Sky Anchor Wifi / SDR Hexacopter with Tether

Wifi AP and SDR communications on a Hexacopter. Unlimited flight time and high speed internet provided by ground tether.

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Sky Anchor ,at its core, is a rapid deployment extended flight time heavy lift hexacopter with communications payloads like Wifi and SDR. It simply takes off and holds a vertical position over the base target it is physically tethered to. Onboard machine vision locks into the base glyph to use visual confirmation for hover corrections. This is a secondary position management system in the event the gps is scrambled or lost. Imagine a compact heavy lift 6 prop, 18 blade Hexacopter that can lift and anchor equipment in a relative stationary position called loitering. Onboard is a Wifi AP antenna and a lightweight SDR radio communications antenna hoisted 100-200 foot into the air. Extended and practically unlimited flight time is provided by ground power line tether. Also it is planned to have onboard is a 110v AC to DC Full Bridge Rectifier and step down power supply for the correct motor voltage.

Features to work in

100-200" Ethernet tether, which if weight offset allows I would use fiber instead.

100-200" Power Tether:

     This can be DC or AC, there are many options right now, possibly 60-100 volts DC then a drop down before the motors.

RGB Animated Ring : 

     3D Printed RGB ring to encompass the parameter of the hexacopter. 3.25" tall

Custom 3D Printed Arms:

     The arm needs to have a mount on the end for the RGB parameter ring. 

Custom landing gear option:

     The landing gear needs to be made in such a way it can land by itself or land in a round tether base station ring.

Tether tension relief:

     The tether will  attach with carabiner to the landing gear.

Ground Facing 6500K LEDS 50-100 watts each:

     These illuminate the operational area slightly similar to a street lamp, this will only be on when taking off or landing, it does not need to stay on as even 1000 watts is only so useful 100 ft in the air.

i. Concept

A. Is the project creative, original, functional, and pushing boundaries? 

B. Does the project effectively address the selected challenge?

Field Ready > A. YES! not specific to the open challenge example , however having rapid deployment internet and radio communications where cellular signal is either poor or cell network is not suitable for communications between base camps / facilities setup in a disaster.

Conservation X Labs> A.YES!  B.YES! Using  additional downward facing cameras and polarizing lenses to see below the surface, conservation labs could watch for fish, or sharks ect safely above the waters surface which machine vision alerts the lab techs when it sees a potential invasive species below. Monitor for hours at a time.

WILD CARD>  A. YES! B. YES! ,the only requirement here is to be awesome and innovative, I think we have this nailed!

ii. Design

A. Is there a depth of design detail available (like a system design, CAD models, project test methods, etc.)?


B. Is there base-level planning for the functionality (e.g., functional block diagram, list of specifications and descriptions of how they will be met, etc.)? 


C.How user-friendly is the design?

Easy enough someone with a tablet and basic instructions could launch sky anchor as it is stabilized and flown by the onboard computer.

iii. Production

A.Is the project realistically reproducible (taking into consideration necessary materials, skills, and production processes)?

Yes, however there are some skills required like stripping wires, crimping, soldering and being familiar with setting up devices like a raspberry pi will greatly help.

B. Are the manufacturing processes detailed? Are those processes realistic for scalability?

Not Avail yet

iv. Benchmark

A. How well is the project impact and viability demonstrated?


B. Are estimated costs realistic? How well does the project improve upon other currently available solutions?

Currently commercial solutions with extended flight time tether are limited to government and security agencies. They have a very high cost because they are mostly commertial 8 prop huge aircraft. There are examples of kits to make a smaller quadcopter a tethered one for

v. Communication

A. How thoroughly have the Final Round requirements been completed?

B. How well documented is the project? How “open” is the design? 

  • Picking a Light Directional Antenna

    Josh Starnes3 days ago 0 comments

    This is my idea for the long range directional antenna, I have the choice of either running an ethernet up to it, or having a second AP that perhaps is pointed down for example or 360 degrees so that there is general Wifi in the basecamp area as well.

