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Aileron Torque Rods, Explained

Old 05-31-2008, 02:29 PM
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Sky Sharkster
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Default Aileron Torque Rods, Explained

The aileron torque rod system is a way to operate two surfaces with one servo. When the right aileron goes up, the left aileron goes down; pretty simple, so far.
(1) Here's a crude sketch showing the basic set-up. A right and left-hand set are required for a full wing. Only the left-hand side is shown.
(2) Some of the hardware that can be used.
(3) The GWS setup. A thin wire bent into a loop for the vertical leg, with a rubber grommet inserted as the bearing.
(4) Here the vertical leg connection is made from a brass tube, flattened at the tip, with a hole drilled for the clevis pin. This idea is stolen from the ACE "Simple" series of models.
(5) Partially-threaded rod (2-56) is made into the torque rod, so a threaded connector can be used. This provides vertical height adjustment, a way to control deflection amount.
(6) Notice the sweep angle of the vertical leg; This will yield differential, more "up" than "down". This is a top-mounted wing, shown upside-down, we're looking at the bottom or inside of the wing.
Hope this helps, any other ideas for mounting, connectors, installation or comments, please post away!
Ron
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Old 05-31-2008, 02:36 PM
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Default Whooops! The REAL # 4!

Goofed up on photo $ 4, here's the ACE set-up, the flattened brass tube;
Sorry about that!
Ron
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Old 06-05-2008, 03:59 AM
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magic612
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Ron - great thread!

One thing I learned a while back about setting up servos for differential: Use a 90 degree (or better yet, a circle style horn with holes at 120 degrees) horn instead of a "straight across."

In this manner, the aileron that is towards the side of the plane to which you are turning gets far greater "pull" (or push, as the case may be). The opposing side only moves a little, comparatively. It really helps avoid problems of adverse yaw, such as when there is equal movement of the control surfaces, since with this set up the surface on the "inside" of the turn gets greater movement.

(I hope all that made sense.)
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Old 06-05-2008, 12:34 PM
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Default Circle Control Arms

Hi Dave,
Thanks for mentioning the disc servo arms, I forgot that!
I agree the circle or disc servo output arms are another way to provide differential output. If the pushrod is located ahead of the center of the disc (pivot) it will "push" more than pull, and vice versa.
The problem I've had is most of the discs are too small to generate much overall deflection. At least on Hitec + GWS micro servos, the disc diameter is smaller than the length of a straight or "X" arm.
If I could find larger discs that fit the output shaft splines, it would be a more accurate way to provide differential then bending the vertical leg of the torque rod off 90 degrees.
Ron
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Old 06-05-2008, 09:18 PM
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magic612
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Originally Posted by Sky Sharkster View Post
Hi Dave,
If I could find larger discs that fit the output shaft splines, it would be a more accurate way to provide differential then bending the vertical leg of the torque rod off 90 degrees.
Ron
I've made my own. Take a disc horn (or an "X" horn, or whatever) and then use the small mounting screws to attach a disk of 1/16" plywood to the top. Drill holes in the plywood. The mounting screws heads are usually fairly flat, and don't interfere with the pushrods.
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Old 06-06-2008, 12:28 AM
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fr4nk1yn
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I can't find my photos. I use popsicle sticks. I drill a hole large enough for the rod and put either a 90 or a Z-Bend through it through it then wrap with thread and CA.
It works rather well and keeps me from buying stuff (: I can get a bunch or torque rods from one threaded 2-56 rod.

Great write up.
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Old 06-06-2008, 02:55 AM
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Default More Torque Rods, Differential

