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HomeAircraftHelicopterHelicopter Main Discussion › 90,120 140 swash
09-04-2018 06:06 PM  72 days agoPost 21
wjvail

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Meridian, Mississippi

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BeltFedBrowning
My JR gasser had something similar. I considered it MCCPM
I would agree and I think that is how many people use the terms mCCPM or eCCPM. How are the servos mixed to achieve the desired swash control - mechanically or electronically?

I believe the point TMoore is making is that at no point are pitch, roll and collective mixed. In fact, great lengths have been taken to see that roll is just roll - no pitch or collective input required or desired. Same for pitch and collective - no mixing involved.

Still, there a question mark... have I got that about right?

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09-04-2018 06:07 PM  72 days agoPost 22
TMoore

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Cookeville, TN

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wjvail
As it applies to model helicopters... The outer ring of most of our swashes has three control balls. We also have to achieve three control functions - pitch, roll(cyclic), and collective. Very conveniently we have three servos to achieve these goals. 3 servos, 3 input points, 3 functions. It would seem pretty simple to hook one servo to each of the input points and call it job done. Obviously that isn't going to work. We need some mechanism to mix these three servos to input the proper control to the swash. We need a mechanical mixer (to achieve the desired Cyclic/Collective control). We need a Mechanical Cyclic Collective Pitch Mixer.
No, we don't need a mechanical cyclic collective pitch mixer. I would think that someone that flies full size would understand what you just said is not mixing? Why does a swash have to have 3 control balls? Schluter didn't for years using the System 80. Where is the mixing in your scenario above? There isn't any mixing. The control functions you describe aren't mixed they are separate. It doesn't matter how collective pitch is input to the rotor head, whether you do it through a moving swashplate, pitch slider or sliding washout base, the fact remains that THERE IS NO BLOODY MIXING GOING ON in that system. Collective pitch is a standalone function just like pitch and roll. There is no radio mixing, no mechanics that are mixing anything. Mixing means that two or more inputs are combined into one output. That's not happening in a mechanical collective system. Here's the acid test. The system you describe can be flown with a 4-6 channel airplane radio while a CCPM heli with directly connected servos to the swash cannot be flown with an airplane radio. (I'm not going to include an FBL controller in the argument because most FBL controllers take the radio inputs and mix them to the flight control system which is a completely different subject)

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09-04-2018 06:32 PM  72 days agoPost 23
TMoore

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Cookeville, TN

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wjvail
BeltFedBrowning
My JR gasser had something similar. I considered it MCCPM
I would agree and I think that is how many people use the terms mCCPM or eCCPM. How are the servos mixed to achieve the desired swash control - mechanically or electronically?

I believe the point TMoore is making is that at no point are pitch, roll and collective mixed. In fact, great lengths have been taken to see that roll is just roll - no pitch or collective input required or desired. Same for pitch and collective - no mixing involved.

Still, there a question mark... have I got that about right?
There is no mixing going on in the JR gasser anymore than with an R90 or R50. Each individual servo controls one function on that helicopter. The terms mCCPM and eCCPM were made up terms by some magazine writer from the UK. CCPM is actually a software function not just an electronic function; case in point; if you take an old analog radio and try to use purely electronic channel mixes to make a CCPM system work on a heli good luck to you. You need software to make it happen and that's what the 8SGHP and the Multiplex as well as the old Royal EVO's and CM Rex'es of the world had, they had software that enabled CCPM, not eCCPM, just CCPM. Even the Japanese in their manuals don't use the term m or e. Spektrum and Futaba doesn't use it, Sanwa, no one. Why is that?

There is no amount of mixing that you could do in a old radio with just mixers to drive a directly connected swashplate unless you had software that was written specifically for that function or you had some form of macro variable based mixing and free programs that could essentially be used to mix the servos into the proper control functions and then map the end point controls to pitch curves and EPA's for fine tuning. Is that electronic? Partly but mostly it's software. CCPM has always been software, the only electronic part is the hardware the software ran on. That's what modern radios can do, they allow you to connect 3 or 4 servos directly to a swashplate and interpolate the stick inputs to meaningful outputs at the rotor head. Adding the "e" to the term CCPM does nothing. CCPM was already well defined and needed nothing more to be added to it to make it mean more than what it already meant.

As I said earlier, if you can fly a heli with a 4 to 6 channel radio, there's no mixing going on.

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09-04-2018 06:58 PM  72 days agoPost 24
wjvail

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Meridian, Mississippi

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I think we are getting hung up on the literal use of the word "mixing".