  • Picking the AC 120v power tether

    Josh Starnes3 days ago 0 comments

    Based on others reporting a max 540 watts and 360 watts hovering with conservative flying, I am planning to have a 16 gauge aluminum wire that is 1.08 pounds per 100 foot, so 2.16 pounds for  200 foot. The planned ceiling that I plan to operate under is 10 amps , 1000 watts

  • Choices Choices, 110v to 12v power supply

    Josh Starnes3 days ago 0 comments

    Ok so without too much explanation, the power supply I use on the air frame needs to be powerful and also reliable. Additionally it much be compact and light as possible. What ever unit I get I will do as much as possible to reduce the weight, likely removing the steel or aluminum casing, as the board will have plenty of airflow opportunity right in the middle of 6 x 10 inch props. In the future I could use a vacuum table to vacuum form a clear or thin white plastic cover just for safety from touching a 110v transformer or capacitors.

    First option I found at only 1.9 pounds WITH THE CASE, losing the case could make a big difference.

    Second Option on Amazon that is physically larger and claims a 100 watts more for a rating but there is also the obvious draw back that the board is a little wider, but the weight is about the same.

    Here is a third options, a little heavier and larger than the slim line but agian also claiming 600 watts instead of 500

    I know there are likely mosfets that need to be cooler so I would opt in for smaller dedicated heat sinks for those and loose the heavier case if at all possible. If nothing else I could drill large holes in the case to swiss cheese it, giving it more airflow and also reducing the weight from the casing. Right now I am leaning towards the first option as the supplier is more credible and it has a smaller form factor.

  • Shopping list

    Josh Starnes6 days ago 0 comments

    RGB  flexible matrix 5 units $35.88 each

    PLA Filament 2.2kg

    I imagine this will take 4 rolls a filament as an estimate, around $25 each.

    F550 DJI frame

  • Second DJI F550 ARF "SOLD"

    Josh Starnes6 days ago 0 comments

    OK so when going through the use case and proof of concept phase. Realistically I need to build two air frames to demonstrate the function of rapid deployment and air to air radio communication bridge. There are other functions too we will discuss, but this is the initial basic use case.

    I try to be clear about what I am using and also offer similar alternatives for those who one day want to duplicate the results.

    I scored another good deal, but take in mind that this format has been cloned several times and you can get entire kits will all parts like remote and flight controller for this price, however we have obvious time constraints as estimated shipping from China would have put us right before the end of the competition.

    Here is an example of buying a full kit with pretty much everything you need all in one for a low price

    Above is an example of China Direct close shipment.

  • 4th of July project, assemble the DJI F550 ARF

    Josh Starnes07/04/2020 at 23:29 0 comments

    OK so I know I cannot do it all today , but I cant  help but get it built right away and I already see places I could reduce weight. Pictures will be added shortly

  • We have a 3450 Watt base station generator

    Josh Starnes07/04/2020 at 22:08 0 comments

    Here is my base station generator which I believe I purchased for 349 with the gas tanks. It is 3450 running watts with 4500 surge watts. This is on a 110v circuit with a 30 amp circuit breaker. Doing some math the "real" wattage is more like 3300 watts until there is a risk of popping a circuit breaker.  This is well within what we need, Honestly in a pinch a 2000 watt tiny generator would work, but having a big pad for additional equipment connected like lights, computer, amplifier etc. is very useful for the project. I actually used this a few days when a tornado came through and knocked out power for nearly 2 weeks. Overall is it just a couple inches bigger than a couple 5 gallon gas cans and even fits in my trunk of my Rav 4 without laying down the seats with both gas cans and more.

    On a side note, I really need to spread some grass seed outside for these bare spots. I have a shameless electric car plug in the background, that's a Mitsubishi Imiev.

  • Shipping update on the DJI F550 airframe

    Josh Starnes07/02/2020 at 23:03 0 comments

  • Bought a Donor Air Frame

    Josh Starnes07/02/2020 at 01:39 0 comments

    I had a few challenges in the selection. The first issue is that there is so much junk equipment that under performs the specifications. I wanted to use something fairly easy to find  and cost effective. There are lots of clones for the DJI F550 Flame Wheel, but many of the options were china direct and could not promise to arrive soon. There were clone kits avail for around 250 dollars, but checking further I found a couple of genuine DJI F550 Flame Wheel ARF ( almost ready to fly) kits that included the ESC motor controllers , the motors and the props as well. The price was.... $200 .... SOLD!  Well that was fun, I asked the seller to send pictures of the contents in all their glory :p

    Now we wait for it to get here.

