General control line discussion > Open Forum

ADVENTURES IN SPECTRA

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Dennis Adamisin:
If you follow the Stunt Hangar Chats (see “At the Bench”) hosted by Charles Carter on Mondays & Fridays, you have probably heard the ongoing discussions on how some of us have been proceeding with Spectra lines.  I will be switching everything over to Spectra, and wanted to share what I have learned, as well as reach out to others with who can share their experiences.

First, for background, here are the rated strengths of SS Cable we currently use.  Thank You to Brett Buck for posting this info in a thread in the Rules forum:

   Nominal Diameter (in.)    Const.                               Material Type                          Minimum Breaking Strength
           0.0120                     1 x 7                          Stainless Steel 302/304                                25 lbs
           0.0150                      1 x 7                          Stainless Steel 302/304                            40 lbs.
           0.0180                     1 x 7                          Stainless Steel 302/304                            55 lbs
           0.021                     1 x 7                          Stainless Steel 302/304                            80 lbs
           0.0240                     1 x 7                          Stainless Steel 302/304                          100 lbs

Spectra lines are not new to CL.  For several years the AMA General rules for Control Line included a chart suggesting sizes for Spectra lines.  However, Stunt event rules limited us to solid or SS Cables in specific minimum sizes.  Starting January 1, 2022, Stunt rules will allow any line material & construction which passes the 10G pull test.

The Combat guys have been using 100# Power Pro line not because of its strength, but because of its diameter; their thinking was that they wanted the same line drag for Spectra versus the normally mandated .018” cable.  The 1/2A Combat rules specified .012” cables, and the appropriate size Spectra line was 40# test.

The 1/2A flyers (except 1/2A Combat) have been using Spectra lines for a long time – it is the prohibitive choice, being way stronger than .008 cable, and far easier to handle.  I use 15# & 20# on my 1/2A's.

Of course, many of our forum members are also avid fishermen who hopefully have practical knowledge and experience with Spectra braids that I hope they can share here.

Spectra fiber is patented by Honeywell, there is another similar fiber called Dyneema that was patented in Europe. Power Pro was the “pioneer” introducing Spectra braided line for fisherman, and over the years there are several more brands available.  Braided lines are advertised as being the strongest, most durable and have “zero” stretch for maximum feel.  Spectra lines do not kink or curl like SS cable can, so they should be VERY user friendly for us.  Most producers have several product lines available, marketed to customers “hot buttons”; highest strength, smallest diameter, best castability – and of course price! Spectra is naturally bright white in color, but most lines come dyed in various colors.

How does it fly?:
Aside from the 1/2A’s, I first tried Suffix 832 65# x 60' on my Ringmaster a few years back. The 65# size (nominally .015”) is what is called out in the AMA General rules; but on a Ringer it is WAY overkill!  Before flying we pull tested to 40# to assure that my knots were secure.  In the first test flight I started off doing 5 inside loops then checked control response – no loss in feel due to lines binding together.  I did a second set of 5 then a third set, each time noting absolutely no loss in feel due to lines dragging on each other.  With 15 loops and no control loss I figured more loops were unnecessary. Later I used these same lines on an All-American Senior - after adding 1/2 oz inboard tip weight!  To those of you who have flown an AA Senior, the idea of inboard tip weight must seem really scarry!

Later I tied a set of Suffix 832 80# for my 55 oz Pathfinder to fly at Brodak the year they allowed Spectra.  Again, these lines are too big but on the PF, I took off 1/2 oz of tip weight and need to take more.
 
Although promising it was pointless to try Spectra on any of my PAMPA class airplanes because it could not be used in competition.  Then in late fall, after the rule passed, I flew my SV-11 (72 oz) back-to-back first with the .018” seven strand cables, then Power Pro 100# line. I noticed the Spectra lines had no discernable stretch or friction.  In fact, my pattern got much better because of the linearity of control I gained over cables – my round loops were finally round, I could go deeper into corners, and level flight was finally locked down.  The lack of line friction may be just what we have been looking for in electric!  Maybe that's why I noticed that here; might not have been as noticeable on a vibrating glow airplane?  Per my usual habit, I had some built-in tip weight, so I could only remove 1/4 oz from the tip weight box, so at the field I stuck on ½ oz weight to the inboard tip for a net ¾ oz reduction in tip weight.  Later, I weighed the outboard tip, then chopped it off to remove the weight I had built in plus the ½ oz stuck to the inboard side.  Finished by installing 3/4 oz in the weight box to achieve the same weight measured at the tip. I think I could have pulled pull another 1/4 oz., but the weather turned for the worse and I have not been able to try it again.  Next time out I will be switching to smaller/lighter Maxcuatro 80# so it is a foregone conclusion that I can remove more tip weight.  In fact, I will keep pulling weight out until it goes too far then put some back.

Given that test I decided to commit to Power Pro Maxcuatro 80# (.016" dia) in place of .018” cable.  Power Pro’s “Maxcuatro” brand is their tightest woven and smallest diameter line for a given rating.  It is conceivable that 65# line would be adequate but seems like that would hit diminishing returns.  Similar logic led me to look at 50# in place of .015" cable. Maxcuatro 50# is .012", thus yielding 20% smaller line than the cable that is also 25% stronger and lighter - not a bad trade!  My main criteria will be stretch, I am not worried (too much!) about strength.

