Lets talk about control Rods, what are you using, what works, what dont work??
 

Starting this thread so lots of us can learn a little bit on this subject. Control Rods are very important, and its crazy to spend 10k on a jet with junk hardware controlling everything. I have been doing a lot of reading on installs, I am gathering up all my stuff up for my new 1/6 f16 coming in later this year. I have put together plenty of planes, using different hardwares, I am wanting to make my own control linkages for this one. To be honest I am really looking at a setup like this for all my controls but not sure if this is strong enough, I have not seen anyone using them in a heavy fast jet??
https://www.centralhobbies.com/subca...ub=124&sub2=46
Anyone know if carbon tubing like this in 5/32 or 3/16 is strong enough for say a 40-50lb Jet? To me this would be an easy route to go, set your neutrals,put your connectors on, measure and cut..

The other route I was thinking was using some threaded rod cutting it to length, then putting some carbon fiber tubing on the outside, and a piece of aluminum tubing on the ends to stop them from ever splitting.
I have been reading of people doing everything imaginable from turnbuckles (work great unless you have an oddball length) and on the other extreme, I read about someone using 4-40 threaded rod with clevis's on both ends, NOT even locking Clevis's. I think that's asking for trouble.
Personally I try to use the Dubro Monster Ball links whenever possible, and sometimes you cant use a ball link, so I stick with the Sullivan gold-n-clevis because they are strong, and have a locking clip on them to stop them from opening. Another trick i do is when I have it all setup I will put some thin Ca on the ball link, or clevis so they can not back off. I see some guys say that 6-32 rod is the minimum, and others say stock hardware is all they ever use, others swear by All metal ball links, etc... I know there are some master builders on here, as well as some members who have been building for years, and Im hoping some will chime in and let us know your opinions,experience, what works Long term and what don't work. as always, taking the time to share your experience is appreciated,,,

This is a great subject!
Those Rods do look good but there are no specs on their usage so I suppose the best thing to do is carry out your own tests just to be on the safe side especially on larger Jets?
Saw some nice Rose joints (Ali ball joints) from I think the company name was Intairco! I could of miss spelt that.
I think you can get them in M3 and M4. I've never really trusted carbon tubes with the threaded ends glued or screwed in, your method of sleeving cold rolled threaded rod sounds like a better option to me but that's just my opinion and I'm sure this thread will pick a lot of interest quickly!��
I personally stay away from cut threads on all the flying surfaces due to inherent weaknesses in the process, I also try to keep control rods as short as possible reducing excessive side load or bowing!

3mm threaded rod with varying clevis's or ballinks. Depends if you have double horns or single horns.

http://www.rcuniverse.com/forum/atta...mentid=2112399this is the way I do it ( tube and rod) . This is a locking clevis.

Well I was told that my rods probably caused my flutter problem. Sm said they have issues with their stock rods, so will switch to a titanium rod. I'm going to use hanger 9 rods with my current heavy duty dubro ball ends. You could put a carbon rod over the stock rods with some epoxy.

On the carbon only rod I would not use them without some kind of rod inside. Carbon has flex to it that could build to form that small vibration that leads to flutter.

The reason I changed my skymaster F-86 is because the stock set up had a lot of slop. This system has no play

he hanger 9 titanium links are great. I use them on my stuff. I am not a big fan putting ball links on the control surface horn. It applies a twisting force load to the horn. I have seen many set up like that and they work fine though. Just something I wont do. I always use a clevis on the control surface side. Ball link is fine for the servo side.

gun, if you have dual horns on the surface you get no twisting.

