Those kites are not cheap so commiserations. 
Iāve used dynema fishing line on my balloons* and always seal knots with a drop of superglue - it works very well. This would be worth trying. It will mean having to cut the line off the insulator if you want to remove it.
*My balloons fall out of the air through natural causes, no missiles required - as far as I know! 
Iām exploring some simple solutions (probably in combination) to avoid losing another kite. They include:
And finally, never again fly the kite with woods down wind.
All knots reduce the strength of rope. A figure of 8 knot (with a stopper that can be a double fishermans) will retain more rope strength than most knots. This would avoid the need for glue, as it wonāt slip.
Hi Andy,
for my experiments with kite antennas I used my power sled with 6 sqm surface. This is for SOTA operations simply overdone but I had the kite at hand and so I gave it a try close to where I live.
The anchor I used and the line gave me sufficient confidence that both would hold the kite reliably:
Anchor Line Data Kite Line - lighter for size comparisonHowever, and to have the belt to the braces, I decided to follow the advice of DD7LP and kept the antenna separate from the kite line. The comprehensive description is - unfortunately - only in German but there are some pictures in it which speak for themselves. He employs a rubber cord between the kite and the antenna (" 1 m Gummiseil") for shock absorption. I think the bleeder box DD7LP shows in another picture on that page is also a good recommendation.
As a fly fisherman, I am used to slippery plastic lines and tried differend knots. With the kite line, although also plastic, a simple bowline hitch has proven to be reliable. This may be related to the āexcessiveā diameter of my specific line and not hold true for smaller diameters. At the end, this remains a trial and error game. 
All the very best for your futher trials,
73, Peter
Hello Peter,
I think your power sled kite has a bigger surface area than my SOTAbeams one. I found mine struggled to lift the ~20m of DX50 wire and the large 49:1 UnUn completely off the ground in a gentle breeze but was fine in moderate and fresh breezes.
Iāve flown the kite many times previously without an attached antenna where it had the provided ~0.5mm braided polyester flying cord terminated at the ground by the plastic cord reel (much the same as in your photo). So, Iām convinced the problem (of losing my kite) was not due to exceeding the breaking strain of the cord but rather the connection between the upper 15m of cord to the top of the antenna wire.
It seems to me (a novice in these things) that knots work best with rope and thick cords but are more likely to fail due to slippage on very thin cord. While Iām waiting for my replacement kite to arrive, I might do some tests hanging weights on loops of that cord for several difference knots.
In any case, on my next kite antenna operation Iāll have two flying cords from two ground stakes, the main one being with the antenna wire and a backup one with only the flying cord.
73 Andy
Andy, I think this is a brilliant idea! I used to tie very thin fishing line to hooks and was surprised how easily the line can slip through the knot if you make the slightest mistake. With your approach you will find a suitable knot for the chosen rope. 
Good look with your experiments!
73, Peter
Sorry to hear that Andy. Iāve had a couple of failures along the way. Itās very much ātrial & errorā. Donāt let it put you off.
It doesnāt really need a second ground stake, especially if you are using a fairly small kite or the winds are light. As long as the ground stake that you are using is secure & not likely to be pulled out of the ground then you only really need one.
Some of the Welsh summits where I have tried this have very soft & spongy groundā¦I wasnāt confident that one stake on itās own would hold (especially as I am using a bigger kite).
Having used my setup several times & now having the fortune of hindsight, using two stakes is probably overkill.
Iām not sure about this idea. My thinking is that it will make the rope less flexible, potentially make it brittle & could weaken it?
Even very thin cord should be fine if tied correctly. I use a bowline for all of my attachments using kite string.
I donāt tie knots in the antenna wire because it tends to weaken the wire. I tried several different types of antenna wire before settling on DX50 & on every occasion that it failed, the break was always at the knot. I think itās because the very tight kink caused by tying a knot in the wire weakens the metal strands of wire.
On this occasion, it looks like it was the string which wasnāt tied securely.
A couple of tips from my experience:-
Use a ābowlineā knot on all of your rope attachments. There are plenty of videos on YouTube & other instructional websites/blogs on the internet showing how to tie this knot if you donāt know how to do it. It might take you a while (and a bit of practise at home before heading to a SOTA summit) to get your head around how to tie it if you are not used to ropework, but itās worth learning. Thereās a reason why this knot is so popular amongst the maritime fraternity!
Donāt tie knots in your antenna wire (especially if you are relying on the antenna wire to take the load of the kite). Iāve found this to weaken it & eventually break the antenna wire. I attach my antenna wire directly to the dog bone insulator by going through the hole, wrapping the wire around the insulator 2-3 times & going back through the hole. This arrangement can sometimes slip which will cause the same issue that you had (with the wire slipping instead of the string), so I also secure it with electrical tape to prevent this. I use this arrangement at both ends of the antenna wire & it has never failed on me yet, although I always have the secondary ābackup lineā just in case. See photo below:-
Hi James,
Iām not disheartened even after many hours re-visiting the scene of the crime hoping to see the downed kite. Anyway, the replacement arrived at the weekend. Iām itching to try again but the wind is only 5-6mph today and next few days.
