Re: hanging antenna lines with a drone

Howard E. Mahran / WA1HEM

This is awesome Paul! Thank you for sharing this and for the detailed “how to”.

On May 29, 2020, at 1:16 PM, Paul Butzi (W7PFB) <w7pfb@...> wrote:

A number of folks have been eagerly awaiting a progress report on my efforts to hang antenna support lines using a drone.

This afternoon I successfully put a rope in an excellent placement over a 85 foot tall Douglas Fir.

Equipment is:
* DJI Mavic Pro Platinum drone
* payload release
* drop weight consisting of a tennis ball with 200 grams of pennies inside and a wire loop threaded through the ball.
* Teflon coated Spectra fishing line
* bright orange nylon twine


One end of a 1.5m long length of fishing line has a loop that is captured and then release by the payload release.  The other end is attached to the tennis ball.  The fishing line to be place over the tree is tied to the tennis ball as well.

Step 1:
fire up the drone and lift off, hover at about 6 feet.  With the drone hovering, place the loop in the line that goes to the tennis ball into the payload release and close the release, so that the tennis ball is now on the ground, a short line runs up to the payload release.  The fishing line to go over the tree goes to the spool held by your Trusty Assistant.

Step 2:
fly the drone up and on to the approach path to the tree you want the line to go over.  With the camera horizontal, fly up until the highest part of the target tree is now below the horizon on the camera, and note the altitude.  Ascend another 10-15 feet so you are sure the tennis ball will clear the tree as you fly over.  While you ascend your Trusty Assistant is letting the line pay out and keeping it from tangling in everything including the line itself.

Step 3: fly over the tree, taking care to pick a path that will place the fishing line trailing behind the tennis ball over the limb you want.  It helps if at this point the camera is pointed directly down.

Step 4: once the drone has passed over the tree and you’re directly above the spot you want the weight to hit when it’s dropped, make sure the target area is free of people, kittens, puppies, and other items of value.  If it’s clear, hit the button to release the tennis ball, and watch in rapt admiration as the ball drops neatly onto the exact spot you had selected.  it’s best to give Trusty Assistant a heads up just before you hit the release, so they can be prepared to let the line spool out freely as the ball drops.

Step 5:
Fly the drone back to a safe landing area, being careful to not hit the tree you just placed the line over.  Land the drone.

Step 6:
Go find the tennis ball, which will be surprisingly close to where it hit the ground.  Tie the bright orange nylon line to the fishing line loop, then detach the fishing line from the tennis ball.  Now go back, grab the other end of the fishing line, and have Trusty Assistant pay out the orange nylon twine as you reel in the fishing line, pulling the nylon twine over the tree.  At this point you’ll be able to spot the twine as it goes over the tree and you can assess how well it’s placed.

Step 7: once you have the nylon twine over the tree you can detach the fishing line from it, and bend on the rope you want as the final suspension rope.  Then you can go back to the other side, and use the nylon twine to pull the rope over.  Make sure the ends of the final rope cannot be lost or pulled up out of reach.

You’re done.  Next step is use the rope to hang your antenna.

Some observations:
* a light breeze doesn’t interfere with flying the drone but will affect how the fishing line hangs as you fly over the tree.  Doing all this during a still period would be a good plan.
* it’s far, far easier to put the line where you want it using a drone than it is doing it will an air cannon.  Much, much easier.
* With an air cannon it’s often a trick to find a good place to stand when you fire the shot, as often there are inconveniently placed objects line houses, trees, etc. in the way.  You don’t have that problem with the drone.
* if you don’t have a good takeoff/landing area for the drone, and a clear flight path to get the line over the tree, you would be stuck.
* the tree I put the ilne over was about 85 feet tall.  I put the line over a branch that is right at the top, a placement that’s hard to achieve with an air cannon.  The same quality placement could be done without increased difficulty and trees 150-200 feet high.  The altitude simply makes no difference.

Having worked out how to do all this I’d like to spread the knowledge far and wide and I’d like to get some practice by putting up lines for anyone who might want it done.  If you want lines put up, or know someone who does, contact me or pass on my contact info as appropriate.

-p W7PFB
73, Don’t forget to smile and have fun!

Howard Mahran
(425) 864-5104

Howard E. Mahran
(425) 864 - 5104

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