Questions and Answers If you have general RC questions or answers discuss it here.

Pull Pull system

Reply

Old 12-06-2005, 10:49 AM
  #1  
Campy
Senior Member
Thread Starter
My Feedback: (1)
 
Campy's Avatar
 
Join Date: Jan 2002
Location: Baltic, CT
Posts: 3,613
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default 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.
Campy is offline  
Reply With Quote
Old 12-06-2005, 11:38 AM
  #2  
jaka
 
Join Date: Dec 2001
Location: Upplands Vasby, SWEDEN
Posts: 7,799
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default 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
Attached Thumbnails Click image for larger version

Name:	Rp42531.jpg
Views:	6
Size:	145.1 KB
ID:	365882   Click image for larger version

Name:	Wq42642.jpg
Views:	5
Size:	47.2 KB
ID:	365883   Click image for larger version

Name:	Db83749.jpg
Views:	8
Size:	136.2 KB
ID:	365884  
jaka is offline  
Reply With Quote
Old 12-06-2005, 12:48 PM
  #3  
ballgunner
Senior Member
My Feedback: (1)
 
ballgunner 's Avatar
 
Join Date: Feb 2003
Location: Payson, AZ
Posts: 2,141
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default 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.
ballgunner  is offline  
Reply With Quote
Old 12-07-2005, 11:31 PM
  #4  
the_madgenius
 
Join Date: Aug 2004
Location: yeppoon, AB, AUSTRALIA
Posts: 338
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default 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 is offline  
Reply With Quote
Old 12-08-2005, 12:34 PM
  #5  
jaka
 
Join Date: Dec 2001
Location: Upplands Vasby, SWEDEN
Posts: 7,799
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Pull Pull system

Hi!
Thank's for the suggestion
I'm aware of the risk so I don't let the wires interfere with each other
Regards!
Jan K
jaka is offline  
Reply With Quote

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service