on giant scale gas, do u need to use kevlar for your pull pull system or is stainless ok? my concern is radio interferance

I have kevlar pull pull on 3 of my gassers. It works really well. I have never had a need to try metal.

Where do you buy the kevlar and what size are you using.. I have a big bingo 180 4s and a 1/4 cub with a 26cc. I have pull-pull on some others but using metal.

I think the best is the vinyl coated Kevlar, it lessens the chance of chaffing and breakage.
2 sizes available from thunderboltrc...... .038 and .058
I bought some .058 for my EF YAK, sounds like you'd be fine with .038

Doesn't really matter to me. If it rubs anywhere the kevlar dies after a bit. Hard to set knots in the kevar and ca glues don't adhere to it very well.

You can buy a Kevlar pull/pull made by Sullivan from Tower Hobbies, Part # 523. It is a kit with 30ft of 100lb. cable. Cost approx. $14.

Troy Built Models

Do you use the crimping method with the double loop back?

I buy a roll of Sullivan S-108 Tuf Strand U-control cable at my LHS. A 60' reel will last you a long time. See this link: http://www.sullivanproducts.com/Cont...eMainFrame.htm

The way I use the Kevlar allows it to be used without having to go in a perfectly straight line. I run the red nyrod outer jacket from front to back in the normal manner. I then put the Kevlar inside the yellow inner push rod and wick a small amount of thin CA into the push rod at one end only. The nyrod acts like a bearing. No chafing. Probably last longer than the model.

Thanks for the tip Big Bird, looks like the solution the the problem I run into with my Ultimate. I am using a tuned pipe which a built a tunnel for, and I now cant get a straight run on the pull pull cables for the rudder. I will definately give that a try. Thank you

Hi Jac, If you are using 72 mhz. radio , then you must stay away form 39 inches of metal parallel to your rceiver antenna, it will cause glitches to you will be unable to fly the plane.
Jack

I've used this method on 4 airplanes and it is fool proof. I'm sure it will work for you.

I have always used metal without any problems. When I cross them I slide on a piece of inner ny-rod do they don't rub. I've been told by one manufacturer that Kevlar stretches, don't know for sure though.

No problems with metal for me either.

I've always used nylon coated braided wire on at least seven 1/4 scale with PPM on 72 MHz and never a problem. The few times I tried to use Kevlar, I had a fraying problem plus it would wear the guides. I have always routed the pull-pull lines through nylon tubes for two reasons; easy to replace if you ever have too and you can easily route the cables around any obstructionsno need for a straight run from servo to controlled surface. At first I was leary about using nylon tubing to route the lines around obsticles but in some 12 years plus of doing it that way, I have never had a problem and it sure simplifies the hookups to the elevators.

All of you using metal that is parallel to your receivers antenna , have just been lucky. Electronics is my vocation, and if you make the metal lines around 39 inches long, You will have trouble with the radio. Just trying to help with a problem I have seen several times over the last 52 years of rc flying. Of course do what you want.

Just measured the cables on 2 of my favorite 50cc planes that I've been flying for several years now and one measures 37" and the other is 42". My antenna wires run directly under the pull pull wires a couple of inches away. So far so good after dozens and dozens of flights on each airplane. Maybe I'm one of the lucky ones or should I start to worry?

Have no idea why I got a double post?[sm=confused.gif]...edit .. but it's gone now.

Would not worry, sence its been working that long, you are far enough from 39 Inches.

I am also an electical engineer, a long time HAM and years of testing instrumention much of it in the RF area. You are not like to get in trouble with parallel runs with wire leads regardless of length on the frequencies we use (unless we get into the gigahertz range) or are very titely coupled (less than a quarter inch). You might possibly get some microsecond periods of antenna blanking but even that is unlikely and will never last long enough on a moving object to ever even know it. Note: this does require that the ends of the wire leads are isolated electically from each other and the airframe.

Just anything to prove someone else wrong syndrome, NPD maybe. You should not give info to folks who are trying to maybe solve a problem, or are trying to prevent one. The ground plane caused by the 39 inch metal wires does not have to be coupled any particular distance, sence the movement of the plane will change it. I have experenced this several times. It can be as simple as a lot of glitches while flying, to complete solid interference, which is too bad to allow flying. I will not boast about my electronics education on here, no need.

The ground plane in your RC systems is composed of the wiring in your system, primarily the ground wires on the servos and battery and are acutally the other half of your antenna, that long single wire attached to the input coils on the receiver is only half your antenna system. Any other metal(s) in the area might act as deflectors, directors and or shields but are not of general significance unless they exceed the wavelengths of the signals of interest. There are many basic studies of field strengths and how they are modified or utilized if you search the literature along with capture area and noise generation.

Jacjac, Don's Hobbies sells a great pull/pull setup for different sizes airplanes, I think up to 40%. They provide a kevlar coated with vinyl cable and also 4-40 loops that will not cut into the cable.

I have used them for a few years on all sizes up to 35% and never had an issue.

Good grief, this kind of stuff is one of the reasons, I for one, am considering not to bother trying to help other modelers on these forums The NPD is running ammuck. Good bye , and good luck with all the quacks on the forums.

WOW!! I for one would hate to see you quit trying to help other modelers. I need all the help I can get. I hope I am not a quack, I know I ask dumb questions sometimes. Have a Merry Chrstmas and a Happy New Year.