I am in the depends on the application catagory

In a SIG Wonder Yes I would use them and mod the TE so they are fitted properly with out carving.

In a 35% CAP no way will I trust two 90 degree bends to twisting from a 170 oz/in servo

personally, I avoid them, but I would not be afraid to use them. I like the idea of having the control point more towards the middle of the aileron, and the idea that I can change or modify the servo if I need. On a trainer type plane, no problem, but if I build a plane for precision or speed, I would put them in the wings with hatches.

Jon

Almost 99% of the rc pylon planes out there utilize torque rods. Some are reaching speeds close to 200mph with out a problem with their torque rods.

Kurt

In the 70s and 80s, we used torque rods in a pattern plane with a screaming 61 on a tuned pipe. Didn't have any trouble with them then. You really don't get any flex with a 1/8 " piano wire.

But sometimes it's easier to use a servo in each wing panel.

Whatever floats your boat.

Frank

On the smaller stuff a 1/8" wire works just fine.

I guess I am looking at this from a different point of view, pattern aircraft and pylon racers have one thing in common; small surfaces especially the old stuff. I fly mostly giant scale these days and on an airplane with a 150" wing span that flies at nearly 120 mph and ailerons that span 60" long each with 7" wide root ribs and 5" wide tip ribs it is not practical to drive these from one end because huge surfaces will excite themselves into flutter mode, you can count on it! So you see it make more sense to drive them from a more centered location or locations when using multi servos. Now if weight is not a concern and one is willing to build surfaces this large that are completely rigid and then drive them with massive torque rods spanning the wing to a more centered location of output, then go for it, I myself am a complete weight freak when it comes to an airframe, so I always take the high road and go the lightest way possible.

Bob

My error interpreting the definition of torque 'rods'. I use rods (wood dowels) on small (<60") stuff and tubes on larger. Even this simple 'formula' of mine is dependent upon lengths needed. It's a personal preference. Steve Wittman had problems with his Chief Oshkosh. The ailerons would flutter and make whole airplane shake. Ground observers thought his tail needed bracing and forced him to do so. Mr. Wittman learned to make small aileron inputs to get them away from the neutral setting which is where the flutter initiated. He eventually rebuilt the wings (even shorter!). The problem with models is they are flown too fast so servos in wing for each aileron needed. Lots of factors to consider before 'damning' one over another.

In my case with the Dirty Birdy (classic Pattern and most current pattern aircraft), these aircraft use very little deflection. I believe the only exception to this is the rudder. Speeds with my DB will reach the 120mph mark fairly easily with a piped Rossi .60 on the nose.

Frank is right when he says... "Whatever floats your boat."

There is some consideration about placing the connection of the push rods in the center of the aileron that helps "induce" a flutter in the control surface. There was a lot of talk about this about a year ago. I am too lazy to research it and pull it up to link it, but it would be worth looking into at least. The just of the conversation suggests it is best to offset the placement of the aileron control horn to correct this.

My context of flying is encapsulated by 40 to 60 size sport and aerobatic aircraft. My considerations in this conversation really don't think any larger. I should have stated this to begin with.

Brian

A geebee R2 used torque rods on its ailerons (yes the full-scale). Torque rods are used used on the elevators and rudders on kingairs and other full scale aircraft.

If they are designed and installed correctly, they are as good if not better than most other control setups (but there are cons to them as well)

My opinion for 40/60 planes with torque rods:
pattern/racer/scale => torque rods
3D => wing-mounted servos

Cons for torque rods:
space inside fuse, installation of torque rods

Pros for torque rods:
cleaner aerodynamics, scale realism, lower moment of inertia for roll rate.

Love those torque rods!!!

Brian,

Not so sure what your issues with dual aileron servos are. If one issue is clean airfoil, forget it. Those gaping holes that retracts reside in are far more disturbing to the air mass. If another issue is weight for a given stiffness required, dual servos and tork rods are possibly a wash. Depends on how long the tork rods are. Stiffness of strip ailerons is inherently small and that doesn't help or favor tork rods. Mini servos today produce more than enough tork for ailerons considering the available tork of the day back then. If we had 40 oz-in we were doing good. Heck a micro servo can deliver that much tork today for around 10 gram weight. If an issue is cost, then I agree, tork rods are less costly up front but if done the way I did mine, they cost time and effort

Having said all that, tork rods can be stiffened up nicely using carbon tubes rather than steel. Back in the day, ca 1985, I used 5/32" carbon tubes and applied a layer of carbon tow around the tubes to keep them from splitting and to a tickness just enough such that the carbon tube would slide nicely inside outer NyRod sheath. I usuallyused epoxy but have also used ca with similar results. Produced a light, stiff and strong driver for ailerons. Sorry no photos, but I think the description should be self explaining.

