Hello everyone,
I am building a Goldberg Chipmunk ( .60 size ) , and was thinking of using a pull pull system for the rudder.
This is the first time i would be using a pull pull control and thus had 2 concerns :
1. Should i use a 2-56 pull pull setup or a 4-40 one
2. Does anyone have any pictures of this , to share, so i can see how they have done it on the Chipmunk ?


Thanks to all !
Gaurav

Forget the specialized pull-pull "sets." Just head to a hardware shop (or fishing shop) and get some those "wire cable." I've used .50mm size cable on 40-size models, but it's such strong stuff that I'm sure the rest of the model would break before the cable does.

Remember that very commonly, the rudder cables will cross over each other so that the right arm of the servo (or bellcrank) is connected with the left rudder horn and vice versa. This usually allows a straighter cable run.

The other thing that many people worry about is a bit of geometry called "Ackerman." Personally, I don't think this is a big issue on most models, but you're looking to wring out the most performance on a high performance model then you'll want to look into this.

I used a Pull-Pull on my CG Chipmunk.. It was a really nice plane, while it lasted.. But that was just another hard lesson and not due to loss of control.

With the pull-pull I used a regular Sulivan 2-56 wire setup and it was plenty. I "crossed" my pull-pull wires between the rudder and the servo (wire from right side of rudder went to the left side of servo), because it gave me the best straight lines to the control points.

I also made some nice exit guides out of thin aluminum tube that just fit a piece of spray tube inside. Like the tube that comes on WD-40 cans. This allowed me to glue the tube into the fuselage side easily and the tube provided a vibration barrier for the pull-pull wires.

The setup worked great, just mount the rudder servo in the center of the fuselage.

I just ordered a G,B Chipmunk kit. Is it a good kit? is all the parts there or will I need to buy other parts? How many hours do you have into it, How are the plans any info would help.

Hi,

IMHO the CG Chipmunk kit builds into one of the "best flying" models around albeit it isn't a 3D machine. However it is not just a matter of throwing in some CA and shaking the box. It does require some building and flying skills. Mine has a ST 75 and the following mods.

I used two aileron servos mounted in hatches, one in each wing panel.
I hate adding lead to balance so I mounted the rudder and elevator servos rearward of the position indicated in the plans.
I would strongly recommend that you buy an after market cowl as the plastic cracks and cracks and cracks until I was so sick of repairing I glassed the entire inside.
I sometimes fly off a fairly rough grass strip so I used larger wheels and didn't fit the wheel pants. If you fly off a hard surface runway the standard wheels would be fine. There are a number of good build threads for this kit here at RC Universe. Don't be put off by some of the negative comments about the kit, if you are half way competent at building it is a "no brainer". If it's your first kit you may need some assistance.

Cheers,

Colin

I've built many kits just not this one but always wanted to. I'm just looking for as much info as I can get on building this so as I go along I build it right. I was already putting 2 servos in for the alerons and also maybe some flaps. I like to ask questions before I build.

This kit builds "heavy" so I drilled lots of holes trying to lighten it but it still came in around seven lbs. I haven't flown this one yet but my first one was lots of fun. There is a build thread somewhere on the net, try Googling "Goldberg Chipmunk".
I think the pull-pull rudder is a good idea I should have done it because the rod I'm using is long and it looks like it is going to bend with any air "load" on the rudder.
Post some photos when you get going.