I have used the Central Hobbies carbon fiber rods with the titanium ends on a few fast jets like the Kangaroo with 25 pounds of thrust and I never had a problem. I always use light sandpaper inside of the rod ends before I glue the ends in with JB weld. I also used small brass tubing that would slip over the carbon rods on the ends, about 1/4" long to keep the rods from splitting. The latest install I did was on a Turbinator, and I used 4-40 all thread rod with carbon fiber rods slipped over the 4-40 all thread and held in place with JB weld. Be sure to use a Nylon-lock nut against your clevis to keep the threads from stripping out. If the CG is correct on any plane you build, there is a chance that the load on the elevator or rudder pushrod is light. If you are using full flying stabs, balance the leading edge of the stabs so that the servos don't have to work so hard. Don't balance your stabs so they stay neutral when you disconnect the linkage. This will cause the servo to hunt for neutral, without a load....

Larry/Instructor

Great thread.

This is the stock set up on the Ultra Bandit. (I borrowed the pics from Lasse Palm :o ).The threaded rod IS NOT standard hobby shop supply. I think it may be stainless, but it is all 4-40. (I would like to know where you can get it.).

This system is on the UB elevators/ailerons/flaps with 4-40 clevises on both ends. It works, is slop free, and is very simple. The servo output arm is the JR Heavy duty nylon item on the ali and elevators.

The rudder uses a 4-40 wire closed loop with ball links.. (Rudders are prone to flutter.)


http://www.rcuniverse.com/forum/atta...mentid=2112624http://www.rcuniverse.com/forum/atta...mentid=2112625http://www.rcuniverse.com/forum/atta...mentid=2112626

You can get threaded rod from Fastener suppliers and here in Aust it is called Brooker rod.
It is usually sold in Meter lengths but i am unsure as to how small a thread size you can get

This is my preferred method. Clevis soldered on one end and the other snugged up tight with a nut, both of them secured to the control arm/horn with a locking clip. It's surprising how tiny amounts of play in the clevis/rod and clevis/servo arm will translate to a sloppy control surface. I've even seen ball links with poor bolt hole or ball fit tolerances that allow slop, in addition to possible twisting action. As mentioned, short rods are best with longer ones reinforced with an aluminum sleeve epoxied over them.

Craig

This is why I started this thread, a lot of information and learning to be had on this subject. Lot of good Ideas out there,,
If you are dealing with a setup that really cant use ball links on and have to look at clevis's I have found some HEAVY DUTY clevis's that I think are more than up to any task, and they cant pop open like others.
http://www.rcuniverse.com/forum/atta...mentid=2112650
http://www.espritmodel.com/clevis-th...-6mm-m3-6.aspx

And these
http://www.rcuniverse.com/forum/atta...mentid=2112651
http://www.intairco.net/products.php...is-%28Pkt-2%29

For flying stabs:
I use ball links and a golden clivis. Sometimes ball links on both ends just ensure rod is long enough it cant unscrew.

Use a 4-40 full threaded rod and put a carbon fiber tube around it. Once the lengths are set I use a bit of hysol on the end of the tubes so they don't move or rattle. If you want overkill hysol in side the CF tube too.

For everything else 4-40 full threaded rods with no CF as long as they are less than 5-6 inches. Anything longer use CF. Everything is dubro or Sullivan.

600+ turbine flights on various jets with this setup and not a single problem.

Chief aircraft sells some turnbuckles for the 3d planes that would be great for elevator as well that don't need anything too long.

http://www.chiefaircraft.com/radio-c...rnbuckles.html

The best possible cofiguration using hobby hardware is ball joints. I have seen guys who dont torque the ball joint so it can rotate on the screw........wrong!!! Torque that sucker up. You dont want it slipping on the bolt.

There should be no twisting on the control horn, if there is it just means the ball joint has too much running friction, try lubricating it or switch it. The ball end should also have a jam nut so the rod is not allowed to walk out.....another no-no.

If you want to go "anal", get some links with reversed hardware on one side so you can have a true turnbuckle, but in the world of digital servos it is not needed.

Finally, stay away from cheap chinese Aluminum hardware. It has no place in this hobby.

