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Author Topic: Drone supported stealth antennas??  (Read 33732 times)
W8JX
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« Reply #15 on: November 10, 2014, 06:57:37 AM »

A tank of hydrogen is about $50 for a 200ft^3 tank plus tank rental.  More lift than helium but there's the burn hazard if you're not careful. 

No more burn hazard than gasoline or propane. Inside a balloon, hydrogen cannot burn without oxygen. Also hydrogen is easy to make and in some places easy to get too where there is hydrogen fueling stations. Better lift than helium too. As far as wire crossing a power line when cut free, a thin wire might cause a brief flash when it vaporizes but that's about it. 
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W0BTU
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« Reply #16 on: November 10, 2014, 07:07:17 AM »

FWIW, from http://www.barrygray.pwp.blueyonder.co.uk/Tutoring/BBuoy.html:

The density of helium at sea level and 15oC is about 0.18 kg/m3, compared to 0.09 kg/m3 for hydrogen and 1.22 kg/m3 for air. The difference between the density of helium and that of air is therefore about 1.04 kg/m3, so a 1000 kg helium balloon will need about 960 m3 of helium to lift it - this will fill a spherical balloon with a diameter of about 12.2 m. A useful rule of thumb for helium balloons and airships is that at sea level 1000 m3 of helium will lift about a tonne.

Although helium is twice as dense as hydrogen its lifting capacity is only slightly less because what matters is the difference between its density and that of air. Nevertheless a balloon, and in particular an airship, designed to be filled with hydrogen will not work if it is filled with helium, although a balloon or airship designed to be filled with helium will work if it is filled with hydrogen.
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W8JX
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« Reply #17 on: November 10, 2014, 08:17:21 AM »

FWIW, from http://www.barrygray.pwp.blueyonder.co.uk/Tutoring/BBuoy.html:

The density of helium at sea level and 15oC is about 0.18 kg/m3, compared to 0.09 kg/m3 for hydrogen and 1.22 kg/m3 for air. The difference between the density of helium and that of air is therefore about 1.04 kg/m3, so a 1000 kg helium balloon will need about 960 m3 of helium to lift it - this will fill a spherical balloon with a diameter of about 12.2 m. A useful rule of thumb for helium balloons and airships is that at sea level 1000 m3 of helium will lift about a tonne.

Although helium is twice as dense as hydrogen its lifting capacity is only slightly less because what matters is the difference between its density and that of air. Nevertheless a balloon, and in particular an airship, designed to be filled with hydrogen will not work if it is filled with helium, although a balloon or airship designed to be filled with helium will work if it is filled with hydrogen.

Real world Hydrogen has about 8% more lift and that could easily offset using better balloon material and still having same or more usable lift than Helium with a lower quality and lighter balloon.
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WA7PRC
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« Reply #18 on: November 10, 2014, 06:15:23 PM »

This is what I've learned from reading about Helium balloon-supported verticals...

"Party Helium" is 50% air. If you buy Helium from a welding supply outfit, it'll be nearly pure.

Balloon materials:
Mylar
Pro: Lightweight, seals well
Con: Does not handle overpressure well - easily bursts
Latex
Pro: it easily stretches to accommodate changing pressure w/ changes in temperature
Con: its porosity causes Helium to escape over time. Heavy, compared to Mylar.

Baloon shape/size/number:
1) A single round balloon at the top is the worst application -- it tends to lay over in light breezes. A disc below the balloon helps minimally.
2) Multiple round balloons attached to the rope/wire tend to fly slightly closer to vertical in light breezes.
3) A 'Kiteoon' tends to orient itself into the wind. Its design adds lift with increasing wind.

I've seen all types used in advertising.  The Kiteoons seem to fly the closest to vertical. They also appear to be not inexpensive but could be a good candidate for portable/FD use. Everything attached to the balloon needs to be lightweight. I would use something like small gauge wire-feed welding wire (copper-covered steel), connected to RG-174/U coax (0.1" OD, copper-covered stranded steel center conductor). The coax can handle up to about 100W as long as the duty-cycle and VSWR aren't too high.

