 |  | Cyclic Collective Pitch Mixing, or CCPM for short, is one of the two popular methods for controlling the swash of a RC heli. CCPM has been around and available for numerous years, but has really taken a foothold in the hobby recently. Modern radios make CCPM easier and more problem free than earlier hobbyists could have ever dreamed. With a little understanding and some simple tips, any heli pilot can be a CCPM expert.
Explanation of CCPM
CCPM can simply be defined in a helicopter as multiple servos working together, interdependently, to execute all the control movements (collective, aileron, and elevator) of the swashplate. There are 4 servo and 3 servo CCPM setups, this discussion will focus on what the majority of the CCPM helicopters use, a 3 servo 120° setup. The other method of swash control, non-CCPM, is often called Single Servo Mechanical. What is the difference one may ask? In simple terms, Single Servo Mechanical control uses a single servo for each control movement, and these servos are completely independent of each other--each has a duty that is distinct on the swashplate.
On the other hand, CCPM mixes a combination of the three servos together to complete the control movements. For example, when the collective stick on a radio is moved all three servos will flow in unison to raise or lower the entire swashplate accordingly. In CCPM no swash movement occurs without at least two servos doing the job.
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| Mechanical AND RADIO SETUP
The mechanical setup of a CCPM heli is extremely important, just as on non-CCPM machines. Doing proper setup in the beginning saves time and prevents troubles later on. It is important to follow the manufacturer directions as closely as possible from the manual. The crucial thing to remember with a CCPM setup is symmetry and right angles. The radio setup is also included in this section as they are intertwined.
1. Build the helicopter per the instructions, setting all linkages (and bellcranks if applicable) to the correct lengths. Install the servos and plug them into the proper channels. Many pilots get stuck at this stage, deciding which servo plugs in where. This can be confusing but there is a simple way to do it. Plug the servo that controls the ball that is inline with the frame of the heli (the ball that sits directly behind or in front of the mainshaft) into the elevator channel of the receiver (channel 3 on a JR system, channel 2 for Futaba and Hitec, for other makes check the radio manual). Then plug the other two swash servos into the aileron and pitch channels (channels 2 and 6 on JR radios). Do not worry about which of these two servos ends up in which channel, they will be taken care of in the radio setup. | |  | | | |
|  | | 2. Turn on the transmitter and set it to 120° CCPM in the swash type menu (or 140° if the heli is a 140° machine). Center all the trims, get rid of any sub-trim, and make sure all endpoints are at 100% for the 3 swash servos. It is also crucial at this point to set a linear pitch curve (0, 50,100) for the initial setup.
3.Make sure the throttle stick is at the halfway point (for electrics, make sure the motor is disabled). With the servos centered, try attaching control arms to the servos so each arm is perfectly lined up, either parallel with the servo, or exactly 90° to it depending on the heli. It is important that it be as close as possible to perfect, try various servo wheels and arms until one is found that fits the bill. If necessary, use a small amount of subtrim to center the arm, but only as a last resort. It is best to do as much mechanically with the arms and links. Once the three "perfect" arms have been found, install the ball links to them at the distances instructed in the heli manual then install the arms on the servos. | | | |
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