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Old Aug 25, 2007, 11:55 PM
BeeZaur 480
BowerR64's Avatar
Parkville Mo.
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90 vs. 120 swashplates?

What are the good and bad about both types of swashplates? is one better fo like 3D and stuf then the other?

Would one be better if i just hover and some light FF
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Old Aug 26, 2007, 02:00 AM
Keep'em Spinning High!
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Miami Florida
Joined Feb 2007
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90 is used for MCCPM and 120 is for ECCPM.
In other words if you have a separate servo for the pitch control and only 1 aileron servo then you need a 90 degree swash plate. If you have ECCPM with 3 servos, 2 aileron and 1 elevator, then you need a 120.

The Raptor and the stock Trex XL are MCCPM and have a 90, the Trex SA & SE are ECCPM and have a 120.
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Old Aug 26, 2007, 06:04 AM
BeeZaur 480
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Parkville Mo.
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So there are really no benifits over one or the other?

If i used the 120 then ill only need 2 servos like an FP right? i could get all the same swash movements but with only 2 servos? wouldnt this be better for saving weight?
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Old Aug 26, 2007, 06:17 AM
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Quote:
Originally Posted by DeliriousIntent
90 is used for MCCPM and 120 is for ECCPM.
In other words if you have a separate servo for the pitch control and only 1 aileron servo then you need a 90 degree swash plate. If you have ECCPM with 3 servos, 2 aileron and 1 elevator, then you need a 120.

The Raptor and the stock Trex XL are MCCPM and have a 90, the Trex SA & SE are ECCPM and have a 120.
Not true.
The stock Eco is 90 degree eCCPM, but with only 3 servos. Transmitters support 4 servo 90 degree CCPM.

The advantage of 120 is a reduction of 1 servo but you still have even force when you use collective.
Disadvantage would be some cyclic interactions with rapid collective movement since the servos move different amounts so the roll servos will get where that are going a bit faster that the "elevator" servo.
(I think this is why some propose 140 degree CCPM, to reduce these interactions)

4 servo 90 degree would not have this problem, but has the extra mass of the 4th servo.
All 4 move identically for collective and the roll and "nick" functions are nicely isolated.

The ECO 8 method of 3 servo 90 degree CCPM has the disadvantage of uneven force on the swash plate.
Slop in the system shows up as slightly "springy" elevator control.

Pat MacKenzie
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Old Aug 26, 2007, 06:20 AM
I don't want to "Switch Now"
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Quote:
Originally Posted by BowerR64
So there are really no benifits over one or the other?

If i used the 120 then ill only need 2 servos like an FP right? i could get all the same swash movements but with only 2 servos? wouldnt this be better for saving weight?

You need 3 servos for a 120.
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Old Aug 26, 2007, 06:28 AM
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My understanding is, for the 450 size heli's is this, 90 deg is mCCPM were the links to the swash are push/pull such as the HDE TRex and 120 deg is eCCPM direct to swash links. That said, the Rex SE and many others use a 90 deg swash with direct links which causes interaction. I chose an aftermarket frame for true 120 eCCPM.
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Old Aug 26, 2007, 06:49 AM
BeeZaur 480
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I have 2 similar helis, one is the RC-Tek phantom, the other is a T-rex HDE or somthing (not sure the exact model)

I have an extra swash from a helidirect MX400pro and i put it on but it doesnt seem to fit right.

The RC-Tek has links at 6:00 for pitch and 10:00 and 2:00 for the cyclic

The MX400 swash has 4 points a 12:00, 3:00, 6:00 and 9:00

Wich is wich? I figured the 120 degree was the one with all 4 points and the 3 point triangle swash was 90? this is incorrect?

The stock rex swash has the 3 points like the RC-Tek, so i was wondering if i should just use the stock 3 point swash or the 4 point one thats red would be better?

Ive always wondered why the FP uses 2 servos, and CP type uses 3 and why it had to be like that.
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Old Aug 26, 2007, 07:13 AM
I don't want to "Switch Now"
pmackenzie's Avatar
Toronto (Don Mills), Canada
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Quote:
Originally Posted by BowerR64

Ive always wondered why the FP uses 2 servos, and CP type uses 3 and why it had to be like that.

Fixed pitch only need 2 servo because the swash plate only has to move in 2 ways, tilt fore/aft and tilt left/right.
Collective pitch needs a third servo to add the up/down movement to produce pitch changes. This additional movement can be added mechanically or electronically.
3 degrees of motion = 3 servos (minimum).

Pat MacKenzie

(p.s. just for completeness you can produce collective motion without moving the swash up and down by instead moving the washout up and down.
The Shogun uses this method. Still needs a third servo of course)
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Old Aug 26, 2007, 07:51 AM
In love with my Rappy
Leonora, Western oz.
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BowerR64, the 120 CCPM swash get its name from the amount of degrees the movement points have between them. also determines how many servo's are required.IE, 360'/120 = 3 thus 3 servo's. 360/90 = 4 thus 4 servo's.
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Old Aug 26, 2007, 08:43 AM
BeeZaur 480
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Parkville Mo.
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So the 2 i posted pictures of are both the same?