  • Idea Conception

    Josh Starnes07/01/2020 at 23:25 0 comments

    Before I start, for the record, I despise the word drone being used to describe a multi copter. It gives them a negative reputation as drones are the workers and defenders of bees and wasps and that gives off a negative reaction in our lizard brain in the back of our minds. So there I said it. I will probably still refer to it as a drone however because that is what most people call them now as that is what they have been labeled by the media starting a few years back.  Thanks Fox news :\

    I have been wanting to do this project for the last couple years, as a matter of fact since the 2018 Hackaday Super Conference. I needed a way to lift an AP up into the air for extended times to control robotic projects like rovers, lawn mowers and such. Long range mostly unobstructed high speed internet access. This way I can collect data in real time and HD video from several cameras. That is how this project was born. I realized it could not only be used as a fast way to get a long range Wifi AP high enough to use , but other options too. To be useful the multi-copter needs to have an extended flight time, hours if needed without coming down. I came to the conclusion it needs a power cord tether coming from a generator or other power source on the ground. Given that the multi-copter will already have a wire tether, I realized it could potentially lift other things too. The next idea in the concept was getting either ethernet or fiber optic cable up to the multi-copter, fiber optic cable is much lighter than ethernet over a long length, so if I can get that to work that is ideal. but I will ether need a AP that is light and takes fiber or some kind of fiber to ethernet adapter.

    I started researching if this has ever been done before, I did find a couple of groups that did it so they could fly their quad copter demonstrations at shows all day without swapping batteries.  They did that by using high voltage , 600 volts I believe I remember and stepped it down on the quad copter frame and it drug around about 20 foot of extension cord. It didn't look like anything special and it was certainly thrown together for this one purpose, and a temporary solution for shows for their product demonstration. Now that I knew it was possible, I really started digging into types of wire I could use to be lighter and other solutions to make this a overall better system.

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target drone wrote 6 days ago point

As the weight of the copper is likely to be the most constraining aspect, consider using step up/down transformers to send a much higher voltage over thinner conductors. As described, 120V @ 30A for 200’ would require 50 pounds of stiff 6 AWG copper. If you up the voltage to 480, the current drops to 7.5A, and you could carry the same power over about 4 pounds of nice, flexible 16 AWG. 

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Josh Starnes wrote 6 days ago point

I appreciate the idea, but do you have suggestions of how to do that, what would I use?

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helge wrote 3 days ago point

1) leave galvanic isolation, rectification and PFC on the ground. Create 350-400V DC (don't worry too much about that, can always start with a modern 1000W ATX power supply and tap off the DC link capacitor + proper filtering, RSHN series filters maybe)

2) use heavy power filtering

3) use a quasi-resonant, non-isolated buck converter on the hexacopter (non-isolated:, isolated:, they can also be paralleled with load sharing)

4) with appropriate filtering on both ends, you can also use HomePlugAV modules, without the 50/60Hz mains sync they generate their own synchronization (I used the ones from BEL in a project, excellent performance and support

good luck

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Josh Starnes wrote 3 days ago point

I moved to a 120 volt tether, with a switching step down 500 watt RMS power supply , the Power supply is 1.5 pounds and the power tether is a little over 2 pounds. I think I will move to an copper clad aluminum 16 gauge power wire.

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Neo wrote 07/04/2020 at 19:13 point

Very interesting project. I hope you get somewhere with it. I was thinking of a similar solution for quick surveillance of sites.

As some have very eloquently and expertly pointed out, the power system will be crucial. I also see issues with the motors, you need to find motors that are reliable enough to run for hours on end when they are designed to run for 30 minutes tops. If you go for a hexacopter, losing a motor would be less of an issue, but if you go quadcopter it would mean a crash. Changing motors out could drive the cost of maintenence up a bit.

I remember NASA had some similar concept a while back, but now it's using tethered balloons. Seems a bit easier that way since they just stay up there without moving parts.

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Ethan Waldo wrote 07/03/2020 at 21:20 point

Meant to say monocrhomatic light source

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Ethan Waldo wrote 07/03/2020 at 21:19 point

Great idea.  A much more difficult feat to pull off that wouldn't require the tether would be lightweight solar panels as the base pointing down.  Generate a light source from the ground and use mirrors to focus light to illuminate solar panel to maximum efficiency.