Let's come at it from another direction. I think we can agree that the "device" at the front of the below helicopter is required for it to fly as it was designed. I cannot remove it and expect the helicopter to fly. The 3 electromechanical devices we call servos are combined (not mixed) in such a way as to tilt, roll and lift the swash in the desired fashion.

I think we are hung up on calling this a mechanical mixer.?.? I agree - semantically we are not mixing the servos. Then what - we are combining them? That isn't it. We aren't combining in the literal sense. We aren't ganging them together.

What would you like to call the device in question? What could we call this control system? If not a mechanical mixer (and I think I see your point) what should we call it? Mechanical Cyclic Collective Pitch Controller? What would you call a system that combines the input of 3 servos in such a way as to achieve the movement of the swash. Mechanical mixer is out. Mechanical controller? mCCPC?

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09-04-2018 07:16 PM  72 days agoPost 25
TMoore

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Cookeville, TN

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wjvail
I think we are getting hung up on the literal use of the word "mixing".

Let's come at it from another direction. I think we can agree that the "device" at the front of the below helicopter is required for it to fly as it was designed. I cannot remove it and expect the helicopter to fly. The 3 electromechanical devices we call servos are combined (not mixed) in such a way as to tilt, roll and lift the swash in the desired fashion.

I think we are hung up on calling this a mechanical mixer.?.? I agree - schematically we are not mixing the servos. Then what - we are combining them? That isn't it. We aren't combining in the literal sense. We aren't ganging them together.

What would you like to call the device in question? What could we call this control system? If not a mechanical mixer (and I think I see your point) what should we call it? Mechanical Cyclic Collective Pitch Controller? What would you call a system that combines the input of 3 servos in such a way as to achieve the movement of the swash. Mechanical mixer is out. Mechanical controller? mCCPC?

I call it nothing. There's no mixing going on. There are three separate functions there. What two functions are combined into one output?

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09-04-2018 08:19 PM  72 days agoPost 26
wjvail

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Again, I see your point but I think you're being very literal.

Years ago model helicopters had a fly bar. They had two control systems - Bell and Hiller. One controlled collective and the other controlled cyclic. These two systems met at the mixing levers. (You knew all that.) I think what you are saying is that this too was a misnomer. The "mixing" levers were, in fact, designed to prevent the two systems from interacting. At no point did a collective input "mix" with cyclic and vice versa. One side of a "mixing" lever was responsible for collective and the other for flybar cyclic controls. No amount of flybar displacement resulted in collective. Likewise, extremes in collective would never result in a pitch/roll input. Literally these would be better called anti-mixing levers.

V-Tail mixing? Nope - no mixing. Rudder is Rudder and Elevator is Elevator. Mechanical and electronic "mixers" don't exist. There is no mixing. No amount of up elevator will result in a rudder input. Hard rudder will not induce a pitch command.

Similarly what has become commonly called mechanical mixing in helicopters is actually carefully designed to preclude mixing. I suppose we could call it Mechanical Cyclic Collective Pitch anti-Mixing.

No mixing. Got it. I see your point but find the reality cumbersome. The terms mCCPM and eCCPM may be grammatically incorrect but they do serve a purpose. They have come to mean a specific thing and with their use, everyone knows what you are talking about.

Am I getting close to understanding your message?

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09-04-2018 10:33 PM  72 days agoPost 27
TMoore

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Cookeville, TN

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wjvail
Again, I see your point but I think you're being very literal.

Years ago model helicopters had a fly bar. They had two control systems - Bell and Hiller. One controlled collective and the other controlled cyclic inputs. These two systems met at the mixing levers. (You knew all that.) I think what you are saying is that this too was a misnomer. The "mixing" levers were, in fact, designed to prevent the two systems from interacting. At no point did a collective input "mix" with cyclic and vice versa. One side of a "mixing" lever was responsible for collective and the other for flybar cyclic controls. No amount of flybar displacement resulted in collective. Extremes in collective would never result in a pitch/roll input. Literally these would be better called anti-mixing levers.

V-Tail mixing? Nope - no mixing. Rudder is Rudder and Elevator is Elevator. Mechanical and electronic "mixers" don't exist. There is no mixing. No amount of up elevator will result in a rudder input. Hard rudder will not induce a pitch command.

Similarly what has become commonly called mechanical mixing in helicopters is actually carefully designed to preclude mixing. I suppose we could call it Mechanical Cyclic Collective Pitch anti-Mixing.

No mixing. Got it. I see your point but find the reality cumbersome. The terms mCCPM and eCCPM may be grammatically incorrect but they do serve a purpose. They have come to mean a specific thing and with their use, everyone knows what you are talking about.

Am I getting close to understanding your message?

