I have already installed the outer tubes in a kit I am building but reading throught some threads it seems people are advising against them; apparently temperature changes affect them too much hence requiring re-trimming of control surfaces.

Question is: are they that bad to warrant me to yank out what I have and replace with metal control rods? If it's not too bad I'd rather stay with what I have.

What kind of model are you building? For a full-banger pattern ship or a 3-D model they may be disappointing. For a less precise model probably fine.

I usually trim my models on the first flight of the day anyway and one "blip" on the trim button isn't much of an inconvenience. Offset that with the benefits of no potential metal-on-metal radio interference, no radio shadows from the metal, ease of installation and light weight (lighter flies better).

Life is full of compromises.

I agree with Charlie P.

If you find that humidity and temperature are making your planes out of trim you can substitute Sullivan carbon fiber pushrods within the guide tubes you have already installed.

I've been using Sullivan Carbon rods for my aircraft, even the larger ones (larger meaning my Venus II, Goldberg Skylark 70, and the Tiger 120). They work just fine, but they do need to have the tubes reinforced, ie. epoxied to each and every former as they pass through the fuselage to the rear. I have written up a description as to how I secure the metal clevis rods to the ends using CA and a variable speed drill. I can elaborate if you wish.

CGr.

I built a Four Star 40 several years ago with the stock plastic rods. I never noticed any changes in trim due to temperature changes, but I did notice that they started to get sticky after a couple of years. While doing a bunch of other work on the plane, I took out the nylon rods and replaced them with metal pushrods in the same outer tubes. Things move a lot more freely now, and there wasn't enough of a weight penalty to notice.

I put a drop of "after-run" oil in the tubes from time to time.

Thanks for the responses guys - and sorry I omitted an important part: the kit I am working on is a 4*-sixty. The same project that has been going on for a couple years now [sm=red_smile.gif]

Nyrods it is, I am leaving them in.

I've use nyrods for most of my models and have flown in the desert area in the west and all seasons in the mid west (where temperatures vary from below freezing to well over a hundred) and never have had a temperature problem with them. The main thing is to be sure and anchor the guide tubes every 4 to 6 inches inside the fuse or wing so they can not bow. Now on my big models, I always use pull-pull and lately even use that on the small ones as it is lighter and very precise in all aspects when you use the proper Ackerman setup.

I don't like oil on these as it actually collects dirt/dust which causes drag. Keep them dry and clean for best operation.

I quit using them as they do cause the trims to change. I only use the metal push rods now a days and the cable for my throtle and steering. Good Luck, Dave

I too quit using them years ago. The temps can get to 115 here and in Calif. and inside the plane sitting in the hot sun it's a lot warmer. My trims would change quite a bit, nothing that couldn't be corrected in flight though. It's not a big enough deal to bother changing them out though. A lot depends on what part of the country you are living in. I haven't lived in a place with the humidity but I wouldn't think that would effect the rods as much as the heat I fly in??

The only airplane I have with nyrods needs a trim every first flight of the day - a wild trim!!!
other wise the airplane is in a wild down elevator, some times the servo is at the end of the trim and its still in down elevator so link need to be moved and moved again later during the day when they come back to their initial size.
all other airplanes I use sullivan composite rods and trim it only at the maiden and thats it.
I use the method CG retired described with the drill and make sure the tip of the metal rod is rounded its very important.

Alex

I also quit them years ago. We fly year round here. That means 100 in the summer ans 30's in the winter. Nyrods are just a pain. I did retro fit one long ago. If the outer sleeves are faily straight ,you can just use the metal in them.

David

They are OK for throttle, you can also place a segment of fuel tubing in between 2 lengths of the inner nyrod to totally isolate the servo from a high rpm engine.

If there is a bend in your linkage from point A to point B nyrods will slide through the tubing a lot better than plain old wire will and the binding that the wire creates will run your batteries down faster than if you were to use nyrods. I fly my tiger 60 in different temperatures and I don't find the need to make trim adjustments from one day to the next.

If you wanna talk about pain, that's when you try to get a wire through a bent tube without it binding!

Use your nyrods and you'll be just fine.

These days I would only use them on throttles of engines with spark ignition systems and and no where else.

Everywhere else on all the new airplanes for the fuselage pushrods I use only rigid CF rods that are a slip fit for either 2-56 rod ends or 4-40 rod ends depending on the length of the run.

John

I always trow the nylon in the garbage....

I like metal pushrods...either 2-56 or 4-40 for moving control surfaces. I run them in the tubes....secure the tubes real well....no issues.

No sticking, binding, expanding/contracting, brittling....etc.