Jump to content

Easy to hang dipoles!


KD3Y

Recommended Posts

  • Ionosphere


Well, I finally "upgraded" from the strings with lead weights on the end, tater guns, rods and reels with a lead weight on the end, slingshots, and bows and arrows.

I could only get my 40 meter dipole up 26 feet in the pine tree because thats as far as I could sling the string with the fishing weight on it.  Took me about 15 tries and I almost put my eye out.  Got tangled up twice, broke the string trying to get it loose, and the weights are still up there hanging in the tree.  But them limbs up there 60 or 70 feet up sure are appealing.  I just didn't have a way to get my rope that high.   I bet my dipole would perform a lot better at 70 feet than 26.

SO... I got my drone license so all I have to do is tie a string to the hook on the belly, and fly it over the branch I want the dipole leg to secure to then land the drone.  Once the smaller string is over the limb I can tie the larger rope on the end of the dipole leg to it and pull it over the limb.   Why is it that everyone in the club all of a sudden has a dipole they need hung???????
 

DronePilot.png.44dd9a58531336099bb6f53452d25962.png

 

Drone.jpg.e5f9d9f2017dea29e8f03a4e99a52a1c.jpg

 

  • Agree | Support 1
Link to comment
Share on other sites

  • Administrator


Nice! So, a little story... A few years back, methinks it was for Field Day 2019, I used a DJI Phantom 2, I think that's what I have, to run our dipoles over a ±60 to 80-foot tree. I also used a release mechanism that they use for drone fishing. I can't right now, but in a couple of days, I'll take a few pics and put them up. But the story does not need pics. The story is that the first couple of tries went well. We managed to get some braided fishing line over the tree and then pull the antenna wire over the top. However 🙄 when it came time for the third or fourth wire, we got a sudden sustained gust of wind, and here I was with @K3MZ and @W4TG chasing after this drone which by now was well to the other side of Washington Monument State Park. To make matters worse, 😩 the braided line had decided to wrap itself into one of the rotors making control quasi-impossible. Ultimately, I had to ground the drone, hoping it would not get mangled in the trees. We did manage to retrieve it with, as the only damage, a broken rotor which I then fixed. Moral of the story, just when you think there's no wind, there is wind 🥵

  • Funny 1
  • Like | Congratulations 1
Link to comment
Share on other sites

  • Ionosphere


You'd be surprised the number of drones I find on the bottom of the ocean when scuba diving some of the more popular wrecks, Jim.

Back in September we were leaving the Port at Morehead City on my buddy's boat and my other buddy was trying out his new drone, taking some arial video if us leaving the port.   A few hundred yards away the USCG was doing "man overboard" training where they'd throw a manequin overboard and the fast boat crew had to go find him and get him.   From out of nowhere the USCG fastboat came up with his blue lights on.  They thought he was videoing their training and didn't like that.   I'm not sure if the State port is a "no fly" area but when you're flying all around a secure area like that where a TWIC card is required for access it's sure to draw some attention.

He told them he was testing out his new drone and they said OK and left.
 

Link to comment
Share on other sites

  • Administrator


Well, let me tell you, where I live... you so much as unpack a drone from the box and you'll have Federal Agents offering to give you a lift to a cosy one-bedroom studio with apparently great fitness facilities. Kidding aside, the Nation's capital drone flight rules are so so simple: No No No! I really don't know why I even keep mine 😞

  • Unfortunate | Sad | Too bad 1
Link to comment
Share on other sites

  • Ionosphere


The Drone is an outstanding idea!

But, I don't have one, and I'm usually in the woods.  Expensive drone, bad pilot, unhappy wife.  So, I use a neon orange golf ball with a hole drilled in the center. The roundness and the weight of the golf ball seems to work very well at sneaking back down through the branches.  Through the hole in the golf ball, I tie very brightly colored fly line backing to the ball.  This helps to see where the line actually went.  I then tie "bank line" to the fly line backing to hoist the antenna.  I use a wrist rocket as the propulsion device.  This system seems to work really well for me.  I hope it helps others.

  • Agree | Support 1
Link to comment
Share on other sites

  • Administrator


47 minutes ago, K8JCL said:

The Drone is an outstanding idea!

