RunRyder RC
 16  Topic Subscribe
WATCH
 5 pages [ <<    <     1     ( 2 )     3      4     NEXT    >> ] 9061 views
HelicopterMain Discussion › 120 or 140 CCPM
11-30-2007 03:00 PM  10 years agoPost 21
ChristianM

rrVeteran

Oslo, Norway

My Posts: All  Forum  Topic

CSM CycLock does not get rid of the 120 interaction issue.
Well it really does a very good job of it. You can actually specify the servo speed and the CycLock will electronically slow down the servos that have a shorter travel distance to keep them all in sync. It also has a number of mixes to get rid of most interactions in any CCPM system just like the 14MZ. Also as you mentioned it can drive the servo at digital frame rates. I am currently using the CycLock on my 90 size and I noticed a significant improvement but then again I am still using the Futaba 9C

Kingair, that is a nice figure of the 120 and 140 swashplate. I was thinking of creating one myself but now I don't have to

Christian

Burn fuel, be happy

PM  EMAIL  GALLERY  Attn:RR  Quote
11-30-2007 03:45 PM  10 years agoPost 22
DenisS

rrKey Veteran

england

My Posts: All  Forum  Topic

Christion
When you say you notice a significant improvement, is this when flying or when visually checking it on the workbench? If it is when flying then what is the actual improvement you notice? i.e. straighter flips, less tendency to roll when on max power climbs etc?? I have noticed even on non eCCPM helis that they can tend to roll slightly when doing max power climbs, and roll slightly differently when doing inverted max power climbs. Strange I know but I've noticed this with different helis so not all the tendencies are totally down to eCCPM.
I think the newer faster servos overcome this to a great degree as with the older servos, 10% speed difference of .22 sec servos was noticeable, but 10% difference of a 0.09 sec servo MUST be less noticeable.
Just my thoughts
Denis

PM  EMAIL  Attn:RR  Quote
11-30-2007 04:30 PM  10 years agoPost 23
JKos

rrProfessor

Redondo Beach, CA

My Posts: All  Forum  Topic

> The purest set-up is mechanical - one servo for each axis. Zero
> interactions..

Even mechanical mix machines are NOT perfect. Some are very good and some are abysmal. On the same thought, some helis have better eCCPM geometric implemenations than others, regarldess of 120, 140, or whatever.

The CSM CycLock is simply amazing. Yes, it can eliminate 120 deg interactions at least math wise. It is then up to the servos to actually be where the CycLock is telling them to be. The increase in resolution is also amazing. I've posted numbers before on the increase in resolution for a Vibe 90 with 140 deg eCCPM.

- John

RR rules!

PM  EMAIL  GALLERY  Attn:RR  Quote
11-30-2007 05:30 PM  10 years agoPost 24
synodontis

rrKey Veteran

United Kingdom

My Posts: All  Forum  Topic

The CSM CycLock is simply amazing. Yes, it can eliminate 120 deg interactions at least math wise. It is then up to the servos to actually be where the CycLock is telling them to be. The increase in resolution is also amazing. I've posted numbers before on the increase in resolution for a Vibe 90 with 140 deg eCCPM.
No it cannot, it can get close. "Maths wise", don't make me laugh, nothing can get to mechanical mixing, although certain implementations of mechanical mixing are abysmal. CCPM is "geometrically awkward" because of the arrangement of the servos, that's the price you pay for the power and speed you want. Also this interaction that we are talking of is to do with servos "fighting". If you think about it for a moment, the "fighting" seems to do with the axis of rotation of the servo discs parallel with the body of the heli. If we have a 120 CCPM setup where all the servo discs we inline with the outward plane to the shaft we won't have these "interactions", but we need to change the 120 CCPM software to allow for this. Need a diagram to explain this.

PM  EMAIL  GALLERY  Attn:RR  Quote
11-30-2007 05:38 PM  10 years agoPost 25
JKos

rrProfessor

Redondo Beach, CA

My Posts: All  Forum  Topic

> "Maths wise", don't make me laugh,

It's all about math. You can mathematically derive absolutely perfect swashplate motion for any given eCCPM setup. It is then the physical limits of the servo (speed, precision, etc.) and mechanics (flexing, slop, etc.) which limit the actual perfection of the swashplate positioning both statically and dynamically. Some limitations of real servos such as speed and static travel non-linearities can also be accounted for in the math.

- John

RR rules!

PM  EMAIL  GALLERY  Attn:RR  Quote
11-30-2007 06:29 PM  10 years agoPost 26
synodontis

rrKey Veteran

United Kingdom

My Posts: All  Forum  Topic

I agree it's all about the maths, but you miss read what I was getting at: the servos are digital (read discrete), this means DISCRETE steps (1/2048 x 60 degrees or so). So in effect you are implementing discrete step functions to fit a continuous smooth curve - go figure. At extreme swings we might not as "smooth" a fit as we should. By your argument CCPM on the tranny would be mathematically correct - just that the resolution is lower.

A mechanical implementation will not have this problem because although the control is discrete, each component is independent of the others and does not interfere where is should, and have to be allowed for.

But mind you we can take the analogy of the computer graphics programmers say: if it looks good enough, it is, regardless of implementation. So in this case, if CCPM is good enough that most pilots cannot tell it from mechanical then it is good enough.

PM  EMAIL  GALLERY  Attn:RR  Quote
11-30-2007 06:44 PM  10 years agoPost 27
JKos

rrProfessor

Redondo Beach, CA

My Posts: All  Forum  Topic

> By your argument CCPM on the tranny would be mathematically
> correct - just that the resolution is lower.

