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Other › Disadvantages of CCPM?
04-04-2005 05:20 AM  13 years agoPost 1
monts

rrApprentice

San Diego Ca

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I am thoroughly enjoying my T-Rex and this forum.

I've noticed a lot of talk about CCPM and eCCPM and I am impressed about the apparent simplified looks of these setups.

Aside from having to do the modification, are there any downsides going this route? By the looks of it, it seems like a simpler, more efficient and lighter method to control the helicopter. Why wasn't the T. Rex designed this way initially; less parts, less weight, better control?

Also, is eCCPM and CCPM the same thing?

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04-04-2005 05:28 AM  13 years agoPost 2
LTEDT

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Westminster MD

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Im not sure but i would belive that it wasnt desinged this way due to the TX requirments you have to have CCPM capibility to run CCPM heli.
Also So far there is no drawback I can see with my CCPM setup.

As for the difference eCCPM is electronic mixing (radio)
CCPM would be mechanically mixed. (not positive about this thought )

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04-04-2005 05:32 AM  13 years agoPost 3
rabot

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New Brunswick, Canada

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The biggest disadvantage is that you require a transmitter that supports eccpm so that rules out a lot of non-computerized radios. Also if you have the old fma co-pilot kicking around and would like to use it with the trex, it won't work with eccpm mod.

Robert

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04-04-2005 05:35 AM  13 years agoPost 4
rabot

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New Brunswick, Canada

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Sorry LTEDT, I must have been typing at the exact same time as you.
Cheers

Robert

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04-04-2005 05:49 AM  13 years agoPost 5
LTEDT

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Westminster MD

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LOL it happens. Ive done it a few times myself.
Matt

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04-04-2005 05:51 AM  13 years agoPost 6
monts

rrApprentice

San Diego Ca

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Thanks for the input guys. Too bad it didn't come with CCPM stock, or offered as an option! My guess is that most flying these new micro heli's also have a computer radio. I could be wrong though.

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04-04-2005 06:04 AM  13 years agoPost 7
LTEDT

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Westminster MD

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Not to beat the subject into the ground but I had only a 6 channel non computer radio until I saw the T-rex and decided to get a better TX.

Matt

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04-04-2005 06:14 AM  13 years agoPost 8
rcmarty

rrVeteran

Penticton , B.C. CANADA

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The t-rex is a copy of the raptor heli. Part for part from what i see.
The t-rex tips the scale on the heavy side because it's a scaled down nitro ship.

For the CCPm mod , I've heard the servo's are more likely to get stripped in a crash than with mCCPM. But the benifits (if you got the TX) are worth it. About 40g if weight is removed going to CCPM which helps the little piggie loose some weight.

Martin

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04-04-2005 03:50 PM  13 years agoPost 9
dogon1013

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Orlando, FL

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another disadvantage to the eCCPM is that it takes alot more radio setup to get it flying. you basically transfer mechanical complexity to electronic/computer complexity. It took me a good evening to get everything setup for eCCPM. Well worth the work though.

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04-04-2005 04:23 PM  13 years agoPost 10
dogon1013

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Orlando, FL

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yes, but from the pictures i have seen they still use bellcranks. (why they would do that is beyond me)

So there is still an advantage to going to direct servo connection eCCPM. (less linkages, therefore less slop and less weight)

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04-04-2005 04:43 PM  13 years agoPost 11
wildstallionuk

rrKey Veteran

ENGLAND, FOLKESTONE, KENT

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I suppose another disadvantage is that if you loose the pitch servo in MCCPM you can still land it flat on the skids although it may be a hard one.

Check out the items I have for sale in the clasifieds including a CSM 420

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04-04-2005 04:44 PM  13 years agoPost 12
Buznee

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Palm Beach Gardens, FL

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yea definately if you lose a servo in flight your toast. unless you have the 4 servo redundant eccpm setup.