But, I don't have one, and I'm usually in the woods.  Expensive drone, bad pilot, unhappy wife.  So, I use a neon orange golf ball with a hole drilled in the center. The roundness and the weight of the golf ball seems to work very well at sneaking back down through the branches.  Through the hole in the golf ball, I tie very brightly colored fly line backing to the ball.  This helps to see where the line actually went.  I then tie "bank line" to the fly line backing to hoist the antenna.  I use a wrist rocket as the propulsion device.  This system seems to work really well for me.  I hope it helps others.

Do you know that I never heard it called a wrist rocket? I figured it was a sling shot, but I still had to look it up 😩

Yup, used mine many many times. I personally prefer it to the usual compressed air PVC pipe launcher.

Link to comment
Share on other sites

  • 2 weeks later...
  • Ionosphere


Nah no tater guns for me.  I'm a DOT cyliner inspector and I've seen what an exploding pressurized vessel can do.   Instant release of compressed gas is no fun a'tall.  PVC isn't rated for pressurized gas.  My face is too beautiful to be messed up with scars from PVC shrapnel.  Heck, something like that would end the income from my part time job as a Chipendales model.

I watched a guy at the dive shop remove the valve on a scuba cyllinder that had only about 50 PSI left in it.   He thougth the cylinder was empty.  When that last thread let go as he was unscrewing it, the valve flew past his face, thru the sheetrock ceiling, thru the subfloor of the upstairs, and lodged in the second floor ceiling.   If that 1/2 lb of brass had hit his face you can pretty much guess what it would've done.  If DOT heard I was pressuriing PVC pipe with compressed gas, the DOT inspector would be over here with his ID badge and clipboard faster than a fat girl can eat a twinkie.

I've done enough handyman work with PVC to know it's brittle, it gets more brittle as it gasses off over the years, cold weather makes it even more brittle, glued joints often fail, and it's not a DOT approved container to hold pressurized gas.  Any container over 2" diameter and that holds over 12 PSI must be DOT approved and must be recertified every 5 years.   That's why all the tater guns you see on field day are home made.  No manufacturer can get DOT approval for a PVC bomb, and if they did, the lawyers would bankrupt them within a year.  

I've seen a few hams who offer the plans for sale to build your own.  Usually have some disclaimer about they aren't responsible for the results.  One word..."Strict liability".  You can disclaim negligence in the U.S. but you can't disclaim gross negligence. 

I know a lot of hams use them.  There's one in our CERT trailer that's probably 10 years old.  When it explodes, the club doesn't have a large enough insurance policy to cover what my attorney is coming for.

  • Thanks 1
Link to comment
Share on other sites

  • Administrator


30 minutes ago, KD3Y said:

Nah no tater guns for me.  I'm a DOT cyliner inspector and I've seen what an exploding pressurized vessel can do.   Instant release of compressed gas is no fun a'tall.  PVC isn't rated for pressurized gas.  My face is too beautiful to be messed up with scars from PVC shrapnel.  Heck, something like that would end the income from my part time job as a Chipendales model.

I watched a guy at the dive shop remove the valve on a scuba cyllinder that had only about 50 PSI left in it.   He thougth the cylinder was empty.  When that last thread let go as he was unscrewing it, the valve flew past his face, thru the sheetrock ceiling, thru the subfloor of the upstairs, and lodged in the second floor ceiling.   If that 1/2 lb of brass had hit his face you can pretty much guess what it would've done.  If DOT heard I was pressuriing PVC pipe with compressed gas, the DOT inspector would be over here with his ID badge and clipboard faster than a fat girl can eat a twinkie.

I've done enough handyman work with PVC to know it's brittle, it gets more brittle as it gasses off over the years, cold weather makes it even more brittle, glued joints often fail, and it's not a DOT approved container to hold pressurized gas.  Any container over 2" diameter and that holds over 12 PSI must be DOT approved and must be recertified every 5 years.   That's why all the tater guns you see on field day are home made.  No manufacturer can get DOT approval for a PVC bomb, and if they did, the lawyers would bankrupt them within a year.  