Hi Dave and Fr4nk1yn,
Thanks for the contributions and suggestions! I hope this thread helps anyone looking for ideas.
Here's another photo, the servo has a disc control arm, with the pushrods mounted ahead of the pivot. This means they would "Push" a greater amount than "Pull", by a ratio of about 2:3.
Next to the servo is an "X" arm with two arms removed. By mounting it on the servo in this configuration, it would "Push" more than "Pull" by a ratio of 2:1.
Below the servo are a couple of "Z" bend pushrods, 1/16" wire. The threaded couplers next to it complete the set-up. They are threaded 2-56 at one end and hollowed for 1/16" wire at the other. A drop of solder and you're done!
Ron
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Old 06-06-2008, 04:37 AM
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Ron, those pictures perfectly demonstrate what I do for single-servo aileron set ups. Great shots!
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Old 06-06-2008, 03:44 PM
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Thank you for this helpful thread. I'm thinking of using a torque rod system for a flying wing I plan to build, with one servo per elevon. I'm thinking that I would put the servo directly in line with the control rod and directly attach the torque rod to the servo arm. I tried to illustrate what I mean below. The problem I see with this method is that I cant really adjust the elevon deflection vs servo arm movement, the ratio would be 1:1. I may re-consider using you method with one servo per elevon so that I can adjust the amount of throw.
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Old 01-22-2010, 01:13 PM
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Old 06-20-2013, 10:06 AM
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I have found this thread very useful guys. I have unequal amounts of movement on a torque rod aileron system on a new model and am hopeful that I can solve it with the use of a v-servo arm or disc.

Does anyone have the time / inclination to also throw up an explanation on recommended hinging methods for use with torque arm systems?
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Old 06-20-2013, 05:50 PM
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fhhuber
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Originally Posted by aero_k View Post
Thank you for this helpful thread. I'm thinking of using a torque rod system for a flying wing I plan to build, with one servo per elevon. I'm thinking that I would put the servo directly in line with the control rod and directly attach the torque rod to the servo arm. I tried to illustrate what I mean below. The problem I see with this method is that I cant really adjust the elevon deflection vs servo arm movement, the ratio would be 1:1. I may re-consider using you method with one servo per elevon so that I can adjust the amount of throw.
This can be done and will work.

There is a system based on this style setup where the "L" going into the control surface goes into a plywood lined slot and instead of the torque rod being on the hinge line it is at some other angle. By adjusting the angle of the bend at the control surface/hinge to be appropriate you can even have the torque rod at 90 deg to the hinge line.
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Old 06-20-2013, 06:19 PM
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Originally Posted by fhhuber View Post
This can be done and will work.

There is a system based on this style setup where the "L" going into the control surface goes into a plywood lined slot and instead of the torque rod being on the hinge line it is at some other angle. By adjusting the angle of the bend at the control surface/hinge to be appropriate you can even have the torque rod at 90 deg to the hinge line.
It's called Rotary Drive System: http://www.irfmachineworks.com/rds/

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Old 06-20-2013, 09:36 PM
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"It's called Rotary Drive System": http://www.irfmachineworks.com/rds/

Yes.........

Seen these used on heli's with pretty good results......seems the servo "torque" issue so prevalent with the larger heli's can be stabilized with this system......I've never used them on 450's since typical mounting on that size frame can be an issue.
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Old 06-21-2013, 01:31 AM
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Just about any control linkage you might need can be worked out... We have a lot of "tricks" available.

Torque rods have been very helpful in keeping the control system hidden. That means less drag and better looking scale models.
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Old 06-22-2013, 10:49 PM
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solentlife
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Hingeing of torque rod ailerons is not usually any different to others as the L of the torque rod is usually only just inside the aileron slot area.... leaving majority of aileron hinge line free for hinges.
It becomes a problem when a weak aileron structure is used as some foams are ... then the L needs to be further along the aileron hinge line. The solution then is to use hinge tape where torque tube is and whatever where no torque tube.

There are variations on the tube idea - such as the HK Pitts where the torque rod lays ON the wing ... instead of IN the hinge line. Rod extends out from fuselage, L lays on wing with outboard end passing through small O on aileron ... rod turns pressing down or pulling up the O fixed to the aileron. This system allows hinges to be full width foam or whatever you wish ... it also can let servo be carried in fuselage and all you do is insert L into O when mounting wing etc.

Nigel
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Old 06-23-2013, 01:06 AM
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fhhuber
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There are ways to make hinges with the torque rod as the hinge pin also. This puts the torque exactly on the hinge line.

One method is to grind the heads off of the pins in hinge points so you can remove the pin then enlarge the holes.
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