~Danny

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04-04-2005 06:22 PM  13 years agoPost 13
WRXRonald

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Auburn, OH

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ok...
well i'm also going to do the eCCPM mod...

but i'm wondering... i have a somewhat 'limited' Futaba TX6Hs transmitter....

i've noticed and discussed with others in the forums that this Tx just isn't really too great for helis, and setting up curves, etc........

i'm wondering if it will work for the CCPM mod... its got a mode called PCM ? i don't know exactly what they mean by this... but the manual DOES have layouts of swashplates, and you input what type swashplate you'll be flying with to the Tx.... two of those swashes are drawn looking just like the ccpm setup, with servo/link points at the 120 degree marks, one of them is 2 connections at rear-side, 1 front. the other is the opposite, 2 connection at front-side, 1 at rear...

so couldn't one deduce that Futaba designed this Tx with the ccpm setup in mind, since the only way to fly a bird with this swash type would be in a ccpm mode, right?

i don't want to shell out $160 for a 7CHP, but of course if it comes down to it, i will. but i think i'll give this Tx i have a shot, and see if its capable or not.

thanks if you guys have any opinions/input about it....

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04-04-2005 06:28 PM  13 years agoPost 14
Tim B

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Pasco, Washington

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I think using bellcranks would give smoother swash motion and be easier to setup than trying to get 3 servos positioned with throws that don't twist and distort the swash movements while working in unison.

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04-04-2005 08:06 PM  13 years agoPost 15
dogon1013

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Orlando, FL

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A bellcrank can "twist and distort" the swash just as bad as a servo can. It all depends on how the linkages are placed and designed. If you do your eccpm mod well everything will line up fine (see gallery). and most everything can be linearized through the radio setup (exponential).

as for the futaba radio make sure that manual is not for other model radios as well as your own (some manufacturers do that). check the radio itself to see if it has a 120degree swash setting.

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04-04-2005 08:11 PM  13 years agoPost 16
WRXRonald

rrKey Veteran

Auburn, OH

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Thanks...
is does have the 'swsh' selection mode in the computer menus... i don't know if it has all the selections that appear in the manual, and i do get what you're saying, (one manual, several different Tx models covered)... so i'll check for the right swash mode tonight to match the pic in the manual,

but long as it matches, you think i'm ok so long as i select the mode that goes with the correct 120 swash setting, that basically means ccpm is supported i would think...

otherwise how could they picture a swash with 120 degree connectoin points w/out a CCPM function, right?

as for using EXPO for ccpm... how does that help setup? i've never used expo before in my normal setup, i now some use it, but i forget what exactly it does (only read about it once) and have never used it. does it get each of the servos movements more 'inline' with each other?

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04-04-2005 08:37 PM  13 years agoPost 17
soundbwoy

rrApprentice

Fort Lauderdale

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Tim B you quite correct
I think using bellcranks would give smoother swash motion and be easier to setup than trying to get 3 servos positioned with throws that don't twist and distort the swash movements while working in unison.
, also that ccpm setup they using is used by Hirobo for their ccpm setup on the EVO. Also as for knocking of the raptor they onlyused the pitch control they took everything else from Hirobo including the CCPM conversion they have in the drawing, bellcranck push pull and so on.

Fly Hard… Crash Harder… Have Fun!!

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04-04-2005 09:08 PM  13 years agoPost 18
Tim B

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Pasco, Washington

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I keep reading about how people think exponential somehow makes thier servo throws linear. This is rediculous and I just don't buy it. Exponential is just a program curve for different control sensitivities depending on the position of the stick. The further the stick movement, the faster the controls. This allows the middle area of the controls to be less sensitive, but also allows full servo travel on the outer limits of the controls. This in no way changes the "linearity" of servo throw. I don't even see how someone could get the impression that it does.

Now about the bellcrank post I made earlier.. That was just a major brain fart and I can't believe I thought a bellcrank moved any different from a servo long enough to type that up. Heh.
Easier=maybe/different=no.

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04-04-2005 09:12 PM  13 years agoPost 19
dogon1013

rrNovice

Orlando, FL

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you can use expo to counteractt the non-linear motion of the servos/ pushrod assembly, but only to a point and most of the time it is not needed. You may need it if you use very short servo arms.

usually a servo hooked up to a pushrod will have more linear motion per degree in the first 5 to 10 degrees of motion, and less linear motion at the ends of it's travel. you can use expo to decrease the motion near the center of the stick to counteract the linear motion increase mentioned above.

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04-04-2005 09:42 PM  13 years agoPost 20
Tim B

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Pasco, Washington

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I'm sorry, but I still don't agree about expo compensating for anything but your own comfort on the sticks. As far as I can fathom, that's all expo can possibly do is give a sensitivity curve for comfort so that the heli won't make large movements from small center-stick inputs allowing smoother and easier control of the heli. We may not really want to get into this, but I would need some detailed explaining as to just how expo could compensate for anything else.

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