I've seen a few hams who offer the plans for sale to build your own.  Usually have some disclaimer about they aren't responsible for the results.  One word..."Strict liability".  You can disclaim negligence in the U.S. but you can't disclaim gross negligence. 

I know a lot of hams use them.  There's one in our CERT trailer that's probably 10 years old.  When it explodes, the club doesn't have a large enough insurance policy to cover what my attorney is coming for.

Thank you for this, I think this is very valuable information and definitely food for thought for all those who use PVC compressed launchers. I know that I for one will no longer use one, thank you.

Link to comment
Share on other sites

  • Ionosphere


I believe the topic has been discussed on eHam before   (https://www.eham.net/article/21921)   Theres some good points there and some of the comments are pure bull from people who have no idea what they are talking about.  PVC is engineered to hold water, which isn't compressable, not gas, which compresses and then rapidly expands.   Think of a water ballon.  When you fill a ballon with air then stick a needle to it, it pops violently...loud bang.  When you fill a balloon  with water and poke it with a needle, it just collapses, no boom.  Thats because gas compresses.  Liquid doesn't.  That's the physics of why a bottle jack the size of a coke bottle can lift 20 tons, we fill bottle jacks with oil, not air.  Household water pressure is normally 40 PSI so you can pressurize a PVC pipe with water in your house, and if the pipe breaks, it simply leaks, it doesn't explode and fly apart.  But if you pressurize that PVC pipe with 40 PSI of gas, when it breaks, it explodes and sends PVC fragments everywhere.  When we test our SCUBA cyliners, DOT requires us to pressurize the aluminum cylinders to 5,000 PSI and most steel cylinders to 7,000 PSI.   Sometimes they fail.  We test them by submerging them in a water-filled sealed steel vault, then pumping them full of water, up to 7,000 PSI and hold for several minutes.  When they fail DOT recertification and burst, nothing much happens...they don't explode (water doesn't compress).  There's a "thud" noise and the PSI gauge goes from 7,000PSI to 0 almost instantly.  If we filled them with air and they failed, they'd blow the whole buildng apart...gas expands violently.  There was a guy here in NC a few years ago who had stored his scuba cylinders full in his garage with 3,000 PSI of gas in them.  He was in his garage and knocked one over when he bumped it with his leg.  The resulting explosion killed him, his wife who was in the house lived but lost her legs, it blew the garage off the house, and the concusion shattered the windows in the next door neighbors houses.   Compressed gas is nothing to play with.

When I became club secretary (and webmaster) there was a PDF instruction for how to build a PVC "line launcher" on our website one of the members had drawn up years ago.  The first thing I did was remove it.  As soon as some Internet dude builds one and uses our clubs plans and blows his face off, our club wouldn't be able to afford the lawyer to defend the lawsuit.

Have you seen these soda machines at Bed, Bath, and Beyond?  The little cannister of nitrogen is about the size of a can of hairspray.  It's what puts the fizz in the soda you can make at home with this machine.  That cylinder has to be DOT approved, bear a DOT stamp, be requalified every 5 years by a DOT licensed tester, and it's classified as HazMat and illegal to refill.  That little can will literally blow your kitchen away if it fails. 

31673540860688p.jpg.068909813ef822ec1b793ea7a2d433dc.jpg

 


I mean, if I was in some emergency situation and my life depended on me using a tater gun to  get a resuce line to safety, sure, what would I have to lose in that scenario.  But my opinion is, ham radio isn't worth blowing my face off and spending $200,000 on plastic surgery if I survived just to get an antenna line over a tree limb.  When PVC filled with gas fails, it fails violently.

