My old Raptor 50.
I meant when the stick is at the center or 0 degrees the servos should be at the center of their travel.

Here is a little (incomplete) writeup on how to set up a radio. It was for Mechanical mixing but I tweaked it a little for ECCPM.



The following assumes a modern computer radio with at least 5 points in the Throttle and Pitch curves. If the radio has more than 5 points simply interpolate. Less than 5 points, save up for a better radio.

The basic concept for mechanical setup is to provide a linear, mirrored response from the controls over the entire positive to negative pitch range. To do this, the mechanical levers and pushrods must move an equal amount on either side of the 0 degree center point. Once the mechanical setup has been completed, the radio software is used to tune the pitch and throttle curves for the desired flying style and response. The mechanical setup is identical for all flying styles and levels. This prevents constant readjustments of linkages and servos as flying skills increase.


Preliminary Setup:
Radio system is assumed to be fully charged, correct model and modulation is selected, and servos are plugged into correct ports. Helicopter is fully assembled and has mainblades installed.

- Pitch Setup
- Disconnect linkages from all servos.
- Power up Tx and Rx.
- Select Normal Mode, ensure pitch and throttle curves are 0, 25, 50, 75, 100%.
- Set all trims to center, subtrims to 0, ATVs to 100%.
- Pick one mainblade grip and mark the grip and blade. This will be the Master Blade. All setup adjustments will be done to this blade.
- Set linkage lengths according to the manufacturers manual.
- On the Tx move the pitch stick to the center position. On the cyclic/pitch servos, move the servo arms so they are at a 90 deg angle to the pushrods. Move the arms until a position is found as close to 90 deg as possible. If it is still a little off, use the Subtrims in the Tx to move the arms. Screw on the servo arms.
- Physically move the swashplate up and down. Find the center point of travel. This will be the Center/Zero point and the entire setup is referenced to this point.
- Look at bell cranks, mixing levers and washout levers. Adjust linkages as required to physically align all items to a 90 deg angle to pushrods, center of movement or level. The swashplate still stays at the center/zero point.
- Holding the swashplate so it stays at the zero point, adjust the length of the linkages so they connect to the servo arms.
- Install the pitch gage on the Master blade and move the blade perpendicular to the tailboom. The flybar should be exactly over the tailboom.
- Adjust linkages (usually the long links from the swashplate) on the main rotor head to obtain a zero pitch indication on the pitch gage.
- Now the Tx pitch/throttle stick is at center, swashplate is level at center/zero point, mainblade pitch is at 0 deg, all servo arms, bell cranks, mixing levers are at 90 deg to the linkages.
- Move the Tx pitch stick all the way up and down. Make sure the swashplate moves over the entire range of travel. If it does not, adjust the Swash Pitch CCPM percentages If it binds at the end of servo travel, reduce them. If the % is less than 30% or more than 80%, move the balls on the servo arms out or in and readjust the %s.
- Using the pitch gage check mainblade pitch to be in the range of at least –10 deg to +10 deg. Some helis may have pitch in excess of -/+ 12 deg. Reduce the CCPM % to evenly to show -/+ 12 deg approximately.
- Adjust linkage on the other blade to match the Master blade pitch.
- Adjust elevator and aileron CCPM % to get a mainblade deflection of about 6 degrees when the Tx stick is fully deflected. The head with the mainblades must be rotated 90 deg to get both aileron and elevator deflection readings on the pitch gage. The flybar must be held steady while taking pitch readings on the blade.
- Now the Pitch/Cyclic part of the mechanical setup is complete. The up and down movement mirrors each other and the response is linear. At center stick, everything is centered/level: servo arms, bellcranks, mixing levers, swashplate and mainblades. Adjustment for flying style is done later.
- Throttle Setup
- Set the throttle trim all the way down. Set pitch/throttle stick on the Tx to the midpoint (zero degree) position.
- On the carburetor, move the arm to the center of its travel range or on the midpoint tickmark on the carb body. Adjust the carb servo arm so it is at a 90 deg angle to the linkage if it would be connected to the throttle servo arm.
- On the throttle servo, move the servo arm so it is at a 90 deg angle to the linkage if it would be connected to the carb arm.
- With the throttle linkage connected at either the carb or throttle servo (not both), move the Tx pitch/throttle stick all the way up and down. Adjust ATV to fully open the carb without binding if the linkage would be connected. If the ATV is less than 90% or more than 120%, move the ball on the servo arm in or out and readjust the ATVs. Do the same at the fully down position to close the carburetor with the Tx stick in the fully down position. Both ATVs should be within 5% of each other.
- Connect the linkage and check again that the range of travel is sufficient to fully open and close the carb.
- Move the throttle trim up to the ¾ position. This will open the carb enough to allow the engine to idle. Enable throttle cut (if available) and check to make sure that activating throttle cut fully closes the carb. Alternatively, make sure that full down throttle trim closes the carb.
- The throttle should now be fully open at up stick, ½ way open at midstick and a little open at full down stick. Opening is CCW, closing is CW. ATVs should be evenly matched.
- Tail Setup
- As there are many gyros on the market, RTFM is required.
- Several items are universal in regards to gyros and tailrotor control. The linkage must be as smooth and drag free as possible. There must be no play in the tail components. The gyro sensor must be securely mounted to the heli. The tailrotor servo must not bind at end of throws.
- It is very important to correctly setup the tailrotor servo throw direction and gyro direction. The nose of the helicopter must follow the rudder stick. Left stick and the nose of the heli should swing left. If the heli is rotated, the gyro should input an opposing rudder command.
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- Final Setup
- Now the helicopter is setup mechanically. This setup should never change. All pitch and throttle curve adjustments for individual flying styles will be done with the pitch and throttle curves in the computer radio.
- Install the pitch gage on the master blade, move blade perpendicular to tailboom, ensure flybar is in line over the boom.
- Adjust Pitch point % iaw the appropriate level of flight experience.
- Adjust Throttle point % to give approximately 30% throttle at 0 deg stick, 50% at hover stick and 100% at full throttle.




Fritz