As i was typing my last post i realized that the swash needs to move up for CP type helis. Yeah, you cant do that with only 2 servos.

Looks like ill have to put the stock plastic one back on.
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Old Aug 26, 2007, 08:47 AM
In love with my Rappy
Leonora, Western oz.
Joined Mar 2006
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Picture one is a 90, with one ball not being utilized, picture two is a 120.
the heli they are mounted on is designed for a 120 (picture two). notice the straight shot the servo links have to the swash, compared to the 90?. that will give a much linear push on the swash with little interaction, whereas the other one will want to push the swash backwards as well as up in the pitch.... the rear servo will have a different travel range and speed due to the straight shot it has to the swash compared to the other links
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Old Aug 26, 2007, 09:57 AM
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Eatonton Ga. United States
Joined Sep 2004
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Quote:
Originally Posted by wiz310
BowerR64, the 120 CCPM swash get its name from the amount of degrees the movement points have between them. also determines how many servo's are required.IE, 360'/120 = 3 thus 3 servo's. 360/90 = 4 thus 4 servo's.
A 90 degree swash does not neccesarily require four servos! The T-rex HDE has a 90 degree swash and uses three cyclic servos, up/down by one, left/right by one and blade pitch by one. Only one servo moves at a time to accomplish any particular action. I'm currently changing out the upper portion of my HDE CF frame to make it 120 degree direct to swash. I'd be done if there wasn't so much confusion about the mounting of HS-65MG's in the frame to get the best linkage alignment. I've already had to pull them out once and start over!
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Old Aug 26, 2007, 10:22 PM
BeeZaur 480
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In the manual there is an "upgraded swashplate" it looks like the 4 way one i had on it.

How is it suposed to work?
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Old Aug 26, 2007, 10:32 PM
Only electrons, Martha
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FWIW, 90 degree CCPM is not the same as mCCPM... The "real" pros will tell you there is no such thing as mCCPM. The proper term apparently is "standard". This information was provided to me by Curtis Youngblood himself.

Even in a 90 degree CCPM setup (I think this has already been said here) all of the servos are still working together to change the orientation and elevation of the swashplate.

On a standard mixing setup, the servos work independently.

Another item that confuses things, but still doesn't change the "official" terminology is direct ccpm vs in-direct ccpm. Even though with in-direct ccpm there are additional linkages that transfer inputs to the swashplate, the underlying servos are still working together to make the change.

Hope this helps. I posted this because I made the mistake once of asking about CCPM vs mCCPM and one of our resident experts made me feel like a fool over it... mentioning no names fffiiinnnnllllleesss...
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Old Aug 26, 2007, 11:36 PM
Digitally modulated
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Quote:
Originally Posted by ShellDude
FWIW, 90 degree CCPM is not the same as mCCPM... The "real" pros will tell you there is no such thing as mCCPM. The proper term apparently is "standard". This information was provided to me by Curtis Youngblood himself.
Eh, I have to disagree. Yep, I'll stand up to Mr. Youngblood and anyone else, as I truly believe they've been misinformed.

Here's a post from RunRyder that sums it up better than I can do in my own words: (emphasis mine)

Quote:
Originally Posted by
Matt-Drummer
The answer to these questions is really simple, most modern model helicopters use collective and cyclic pitch mixing (ccpm). Collective pitch changes are accomplished by moving the swash plate up and down the mainshaft. Whether the mixing is carried out electronically or mechanically is irrelevant, they are all using ccpm and can be distinguished from each other as either mCCPM (mechanical mixing) or eCCPM (electronic mixing). In mCCPM each servo performs only one function (collective, lateral cyclic and fore-aft cyclic) and in eCCPM each servo carries out more than one function.

There are not too many modern examples of non-ccpm helicopters made these days but one recent example was the Zoom 400 where the swash plate remains in one place on the mainshaft and collective pitch changes are accomplished by moving the washout mixer up and down the mainshaft by rods running either inside the mainshaft or in grooves on the outside of the mainshaft.

As far as I can remember all Kalt helicopters were non-ccpm as where the original Kyosho Concept 30's and 60's. Ther are probably numerous other examples of non-ccpm helicopters.

The confusion arises these days because non-ccpm helicopters are rare and people (mainly those with no experience of non-ccpm helicopters) use ccpm to differentiate between electronically and mechanally mixed ccpm.

Hirobo's SWM and HPM are just their way of differentiating between mCCPM and eCCPM.

Matthew.
Sums it up perfectly.

Hope I haven't started another religeous debate... <ducks>
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