Wire vs Cable

Forget the rules for a moment. From a flyability, durability, safety, and ease of use point of view what would you fly (length, dia, type) on an old Plain Jane Fox .35 Flite Streak size plane? Up it a notch, and the same question for Leonard Stunt .35 on a Tananger size plane?
An old friend from 25 years ago and I have spent several hours on the phone in the past weeks. One of the subjects we always agreed on is that light is good (small dia) and safe, and adds to the performance of anything on the end. He thinks wire is coming back to backyard and perhaps competitive flying. His logic is that there is more variability in cable than in wire, which is drawn to an absolute diameter. Every set of wire is like every other set. Agree?
What about elasticity? Does cable feel spongier to you? Would you choose a larger diameter cable than if you were flying the same plane on wire?

Thanks -- LF

If you are talking solids, don't. Following AMA guidelines, you can fly with .012 solids instead of .015 stranded with the .35 size planes and you can fly with .014 solids instead of .018 stranded with the over .040 size engines. It sounds like a winner, but... Solids get sticky in humid air. Solids get very sticky if they get dirty. Solids can lock up if they get small bends in them, or too many turns in them. They are much more difficult to take care of. There isn't a lot of difference in weight between the solids and the stranded (There is air between the strands), but there is a little more drag with the stranded. Still, we have gone to .018 stranded even with the .35 size ships. Let's face it, we've got pull and the .018 stranded lines give an added margin of safety. Matt has often said that his .35 powered plane pulls a lot harder in the wind than the AMA pull test for these size ships. With that pull, drag is not that much of a factor. Although a lot of the top flyers had gone to solids just so they could use the smaller diameter lines, a number of them have gone back to the stranded lines simply because of the "sticky" factor and the extreme care needed in maintaining them. You can use the .015 stranded, but I sure would not recommend solids for the average flyer.

Thanks on several levels --

1. I couldn't remember the correct terminology. "Solid" and "Stranded" not "Wire" and "Cable". Got it, and you didn't make fun of me!

2. Yeah, I remember the problems you mentioned with solids. We spent a lot of time wiping them down. But flying rat and combat, lines were disposable items. Stranded makes more sense for "one man in a circle at a time" flying. More often than not, they were discarded for a kink after not too many flights.

3. Elongation / elasticity obviously is not a factor if those are Matt's lines of choice.

A couple of follow-ups if you don't mind, then I will leave you alone for a while. . .

Solids were easy to build -- two pre-formed loops around the eyelet, twist the ends together, wrap with copper, and sweat solder. Stranded was a little more difficult because you couldn't pre-form the loops. Is it just one loop around the eyelet with stranded and all else the same? OK?

Any data on the tensile strength of the raw stranded? I assume even .015 exceeds the pull test numbers by a large margin. What is your secret reason for .018? I am sure it is quite logical.

Thanks again,

Why should I make fun of You? I know what you meant. I just used the terms we normally use. Yours worked, too.

Cost difference between .015 and .018 size lines is negligible. There is a difference in drag which you will notice if you don't have a lot of power or pull. Thus, on a Fox 35 or an OS 20FP you are probably better off sticking with the .015 size. But we set our planes up for tension. We get a lot of power out of our engines, use large props for more thrust and equal panel wings which also set up for more tension. We want the confidence of knowing that when flying overhead in the wind the plane will stay up there. And with that extra tension, the use of .018 size lines doesn't make that much difference. (If there is a lot of bow in the lines which will happen if you have lower tension, you are going to get more "wiggle-waggle"--hinging--in the corners, for instance. That you will notice.)

The .015 size lines will stretch a little more, but it is really not that noticable, and a lot of the top flyers, even, stick with cables for the above named reasons.

Now, on wrapping the lines. It is best to double loop around the eyelets. It keeps them more secure. Then wrap down to about 5/8 of an inch, wrap back, and twist. Don't solder, glue, or anything else as this could cause a hard point which could lead to stress and eventually failure. We have had commercially crimped lines fail at the crimp for this very reason, which is why we do not like crimped lines--even when "properly" terminated. Fortunately, we have never had a crash due to broken lines. Every failure caused by crimps has resulted in one or two strands letting loose, and we immediately quit using those lines when that happened. So, in answer to your question of how much pull the lines can take, there is some margin of safety. But not a lot. Maybe somebody else can come up with those figures. I don't have them immediately at hand. But if we did the same pull test on one line only, we would have very little margin for error. Thus you should never set up your plane where it is even possible to "hang" it on one line. If that one line lets go, the other will let go, too.

