Pull Pull on rudder questions
07-28-2003, 03:01 PM
#1
Thread Starter
Pull Pull on rudder questions
Hi,
I am setting up a pull pull system on a 24% extra 300. The servo is placed right behind the engine and absolutely in the center of the fuselage. My 2 questions are:
1. Do BOTH the wire stay TIGHT through the entire motion, TOGTHER!!!!
2. I am using an offset arm. Which direction is the arm supposed to be attached to the servo. To clarify firther, presuming the offset arm is a very WIDE VEE shape, what direction is the VEE pointing towards? The rudder or the engine?
I am setting up a pull pull system on a 24% extra 300. The servo is placed right behind the engine and absolutely in the center of the fuselage. My 2 questions are:
1. Do BOTH the wire stay TIGHT through the entire motion, TOGTHER!!!!
2. I am using an offset arm. Which direction is the arm supposed to be attached to the servo. To clarify firther, presuming the offset arm is a very WIDE VEE shape, what direction is the VEE pointing towards? The rudder or the engine?
07-28-2003, 03:10 PM
#2
Pull Pull on rudder questions
Wow,
That sounds really up far for the rudder servo, usually it is put right on the CG. Reason being that you don't want to mount stuff under and around the wires that could contribute to interference or get mechanically caught up in the wires.
Answer to your questions,
-both wires are "supposed" to stay tight. It is all based on geometry and eaiser said then done.
-the "V" should point to the motor. What you are trying to do is match the geometry of the rudder horns. i.e. your hinge line = arm pivot and the control horns = the outer holes.
Check out WWW.aeroprotect.com for some set up pictures.
RickP
That sounds really up far for the rudder servo, usually it is put right on the CG. Reason being that you don't want to mount stuff under and around the wires that could contribute to interference or get mechanically caught up in the wires.
Answer to your questions,
-both wires are "supposed" to stay tight. It is all based on geometry and eaiser said then done.
-the "V" should point to the motor. What you are trying to do is match the geometry of the rudder horns. i.e. your hinge line = arm pivot and the control horns = the outer holes.
Check out WWW.aeroprotect.com for some set up pictures.
RickP
07-28-2003, 03:22 PM
#3
Thread Starter
Pull Pull on rudder questions
Rick, the servo has been setup close to the engine due to CG concerns. The CA24% ends up being tail heavy and hence I have got the servo up ahead.
Can you elaborate more about part 2 of the question.
Can you elaborate more about part 2 of the question.
07-29-2003, 01:56 AM
#4
Senior Member
Pull Pull on rudder questions
When the rudder is at neutral, the wires should be tight, once they are deflected, the wire that's "pulling" will be tight as blow back will keep pressure on the rudder thus keeping the wire tight. However the other wire can get limp at that piont with no problems (i.e. flutter can not occur).
The bottom of the "V" should point to the motor.
As Rick said, be carefull that the rudder servo and it's extensions and even pull-pull wires don't pick up Rf noise from the ignition (assuming your using a motor with an elec. ignition).
Also keep in mind that if you cross your pull-pull wires (usually done to create better angle to leave the fuse sides) that they don't rub on each other. There are a few tricks to prevent this from tipping the servo tray to running the wires through a piece of inside nyrod.
Best of luck...........Mark
The bottom of the "V" should point to the motor.
As Rick said, be carefull that the rudder servo and it's extensions and even pull-pull wires don't pick up Rf noise from the ignition (assuming your using a motor with an elec. ignition).
Also keep in mind that if you cross your pull-pull wires (usually done to create better angle to leave the fuse sides) that they don't rub on each other. There are a few tricks to prevent this from tipping the servo tray to running the wires through a piece of inside nyrod.
Best of luck...........Mark
07-29-2003, 05:10 AM
#5
Thread Starter
Pull Pull on rudder questions
Thanks for the info guys. Much appreciated...I have setup the system now..and there is slight slack on the push side. Looks ok. There is no gas engine and no wire crossing, so I guess I am ok on that account to.
07-29-2003, 11:22 AM
#6
Pull Pull on rudder questions
No problem,
It's basically a geometry issue, and perhaps you could draw it out for a better picture. The problem is that the clevis mounting points are not in a straight line with the hinge pin on the rudder. so when you deflect the rudder the clevis that moves away from the servo doesn't move as far. so the line gets slack. I hope this helps - but consider the perfect case. If the pickup points and the hinge point are in a straight line on the rudder and the matching points and center of the servo arm are perfectally lined up there will be no geometry problems and, ideally, no slack. On a 1/4 scale some slack is acceptable, but I just finshed a set up on my 1/3 scale and it works awsome.
Check that site, allot of good info (follow the construction links) there
RickP
It's basically a geometry issue, and perhaps you could draw it out for a better picture. The problem is that the clevis mounting points are not in a straight line with the hinge pin on the rudder. so when you deflect the rudder the clevis that moves away from the servo doesn't move as far. so the line gets slack. I hope this helps - but consider the perfect case. If the pickup points and the hinge point are in a straight line on the rudder and the matching points and center of the servo arm are perfectally lined up there will be no geometry problems and, ideally, no slack. On a 1/4 scale some slack is acceptable, but I just finshed a set up on my 1/3 scale and it works awsome.
Check that site, allot of good info (follow the construction links) there
RickP
