The pushrod tubes for the tailfeathers are tighter than I remember them being in my LT-40, and I can not fit in a traditional set of nylon pushrods and I am wondering if the cable pushrods can be used safely for the control surfaces of a plane this size as that is all that will fit in the tubes? Please tell me yes as it would make the completion of this plane alot simpler, rather than cutting open the fuselage covering, ripping out the pushrod tubes and reinstalling new ones.

I would not use cable except for the throttle and nose gear. It will deflect too much on the elevator and rudder surfaces. Did you try steel pushrods? You may have tubes for metal pushrods, which is why the nylon will not fit.

Bill

Why not just get new pushrods? I would worry braided cable might buckle over that length.

Because I already have the yellow pushrods which appear to be the thinnest circumference made and they are tight in the tubes. I dont believe they make them with smaller circumference. And like I said I would hate to rip open the covering and rip the old tubes out. And steel rod pushrods are too tight as well because the tubes are not perfectly straight the length of the fuselage.

You can allways try chucking up the inner pushrod in a drill and use a something like a Scotchbright pad to loosen it up.

It sounds as though you have a different brand of pushrods than what your plane came with. Did the originals come with the plane? If so call Sig and ask them. They may be dubro instead of Sullivan, etc...

Would sanding the pushrod help make it run smoother thru the tube or make it weaker?

No they were not the originals that came with the kit

I used the drill and Scotchbrite method on the yellow tubes before and it worked.

Could someone explain this technique in more detail? Maybe I am a complete idiot but I am not following.

Put the inner tube part in the end of a drill. While rotating the inner tube in the drill, use something like red Scotchbrite or a fine sandpaper to reduce the outside diameter of the inner tube.

Just don't let anyone see you do it. [X(]

OK I have the elevator pushrod installed and here's the status.
When the elevator raises and lowers you can see the tip of the stab flex a tiny bit with the movement of the elevator. Is this a major issue as far as flying? Very seldomly the servo will buzz the tiniest of bit with the motion, will this reduce the effectiveness and cause the battery to drain or servo to become damaged?

Now onto the rudder and nosegear.

Anyone care to see photos?

Photos would be good.
If your horizontal stab is flexing with elevator movement I would suspect the two are misalligned or the stab has a crack. You are correct that any sort of binding will draw more power from the battery. May not make it unflyable but is to be avoided when possible.

I got the elevator servo to stop buzzing so there is no binding. Just a tiny bit of flexing at the tip of the stab is all, just enough to see but does not affect pushrod or servo motion, I think it will be ok.

G'day

I recently built a Sig Somethin' Extra and the supplied plastic pushrods bound easily. They were smooth round tube type. I replaced the inner with the yellow inner from a set of Goldberg Golden Rods (the red smaller size) and everything worked well with this setup.

I don't use the small one inch threaded section that Goldberg supply. I use 12 inch threaded (on the end) Dubro pushrods (2-56 size). To stop the end of the yellow rod flexing where it comes out at the rear (it is usually about 3 or 4 inches long here) I cut a length of Dubro rod about 5 or 5 inches long then push it inside the yellow rod and then screw about half of the threaded section into the yellow tube. This gives me a nice stiff section which will not flex in flight which to attach to the clevis and the elevator or rudder horn.

At the other end I screw the threaded section of a Similar Dubro 12 inch rod into the end of the yellow tube and either bend it to a Z bend or use it straight with an EZ connector (the type with the Allen headed cap screw to secure the rod to the connector.

Does this make any sense?

Mike

Why don't you just use a regular old 2-56 metal pushrod? It would easily fit in the tubes and the LT-40 wouldn't notice the extra ounce.

Because the tubes are not set perfectly straight so the metal rods dont slide in easy.

Have you tried bending the rods to match the curve of the tubes?