Link to comment
Share on other sites

  • Ionosphere


Just some background for any interested of how it works

Here's the vessel we use to test scuba cylinders.  The scuba cylinder goes into the blue vessel thats filled with water.  The 1-inch thick lid is bolted on, then the scuba cylinder is pressurized with water.  The pump can pressurize a cylinder up to 11,000 PSI but most scuba/oxygen cylinders DOT specs is 5,000 PSI to 7,500 PSI.   A steel cylinder, when pressurized with 7,000 PSI will swell a tiny bit from the pressure.  We measure on a set of gauges how much water the swelling displaces.  If that amount exceeds DOT specifications, it indicates the molecules in the metal have become too elastic, the cylinder fails DOT testing and is condemned, and isn't legal to ever use again.  If the swelling is within DOT specs, after the pressure is held inside the scuba cylinder for a DOT specified time, usually about 3 minutes, then the water is removed from the scuba cylinder and it returns to ambient pressure.  When the pressure inside the cylinder returns to ambient, the scuba cylinder is suppose to return back to it's normal size.   If the cylinder doesn't return to normal size, it indicates the molecules in the steel have become hard and brittle, and the cylinder fails DOT testing, is condemned, and cannot be used again.   Generally speaking, a pressurized cylinder is suppose to expand and return back to normal but within a specification.  It has to expand, but not too much.  Meaning the molecules in the metal are not too elastic but are neither too brittle.  Too elastic metal, a cylinder will simply blow apart from over expansion, and too brittle, the metal will crack under pressure and blow apart.

When we get a cylinder that looks "janky" and we think it may fail, we test that one last.  Reason is, as the pump is pumping the cylinder up to 7,000 PSI and the cylinder bursts, the pressure will go from several thousand PSI to zero instantly.  While the cylinder can't "explode" since it's filled with water not gas, the sudden drop in PSI will damage the impeller in the water pump and the pump will have to be rebuilt.  Rebuilding the pump takes about 4~6 hours and will put us behind for the day.   If we blown out the pump at the end of the day we can stay overnight to repair it and it doesn't cost us daytime.  Price is $25 per cylinder and we can test 5 in an hour, so 4~6 hours of downtime during the day would cost us $400~$700 of loss revenue for the day if we blew the pump early in the day.

We test Scuba cyinders, LP gas cylinders, medical oxygen cylinders for the hospitals/doctors in the area, and cylinders the fire department uses.   Here in the U.S. all cylinders have to be re-tested using this procedure every 5 years to ensure they are safe to use.   MCAS Cherry Point and Fort Bragg has their own facilities that they test their cylinders that the Marines/Navy uses.

This might interest you Jim.  I had the pleasure of seeing a cylilnder at Fort Bragg that the Special Operations guys use.  It was a titanium cylinder that could hold 10,000 PSI for special forces use.  It had NO markings on it at all.  While it is illegal in the U.S. to have a pressurized cylinder without DOT approval No and DOT specs stamped on it, the military has special exemption.  That way, if for some reason the cylinder had to be abandonned on a mission, it would have no markings on it to indicate what country/what military it came from.  Delta Force could abandon the cylinder, or if their guy was caught with it, it wouldn't compromise the mission.

Hydro.jpg.0a152de91d82c8b89800892c3a856c96.jpg

Hydro2.jpg.95314f8695ceb3a54ceac1ae3b3fd5b3.jpg

Link to comment
Share on other sites

  • Administrator


Now that is something I have seen done... 😎

I have also had the pleasure 🤔 of being 'inside' one of those, so to speak. We regularly trained inside altitude chambers like this one: https://www.etcaircrewtraining.com/altitude-chamber-military-training.html

It's always fun to see the newbies. "When the explosive decompression hits, make sure your pant belt is loose and let the 'gas' out." Of course half of them don't. Not a pretty sight.

  • Agree | Support 1
Link to comment
Share on other sites

  • Ionosphere


That's a cool link Jim.
The only experience I've had with airplanes is jumping out of them (usually covered in puke from the cherry sitting beside me).  Now that there ejection seat simulator, I wouldn't mind a ride on that.  

"If your parachute fails to open, immediately after contact with the ground, you will snap to the position of parade rest and give a loud and boisterous AIRBORNE!"
 ~ Fort Benning University of Gravity, 1988 (magna cum laude)  🙂

Link to comment
Share on other sites

Please sign in to comment

You will be able to leave a comment after signing in



Sign In Now

Ham Mega Pad (XXXL)

Ham Word Cloud Pad (XL)

Ham Codes, Signs, Words (Medium)

Ham Band Edges mousepad (Small)

Ham Alliance

Ham Alliance - Billboard - 970*250px

×
×
  • Create New...