Are golden rods a good way to connect the elevators? I am using a pull/pull for the rudder. Can you poost pics ofyou set ups. I flew pattern planes long ago and Ihave recently become interested again.I have a leo 110 with a ys 140 and I'm building a Black Magic VF3. I could use advice on servos, and general info on setting up the radio gear , etc. to current day standards.

Absolutely not. Way too much flex, and they also have significant changes due to temperature. The best method is the DEPS system from Central. Even though it looks similar, the carbon does not stretch like the golden rod, nor does it flex. I've been flying the DEPS system in my V3 for 18 months now and wouldn't use anything else,

For servos on the V3, get the best you can justify. Do not go cheap on servos. The V3 is an airframe that you can tell...just like most of the new designs. Either Futaba, JR, or Airtronics. Stay away from Hitec as they have centering issues. In my V3, i'm currently flying all Futaba..

BLS-451 - Ailerons X 2
BLS-351 - Rudder
BLS-451 - Elevator (9254 heli tail rotor servos works REALLY well here also)
9650 - Throttle

Arch

I use golden rods for throttle, they are fantasti for that application. Aother one might be Water Rudder in a seaplane. Other than that...
In modern applications the servos are usually VERY close to the surface, and a solid rod is the best solution. If you plan to put the Elevator servo in the center fuse sections, a solid 2-56 rod in a plastic sheat is my preferred solution.
Ciao
Beppe

I wouldnt even run a golden rod on the throttle in a pattern plane. The expansion problem will cause your throttle to vary slightly, and it may sound insignificant, but you want absolute repeatability on a pattern plane. The 2-56 rod, even in plastic is definitely not sufficient for a 2 meter pattern plane, unless you have it mounted several places along the way, and I still wouldn't trust that it wouldn't flex or even worse flutter under certain conditions.

Arch

Does that apply to 3D planes also? Iam building a 60" ultimate and I am to the point of doing the elvators.

Lets just say the best install i ever had with golden rods was in my Zagi flying wing combat glider.....

because they DID bend..... when they needed to........

I was looking at these... Sullivan Composite Flex Rod 4-40 48" (1) at Tower Hobbies. They do not change with temp. and are carbon filled nylon. The carbon content is however low enough that the do no cause rf noise. I fly Futaba 12fg radio on all my models and rf noise is always a concern . I have over 30 planes but still would hate to loose one of them. What do ya think? Have you guys tried these? I always mount small ply tabs about ever 6" through the fuselage to support the outer tube.

Just say no...you will be very unhappy with any of the flexible nylon rods on the market for elevator pushrods. Solid CF rod to MK bellcrank or DEPS or dual servos in the tail if your plane can balance that way are the best options.

I would follow rcpattern/arch's advice about the DEPS system especially for the VF3, but it could be good for the Leo also. As with anything new there is a little bit of a learning curve, but if you'll take the time to look at the directions from Central Hobbies on their website, and plow RCU's pattern area for setting up and installing the DEPS you'll be fine. I will admit to being skeptical as to how two skinny carbon fiber rods running in plastic tubes could stand up to the rigors of YS poewered 2m pattern flying, but after watching a friend's pattern plane fly with it for two years with no problems or maintenance required, I tried it. I actually installed it in a completely finished Temptation that had flown for a season a bellcrank system needed maintenance and I wanted to lose some weight in the tail. It worked very solidly and has been used in every plane since then. As to being sturdy, some posts I've read, and from my own experience agree, it will survive a crash outlive the airframe didn't use it again but the DEPS part was intact.

Servos again follow Arch's advice. You want that repeatability that you get from high quality servos that go back to the same center all the time.

Enjoy the planes!
Tom

What diameter rods do you use 1/8", 5/32"? or larger? How do the ends connet to the rods ? are they solid or hollow? Oh , thanks to all that have replied so far. Any more pictures of set ups?[sm=shades_smile.gif]

The Leo I had I used The dowel that came with it. It had two rods wrapped with string and epoxy, you know the typical two to one set up.
It seems to be very stiff no slack. I wasn't concerned abbout the weight because I put my YS140 in it because I didn't have a 110 engine. It should be fibe don't you think? It's just a practice plane until I finish the Black Magic.

I use these on the elevators of my Prestige. They do change length with temperature, just not nearly as much as a standard golden rod. The way I have it set up, there's no issues at all with flex, but due to the temperature effects on dimension, I'm not taking this approach in the future.