All of the above may still be contrary to a HOA contract.

vy 73,
Bryan WA7PRC
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K4PIH
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« Reply #19 on: November 20, 2014, 10:08:33 AM »

Ya'll do know that aluminized Mylar balloons are required by law to be tethered? The wire would keep it tethered, but if it gets loose or you cut it and it gets into a power line, you could be liable for damages to the power company, not to mention the danger factor. When you buy those balloons at party places they always come with enough weight to hold them down due to the danger factor of them getting into power lines.
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IZ5PQT
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« Reply #20 on: November 23, 2014, 03:48:38 AM »

The serious safety problem with power lines could be the hanging wire. So the antenna wire should never be cut.
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K5TED
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« Reply #21 on: November 23, 2014, 08:39:45 AM »

  OK, this was a shocker even to me.  While tuning around, I happened to come across a few local CBers discussing how to get on the air evenings in HOA antenna restricted communities.  Amazingly enough, one was using a small drone to hold up a wire for a half wave 11 meter vertical!  The flight time was supposedly over 30 minutes, and he would change batteries if he wanted to stay on the air longer.  He even discussed how his next project was to attach a balloon to the drone to keep it up for even longer periods!  Could this use of drone technology have any implications for HOA challenged hams?

Amazingly, this sounds like a load of hooey...



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N5PZJ
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« Reply #22 on: November 24, 2014, 05:46:07 AM »

  OK, this was a shocker even to me.  While tuning around, I happened to come across a few local CBers discussing how to get on the air evenings in HOA antenna restricted communities.  Amazingly enough, one was using a small drone to hold up a wire for a half wave 11 meter vertical!  The flight time was supposedly over 30 minutes, and he would change batteries if he wanted to stay on the air longer.  He even discussed how his next project was to attach a balloon to the drone to keep it up for even longer periods!  Could this use of drone technology have any implications for HOA challenged hams?


Sounds more than a load of Hooey!!!!   11 Meters, a cesspot of great ideas!?   Nope, drones would have to lift substantial weight, over 5 lbs is not happening!!!! 
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NR9R
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« Reply #23 on: January 21, 2015, 12:11:30 PM »

I'll just add that if the objective is to be discrete, even a small quadcopter produces a noticeable amount of noise, sounding like an electric weed wacker.  It would, without a doubt, bring more attention to the antenna.  I think people usually assume they are being video recorded when they see these things too. So...no.     
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W5SNM
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« Reply #24 on: January 23, 2015, 02:58:10 AM »

There was a story on the news last night of a drone crashing down in someone's yard with a 6 lb. brick of crystal meth attached to it.   Guess some folks were trying to send it across the border and the motors gave way due to the weight.   Anyhow, the drone was three feet across and runs about $1400 bucks and will hold less than 5 lbs. (specifically a camera).   Seems like a drone capable of holding an antenna would be a high enough cost that a better option could be found.   
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KK5DR
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« Reply #25 on: February 03, 2015, 06:35:59 PM »

Even better idea! Use a quad drone capable of lifting a few pounds, help deploy a thin wire antenna up in to the high tree tops after sunset. Then pull the wire back in before the sun comes up. No body would ever know you had an antenna up.
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W8JX
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« Reply #26 on: February 04, 2015, 04:32:16 PM »

Even better idea! Use a quad drone capable of lifting a few pounds, help deploy a thin wire antenna up in to the high tree tops after sunset. Then pull the wire back in before the sun comes up. No body would ever know you had an antenna up.

Better have a long extension cord to power it and hope RF does not crash it and no one notices the droning noise of props. I balloon would be WAY better here. 
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You can embrace new technology and change with it or cling tightly to old technology and fall further behind everyday....
AE5J
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« Reply #27 on: February 07, 2015, 09:20:44 PM »

Better have a long extension cord to power it and hope RF does not crash it and no one notices the droning noise of props. I balloon would be WAY better here. 

The nincompoop meter has soared off into the stratosphere!
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AE5J
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« Reply #28 on: February 07, 2015, 09:36:50 PM »

Even better idea! Use a quad drone capable of lifting a few pounds, help deploy a thin wire antenna up in to the high tree tops after sunset. Then pull the wire back in before the sun comes up. No body would ever know you had an antenna up.

Actually go look at the 26 ga wire (part #534) sold by The Wireman. It is so tiny you could leave it in the tree permanently. I have used it and you have to look real hard to see it in the clear from 15 feet away. Run up into a tree it would be as close to invisible as you could get.

Here http://www.antennalaunchers.com/antlaunching.html. is an antenna launcher that will put your wire over the top of a 130-200 foot tree. No drone needed. To top it off, if you crash a drone in that same treetop, you're going to need some serious help getting it down. Good luck.
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W8JX
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« Reply #29 on: February 08, 2015, 06:19:41 AM »

Better have a long extension cord to power it and hope RF does not crash it and no one notices the droning noise of props. I balloon would be WAY better here. 

The nincompoop meter has soared off into the stratosphere!

Yes it has when someone suggests using a drone to support a antenna..
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You can embrace new technology and change with it or cling tightly to old technology and fall further behind everyday....
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