies a bit with different motors, prop size, rpm. Bigger is a little scarier but I'm not sure how much tip speed varies.

    I think your worst case scenario would be your chainsaw method at max speed (is it hard to hold?). You could try with aftermarket props. Just don't hurt yourself. Also: having greater line tension would give the line less of a chance of getting out of the way = more damage?

    http://www.gearbest.com/rc-parts/pp_26857.html?currency=USD&gclid=CN6Pn7z1vMoCFRSRfgodatAPrQ

    I think they gave this a fair test after seeing some of the injury photos on the RC forums. Carbon props deserve some caution. Dacron is pretty tough though.
  • Nice work Jim, thank you.
  • That's reassuring to us kite fliers. Thanks Jim and (nameless) drone pilot for these experiments.

    Fly High

    Sue
  • Jim,

    Nice work!

    You speculate that the drone's electronics may be sensing a rotor that is impacted and shutting it down. I doubt that's designed in intentionally, but after working with similar brushless DC motors I'm not surprised by the effect. In order to spin the motor, the drive circuit needs to produce signals that are synchronized with the motor's speed and position. As soon as there is interference, the position and speed of the motor get out of sync with the result that torque is about nil. Similarly, the torque when stalled is very low with these motors.

    Dave W.
  • Excellent stuff! I think we all breathe a sigh of relief, thanks for your expert analysis on this scenario. I know I was wondering quite a lot what might happen!

    -Nathan
  • I'll add my thanks to the growing list. Excellent work, both of you! So far my interactions with multirotors have been very few and very far between, and so far have been handled by not flying in the same airspace. But it's good to know what the outcome is likely to be!

    Tom
  • edited January 2016
    Jim,
    This subject is very interesting !
    Kite flyers and pilot of drones choose interesting together photographic subject .
    The target can be the same !
    It happened for me one time.
    I was ready to take off my kite (the wind was very low ) when I see a group of two persons carrying the box of a Phantom box .
    I prefered to wait and deliver us a free flying site.
    I prefer to wait a little bit and I have seen a demonstration of about 20 minutes: Taking off and positioning the drone on the 4 cardinal points and coming back , back ground on the exact point of the beginning of the flight !
    José
  • Nice work! Thanks for taking the time to do this test and then sharing. :-)
  • THANKS Jim and Jon for the peace of mind your experiments give!
    I have experienced one close encounter with a drone, did not hit my line but I was very nervous as my rig and camera were up high when the drone buzzed by and I wondered about a line strike and what the results would be.
    I did have a small electric RC prop plane hit my line, with almost the same results you document above. The prop bounced off the line and the plane crashed but my line was unscathed.
    I wonder if a combustion motor driving the prop would produce a different result?
  • Thanks all for the fine comments.

    This was a fun project to work on. Took a bit of time as I had to learn how to edit video....

    The data collected gives me comfort knowing the odds appear to be low of having my line cut by a drone.

    Two KAP sessions in October (Iceland and Bangkok) both had unexpected drone flying in the same airspace with my kites and KAP gear. These unexpected encounters help stimulate these experiments.

    The videos really showed the action up close. I still have not found a way to edit the high speed 240 fps slow motion videos and post them to YouTube (frame rates are too high for my simple video editor...). Perhaps I will post these in the future.

    Thanks tgran for the mythbuster link. I had not seen that episode. Looks like our test results confirm what they found.

    WW

    Kite vs. Drone
  • Congratulations,you have done a very good subject to see how a drone can disturb a kite flight .
    It is a actual problem and some research has to be done to explore this kind of situation !
    You reproduce some events with your own KAP material and one of your friend.
    You put yourself in theses bad flight configurations to understand how it can happen and the results on kite line and on the kites .
    It will help us to be careful on our next kap flights.
  • Thanks for the work Jim (and thanks for the insight on power after impact Dave),

    Another reason for a stratospool. You can reel in a tangled drone before it and/or your rig hit the water ;).
  • Go snag yourselves a drone!
  • Do some drones have metal props? They could do more harm to the kite line (and people)

    Fly High

    Sue
  • There are drones and drones. The ones used for broadcast quality TV that get used for countless documentaries are pretty heavy pieces of kit, and have some serious power. Not sure about metal blades but contacting one of these with a kite line might be a different experience than the Phantom. Nonetheless the big ones are rarer and less likely to be flown by idiots.

    Great work Jim, answers a question that was nagging many of us.
    Simon
  • Fair comment there, Simon.

    I'd say anyone flying something more professional is 99% likely to be on the lookout for hazards such as kites before they even take-off. It is also very likely that a 'pro' setup will involve at least a 2-person team and so there should be a set of eyes permanently on the machine and the surrounds.

