Has anybody ever done a pull pull setup on elevaters on a 33% or larger plane? If so how? Can you post any pics? Thank you.

Crash, I'm no expert on the subject but I would imagine you would do it the same way as the rudder. Use two servo setups, one for each half with pull pull wires to each. There would be lots of wires going back to the tail but they do it in full size all the time.

Im a little unsure of servo monting. I guess I would have to mount the servos on their side?

I wonder if there is any type of servo tray out there designed specifically for this application.

It is going into a 33% sukhoi so I don't think space will be an issue.

I know it's smaller but on my extra300, the elevator servos are mounted on each side of the tail sticking out of the side right under the leading edge of the stabilizer. A short stiff rod to the elevator is all I have used. I guess if you wanted to you could mount them inside the fuselage and run wires out the sides to the elevator. Better make an access hatch though so you don't ahve to tear the covering off to work on the servos.

They will be mounted directly behind the wing tube.

That sounds good, just make sure that you don't have to move them for balance problems before you nail them down.
They should still be mounted on their sides so that you will have proportional throws to each side of the elevator.

I looked at several pull pull setups on the market and decided I didn't like any of them so I went to Wal Mart and bought some 90 lb stainless steel nylon coated fishing leader material and some crimp sleeves and made my own. Works very well and I can get several sets out of one roll.

Fishing Line? Good idea. Thanks for the help. Do you know any of the dos and donts' of setting up a pull pull? I guess that with a pull pull on the rudder you want the servo centered in the fuselage from left to right to keep everything porportional. With elevator pull pull I would want the servo arm centered vertically with the stab?

That is true, make sure it's centered and make sure both wires are tight, not to the point of straining but good and snug so as not to inject any slop into the system.

Look at Dave Patrick's web site davepatrickmodels.com . There is a step by step process on converting the Extra 330l to pull pull split elevators. When you get on the site go to Kits and click on the Extra 330L . You will find a heading called Notes about the Extra 330L You will find it there.
It's for a 25% Extra but I am sure it will work on any scale. The servo towards the top is the elevator servo which has two sets of cables connected to it. The bottom servo is for the rudder.
jef

Thanks again Jim. So if I'm reading it correctly. They are using 1 servo to controll 2 seperate elev. Halves? That would make things alot easier. And I also see that they haven't mounted it on its side. I am going to post that pic in a new thread to get some opinions. I appreciate all of your help.

Crash90, I had a Cermark Pitts that userd pull-pull rudder and elevators, making for SIX wires going back to the tail. I had ZERO problems with the setup and had 175 flights on the plane before I sold it. It used a single servo for the elevators and the servo was not mounted on its side.

I see JimRoss warned of balance issue before nailing it down, but I'm betting that's why you're considering using a pull-pull in the first place.

I'm considering setting up a pull-pull elevator system in my Wild Hare Extra (Later on, of course, I'm having too much fun flying it right now). I'll soon have a BME Extreme 110 for it (BME 105 now) and even now need 7 ounces of nose weight which will increase to almost 3/4 pound with the Extreme. Removing 5 ounces of servos from the tail will help considerably, since the receiver batteries could be moved back to easily balance the plane. Another thought is moving the wing tube mounting in the fuse back. Seems most 1/3 scale aerobats are set up for 6+ pound engines.

Like I said, I'm having too much fun flying it for now so any changes have to wait for cold weather.

When setting up the pull pull for the elev. is there anything I need to know? For example. Does the servo need to be mounted in the center of the fuse? Does it have to be mounted at the same height ad the stab?
It will be going into a 1/3 sukhoi which calls for a minimum of 80oz torque minimum per elev. I have 3 options.
1 Install 1 jumbo servo capable of handling the load.
2 I can install 2 servos connected together in the middle of the fuse

3 I can install 1 servo on each side of the fuse.
I think this is the best option as it will offer some redundancy.

Crash90, what engine are you planning to use in that Sukhoii?

BME 110 Xtreme.

I've seen several of that plane that use the ZDZ 80 single and have few balance problems, so your balance problems with the light Extreme may not be as pronounced as you think.

I would first mount the engine as far forward as possible (whenever you finally get it), set up a rudder pull-pull, and then mount your other components except for the receiver battery(s) and see where you are. If, after setting your receiver battery in front of the wing tube as close to the firewall as you dare, you STILL need over a pound of nose weight, then setting up an elevator pull-pull might be worthy of consideration.

I'm also thinking that if manufacturers would set planes up so they balance with, say, a 6 pound motor like the DA while using twin rudder servos in the tail, that would offer some latitude for lighter engines (use a rudder pull-pull) of heavier engines (probably just move receiver battery to the rear).

Another thing, before someone says it, the solution is NOT "Get a DA".

Pull Pull on elev is unavoidable. Most people with a pound of lead in the nose are still balancing well behind the factory recommended CG. The BME is almost a pound lighter that the zdz80. There is no question of "if" it is a matter of "how".

So move the rudder servo's if you must, leave the elevator servo's where they are, and put a pound of lead on the nose, the plane wont know it. Adding dead weight is a nono, but with enough power who cares.

Try a heavy spinner, or heavy prop. May help a bit.

Sorry JohnVH. I am looking to avoid as much weight as possible. I have all winter to work on it so time is not an issue. I am shooting for 23lbs. cant get there with the elev servos in the tail. Not without moving the wing back and I am hoping to avoid that.

why the 23lb goal? Maybe you should have picked a different plane that wouldnt have needed so much messing aroung to get it right with that engine? That engine should pull a 30lb plane no prob, so whats 24 or 25lbs going to matter?

Just trying to figure out why you would want to go through all this.

Bought the plane. Was gonna put the zenoah gt80 in it. A week or 2 later I decided to install the ZDZ 80. OK No biggie. A little CF here and there and a pull pull on the rudder and I should be fine.
Then the BME came along. Couldn't resist. Now I have a few options. Could add lead. Don't wanna. Could balance 3" behind the wing tube, don't wanna. Could install pull pull on elev. Sounds good. I am looking at it this way. There is no doubt in my mind that a 23lb Sukhoi will fly better than a 25lb Sukhoi. I am not as concerned about lead in the nose as I am with overall weight. I don't care if I need 3lbs of dead weight in the nose if I end up at 23lbs I will be happy.

I am doing alot of mods to this plane in preperation for the engine. There is a small chance that I wont need pull pull on the elev. However, I want to be prepared just in case.

I am having a blast with this plane. I am hoping that I do need the pull pull because I have never installed one on an elev. before. It will be fun. I think that arf building can be just as exciting as kit building if you put enough of your own personality into it.

So. That is the reason I bought this plane and this setup. Sounds corny I guess but I am having alot of fun and gaining a whole lot of knowledge. Thanks for your help.

I hear you, a lighter plane flies better. Sometimes there is a point at which I guess you have to decide how much work you want to put in it. Personally, thats too much messing around for me, But soulds like you like it!

Have fun! Will be insane with that big of an engine on a super light airframe!

Yeah. I guess insane is a good word. Actually I seriously doubt I will reach the 23lb mark. If I was willing to move the wings back 2" then definately.

I know that pull pull elev seems like more work than it's worth but for some reason I really want to do it. I will keep you posted and i'm sure I'll have more questions as I go. Thanks.