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KD9KCK wrote 07/03/2020 at 20:41 point

This is very interesting. I wonder if you could also use this type of tether to lift up the end of a vertical HF antenna. 

Also as a WiFi access point you could have it extend a AP that exists at the base station up to it, that would make the access point set up cheaper. Seeing a an AP that takes Fiber or a Fiber to Ethernet adapter is going to cause a good amount.

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BotLawson wrote 07/02/2020 at 04:58 point

A couple of comments from when I built a big tether at work. 

Your power tether needs a high surge power capability as current flight controllers are designed for batteries which have tight energy budgets, but loads of surge power capability.  Most power converters for a tether have exactly the opposite limits with "infinite" energy available but a fixed rigid power limit.   (re-coding the flight controller to stay in a power budget would be another option)

There is/was a chineese drone company that makes 400Vdc motors and controllers. looks like what I remember, though it's not loading.   (still alive on facebook )  Fun fact about motors and controllers, for a given power a 40Vdc and 400Vdc motor and controller is about the same size.  So ideally you just run the motors directly off the high voltage tether.  This also allows battery backup to stay on the ground.  Also the typical DC link voltage in a active power factor correction AC-DC power brick is 300-350Vdc so it's easy to get high power non-isolated supplies near 400vdc.  (oh, and these same universal AC-DC power supplies often happily run off of 100-270Vdc as well, some are even rated for HVdc input.)

The next best would be high voltage high frequency AC so you can use a small ferrite core transformer and diode pack to make low voltage DC on the drone.  100KHz to 1MHz would do.  But keeping emi and rfi in check will be a challenge.

Mil spec M27500-22RC2S09 high temp 200C 600V 2-core shielded wire is a good place to start.  The shield is a bit heavy, but makes a solid safety/lightning ground.  And the cable comes with 26awg to 8awg or lower conductors.  Aluminum wire will save you weight, but is more difficult to make reliable connections to.

Speaking of lightning, you should also be able to monitor ground current to estimate your lightning risk.  Check Wikipedia, but lightning storms have 1000-10,000x higher electric fields that most clear air, so if your ground current jumps to more that say 100x typical, you can be pretty sure a storm is nearby. 

For communication, home AC wiring Ethernet bridges will work great and be very happy to use a shielded twisted pair vs AC wiring.  (lots easier than finding tether wire with conductors and a fiber-optic) 

Finally spooling the wire.  The wire is going to get hottest on the storage spool.  You'll want to wind it in a way that you can keep it cool.  I eventually wanted to wind the wire with a fishing reel or yarn ball-winder mechanism as these can wind in a sparse pattern for wire cooling and potentially eliminate the need for a high voltage slip ring. 

Finally Finally, I'd look configure your drone like the endurance record drones featured in some YouTube videos.  They can get >2h flight times on LiPo's so should minimize the tether power system size. 

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Dan Maloney wrote 06/24/2020 at 00:27 point

I had an idea to use a drone to take a small amateur radio repeater aloft to get line-of-sight between two points in mountainous terrain, rather than put up a tower. Flight time limits would have made it only marginally useful though. I hadn't thought of tethering it like that - clever move.

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Josh Starnes wrote 06/23/2020 at 21:31 point

Thanks Bill, Yes one of the uses is lighting. I intend to 3d print a ring that will house 50 watt 6000k LED modules downward pointing and RGB LED array all the way around the ring. In the event high speed communications have too much interference, or one party away from camp does not have a mobile base station, they can also communicate through a morse code style short message by blinking the LED horizontal lights and the field crew only needs a bright light to reply to the Sky Anchor.

I do intend to do a higher voltage, I was thinking of a 110v line straight from a power conditioner up the power line tether.

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James Hall wrote 06/29/2020 at 19:00 point

You could do a Close Encounters like thing with the LEDs.

Alternatively, I've seen pages talking about doing long range free space optic style communication by modulating LEDs. That would be neat to see. is one site.

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billguetz wrote 06/23/2020 at 17:02 point

Interesting.  Some thoughts:

- it could also be used for temporary lighting

- it would be useful even if it didn't go up 100' ,  think tree canopy.

- high voltage power would require smaller cable, but increase safety concerns

- wind is major limitation.  tilt of platform due to wind may limit usefulness without stablized platform

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