Now don't misunderstand, I am no expert and I've been seeking information in the same genre because of my hopes in being a part of the Cox Engine Forum's 1/2A Profile Scale  Event.  So I posted my question and received a couple of very helpful and enlightening responses.  If you don't mind, I'd like to share this one with you and maybe it will help you as it did me:

Re: CEF Profile Scale Speed 2015!
Post  Ken Cook Yesterday at 10:36 pm
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If your going for speed, solids are your best bet due to being able to use a thinner diameter.  Problem is that unless you know where to locate them, they're increasingly becoming harder to find. The other problem with solids is that they're a pain in the rear. One kink, throw them out. If they get wet, they stick and they're a maintenance headache.

That being said, .008's are EXTREMELY fragile and they work well in terms of lower drag over Dacron with a very positive feel. Once someone steps on them or even running your fingers through them to separate them can lead to a kink and they become anyone's guess as to when they will break. They generally fail at the terminations on one end or the other due to flexing. I don't wrap the ends of .008's rather I swage them. I always chamfer the ends of the crimp tubes on both ends prior to doing so. I also provide a length of heat shrink tubing about 1 1/4" long from the line to the eyelet to prevent flexing. This increases the life expectancy X 3.

.012 lines are my go to lines. They're twice as durable as .008's and they handle even the most powerful 1/2A's made to date. They're also less draggy than synthetic fishing lines.  They can take a lot more abuse in terms of handling and unwrapping when used for stunt and they just have a lot more durability over the .008's. For the small amount of drag penalty over the .008's, it makes using the .008's inconceivable.

Using Spiderwire or similar offers a huge benefit if you or others can't seem to keep their feet off of your lines. These lines TIED properly will take the abuse. However, if speed is your concern, they're going to be very draggy and they will increasingly get worse and worse due to oil soaking with successive flights. I personally use 30lb due to flying 1/2A combat. This is for high powered 1/2A engines far superior to a TD. If the line passes through a leadout guide of any sort it will chafe the line by fraying it in a very short time. My leadout guides use a ceramic guide from the top guide of a fishing rod. I use one hole for both lines on much of my equipment.  I can see 15lb test being fine for Cox equipment but it really depends on how well you tie that knot. Adding adhesive or glue to the knot only weakens it further and causes it to fail.

No problemo!  I'd been using 80# Spiderwire for my fishing reel and have been really pleased .  Well, I opted to try some for my Fox.35 Ringmaster and my OS .40 FP Banshee when my .018" stranded lines got too kinked up to trust .  Man, I've been really pleased .  I've used these lines for just over a year now and I s'pose I've got at least 200 flights on them and I honestly can't see or find any signs of fraying and I've looked .  As a result, a few days ago, as a test, I made up a set of 35' lines using the same 80# Spiderwire for my 1/2A's  .  Now, I know I need to use something lighter as there was a tremendous bow/lag in the lines .  Oh, the planes flew all right but it was seeing the drag of the lines and probably had there been any significant breeze I s'pose the planes would have turned into me .  I read where one fellow was using some 15# line for his 1/2A's and I'm thinking I may give it a try because while the 80# works great for the bigger engines it ain't all that for the 1/2A's!!     Good luck!!

Jim

I have not used that exact product.  I like Power Pro in Hi-Viz yellow.

go to modelaircraft.org
under competition and events => rules & regulations
find CL general

It recommends 20# minimum, and a doubled 5 turn uni-knot.  The instructions are there as a diagram, with a video link.  (Doubled in this case means take the end 4+ inches of line, and fold it over on itself.  Tie the knot in the 2-strand section treating the pair as a single strand)

In my experience, tie one end to a eyelet(or a line clip) Run out the desired length plus some and cut it off.  Tie one end of line 2 to an eyelet (or a line clip) Run off the desired length plus some.  Mark both lines together.  The mark has to end up inside the knot.  Use an eyelet or line clip for the second end.

Phil

This thread propmpted me to do something I've been maning to for a while now.  I just looked up the diameters for the Power Pro braided line.  Here is the manufacturers website listing the diameters for the different weights of Power Pro:

http://www.powerpro.com/publish/content/global_fish/en/us/power_pro_v2/info/powerpro_superline.html

Mark

Well, I am now able to say confidently that it does work.  I am just flying by myself for fun.  I have it currently on a Man-Win trainer and it does what it is supposed to do.  I will keep monitoring it but so far it appears to be ok.  I mainly get to only fly out at the cottage on the weekends, but due to work, I have not made it out much, and after work, I have a lot of other jobs to do as priority, but I am making serious headway so I can free up some flying time.

So why are you hitting your head on the wall over this....
If I have read the history of "the new super lines " correct.
Spectra was the first one created and the new formula is Micro Dyneema.
Which means these new lines are the New formula in the spectra material Group.....
All Gel Spun Lines....
Or am I missing something here ?

Well here is the problem as I see it......
Spectra seems to be a term Like saying Cotton.

Power pro says " We begin with ultra-strong braided Spectra Fiber,, then use Enhanced Body Technology to create an incredibly round, smooth, and sensitive line. PowerPro outperforms monofilament lines in any situation and leaves other superlines in the dust"

So is power pro 100% spectra

I haven't seen many lines saying 100% Spectra.
Spectra is 100% a product produced by HONEYWELL. And I do not see Honeywell selling to anybody but companies.

Just saying that Dacron lines are available from Cox International and maybe Ex Model Engines. It is the original Cox product and it really is stretchy! I use it for nostalgia and realise that anything is better!

Andrew.