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Old Jun 20, 2011, 03:22 PM
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Allan Gibbs's Avatar
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What's the difference between a CCPM and non-CCPM helicopter?

Sorry if this is a dumb question but what's the difference between the two?

I'm a little more familiar with CCPM. You have three servo where one governs the aileron, the blade pitch, and the elevator and all three work in concert to manuver the helicopter.

But what about a non-CCPM helicopter? The only one I'm familar with is the Walkera Creata which has a fourth servo in the bottom. The description below is from HeliPad's ad. And the way I understand it, the 4th servo in the bottom is actually the blade pitch servo? So, then what does the right servo (typically the pitch servo on a CCPM) do? Does it move the swash to the right?

Lastly, what's the advantage or disadvantage of the CCPM vs. NOR/HPM? Thank you.

Quote:
What is the difference between 60#B and Creata 400?
The Walkera Creata 400 is a NOR design (non-ccpm mixing method, walkera name this technology "NOR", other manufacturer may call it "HPM"), when you add throttle, there is a "Pitch" servo that moves to push up the Main Blade pitch, this servo is located at the bottom of the main frame. The Walkera 60#B is a CCPM design, it means when you add throttle, the transmitter tells the motor to spin faster and tell all 3 cylic servos to move to increase the Main Blade pitch. CCPM design requires good quality servos, becuase you want 3 servos to work seamlessly to get percise blade pitch. CCPM is a common design for now-a-days RC helicopters.
http://www.helipal.com/walkera-creat...d-edition.html


You can see the fourth servo in the bottom:
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Old Jun 20, 2011, 05:01 PM
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Bundesrepublik Deutschland, Rheinland-Pfalz, Kaiserslautern
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Non-CCPM just means, you have 3 servos, that are mechanically mixed to control the swashplate. It has nothing to do with the throttle. Get the T-Rex 450 HDE and the CDE manual to see the difference.
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Old Jun 20, 2011, 07:49 PM
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Quote:
Originally Posted by Allan Gibbs View Post
Sorry if this is a dumb question but what's the difference between the two?

I'm a little more familiar with CCPM. You have three servo where one governs the aileron, the blade pitch, and the elevator and all three work in concert to manuver the helicopter.

But what about a non-CCPM helicopter? The only one I'm familar with is the Walkera Creata which has a fourth servo in the bottom. The description below is from HeliPad's ad. And the way I understand it, the 4th servo in the bottom is actually the blade pitch servo? So, then what does the right servo (typically the pitch servo on a CCPM) do? Does it move the swash to the right?

Lastly, what's the advantage or disadvantage of the CCPM vs. NOR/HPM? Thank you.



http://www.helipal.com/walkera-creat...d-edition.html


You can see the fourth servo in the bottom:
You basically described the differences already in your post Allen. CCPM or cyclic collective pitch mixing came about with the use of computer TXs. The TX can mix the three cyclic servos to move in unison so that they can also move the swash for pitch changes. Non CCPM heli use an additional servo for pitch movement and cyclic movement is independent of pitch. There are still some popular helis which use non CCPM such as Thunder Tiger.

The advantage of CCPM is the heli itself is less complex.The disadvantage is there can be cyclic interactions if all the servos are not moving at exactly the same rate or stopping at the same position. This is why you will always hear people say to always use the same servo types for cyclic control. You have to also consider that the servos are doing double duty and there will be limitations of the servo movement since they have to be able to provide enough cyclic movement while sliding the swash up or down at the same time. Cyclic travel will influence the amount of pitch travel that is available before something binds and so forth.
I've heard some hard core 3D guys claim that the non CCPM helis are much more "pure" because they don't suffer from cyclic interactions but I don't think I will ever fly good enough to notice this difference and I will take the simplicity of the CCPM anytime......less stuff to break or replace.
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Old Jun 21, 2011, 02:45 AM
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Thank you.
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Old Jun 21, 2011, 04:55 AM
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In both cases you need 3 servos for the swash, right? You just don't need the mechanical mixer...
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Old Jun 21, 2011, 11:09 AM
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Originally Posted by daybyter View Post
In both cases you need 3 servos for the swash, right? You just don't need the mechanical mixer...
Yes, there are three servos on the swash either way.
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Old Jun 21, 2011, 11:39 AM
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I can only remember a servo for the aileron, a servo for the elevator, and a servo for the pitch. That was with my Hirobo Shuttles and others. You need another servo for the engine. In any case, they were miles easier to set up than the CCPM helis today.
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Old Jun 21, 2011, 05:29 PM
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In a related question, do the servos horns on a non-CCPM helicopter need to be at 90 degrees like on a CCPM heli?
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Old Jun 22, 2011, 04:06 AM
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Yes...
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