Collective pitch is totally separate from a servo rotor(flybar) and besides this discussion has not one thing to do with that. The terms m and e are misapplied and don't mean squat. CCPM is software mixing of the swash motion and mechanical is separate functions that allow you to drive the swash. If you unplug aileron and elevator, does collective still function on your X-Cell? Of course it does, hence NO MIXING. Same applies to elevator and aileron channels, unplug the collective and you can still operate pitch and roll, hence NO MIXING.

If you do the same test on a CCPM heli the machine is unflyable because there is mixing to achieve input to the blades. Same coming out of an FBL controller. Like I said, why don't the radio manufacturers use those terms? They don't for a reason.....because they don't apply.

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09-22-2018 12:16 AM  55 days agoPost 28
CBell

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Nova Scotia, Canada

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This used to be my favorite RR topic to debate. I'm with wjvail... just wanted to chime in for old times sake

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09-22-2018 02:56 PM  54 days agoPost 29
Jerry K

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Houston Area

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I have to tell you Mark has a big smile on his face, thinking just like the old days, that you two put there. I think it is great for Mark. You are arguing semantics, and it must be raining because you both have too much time on your hands. I am going flying.

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09-22-2018 03:56 PM  54 days agoPost 30
wjvail

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Meridian, Mississippi

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Jerry K
I have to tell you Mark has a big smile on his face, thinking just like the old days, that you two put there. I think it is great for Mark. You are arguing semantics, and it must be raining because you both have too much time on your hands. I am going flying.
A few of us in this thread have been here a while. Terry and I have exchanged thoughts here for more the 15 years - sometimes more pointed than others but always respectful. Of course Mark has been here the longest - but not by much.

Colin... Thanks for the support and may I add it's good to hear from you.

Sometimes I just feel like writing. It clears my head and forces me to focus. Very often I feel like writing when it's better to stay indoors. Often that means it's raining but most times, here in Mississippi, it's uncomfortably warm (i.e. really friggen hot).

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09-22-2018 04:01 PM  54 days agoPost 31
BeltFedBrowning

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Kansas City

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I agree that it is semantics. The helicopters that we call MCCPM are mixing, just not with electronics. The mixing happens when the pitch servo moves the mechanical outputs of the ele and ail to change the pitch of the blades.

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09-22-2018 04:41 PM  54 days agoPost 32
CBell

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Nova Scotia, Canada

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wjvail, likewise! I completely understand where you're coming from. Reading/writing is a stress reliever for me, plus it's raining outside.

We all understand how it works, and it comes down to debating the wording. There are tons of mechanical mixers available for a number of applications. The mixing valve in your shower is one (two inputs, a mixed output). At the end of the day we all know what it's doing.. but I'm gonna keep calling it mechanical mixing

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09-22-2018 05:37 PM  54 days agoPost 33
dialarotor

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Traverse City, Michigan

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now that is how you "rain" on an argument/debate/opinion/theory, whatever, good one Colin.

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09-23-2018 04:17 PM  53 days agoPost 34
Danny Calderone

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South Jersey

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I always enjoy when the helicopter theory and / or fundamental subjects get resurrected. Not for anything other than forcing us to review what we have learned (and for some of us to learn more yet), as well as serving as the perfect example to newcomers (and reminder to us old dogs) of what makes this forum such powerful database to support the hobby. I see both sides of this one completely.... but with an engineering and machinist mind, I will always favor literal accuracy.... I'm team TMoore on this one

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09-25-2018 01:07 PM  51 days agoPost 35
wjvail

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Meridian, Mississippi

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I've given this far too much thought.

I think the root of the discussion is that some of us see "CCPM", Collective Cyclic Pitch Mixing, and see the output side. Terry is pointing out Collective and Cyclic Pitch are not mixed. He, of course, is correct. Putting an "e" or "m" in front of CCPM makes little grammatical sense given that there is no mixing.

I on the other hand have always seen the input side. How are the inputs established to achieve the desired output? It never occurred to me to look at what I have traditionally known as a mechanical mixer and ask, how are the output functions mixed. V-Tail mixing, mechanical or electronic, never implies the mixing of the output functions.

Going on... Terry, I do see your point that in a mCCPM control system, each servo, taken independently of each other, serves one function and for any given desired command output, only one servo is commanded to move by the transmitter.

But, the act of moving one servo by another servo to achieve the desired output, is mixing. The mechanical moving of the roll servo by the collective servo, as happens with a Raptor30/50, is to my thinking, mechanical mixing. Admittedly the aileron servo is never commanded to move with a collective requests but it is instead mechanically and physically moved by another servo.