>Now, on wrapping the lines.
>It is best to double
>loop around the eyelets.
>It keeps them more secure.
> Then wrap down to
>about 5/8 of an inch,
>wrap back, and twist.
>Don't solder, glue, or anything
>else as this could cause
>a hard point which could
>lead to stress and eventually
>failure. We have had
>commercially crimped lines fail at
>the crimp for this very
>reason, which is why we
>do not like crimped lines--even
>when "properly" terminated. Fortunately,
>we have never had a
>crash due to broken lines.
> Every failure caused by
>crimps has resulted in one
>or two strands letting loose,
>and we immediately quit using
>those lines when that happened.

I forgot about those commercially crimped lines, and I agree. But I tell you, I just have to solder them! Honest, I will watch for breakage of one strand and discard lines at the first sign of failure.

Your experience and technical knowledge tells me I am just paranoid. OK, so I am paranoid. I would have nightmares every night flying on stranded wires just twisted together at the ends. I can picture this movie scene in my nightmare where it starts to unravel, and a zoom-in on the twist going "tink - tink - tink" as it starts to go. I doubt neither your knowledge nor experience. I am going to solder them just so I can sleep better. Don't bother explaining to me why I am wrong. I am sure I am wrong. Solder is my binky.

I STRONGLY recommend wrap only on cables. DO NOT solder them. Most cables are of stainless steel and require a flux of some sort to get solder flow and adhesion. The flux flows down into and between the strands of the cable and is almost impossible to get either neutralized or cleaned out completely. The flux then just stays there slowly corroding the strands of the cable until they become weak enough that either the pull by the plane or pull imposed by the pull test causes breakage.
Properly wrapped around the eyelet (two turns), then wrapped with soft copper wire (serving wire) down to 5/8ths inch from the eyelet and then folding the cable back toward the eyelet and wrapping the serving wire back up to the eyelet willprovide a tie that will be stronger than any soldered end and will never slip.
The proper method can be found on the AMA web pages under competition rules and can be down loaded page by page so you do not have to copy the entire document.
Bigiron

Reconsidering all the information above, perhaps I was mista . . .

Naw, that's not what I want to say.

My picture was that copper wire was why soldering . . .

Naw, that's not what I want to say.

Wr... Wron... Er, Uh, the word I am searching for is WRONG. My memory flashed back when Bigiron spoke. I remember now. Heck, I have done it! I don't need the AMA pages.

Leonard, do me a favor and kill this whole thread. Or do I have to spend weeks and weeks trying to commit Hari-Kari with a piece of .012 "wire" to save the honor of my family?

Larry,

I don't believe that .012" wire complies with the safety requirements in the Hara Kiri Rules Manual. In order to participate in H.K. contests, one must use a minimum of .025" wire, and .040 is the recommended size. And, of course, cable (Stranded wire) has been banned from this activity for years, unless, of course, one enters the garrote competition.

> But we set our
>planes up for tension.
>We get a lot of
>power out of our engines,
>use large props for more
>thrust and equal panel wings
>which also set up for
>more tension. We want
>the confidence of knowing that
>when flying overhead in the
>wind the plane will stay
>up there. And with
>that extra tension, the use
>of .018 size lines doesn't
>make that much difference.
>(If there is a lot
>of bow in the lines
>which will happen if you
>have lower tension, you are
>going to get more "wiggle-waggle"--hinging--in
>the corners, for instance.
>That you will notice.)
>
>The .015 size lines will stretch
>a little more, but it
>is really not that noticable,
>and a lot of the
>top flyers, even, stick with
>cables for the above named
>reasons.

I agree, if cables are good enough for Ted Fancher they're good enough for the rest of us. For everyday flying, there is no good reason to use solid.

It's also more than a matter of line tension and safety margin. .015 stranded lines are plenty strong enough for most planes up to 65 sized planes, as is seen every two years at the FAI trials. Safety really isn't an issue if the lines are in good shape. If .018s will stand up to the B-17, .015's will hold anything normal.

But when I cleverly started using .015 lines on my PA61 airplane getting ready for the team trials last year, I was amazed at how hard the airplane was to control. The .015 lines felt like rubber bands! It wasn't a line tension issue - it was that the stretchiness of the lines had a very significant effect on the control response. It was almost as much difference as going from a Baron-style handle to a solid-contact handle.

Long story short, I use .018s on even 40-sized planes and in FAI contests. The pinpoint control possible greatly outweighs the issue of drag, and I think the line whip is probably less of a problem than the filtering of control inputs.

Note that .014 solid is even better in this regard, and David uses these. Until it rains that is, then he has to switch to cables, lots of times without practice. But to me and most others, it's just not worth the trouble.