Having watched another YouTube video on kite antennas, Iām going to try a different method that does not involve making a join (via a knot) between the top end of the EFHW wire and the flying cord.
This time, the flying cord will not be modified. Iāve flown that SOTAbeams sled kite many times often in strong wind with no problems. Iāll attach a small carabiner holding the EFHWās dogbone insulator to the cord using a clove hitch.
The clove hitch (like other hitch knots) can be made in the middle of a rope/cord/string without access to the working ends. Whatās more the knot ādissolvesā once the carabiner is removed leaving the cord unaffected or weakened.
Hereās how I think launching works:
Launch the kite to desired height in the usual way and fix the plastic reel to the ground stake.
Lay the EFHW DX50 wire on the ground under the line of the kite cord.
Use a big carabiner to āwalk downā the bottom end of the kite cord until you reach the far end of the DX50 wire.
Make a clove hitch in the flying cord and attach the dogbone insulatorās carabiner, then release the cord to let it fly up.
Back at the ground stake, let a bit of flying cord off the reel until the DX50 wire is taut (so the EFHW is 40m resonant) and the flying cord slack.
Itās always a bit windier on the strand of the Kent estuary at the bottom of my road. If the tideās out, I might try launching the kite and EFHW and check the SWR with my AA-35 AA.
73 Andy
The launch and un-launch procedures went well. Pity about the estuary location, windy, but now my jacket, trousers, boots, kite, antenna, etc are covered in damp muddy sand.
After a while the DX50 wire and flying cord wrapped around each other about 20 times. It took me ages to separate them once on the ground. A second dog-tie ground stake a few feet from the first one would keep wire and cord apart.
The wind forecast for Lambrigg Fell on Tuesday afternoon is only 7mph so Iām hoping thatās enough to lift the 40m EFHW.
My first kite antenna SOTA today ā Lambrigg Fell G/LD-046
With very light wind at the base, I was doubtful whether the kite would pull strongly enough to lift the antenna. This time I used two dog-tie screw-in ground stakes about 1m apart, one for the flying cord and the other for the antenna. Once the EFHW was in the air, I slackened the flying cord a bit to let the DX50 antenna wire take the strain in order to keep it as taut as possible.
The wind wasnāt strong enough to keep it completely taut most of the time but ā as it turned out ā it was more than good enough. The 40m SSB sub-band was very busy and most stations were 5/9 on my FT857, and I had trouble finding a clear frequency.
With 45W SSB via an ATU, once started I had my biggest pileup to-date with as many as 5 chasers calling at once. I worked through 25 callers back-to-back, giving mostly 5/9 or 5/9+ reports and getting mostly 5/9ās. This is much better than when Iāve used EFHWs on my 6m and 8m poles and I assume the height of the EFHW with the kite made all the difference.
Like the trial on my local estuary sands, the antenna wire and flying cord had wrapped around each other at least 20 times, and that took ages to unravel. Next time, Iāll try putting the two ground stakes much further apart.
Despite the cold (~4C) it was very sunny and I was comfortable hunkered down in the heather. Yes, a kite antenna takes much more set-up and tear-down time than the usual antennas, but the increased performance was a joy. Not suitable for most SOTA summits but having ābroken the iceā Iām looking forward to trying it again, and next time on other bands and including CW.
You deserve some good pileups @G8CPZ given the time and effort you have put into making this a success.
Happy to have worked you today which must have been groundwave given our proximity.
Regards, Mark.
Well done Andy - as you hopefully heard your signal was significantly stronger here than usual for most LD activations - we were about 35 miles apart which is normally hopeless on 40m - in the dead zone but you were a good signal. Not sure if it was ground wave but the kite was working very well over this distance. I do have the sotabeams kite, but havenāt yet flown it with an antenna, and am going to re-read your experiences first! Looking forward to the next one! 73. Paul
Andy,
Great outcome Andy @G8CPZ ; The antenna worked extremely well.
You were 59 +20 without any fading throughout the activation - at least from my QTH - and you were the strongest station today on 40m. Good to see the image of the setup.
73, Robert
Thanks for the so so strong contact Andy Iām pleased to see all your effort was rewarded.
Stay safe and well. Best 73
A very successful activation, Andy. Well done and thanks for the contact. Far stronger than any recent activations and most chasers that I hear while waiting. Looking forwartd to the next one.
73,
Rod
What kite is it and where from?
SOTAbeams sled kite - see photo post #89 above.
Sorry I meant M0GQCās new kite.
I have a sotabeams one and am looking for recommendations for a bigger one.