Now the ultiamte low loss configuration would be the clamped bushing type. I've only seen this on Fly Eagle kits and unfortunately they are made of aluminum, which I do not prefere. This is similar to a ball link except there is an internal bearing that eliminates any slop. Problem is it doesnt take misalignment of the link very well, so the servo arm and the control horn need to be aligned.
In any case, these methods can provide all the precision and strength you need, but ultimately it is the servo and servo mounting which will give you slop, and that is a lot more difficult to address = in the end Sullivan golden clevises + plain threaded rods work just as good!

David

Falconwings are these the ones you were posting about it and can be supplied from http://www.intairco.net/products.php...it-M3-Push-Rod.

I have a 1/6 f16 and I used 3mm stainless steel threaded rod if you wanted to you could cover this with a carbon tube but I doubt you will need it, avoid anything that needs ends gluing or fixing on its just another failure point.
if its in one piece when you use it, there is nothing to go wrong later when you least expect it, get good quality ball joint for the ends and a slope free linkage and you will be fine

Hi,

I've seen SO MANY setups where the original builder or, in some cases, the guy who was paying me to assemble his ARF, thought he was buying the best 'insurance' hardware but really wasn't. Like Gunn mentioned, there's a twisting moment that a ball can induce on a horn. On the stock setup that came with the JL MiG-29, they had huge metal ball links attached to a relatively flimsy 'plastic' horn. The client got mad when I changed it out for Sullivan 4-40 clevises. I explained that the metal links AND their metal ball-bearings were complete crap and would fail 100 times faster than a Sullivan 4-40 clevis PLUS no twist. For my planes, I have yet to encounter an application where the black Dave Brown fiberglass pushrods with 4-40 hardware wasn't up to the task. They're pretty impervious to heat and with a screw through the bullet, they're pretty foolproof.

Number27 those are the ones I found and come in M3 and M4!
serious rod ends!

If I use 4-40 all threads, I ALWAYS use CF tubing over them. Also, seek to always use double Horns (hard to do on internal pushrods for Flaps) and a Dubro SS Ball Link in the center, cranked down and tight for sure! The KingCat setup for Elev's require bending 4-40 All Threads but they are so short...and they haven't ever had issues over the course of the airframe history as a weakness.

I am very careful when using Golden Clevis's though...known to break the pin when inserting into arm and not knowing it until you fly!!! Will only use them on plastic arms. ALWAYS solder one side of Golden Clevis's if I use them on both sides of the pushrod. Then use locking nut with blue threadlock on the other to gain pressure on the Clevis threads.

Rex

Those are similar, but those are ball links. The ones I was refering to have linear bearings. I'll post a pic tonight,

Central Hobbies has the Kato"B.B. Horn Head" which are ball bearing clevises. Take a look.

The only advantage of titanium here is weight, it is no stronger than steel just lighter. So unless this is some physically larger replacement pushrod I don't see how these titanium rods are any stronger, just more $$$ kind of like kevlar fuel tanks :-)


Flex? I have used carbon fiber pushrods for years and they were bulletproof, mine were Central Hobbies like "Instructor" explained,

.

Thanks Sweeps. The threaded rod we use for push rods is either 3 mm or 4-40. (A strange american sizing:)). Intairco has it. The fastener suppliers rarely go below 6mm dia. .

As an aside, I understand the reason people are wary of using standard hobby steel threaded rod, is that the machining process makes the rod quite brittle, and prone to failure under compression, especially if there is any sideways load. I believe this is why people reinforce it with carbon tube..

Agree that carbon is some of the stiffest material around. In the form of a tube that increases moment of inertia properties, it is hard to beat. For the pushrod itself, it all about avoiding bucking under compression load. Keeping it short helps and avoids the lateral deflection exhibited by a pushrod that buckles even slightly. For me, I go with 4-40 rods, sometimes custom, die cut out of welding rod. Mainly go with ball links at the ends. The biggest issue I find in terms of play is the rest of the hardware including servo arms that are no good and don't fit the spline (SWB makes good stuff) and play in the gear train of some servos.