Cyphy has popped up again...

http://www.northeastdronenews.com/start-cyphy-works-developing-high...

What sort of technology is involved in getting 1000W through a filament thinner than headphone cord?

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I would still be interested to know "How high is the voltage". Though Hoverfly's tether looks much thicker than cyphy's tether. So I am guessing they settled for more off the self power supplies in the category of 220v or so.

In case of cyphy, it looks everything custom made even the tether. I don't have such resources at my hand. Such thin wire's will have to have very high dielectric strength sleeve material to be safe. 

Actually, this idea is not so far fetched, both with (normal working) input voltage and a light weight AC-DC converter.  I came across this idea awhile back and looked at using this product (available in either 500W or 1000W versions).

http://www.tdk-lambda.com/products/sps/ps_pm/pfe_f/indexe.html#

Both have a 28VDC working output that would work with a 6S system (that is what I am flying on my big hex).  The 500W version weighs-in at 300g and the 1000W version weighs-in at 500g.  My big hex could EASILY carry this payload (presently, I carry a 6S-16,000mAh battery that weighs 1900g, or 4.5 LBS!).

The AC-DC units in the link above work all the way up to 265VAC (input), and you can easily get 240VAC from your house AC power supply (that's what most dryers, stoves and water heaters operate from).  Now doing the math, let's say you want to run the 1000W model at 240VAC, that's just over 4A on the lead up to the multi-rotor.  #20AWG wire will easily carry this ampacity (up to 12A) with only 3% voltage drop up to a distance of 75'.  You could even carry a smaller battery (for high discharge rates when needed), then the "power-cord" would provide unlimited hoover flight times.  You could even go to 22AWG, but your distance will be reduced due to voltage drop.

I like it!

It is better to step down the A/C first. When you use a D/C regulator the wasted energy is dissipated as heat. That much heat would induce thermal runaway on other components. 

Nice find. I like the look of that product.

Well I am building one. Haven't faced much problem till now. By the way I am in the process of buying one tdk-lamda 16v but they say at that voltage in 500gm wattage is only 720W. Also these are not plug and play. They require a parent board for some external components(nothing much capacitor, resisters and coils). Though the external components required seem lightweight enough But I guess mounting them on a board, required wiring and connector will be additional 150gm of weight atleast.

I am planning to use really thin teflon wire AWG 24/7/32. The wire is rated at 4amps. That will be enough upto 1000W. While testing I have drawn continous 6amps for 20 minutes and wire didn't heatup. The wire weighs only 359gms for 100meters. 

Don't forget, heat sink also.  I'm sure you could still come in under 4LBS.

Watch you amp draw.  Usually Voltage Drop will become your enemy at rated ampacity over large distances.

Why worry about the volt drop, the 3% I saw earlier does not matter in any way. the volt drop does not limit the distance. This is only relevant for a home or industrial installation 

If you start at 240v from your supply and this drops to 220 at the copter it will still work. 

As long as the ampacity of the wire will carry the current then dont worry, you can exceed the ampacity if you wish it will just get warmer. the total losses will actually reduce as the resistance increases. 

Yes forgot to mention the heatsink. I guess in case of something in air I can use something less than recommended and save some precious grams.

voltage drop can be handled. I can actually ramp up to 270V at ground station.  If I remember correctly the supply can handle that. That way at highest current draw also I will probably be around 250V at max amps.


how did this work out...?   i am looking into a tethered drone concept for a search and rescue unit.

dennis


Pritam Ghanghas said:

Well I am building one. Haven't faced much problem till now. By the way I am in the process of buying one tdk-lamda 16v but they say at that voltage in 500gm wattage is only 720W. Also these are not plug and play. They require a parent board for some external components(nothing much capacitor, resisters and coils). Though the external components required seem lightweight enough But I guess mounting them on a board, required wiring and connector will be additional 150gm of weight atleast.

I am planning to use really thin teflon wire AWG 24/7/32. The wire is rated at 4amps. That will be enough upto 1000W. While testing I have drawn continous 6amps for 20 minutes and wire didn't heatup. The wire weighs only 359gms for 100meters. 

it actually works quite well. i had tested upto 60meters. But not with lambda. I decided against it. Local vendor was asking too much money for it. And the carrier board + lamda was coming out to be equal to most ac-dc power supplies available at much cheaper prices. Though lamda might be worth a look if you are going commercial, just for the sake of reliability. I would say for a commercial unit whole power design has to be custom. I would recommend more like 400V plus through the wire as my wire was heating a lot. I was using locally sourced teflon wire. Even though the wire was rated for 4amps it was heating up quite a lot even at 3amps especailly the left wire in the spool as it was concentrated, wire in air was alright, no measurable heating issue there.

do you have a drawing or schematic of your system?  we aren't trying to go commercial - we are looking into helping a search and rescue unit put up a "relay" craft for better communications in the mountains during searches.  any assistance would be greatly appreciated.

dennis

kern county desert search and rescue

calif

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