It's not a huge problem, it's an annoyance. It winds up that prior to the first flight of a day, it's sometimes necessary to bump the elevator trim to get the elevator back to neutral. Unless there is some wild swing in temperature during the day, that's all it takes, with maybe a bump of elevator trim on the first pass , 1st flight. Part of this is also the fuselage changing dimension (especially with humidity changes), so it's not all to blame on the CF rod.

The majority of Leo's I see on the competition circuit when they where popular had two metal geared high touque mini servo's mounted at the rear, pic shows my Swallow that I converted in that way, much better linkage with no slop, and additionally helps with the weight of a four stroke up front.

Mike

Frequent Flyer

The rods that come with the DEPS set from Central Hobbies are .070. All the rods, tubes, and fittings needed for assembly are included in the "kit from Central. You'll have to acquire some 1/4" square balsa sticks, some thread, and glue to finish it up. The Central cite also has a "how to" on the whole shebang: go to the main page >Control Linkages > D.E.P.S. > more info > See the DEPS Installation How to...

Enjoy,
Tom

I've used the Sullivan Carbon fiber pushrods too - they work OK but like Ed said you have to check your elevator trim at the start of a day's flying. I've never flown with a full carbon DEP setup (like the Central DEPS) but I don't see how they would be much better as far as the trim issue goes. The fact is a wooden airplane with a long fuse is going to expand / contract ever so slightly whereas the pushrod may or may not change it's length at the same rate. With either type of pushrod setup you do need to support them well or you'll have a mushy elevator linkage. Not good. And yes the standard Nyrods will not work well in a Pattern plane so don't even think about it. Some guys use pull-pull cables for the elevator but that's a whole 'nother can of worms. I think I'm going to stick with the Sullivan carbon rods until I find a better way.

John Pavlick
Team Black Magic, Tech-Aero Designs

FWIW I used a nylon rod for my throttle in the Venus, and as it got colder the rod started to shrink and gave me issues. Of course you can't adjust for this in your house where it's warm either. Will be moving things around and axing the nylon rods.

A rule of thumb that has served reasonably well over the years is to use the same push rod material as the construction of the fuse...wood - wood; glass glass, etc.
I don't agree that pull-pull cables are a can of worms (sorry John ), but these do require some finnesse to get right, and one should not be afraid to tear the set-up down (easy for pull-pull) and re-do it. I've worked with pull-pull for over 20 years and highly recommend these set-ups. These offer precision without any of the push rod hassles explained here-in.

Another very precise arrangement requiring practically no daily fiddling is the twin servos in the tail that another fellow mentioned...these minimize push rod length. Not for every set-up however since many can't afford the tail weight

FWIW 2U

MattK

Matt,
Yeah I agree that pull-pull can be a good way to handle the elevators but I think YOU'LL agree it's not something you'd recommend to someone unless you know they have a bit of experience. It can be finicky if you don't get everything right. What concerns me with it (and I know we have to deal with this on the rudder) is that as the plane expands / contracts, the cable tension changes. While this doesn't affect your trim, it does sometimes cause problems with the servo. I've been thinking about ways to build "balanced" systems with carbon rods so that we don't have the trim problem but I haven't come up with a good (light!) way yet. If you think about it as if it were electronics, the trim problem is seen as "common mode". We need to put it into the "differential" part of the equation.

John Pavlick
Team Black Magic, Tech-Aero Designs

I have to say I've had no problems with using cables for elevators in the past, as any change in length through tempurature is balanced on both sides of the servo.

You might want to consider a DEPS system or an MK Bellcrank if you can stand the weight.

Yeah that's what I was saying: the trim isn't affected by temperature with a pull-pull system because it's a "balanced" setup BUT the tension on BOTH cables will change and therefore your servo will feel it (tension on the output shaft can increase). If you run the cables too tight you run the risk of hurting the servo unless you use one of those things that JR used to sell. As long as you know what you're doing and how things work, pull-pull is a very good way to control the elevators AND rudder.

John Pavlick
Team Black Magic, Tech-Aero Designs

While there might be a SMALL change with the DEPS, it is fairly consistent. Never more than 1 or two clicks of elevator trim at a time, and many times not at all, and that is in my V3. Certainly not a major issue at all.

I have used the Sullivan carbon rods a lot, and I am stisfied with them. It really doesnt matter a lot whether you use sullivans, or solid c/f rod, you still need to trim every day, as had been stated here, our aircraft and components all move with temp variations, and I have never needed more than a click or 2 of trim using sulivans carbon and will continue to use them where needed