I see that in a mCCPM system multiple channels are never commanded to move at the same time to achieve a single control output. From sticks to swash there is one one servo being commanded to move. But, I also see the physical movement of an entire servo, and its associated control arm, as mechanical mixing. Using the collective servo to physically move the output arm of the roll servo (and the rest of the servo) is almost by definition, mechanical mixing.

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09-25-2018 02:00 PM  51 days agoPost 36
Richardmid1

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Leeds, England

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Rojoalfa
The direct drive of srimok kasama... Explosive!
They are actually very INdirect when you think about it, they are kind of a 'servo saver' system. The reason the swash reacts so quickly on a Kasama is they have less resolution (less servo movement to blade pitch ratio).

60% of the time, it works every time!

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09-25-2018 04:33 PM  51 days agoPost 37
TMoore

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Cookeville, TN

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wjvail
I've given this far too much thought.

I think the root of the discussion is that some of us see "CCPM", Collective Cyclic Pitch Mixing, and see the output side. Terry is pointing out Collective and Cyclic Pitch are not mixed. He, of course, is correct. Putting an "e" or "m" in front of CCPM makes little grammatical sense given that there is no mixing.

I on the other hand have always seen the input side. How are the inputs established to achieve the desired output? It never occurred to me to look at what I have traditionally known as a mechanical mixer and ask, how are the output functions mixed. V-Tail mixing, mechanical or electronic, never implies the mixing of the output functions.

Going on... Terry, I do see your point that in a mCCPM control system, each servo, taken independently of each other, serves one function and for any given desired command output, only one servo is commanded to move by the transmitter.

But, the act of moving one servo by another servo to achieve the desired output, is mixing. The mechanical moving of the roll servo by the collective servo, as happens with a Raptor30/50, is to my thinking, mechanical mixing. Admittedly the aileron servo is never commanded to move with a collective requests but it is instead mechanically and physically moved by another servo.

I see that in a mCCPM system multiple channels are never commanded to move at the same time to achieve a single control output. From sticks to swash there is one one servo being commanded to move. But, I also see the physical movement of an entire servo, and its associated control arm, as mechanical mixing. Using the collective servo to physically move the output arm of the roll servo (and the rest of the servo) is almost by definition, mechanical mixing.
Bill, you are confusing mixing of two separate functions that stay separate regardless. Cyclic pitch is separate from collective pitch. On a Raptor as an example nothing is getting mixed. Any control input that goes to the rotor head is from a separate function in the radio. It it wasn't, a 4 channel airplane radio could not fly the machine and we both know that a 4 channel airplane radio can fly the machine. This is the crux of the issue; in that y'all see servos move the swash up and down, then see cyclic and collective pitch being input and assume that mixing is happening in the case of a Raptor and it's not. Again, I repeat, these are separate functions.

Now, if you connect 3 servos directly to a swashplate and connect that same 4 channel airplane radio to the machine; can you fly the helicopter? The short answer is NO. No combination of stick twiddling will get the swashplate to move in the direction that you desire. Connecting servos directly to a swashplate and trying to get it to move in the same way that the Raptor easily moves the swashplate with separate functions requires one thing; a mixing program. That mixing program is called CCPM or SWM, depending on which system you use. It is a function in software that combines multiple servo channels into a defined control scheme that manipulates the swashplate in an appropriate fashion, combining multiple channels into single but separate functions, hence you have collective pitch and cyclic pitch. Mixing is the definition of combining multiple channels into one as in your V tail example where two servos are mixed to achieve two discrete output values as in rudder and elevator. In the case of a V Tail this is known as a bi-directional mix since two separate channels are combined into two controllable outputs, hence you have rudder and elevator from two discrete sources of motion.

This is why the terms "m" and "e" are non sequitur to this discussion.

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09-25-2018 05:32 PM  51 days agoPost 38
wjvail

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Meridian, Mississippi

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Below is a picture of one of the simplest mechanical mixers I could quickly find. It shows the roll and collective servo (and the rudder).

Below is the roll servo. How will the swash receive a collective input without the roll servo arm moving?

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09-25-2018 06:01 PM  51 days agoPost 39
BeltFedBrowning

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Kansas City

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that looks like classic mechanical mixing.

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09-25-2018 06:44 PM  51 days agoPost 40
TMoore

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Cookeville, TN

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wjvail
Below is a picture of one of the simplest mechanical mixers I could quickly find. It shows the roll and collective servo (and the rudder).

Below is the roll servo. How will the swash receive a collective input without the roll servo arm moving?

Sorry Bill there is no mixing going on there. In this instance what is getting mixed? There is a SINGLE servo that moves the swash UP and DOWN for collective pitch. The fact that it is connected to a roll servo is insignificant and the reason why is that if the collective pitch servo didn't move you still would have cyclic pitch control. Try that on your CCPM heli.

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