Lighter line weight and less tip weight for Spectra is a given, smaller line diameters will show up as less drag, possibly a lower RPM setting, and lower battery usage.  Will less line drag affect lead-out position too?  Seems like it should, but that will be easy enough to find out

Last week I tied 8 sets of lines including 4 sets for flying buddies.  I tied Maxcuatro, 40# Power Pro "Super Slick 8", Suffix 832 (65# & 80#), and FINS XS 50# because it is slippery and because I liked the colors! 
* The Maxcuatro 80# and Power Pro 40# were easy to handle & tie.  I am awaiting a spool of green Maxcuatro 50# to go with my yellow so I can tie dual color sets (green line up!)
* The Suffix 832 (65# & 80#) were the easiest to handle.  It has a real nice feel to it. These lines are larger in diameter than the Maxcuatro, about the same diameter as regular Power Pro.
* Did not like handling the FINS XS.  I do not think I will be using this long term.
* I tied 3 sets with eyelets using the Palomar knot and 5 sets with Modified Surgeon's knot that the Combat guys prefer.  The ones with eyelets should be easier to use with hardpoint handles.
* Crochet needle (with the hook on the end) & magnifiers HELP!
* Mine are close but NOT exact in length like the Tom Morris & Okie Air cables I have been buying.
* Instead of eyelets I think I am going to try small solid (NOT split!) rings and tie to those when not using the loop.
* I wrote the material, test, and length on each reel to keep them all straight.

A couple Links & Attachments:
* Do a SEARCH on Spectra posts SH, there are a lot of good post going way back to before when Combat adopted the lines.
* Dennis Toth found/posted a table of fishing line sizes on SH in the Combat section. I downloaded it and attached it below
* There are lots of vids on YouTube showing how to tie braid for fishing lines.  If you want to keep using eyelets on the line ends, it looks like the best knots for our use are the Uni tied with the line doubled, and the Palomar which naturally is tied with a doubled line. The trouble with these knots is that they are difficult to tie at an exact location.  I think our fishing buddies can help us here!  Ken Culbertson posted a sketch of a tying fixture here (see post #9) that looks like it could help: https://stunthanger.com/smf/combat/spectra-lines-braided-or-solid/
* Michael Stinson has updated & expanded his YouTube video again as of 6-January on tying the Modified Surgeons knot, that the Combat guys have settled on.  He also added a couple of do's & don'ts, including a really slick idea for keeping the loops in place on scissors style clips:





That is just about everything I know on the subject, pending the new flying season!  I seriously hope others will post their experiences and any guidelines they have on how to select and make up Spectra lines

Dennis Nunes:
Good morning,

Great information Denny! There was something that was brought up during the Hangout that caught my attention. It was mentioned that the color lines tend to fade with time due to UV rays, which is no big deal. But I don't recall if anything was mentioned if this affects the integrity of lines.

My main concern is how these lines will hold up when temperatures reach the 90-100 degrees range on an asphalt or concrete surface? These surfaces can get extremely hot in the summertime. I've been in situations where my lines laid in the sun for hours. Any reasons to be concerned or will we learn the hard way through trial and error?

I know that the combat guys have been using these lines for some time now, but they fly on grass areas which don't get nearly as hot as asphalt or concrete surfaces. Should we get into the habit of replacing these lines every couple of years?


Stay safe,
Dennis

Dennis Adamisin:
Hello Dennis N!

From what I can tell Spectra is considered UV resistant, especially when coated.  I found a reference to an accelerated UV test standard which showed Dyneema (considered by most sources to be equivalent to Spectra) to have excellent UV resistance.  Spectra is used in sailcloth, which would seem to be a high-UV application.

Melting point is 300F degrees, that's even hotter than Muncie in July!

Some fosherman claim the see line fade starting on the first day, sounds like it happens faster in sailt water than in fresh, does not seem to affect anything else tho.  Spectra is naturally a bright white, the dye is added on and not a factor of the forming of the Spectra material.

One of the kite line sites says Spectra is 40% stronger than Kevlar for the same weight.  So probably no surprise that other uses for Spectra cloth include ballistics clothing and cut proof gloves.


Here's a chart on Dyneema UV performance:
https://assets.ctfassets.net/q6qgec8ud5tq/2F2XxEQuIxhQnlD9435Ddz/7413e91d3f25447a8f000f94f06aea7d/CIS_YA102_Ultraviolet_exposure_of_UHMWPE_fiber_from_DSM_Dyneema.pdf

Tom Luciano:
Great thread Dennis!!!

Below is a quote from back in '07 it might be worth reviewing as Phil C was answering questions.

742
Open Forum / Re: Rules Proposal for Spectra(tm) Lines
« on: August 17, 2007, 12:28:58 PM »
Hey Guys,
   As I was reading along, my first thought was the effects of sunlight on the spectra lines, and Pat did address that. Then I thought what about a set of lines that has been sitting on the tarmac for 5 minutes or so when your getting ready for a flight. Obviously on a 95 degree day sun gleaming those lines could get pretty hot. Is there any research on these materials possibly softening and becoming weak or even stretching in this case.

Tom
https://stunthanger.com/smf/open-forum/rules-proposal-for-spectra(tm)-lines/msg51033/#msg51033

Perry Rose:
If the line is insulated you can use a granny knot. 30# fly line backing is used to insulate the line.

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