Questions on leadouts and materials

[jim gilmore]

Ok, first off nothing I build is bigger than the .10 thundertiger I have so no fears with large sizes I'd need.
My first thought is why do whe used braided steel leadout ? And why is the size bigger than the actual line size?
I'm wondering if there is a way to use the newer braided fishing line.
 I'm wondering if we could use some larger size of braided fishing line possible with a terminal tackle clip on both ends.
Would this work and would 50# be large enough?
What do you all think ?

[john e. holliday]

I have not used the new fishing lines myself, but, read where some people have used it.  Do a search on Spiderwire.  Also I would not use it on any thing larger than a 1/2A.  The reason I use cable is that it is enclosed in the wing most of the time.  Does not kink at leadout like solid wire does.  Also I beleive the reason for a larger size is that it is handle more.  Well that is my reason.    DOC Holliday

[Scott Hartford]

I would have to wonder about abrasion at the leadout guides with the fishing line. I don't think it holds up well to this and would be a pain to change out after the fact if you caught it wearing too much. The steel does not have to be braided, as many use solid music wire leadouts.

[minnesotamodeler]

WARNING!!!   I used Spiderwire for leadouts in my first few .020-size airplanes, there is no strength issue but they are wearing rapidly at the leadout guide tubes, appearing more frayed as time goes by.  I'm considering cutting into my favorite plane (only 2 yrs. old, not that many flights on it) and replacing the LOs with 7-strand before It Is Too Late...  .012 would be plenty, .008 even.  My recommendation: Do not use anything other than steel for leadouts. No matter the size.

[Geoff Goodworth]

Jim, don't do it.

The lead outs are thicker because we expect them to last much longer. The Kevlar fishing line is strong enough but the knots are an issue. I have heard reports that even the best knots have been known to slip.

We can cope with that in flying lines—within reason— but leadouts are a totally different story. I used 60 lb Spiderwire as flying lines for a Brodak Shoestring and, not trusting my knots, put a drop of Cya on the knots. I managed about six, maybe eight flights and one day, the lines caught some grass at take-off and the model turned in on me. I braced and waited with arms loose so I could absorb the tug that I expected but the tug on the lines never came. The model flew off the lines and destroyed itself. The engine was brand new—just run in—when I fitted it in that model but it wouldn't turn over after the crash.  The crank survived but the liner was knocked out of round. A new piston and cylinder and the engine is as good as new.

Get some 60 lb braided leader wire from the local tackle shop and use that for the leadouts. If you are a fisherman or were a boy scout and are confident about your knots, use Kevlar for flying lines by all means but not leadouts.

Cheers, Geoff

[phil c]

60 lb test Spectra only has about 30lb breaking strength, depending on the knot you use.  You need 80 lb. test minimum on a 35 powered plane.  Use a bimini knot, or a palomar knot for a line clip.  The bimini is better, but takes longer to tie.  These knots get the breaking strength up to 60-80% of the rated strength.

The other thing, Spiderwire had a Spectra line available called Fusion, where it was formed in to one solid strand.  This stuff was adequately strong, but extremely knot sensitive.  You have to use the braided line.

If you want some really fussy lines, get the 4 strand, brass-plated stuff used for F2D.  It is extremely strong and tough, but very sensitive to fatigue.  You can't run the lines to the bellcrank like many fliers do because the lines will break after 4-5 flights.  They also literally melt away from rust if they get the slightest bit wet and you don't soak them immediately in WD-40 or kerosene.  Takes about 2 days to rust through at the termination, slightly longer and they will rust anywhere.

After 50 yrs. most of the bugs have been worked out for stainless steel lines.

[Jim Thomerson]

I've used regular 50 lb test fishing line for sport 1/2a leadouts and no problem.  Some use 018 control line.  I've started using nylon coated leader material I bought at a fishing shop in florida.  Diferent strengths for different airplanes. 

[jim gilmore]

I have a for different ideas for using the spider wire as a leadout material and I highly doubt that the knots I've been considering are an issue strength wise and I may have a way to prevent abrision issues. Also since I'm talking about A sized planes as an absolute max and my planes should not weigh over  16 ounces I'd need about 10 lbs max for my minimun. Even if the breaking strength were to reduced by 50% that leaves me safe with 30 lb test. But I'd still opt for 50 or 60 lb test. the other two things I might consider is to use home made piano wire connections at the bellcrank and the tip with spider wire being used to connect the lengths in between which would eliminate any  abrasion issue.  Later I'll post a link to the knots I'm considering as the actual connections in this method.

[jim gilmore]

here is one example of a knot to try as a in wing leadout made from braided fishing line. I think if the ends can be made from say .027 or .032 music wire this may be functional. I will try this and run some tests soon.
http://www.marinews.com/Common-Snell-352.php