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|  |  | QQTECH TIP
Notice that eCCPM or mCCPM is not mentioned. Since all CCPM is done electronically (in the radio), there really is no mCCPM. What we have is "CCPM" or "Single Servo Mechanical" (can be shortened to just "mechanical" if preferred). No electronic mixing happens in a single servo setup, each servo is completely independent. When one servo fails in single servo machines, the radio still has control of the other two functions. This is not the case in a CCPM setup, where each servo relies on the others to complete their tasks. The terms eCCPM and mCCPM can cause quite a bit of confusion as the terms imply a similarity between the two, which is not the case. If one sticks to the historically more accurate terms of "CCPM" and "Single Servo Mechanical" it will help differentiate the two systems better. In other words, heli kits advertised as CCPM will be eCCPM, since that is the only type of CCPM available.
There is much debate on what the true advantages and disadvantages are for using CCPM over Single Servo. We will stick to the basics here and leave the debate for another time.
Some of the advantages of CCPM include:
• Easy mechanical setup, usually less linkages and hardware.
• Less slop due to less links.
• CCPM helicopters often weigh less, also due to the lower parts count.
• More torque is applied on the swash movements, multiple servos sharing the load compared to one in Single Servo.
Some disadvantages of CCPM may include:
• Interaction--this is evidenced by the "dance" a CCPM swashplate does on occasion, especially when it is moved quickly. Its cause lies in the basic geometry of the system (one servo has to travel a little more than the others to move the swash the same distance for elevator) and in the inherent, minute speed/wear differences between one servo and the next. The slower the servo, the worse the interaction. Modern radios do a pretty good job at taking this into account and rectifying the situation, but some interaction usually remains.
• CCPM helicopters that use direct links from the servos to the swashplate leave the servos more susceptible to damage in a crash.
• In a CCPM heli, when one servo dies inflight, all basic swash control is lost; slightly lowering the chances to save the heli.
• CCPM requires the use of high quality servos that are the same make and model (and preferably age), mixing servos or penny pinching here will cause some headaches in setup and in flight.QQ
4.Next, get the 3 servos moving in the right direction. This can be a difficult and trying task but there are some well known tricks that make it easy. Remember the following detail and things will be simple; servo reversing in CCPM is used to set the relation between the servos. Meaning they move together when they should, and in opposite directions when they should. Servo reversing is not used to reverse a function's direction, such as pitch or cyclic--for this, adjustments in the swash mixing menu will be made. | | | |
| | 5.Before connecting the swashplate to the servos, make sure the servos are moving properly in relation to each other. Use the servo reversing menu to do this. The two side servos (the pitch and aileron channels) are setup first using the reversing menu. Set them so that the two servo arms move in opposite directions when a left/right cyclic command is given (one arm moves up and the other moves down). Set the servo plugged into the elevator channel so that its arm moves in the opposite direction as the other two servos when a fore/aft cyclic input is given (the other two servos will move together with fore/aft swash movement). Only reverse the elevator servo to fix the fore/aft direction, leave the aileron and pitch servos at the settings set in the left/right setup above. | |  | | | |
|  | | 6. Now move on to getting the servos moving in the right direction in relation to the helicopter. Center the controls and connect the swashplate, making sure it is level and in the EXACT center of its travel range by adjusting the linkages. Move the throttle/pitch stick up, if the swash is moving in the right direction (inducing positive pitch) then this function is working properly. If the swash is giving negative pitch when positive is expected, use the swash mix menu to reverse it by changing the value for Pitch in the menu from a positive to a negative (retaining the same number value). For example, if the number next to Pitch in the radio was +70, setting it to -70 will reverse the pitch function and make the swash move in the opposite direction. Do the same thing with the Aileron function (left/right cyclic) and the Elevator function (fore/aft cyclic)--using the mix numbers to reverse the direction if necessary. | | | |
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