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Oct 09, 2019, 02:07 AM
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... and don't forget the wind influence on 100 meters of wire
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Oct 16, 2019, 04:51 PM
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dkemxr's Avatar
The tethered idea is not going to work for 400ft. This has been discussed many times with the same conclusions. It would be expensive, much more than an order of magnitude more than your stated budget, but a multirotor with a fuel boost motor could potentially hover for a couple hrs. Arducopter supports this:
http://ardupilot.org/copter/docs/booster-motor.html

Or as someone may come along and suggest, a gas helicopter. Way more efficient than a multirotor.

Quote:
Originally Posted by Stewartde
G.wayne, This is perfectly what I was looking for, THANK YOU!!
I understand your concern about the batteries, however I do not want something that will require me to bring it down after a short time.
I will keep striving to get something that can deploy and stay up for hours.
That OctoCopter design looks very interesting, but at $100 per motor, the prices are soaring...
I will follow up on your other links.


Renatoa, Do you have any links to that testing or the equation you mentioned?
Using AC to reduce line loss and then converting it to DC sounds like a great idea, I can adjust the filters circuit to match the frequency I use for the power transfer. I was thinking to use Aluminum wire to reduce the weight as it still has very low loss.

Tangent here: {I always explore tangents just in case they might actually work}
Thinking more about using AC, isn't the Motor control itself accomplish be the ESC's converting the DC batteries to a varied AC signal to control the motor speed? Maybe I can eliminate the ESC and some control circuity if I used 5 smaller aluminum wires and fed the motors directly by producing that AC on the ground. Hmm.. I need to understand what the AC looks like leaving the ESC's better... Time for some research.


Macksupersnow, Weather "Balloons" have been done by HAMs many times. The biggest issue there is that they get easily pushed by winds and often come down close to the ground with even a little gusts. I must avoid this at all costs for my target deployment areas. However, if I create a powered "Blimp" that can stay in position, then it may work.

Perhaps a Drone tethered a small distance above a balloon. The Balloon would lift the weight and the drone would only need to keep it in position. This would let me lift much more weight to handle the larger wire to let me power the drone from the ground. I will need to ensure the drone is always above the balloon and never can get close to it and pop it... lol
Or maybe a traditional Blimp with dual directional "Thrusters" / drone motors to keep it in position.

I will put more thought into this consider this further.
Thank you all!
Last edited by dkemxr; Oct 16, 2019 at 05:11 PM.
Oct 16, 2019, 05:23 PM
KC3MBR
Stewartde's Avatar
Thread OP
Sorry, I will not give up because someone says it wont work.
If you have links to show what failed, then great, show me so I'll review to see what to avoid.
If it costs more money that's okay too, it will just take longer so save up for the parts, but I don't want to just throw money at it either.

I'm seeing promise in sending very high voltage (less amps) up the line to reduce losses and using lightweight circuitry to convert it back down to what's needed - looks like I can get lots of Amps and still stay underweight using this method.

G.wayne's reply has been super helpful.
But I will have some questions as I work through the drone lingo.
Oct 16, 2019, 06:22 PM
Registered User
dkemxr's Avatar
You don't have to give up, you just have to spend a lot more money for capability less than your desired goal. Lightweight circuitry to supply high current? So flying a big switching supply (only way for "lightweight")?

Here you go:
200ft
https://hoverflytech.com/livesky-sentry/
100m:
https://elistair.com/orion-tethered-drone/
100m:
https://www.foxtechfpv.com/tethered-...or-drones.html

What do all these solutions, which don't meet your stated goal, have in common? They are very expensive.

Or DIY with an extension cord length flight:
http://ardupilot.org/copter/docs/com...er-tether.html


Quote:
Originally Posted by Stewartde
Sorry, I will not give up because someone says it wont work.
If you have links to show what failed, then great, show me so I'll review to see what to avoid.
If it costs more money that's okay too, it will just take longer so save up for the parts, but I don't want to just throw money at it either.

I'm seeing promise in sending very high voltage (less amps) up the line to reduce losses and using lightweight circuitry to convert it back down to what's needed - looks like I can get lots of Amps and still stay underweight using this method.

G.wayne's reply has been super helpful.
But I will have some questions as I work through the drone lingo.
Last edited by dkemxr; Oct 16, 2019 at 06:27 PM.
Oct 17, 2019, 10:36 AM
We are not men, we are DEVO 7e
xanuser's Avatar
What is it about multirotors that leads people to thinking its the perfect tool for all the wrong jobs?
Oct 17, 2019, 02:10 PM
Registered User
dkemxr's Avatar
Maybe a misunderstanding regarding how inefficient multirotors really are compared to other flying craft.

Quote:
Originally Posted by xanuser
What is it about multirotors that leads people to thinking its the perfect tool for all the wrong jobs?
Oct 18, 2019, 05:25 PM
We are not men, we are DEVO 7e
xanuser's Avatar
Quote:
Originally Posted by dkemxr
Maybe a misunderstanding regarding how inefficient multirotors really are compared to other flying craft.

physics really should be a mandatory subject in all grade levels.
Oct 21, 2019, 09:02 AM
Thermite + ice = Big boom.
boaterguy's Avatar
Quote:
Originally Posted by xanuser
What is it about multirotors that leads people to thinking its the perfect tool for all the wrong jobs?
I think it may also have to do with all the news stories where you can make it on tv with "I attached a [something] to a DJI flamewheel and I fly it at the same height as if someone had strapped it to their chest"

From all the ones I've seen, this one honestly isn't even in the top 10
Nov 08, 2019, 08:32 AM
Registered User
Jeff.1.S's Avatar
To lift a wire 400' and keep it up for any length of time, I would try a large helium balloon,
using a quad would be too expensive.
Nov 17, 2019, 11:03 AM
Registered User
Quote:
Originally Posted by Stewartde
Sorry, I will not give up because someone says it wont work.
If you have links to show what failed, then great, show me so I'll review to see what to avoid.
If it costs more money that's okay too, it will just take longer so save up for the parts, but I don't want to just throw money at it either.

I'm seeing promise in sending very high voltage (less amps) up the line to reduce losses and using lightweight circuitry to convert it back down to what's needed - looks like I can get lots of Amps and still stay underweight using this method.

G.wayne's reply has been super helpful.
But I will have some questions as I work through the drone lingo.
High voltage is the way to go.
Using numbers from DJI S900 as a baseline what would be possible:
3.3kg without battery, 1000W power requirement at hover with 6.8kg takeoff weight (leaving 3.5kg for the wire and on-board power supply)

Lightest Vicor 600W power supplies are only 30 grams per piece. Lets say we use four of these or something of similar performance with 800V supply voltage. Gives us max power of 2400W and only 1.25A at hover.

So now we need aluminium power cable capable to handle 1kW continuously. 0.5mm2 aluminium wire has resistance of 53 ohms per kilometer and 1.35kg per km weight. Doubled up for return patht that is 106 ohms and 2.6kg per kilometer.

Okay, this looks like total overkill with theoretical capability somewhere around 3000 feet.. but proves the point that its possible and doable.


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