    Those flying big and commercially will have done site surveys, risk assessments etc. Although they'll be insured up to the eyeballs, they won't want to see many thousands of pounds of gear plummeting to the ground because of a kite line tangle.

    I think Jim's tests are highly appropriate for the kind of flying we do. Seeing that the different types of line hold up to a Phantom strike is very reassuring should the worst happen.
  • Totally agree Kevin, you echoed my thoughts exactly.
    Simon
  • I shared the sky with a drone on Saturday for the first time. We were flying at Fort Casey State Park, where drones are outlawed.

    Knowing what I know from Jim's testing at the Wind Watcher Proving Grounds, I knew if we tangled, he'd get the worst of it, and my gear would survive to fly another day.

    His DJI Phantom was buzzing around my trusty Levitation Light about 400' over the Whidbey Island to Port Townsend ferry, apparently trying to get photos of my kite. I was hoping he'd fly 200' lower - where my camera was - so I'd have a shot at getting a photo of his drone in flight. But no luck. He seemed to be more interested in my kite for some reason.

    I don't know why he wasn't photographing the ferry. I had a good day, and brought back some decent shots of the MV Salish setting sail for the other side of the Puget Sound. If the drone pilot hit his mark, he now has a stack of photos of an old, faded, ratty looking ( albiet dependable and straight-flying ) Levitation Light Delta.

  • edited June 2016
    {deleted}
  • edited June 2016
    I don't often disagree on this forum, but I do now ! There is nothing more inherently wrong with someone
    operating a drone, than there is with a " fool-on-a-string ", with his "eye on the sky ".

    Think about, some pretty dumb things happen with kites too. Before we start casting stones at equipment,
    let's look at the real problem, " the nut behind the wheel " !

    Paul

    Transparency: I am a long-time Kaper, who recently added 2 Phantom quad- copters to his tool kit.
  • edited June 2016
    {deleted}
  • edited June 2016
    The skies above are about to get a bit more crowed.... US FAA just published new regulations for the operation of small Unmanned Aircraft Systems (sUAS) (i.e., small drones under 55 lbs.) in the National Airspace System (NAS) through a final rule. Title 14 of the Code of Federal Regulations (14 CFR) part 107.

    My first quick read show no direct new rules that will impact kites or KAP, Title 14 CFR Part 101, Moored Balloons, Kites, Amateur Rockets and Unmanned Free Balloons remains intact ;-)

    Few highlights:
    - Unmanned aircraft must weigh less than 55 lbs. (25 kg).

    - Visual line-of-sight (VLOS) operation only

    - Small unmanned aircraft may not operate over any persons not directly participating in the operation

    - Daylight-only operations, or civil twilight (30 minutes before official sunrise to 30 minutes after official sunset, local time)
    with appropriate anti-collision lighting.

    - Maximum groundspeed of 100 mph (87 knots).

    - Maximum altitude of 400 feet above ground level (AGL) or, if higher than 400 feet AGL, remain within 400 feet of a
    structure

    - A person operating a small UAS must either hold a remote pilot airman certificate with a small UAS rating or be under
    the direct supervision of a person who does hold a remote pilot certificate (remote pilot in command). To qualify for a remote pilot certificate, a person must: Demonstrate aeronautical knowledge by either: Passing an initial aeronautical knowledge test at an FAA-approved knowledge testing center; or Hold a part 61 pilot certificate other than student pilot, complete a flight review within the previous 24 months, and complete a small UAS online training course provided by the FAA.

    - Be vetted by the Transportation Security Administration (TSA).


    Details of the new drone (sUAS) rules can be found here.

    - Summary of the Small UAS Rule (PDF)
    - Small UAS Advisory Circular – How to Use the Rule (PDF)
    - Complete Text of the Small UAS Rule (PDF) Warning - over 600 pages of government work here!

    Keep a tight hold of your kite line!

    Separately - the original post on this subject "Close Encounters - Kite vs. Drone - What Happens When a Drone Hits a Kite Line" was just published in the Summer 2016 issue of Kiting, the Journal of the American Kitefliers Association.

    Enjoy the reading!

    WW

  • I find this all a bit pointless,I fly drones and kites,but never together....as I need strong winds to fly my kite,but the opposite to fly my drone....I only fly a drone in wind speeds below 10 p.m.h ....but fly my kite in 15 m.p.h winds or above.
  • I note that tethered powered aircraft are covered by the new part 107 (i.e. they are not treated in the same way as kites and tethered balloons).
  • So is this a blanket 'anyone using even for leisure must have a certificate' type situation?
Sign In or Register to comment.

Howdy, Stranger!

It looks like you're new here. If you want to get involved, click one of these buttons!

In this Discussion