Pull Pull system
12-06-2005, 10:49 AM
#1
Pull Pull system
While I have been flying and building for 'a few years' 
, I have never done a pull pull system.
I am planing on doing a 1/6 scale Boeing P-26 from Cleveland plans as a winter project. This will be a 46 powered plane with a 56" wingspan.
I am wondering if installing pull pull is worth the effort (and headaches ) in a plane this size.
If so, how would you suggest doing the ailerons ? I have some small servos (BlueBird 306 or 308 w/metal gears rated @50oz ) I can use/easily fit in the wing for the ailerons. I am just not sure on how to do a hook up and routing for them. All the instructions I have seen deal either with the rudder or the elevator (Alan's RC page ).
Thanks.
, I have never done a pull pull system. I am planing on doing a 1/6 scale Boeing P-26 from Cleveland plans as a winter project. This will be a 46 powered plane with a 56" wingspan.
I am wondering if installing pull pull is worth the effort (and headaches ) in a plane this size.
If so, how would you suggest doing the ailerons ? I have some small servos (BlueBird 306 or 308 w/metal gears rated @50oz ) I can use/easily fit in the wing for the ailerons. I am just not sure on how to do a hook up and routing for them. All the instructions I have seen deal either with the rudder or the elevator (Alan's RC page ).
Thanks.
12-06-2005, 11:38 AM
#2
Join Date: Dec 2001
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RE: Pull Pull system
Hi!
A pull-pull system using thin fishing wire is the best metode to transfer motion from the servos to the flying surfaces. It also hinders vibration from the flying surfaces to go back to the servos destroying the potentiometer and electric motor. A pull-pull system is perfect for elevator and siderudder and is very easy to set up and weights little.
For ailerons this set up is not recommended as it is to difficult placing the wires inside the wing and having them take a 90degree turn to reach the ailerons.
Here a servo at each aileron is more feasible...or a having a single servo controlling both ailerons via an ordinary piano wire torque link system.
Here is some pictures from my Great Planes GEE BEE R-2 where I use wires to control both elevator and side rudder.
The drawing depicts the elevator linkage made up from a piece of black coloured, Easton arrowshaft (6,3mm thick) and a 100 mm long, 3mm pianowire and two 3mm allen head bolts (with heads cut off). The lenght of the pianowire makes the elevator very stiff.
Regards!
Jan K
Sweden
A pull-pull system using thin fishing wire is the best metode to transfer motion from the servos to the flying surfaces. It also hinders vibration from the flying surfaces to go back to the servos destroying the potentiometer and electric motor. A pull-pull system is perfect for elevator and siderudder and is very easy to set up and weights little.
For ailerons this set up is not recommended as it is to difficult placing the wires inside the wing and having them take a 90degree turn to reach the ailerons.
Here a servo at each aileron is more feasible...or a having a single servo controlling both ailerons via an ordinary piano wire torque link system.
Here is some pictures from my Great Planes GEE BEE R-2 where I use wires to control both elevator and side rudder.
The drawing depicts the elevator linkage made up from a piece of black coloured, Easton arrowshaft (6,3mm thick) and a 100 mm long, 3mm pianowire and two 3mm allen head bolts (with heads cut off). The lenght of the pianowire makes the elevator very stiff.
Regards!
Jan K
Sweden
12-06-2005, 12:48 PM
#3
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RE: Pull Pull system
It can be done on some types of aircraft. Piper J-3's through PA-18 have a single cable connecting the ailerons that runs through
through the wing. Cables connected to the stick run up the struts. If you sit in a J-3 you can see the cable and it's linkage directly overhead. This configuration allows some larger turning points to prevent kinking the cable. Single connecting wire goes to lower
control horns, cables up the struts to upper horns.
through the wing. Cables connected to the stick run up the struts. If you sit in a J-3 you can see the cable and it's linkage directly overhead. This configuration allows some larger turning points to prevent kinking the cable. Single connecting wire goes to lower
control horns, cables up the struts to upper horns.
12-07-2005, 11:31 PM
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RE: Pull Pull system
Jaka , i have looked at your installation, and if i may would like to offer a suggestion to you with regards the setting of the servos. I always use the pullpull system on my models and in setting up the servos i always stagger the rudder and elevator servo by making one a quarter of an inch higher than the other . This eliminates the possibility of the wires rubbing together or the clevices touching each other. When making your servo tray just add two pieces of ply glued to the tray to raise one servo.
the_madgenius, instructor downunder
the_madgenius, instructor downunder
