EVERY MANUFACTURER IS ADVERTIZIZING CCPM – WHY? BECAUSE IT WORKS SO WELL.
What exactly is CCPM? Is it a gimmick, an RC helicopter marketing buzz word like 3D (don’t get me started on that one)? I am glad to say no, it simplifies life for you, makes your servos happy, and makes your helicopter fly better (usually).
Before I get ahead of myself, I better explain what CCPM stands for and what it does... the benefits will then become obvious. It is an acronym that stands for... Cyclic-Collective-Pitch-Mixing. This feature is only found on RC helicopters with
(as the name suggests), it doesn’t apply to
I should mention that you will see CCPM referred to as electronic (eCCPM) or mechanical (mCCPM) mixing. While this is the "correct" way to differentiate between the two mixing types ("e" or "m"), I feel it adds too much confusion for the beginner RC heli enthusiast. Seeing that most CCPM swashplate types these days focus on electronic mixing, that is what I will also call electronic mixing in this discussion and mechanical swashplate mixing I will just simply call mechanical mixing.
Until CCPM came around, we only called our mixing method mechanical. A way to control pitch function and cyclic function by means of a complex series of linkages and levers. Most systems consisted of mixing the collective pitch servo movements with the left/right cyclic servo and the fore/aft cyclic servo movements to the swashplate.
The big disadvantage with mechanical mixing comes from all the linkages and levers; there is always a bit of slop or play in them. This can be minimized on high end helis by using ball bearings on all these levers instead of simple bushings, but of course that adds to cost and weight.
This method of pitch control also puts a lot of strain on the pitch servo. It not only has to move the entire swash pate up and down to change the pitch angle of the main rotor blades, it has to overcome all the friction associated with all the linkages.
Mechanical mixing does have a few advantages, such as no complicated
to avoid variation issues and because the servos are usually mounted in a servo tray and not in the frame, they are exposed to less vibration.
These are minimal benefits seeing that todays servos are much tougher and there are ways to almost eliminate swash plate variations with a good computerized programable radio and knowing the proper setup procedures.
Cyclic-collective-pitch-mixing is only possible because of advances in computerized RC radio technology. The mixing functions are all done electronically within the
all interact and move accordingly.
Now two, three, or sometimes four servos can be hooked directly to the swash plate with out any complex mixing linkages. This of course simplifies the helicopter, reduces the number of parts, weight, and cost. There is less slop in the system and this provides very precise control of your helicopter.
The problem of excessive strain on the pitch servo is also gone. Not just because the linkages are gone, but also because the work load is now spread over two or more servos.
There are basically three different CCPM "modes" available.
The most common uses three servos that are equally placed at 120° intervals around the swash plate. The problem with this is the left and right movement of the swash plate is a bit faster than the fore and aft movement. This will cause some slight variations in control as the servos catch up to one another to create the proper swash plate angle. I should point out that this variation gets worse at the extreme ends of swash plate travel and for us average Joe fliers is totally undetectable.
To cure this issue some manufactures now offer 140° CCPM. With the 140° set up the the geometry is evened out between the side servos and the front or back servo. This gives more consistent interaction between all 3 CCPM servos and reduces swash plate variations. As this is a new development, only a few RC radios are supporting 140° mixing. This method will undoubtedly become more popular because it works very well.
The third method is 90° CCPM in which two or sometime four servos are used and inputs are placed at 90° intervals around the swash plate (fore, aft, left, right). Again because of the consistent placement - swash plate variation is reduced. It makes sense on micro electrics in the two servo configuration saving the weight of a 3rd servo. On larger models however, it does put more strain on just two servos - a 3 servo set up is much better.
4 servo 90° mixing is hardly ever used even on the biggest of helis these days. The biggest problem with the 4 servo set up is the opposing servos 180° from each other, no matter how evenly matched and adjusted will end up playing tug of war. This not only puts excess strain on the servos, it eats into battery time.
OK, no system is perfect and CCPM does have a couple of draw backs. First has to do with that "variation" in swash plate movement I was talking about.
Even with the 90° or 140° CCPM set up, if your servos aren't matched (move at the exact same speed) you will run into variation issues. With today's equipment that is unlikely, but something to keep in mind and watch for as your servos age.
The next possible draw back with Cyclic-Collective-Pitch-Mixing is that with all the servos responsible to correctly position the swash plate, if one servo failed, you would loose complete control of your helicopter.
With the mechanical system if one servo fails, you will still have partial control. I really don't buy this argument at all. First off, servo failure is much more likely with one servo doing all the work instead of spreading the work load over two, three, or four. Second, even with a mechanical system if a servo fails, it is still almost impossible to control and save the bird.
I think you can appreciate the benefits of Cyclic-Collective-Pitch-Mixing are much greater than the "possible" draw backs. CCPM simply works and works well. It is something you should definitely insist on.
Almost all mid to high end helicopters (that have collective pitch) come standard with Cyclic-Collective-Pitch-Mixing these days. There are also CCPM upgrade kits available to convert a mechanical system into an electronic system.
Keep all this in mind when you are getting your Helicopter or Radio. Don’t get a helicopter that has Cyclic-Collective-Pitch-Mixing if your RC radio doesn’t support it. Also make sure your radio will support the CCPM system you have (90°, 120°, or 140°).
If you wanted to learn more about
120/140 CCPM swashplate setup
, I have an e-book that goes through the entire process. Just click on that link or the image of the e-book if you are interested in it.
I hope that clears up any “Mix-ups” you might have had. Sorry - bad humor, just couldn’t resist.
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