Leadouts: Solid vs. Cable

Apparently most experts use solid control lines for reasons of improved feel and response, but what about leadouts? There have been recent discussions on the boards about attaching leadouts to bellcranks, and it appears from what was said that many builders use cable for leadouts. This leads me to question what sport or expert flyers prefer, and why.

I live near the ocean (next to LAX) so I have used cable leadouts because of my assumption that corrosion will be less likely to lead to a total failure than for a single wire. Now that I keep hearing about handle cable failures I may rethink my assumption about cable longevity.

Solid leadouts, at least the way I install them, are far easier to attach to the bellcrank and are much less likely to have internal interference problems with the wing structure, so if it wasn't for my paranoia about long term corrosion of a single wire I would prefer solids.

So...I'd like to increase my knowledge database by getting a few experienced opinions about the problems/benefits of each type. I am especially interested in hearing about leadout failures and causes.

I prefer solids for the same reasons you already mentioned. The only argument I have ever heard against solids is bending at the wing tip when walking through a door. I have not had a problem but the potential is there.

After many years of advocating solid leadouts, Windy apparently switched back to braided ones after the loss of a couple of airplanes.

I never cared much for solid leadouts myself, because they have more potential to vibrate, and are more susceptible to damage - one kink and you are out of business. (I know, I know, under tension in flight, they don't vibrate much..)

Since they are inside the wing, I see no real issues about aerodynamic drag (or are there?). Stretch perhaps? .027" or larger braided wire doesn't stretch that much.

I've heard tales of braided wire "sawing" through bellcranks and leadout guide tubes, but when I applied my baloney filter, very little came out the other side.

Of course, any leadout can fail if the terminations aren't done properly. And you can't be using .018" or smaller CL flying lines for leadouts if you expect them to last.

One small advantage I personally like for braided leadouts is that they are flexible and can be looped back and stored inside the wing until the model finishing is complete. Then they are easily fished out and an end termination added.

As for terminations, crimps with a proper tool are probably the best, but without the proper tool, it is very easy to make horrible ones that quickly cut the wire. For workable "low tech", the old soft copper wire wrapping, covered with thick CA or epoxy are possibly the best.

I'd mention also that I found a source for usable leadout wire at the local auto paint shop - it's called "windshield wire", and is used to pull rubber gaskets around windshields. Under $8 for many many yards, and it is plenty strong, if slightly stiffer. (Its diameter seems smaller than .027"..) The stuff I got was gold colored and solderable (I'm not advocating soldered ends, however).

I use braided cable now, but I've used solids. Usually 032. Truth is, I just don't like the rattle when you carry the plane around or when it's sitting in the rack in the car. Stupid probably.

I use the horseshoe end bellcrank and so the braided cable is wrapped just like control lines and a screw goes through the eyelet. Pretty solid and very easy.

Now, If I can just adapt the idea to my new gear driven, linear bellcrank... <grin>

I've used nothing but cable for the last 30 years and have never had a failure. I normally use the Sullivan C-D cable in anything over a 40 sized plane. I've heard stories of cable sawing through bellcranks but have never seen it myself. Seems like you'd have to have a lot of play and movement for such a thing to happen. I use a piece of brass or copper tubing that has just slightly larger I.D. than the cable and is bent into a U shape for the bellcrank mounting and then wrap the cable just like line ends. The tip end is wrapped around a brass eyelet and wrapped the same way.
The problem with solids is that if any bends are not properly radiused there is a chance of failure of the wire itself. Just ask Windy and a few others about it. Oh yes, I forgot to mention that I always pull test the Sullivan cable before installation as Paul Walker and I each had a piece of defective cable a few years back. PW always uses cable for his models.

I know that Winfred had a failure right in the middle of a run.... the area had never been bent.... I also know that some of the commercially available hobby wire has been looked at through a microscope and that there are unusual "voids" and what seems like slag.... poor quality. I had one break in the middle, but I'm pretty hamfisted and wouldn't measure much by that one.

Windy's through bolted bellcranks with braided leadouts make sense all the way around...

See Ya

There are problems with both kinds of leadout wires.
I have had solids break during a pull test due to the loop at the line being bent too sharply. I have also had solids break while trying to make a loop in the solid wire. I have also had the bell crank saw through Perfect Brand lead out wire. The best I think is to install brass bushings in the bell crank and loop the stranded leadout wire through it, then wrap the wire ends and then solder the stranded wire where it goes through the brass bushing. Grease the bushing liberally.I have not had a failure with this method.

I think cable is the preferred leadout of choice for most experts today. Especially on large models of the piped 40 persuasion and up and any 60 powered model. Cable is very forgiving provided it is properly bushed at the bellcrank and wire wrapped as per AMA standard. I have not for several years used any adhesives on the wrap. However, a light coat of thinned epoxy or simply CA on the wire wraps only after pulling the fastened cable to stretch the cable and check it for weaknesses and tighten the wrap as far as it will go.

I think Matt Neuman still uses solid LO but of a slightly larger diameter than .032. possibly. Matts terminations are bent perfectly round as I recall from this past weekend, but there is always the chance of bending them. My shop area is pretty cramped and I try always be careful when handling my models but I take no chances and use cable always.

Several years ago I watched Bob Hunt lose a brand new Saturn to a solid LO failure at the Nats. Maybe 50 to 100 flights on it so fatigue should not have been a factor quite yet. I do believe he was fairly heart broken as the top five flyoff was the
next morning.

CABLE.....It's better. The wire today sucks. Unless you get good music wire from a music shop. I do.

Scott(high c)Riese

>
>I think Matt Neuman still uses solid LO
>but of a slightly larger diameter than .032.
>possibly. Matts terminations are bent
>perfectly round as I recall from this past
>weekend, but there is always the chance
>of bending them. My shop area is pretty
>cramped and I try always be careful
>when handling my models but I take no
>chances and use cable always.