Merle Hyde was the first guy I recall who put dual servos in the wing, late 80's early 90's, I think....Around the same time frame I remember installing tork rods in one intermediate sized model with plug in wings and driving each tork rod with separate servos. It worked fine but why even go there? Too heavy for certain

I had a .60 sized Kaos that had terrible aileron flex with the stock torque rods. The installation of dual wing servos allowed me to put the push rod in the center of the surface where it belonged. On long ailerons, it is difficult for the torgue rod to hold the end of the surface in position. Unless you use a very long torque rod.
On Q-500 racers though, the torque rod is better. Cleaner for faster speeds. Takes a lot of work to set them up tight without slop though.

Yes, as I stated in an earlier post; torque tubes are used often in control systems of full scale aircraft however they are not generally used in the same fashion as our smaller R/C aileron counterparts. I was an assistant crew chief on the F104 and a crew chief on the F18 Hornet some 25-26 years ago and the control systems in these jets utilizes many torque tubes, some to bell cranks and other from actuators to the control surfaces, so this is certainly no front page news. Anyway if you want to use torque rods, by all means use them.

Bob

The length of the tork rod is critical to whether one gets torsional flex of not. On classic pattern models with strip ailerons, the tork rod run was very short so 1/8" piano wire worked fine.

If the tork rod was much longer, 10" long for example, 1/8" piano would not be stiff enough.

Plug in wings make tork rods impractical.

I didn't vote, because I neither love them nor hate them. Torque rods are OK. So are dual servos. I have built several planes with each. Both work just fine. Dual servos are a little easier to install and give some redundancy.

We can use dual servos with torque rods as well. And you are right, using torque rods with plug-in wings wouldn't work.

MTK-

I have nothing against dual aileron servos. But I do disagree with you saying that torque rods do not clean up the wing. I still apreciate your posting though! I may just use mini servos for the ailerons.

As far as the gaping holes caused by the retracts- Operational landing gear doors have been employed historically in classic pattern with much success without adding too much weight.

Either way- even with the gaping holes for the retracts, the airplane is a lot faster with the gear up.

Weight is a separate issue all together, but my preference for a classic 60 sized classic pattern ship is 7.5-8lbs. I built a 6lb Super Kaos with retracts and HATED slow speed flight charachteristics. It never wanted to land. Sure! It was a lot of fun at WOT, but slow her down and you are carried away VERY easily.

I may disagree with people, but I appreciate the conversation non-the- less. I believe it is important to bring up older building methods that people seem to have written off. Not always are they a waste of time. Sometimes it is worth while just to try something that one hasn't done before. We may find we like it.

Brian

I couldn't agree more, we are all friends here, and we can agree to disagree. It's all good...

Bob

I think the quality of music wire today leaves a lot to be desired and has an impact on the performance of torque rods.
It's hard to find real good wire anymore that isn't either soft or brittle.

You must be referring to piano wire supplied in Chinese ARFs. I have had similar experience. Never was a problem in the past. I sometimes go and buy piano wire from the LHS to avoid any catastrophes.

I like torque rods. Never had a problem with them in over 25 years of flying and continue to use them. I also like this book:


http://www.amazon.com/Control-System.../dp/0911295011

Thank you for proving my point with the pictures on the front of your handy dandy control systems book...

Bob

Really ?

$157.82 for a new book ? Assumed to be United States fund.

Zor

I don't know why the new book is so expensive. There are used ones there for only about $6.

Thanks for your response "carlgrover".

I have a good idea I think.

A friend enrolled in a course that was advertised at atechnological college at $120.00 for ten sessions of 3 hours each. One session per week for 10 weeks.

She found that she needed to buy three books. Two at $90.00 each and one at $120.00 (plus taxes at 13%),
She could not afford that and cancelled. She is still trying to get her enrolment money back after six months.

Education has changed a lot in recent years. It is now big business.

Students now do not even learn how to use their mother tongue, how to write properly and how to format their writings.

Zor

I also get the impression that higher education is a big ripoff, like the return we get on our tax money.