We had been using .031 leadouts with nary a failure, but on the last couple ships Matt has gone to .045. Yes, it weighs a little more, but ... it is not going to break.

>
>Several years ago I watched Bob Hunt
>lose a brand new Saturn to a solid LO
>failure at the Nats. Maybe 50 to 100
>flights on it so fatigue should not
>have been a factor quite yet. I do
>believe he was fairly heart broken as
>the top five flyoff was the next morning.

Bob was using .025 solid leadouts. These are way too light for that size ship. The problem is not in the strength of the wire itself (.014 solids work fine for flying lines -- strength-wise). The problem is that the wire will flex at the ends, and anything that flexes will eventually break. We have had a strand or two break on crimped ends and don't use crimps for that reason. With flying lines you can examine them before every flight and discard (or repair the ends) if there is a failure. You can't see what is going on in the inside of your wing. Thus, whichever way you go, make sure the ends are terminated properly, and, if in doubt, use stronger wire (or cable) if you must make a choice. I would rather pay a slight weight penalty than take the chance that there will be a failure in this key component.

Sooner or later, I'm banging the solids against some part of the old Taurus wagon, and they bend. Other than that, I haven't had any particular problems.

On a big plane, Windys cut bellcrank and cable system is the prefered way to go. But for those of us that like the simplicity of solids, .032 fishing leader wire is available where ever heavy tackle is sold. It is some form of soft stainless that does not kink when bent, and does not corrode, or dis-color, (made for salt water). It comes rolled up in a plasic bag. So far, 8 years in my 60 ship, with no problems. (There is not enough wood to knock on after making that statement!)Jim D.

From a posting on one of the boards a couple of years ago it was mentioned that all music wire is not the same. Many hobby shops carry less than top grade because of costs. At that time, it was mentioned that the wire distributed by Brodak was top grade. I assume it still is.
I guess the bottom line is that you may want to check the source of the music wire you are buying. I'm not implying that John Brodak's wire is the ONLY top grade, I'm just saying make sure what you are buying IS top grade.
Good luck and NO BREAKS
George

> From a posting on one of the boards a couple
>of years ago it was mentioned that all music
>wire is not the same. Many hobby shops carry
>less than top grade because of costs. At that
>time, it was mentioned that the wire
?distributed by Brodak was top grade.
>I assume it still is.
>
>I guess the bottom line is that you may want
>to check the source of the music wire you
>are buying. I'm not implying that John
>Brodak's wire is the ONLY top grade, I'm
>just saying make sure what you are buying
>IS top grade...

> George

Some music wire will break when bent in a sharp bend. The stuff John gets is US made and you can bend it and bend it back without breaking it. I went to the same source and got some of the same stuff in rolls. Unfortunately, I first went to the factory, then to a distributor, then to another distributor, and finally to a third before I found them willing to sell in the quantity I wanted. Surprising how the price per foot goes up when you do that.

But, yes, all wire is not made equal, and that goes for the fishing wire, etc. (solid or stranded) that people may buy "thinking" it will be OK. I feel a little more comfortable knowing it will be OK. Just because the tensile strength is the same, doesn't mean it won't break at the bend or the wrap.

If you lose a fish, well, it's just another day at the beach. If you lose a plane, well, it is another winter at the bench.

(...)

>If you lose a fish, well,
>it's just another day at
>the beach. If you
>lose a plane, well, it
>is another winter at the
>bench.
>

Oh no, Leonard, I'm sorry, I disagree. I lost a fish back in 1963 and the experience left me traumatized and scarred for life..

>If you lose a fish, well, it's just another day at the beach.
>If you lose a plane, well, it is another winter at the bench.

Can't agree with you there Leonard. Offshore fishing tournaments here in Florida and the Bahamas pay out big money in prizes. These things are huge, several hundred boats when the weather is nice and they go on year round. People make decent livings in So. Fl. as captains and mates on these boats. A lost fish could cost a boat owner a half million dollars and his boat crew thousands in bonuses. If you buy stainless cable from an established offshore fishing supply store, you're getting the best. Period.

Sooo...we now have TWO verified sources of good wire

I guess fishin' IS like model airplanes, some fish for fun (and wouldn't cry over spilt fish ), others go all out.

...what is a scale fisherman? One who only catches fresh-water fish?...

George (hooked on models) Bain

Thanks for all the good answers to my questions. I haven't built a new stunter in years (busy restoring the old stuff), so the last time I read anything about leadouts was when the experts seemed to all like solids. I am now building a Brodak Smoothie just to see what modern kit quality is like, and I was about to use solid leadouts because I thought that was the modern trend. Because of the suggestions here, I have done a turnabout and will go back to cables as I am accustomed to.

By the way, I also assumed that everyone was not offsetting the rudder much (from what I'd heard from the experts a few years back). Now I read here that Paul Walker is using 7 degrees rudder offset, so the Smoothie will get Palmers original offset. This bulletin board is helping me with this project a lot.

I think Paul's use of rudder is in a specific application. The original Smoothie was built when there was not much power in the engines. With modern power, I would either build the rudder straight, or at least make it adjustable.

At least some of the "fishing" wire is Monel. This is a type of alloy similar to Stainless, but it has the unique property of trying to return to it's former shape, a "memory". Titanium does the same thing, and can take months to do it. A few weeks ago, I took the Humongus to work in the back of the truck. The tranny went out, and I nursed it into the parking lot (danged blankety automatics!). Before I got it towed, I tried to rent a mini-van, without any luck, and was lucky to get a Cavalier. The Humongus fit in the back seat, but would not have with solid leadouts. Cables are the way to go, IMHO. Yep I went flying after work as scheduled. Steve