It can be and some transmitters are darn close.

> if CCPM is good enough that most pilots cannot tell it from
> mechanical then it is good enough.

I fully agree with that statement. Is it "hard" to get a CCPM setup working so well that all but a select few pilots could tell it from a good mechanical mix system, sure. But that's part of the fun of this hobby, at least for me.

There is certainly validity in the arguments that accomplishing a really good CCPM setup is doable but keeping it really good is harder due to changes in servo operation.

> if it looks good enough, it is ...

And "good enough" is not the same to all people. Some people will never realize their CCPM setup isn't perfect. Other's can't fly a machine until it is.

BTW, have you noticed that the percent of machines sold that are mechanical mix is really low these days. Almost all of the popular machines are CCPM.

- John

RR rules!

PM  EMAIL  GALLERY  Attn:RR  Quote
11-30-2007 07:41 PM  10 years agoPost 28
synodontis

rrKey Veteran

United Kingdom

My Posts: All  Forum  Topic

CCPM has the following advantages from a manufacturing point of view:

1) It's easy to implement
2) It uses less parts (hence less headache for parts support)
3) it wears out servos more (and if you're JR or Futaba this means more sales). Yes, alright call me cynical!!!
4) it's easier to set up and has less linkages.

Also it's good for 3D because it means that in the hands of the average pilot starting out he'd want to go straight into 3D because that's where all the adrenaline is at!!! It also gives him the power to totally brutalize the hell out of his machine in all those outrageous manoeuvres. This means he's likely to crash more, which means more money spent on parts, which means more sales etc... Sometimes giving people too much power can be a bad thing.

Also Hirobo have moved over to CCPM because the FAI schedules are becoming more and more like 3D, even though they retain their smoothless and hovering maneovres are not marked as high as they were.

PM  EMAIL  GALLERY  Attn:RR  Quote
11-30-2007 07:55 PM  10 years agoPost 29
jschenck

rrProfessor

La Vista, NE.

My Posts: All  Forum  Topic

Bottom line: All else being equal (say the exact same heli, servos, radio, etc...) 140 swash has less interaction than a 120 swash.

correct?

PM  EMAIL  GALLERY  Attn:RR  Quote
11-30-2007 08:08 PM  10 years agoPost 30
synodontis

rrKey Veteran

United Kingdom

My Posts: All  Forum  Topic

and 135 is even better if you have the transmitter for it (14MZ). But only machine with 135 CCPM at the moment is Eagle 3 SWM. Now, not many of those are selling as such.

PM  EMAIL  GALLERY  Attn:RR  Quote
11-30-2007 08:15 PM  10 years agoPost 31
GimbalFan (RIP)

rrProfessor

Big Coppitt Key, FL

My Posts: All  Forum  Topic

I'd not before seen extensions like that off the aileron tabs on that standard 120° swash (to make it into a 140° swash) like KingAir posted.

No need to slow down the aileron servos anymore since their swash linkballs' fore & aft distance from the mainshaft is equal to the elevator servo's linkball.

Brilliant!

op-thwop-thwop-thwop-thwop-thwop-thwop-thwop-thwop-thwop-thwop-thwop-thwop-t

PM  EMAIL  GALLERY  Attn:RR  Quote
11-30-2007 10:25 PM  10 years agoPost 32
Rbush

rrKey Veteran

here

My Posts: All  Forum  Topic

Wouldn't the distance from the centre line out two the front balls have to also be the same distance to get a truly equal movement?

PM  EMAIL  GALLERY  Attn:RR  Quote
11-30-2007 10:39 PM  10 years agoPost 33
ErichFrrElite Veteran - Sutton, NH - My Posts: All  Forum  Topic

Gimbal,

After reading your previous statements about loss of aileron advantage, I started to wonder what you were thinkin. The swash on my Caliber 90 is exactly like the diagram you posted. See the pic below:

The Caliber 90 comes with hardware for both 120 and 140° CCPM - obviously I chose 140°.

The particular system on the Caliber is very symmetrical fore/aft, and mechanical interaction is pretty much nil:

As you can see in that photo, the T-levers are identical in length, and rotate on axis equi-distant from the mainshaft. So, there is not differential in fore/aft cyclic actions. It's also proven to be a great flying system with low pilot workload.

PM  EMAIL  GALLERY  Attn:RR  Quote
12-01-2007 12:25 AM  10 years agoPost 34
GimbalFan (RIP)

rrProfessor

Big Coppitt Key, FL

My Posts: All  Forum  Topic

Wouldn't the distance from the centre line out two the front balls have to also be the same distance to get a truly equal movement?
As long as the fore/aft distance from the top (elevator) ball to the mainshaft is the same as the fore/aft distance from the two bottom (aileron) balls to the mainshaft then no slowing of the the aileron servos' elevator functions will be required.

The aileron throws for the two aileron servos will not be the same as they are for the elevator throws for those two servos when setting up for equal degrees of swash deflection, since the port/starboard (left/right) distances from the mainshaft of those two linkballs is (typically) less than the fore/aft distances.
The swash on my Caliber 90 is exactly like the diagram you posted.
Let's remember that Kingair first posted that pic.

op-thwop-thwop-thwop-thwop-thwop-thwop-thwop-thwop-thwop-thwop-thwop-thwop-t

PM  EMAIL  GALLERY  Attn:RR  Quote
12-01-2007 01:56 AM  10 years agoPost 35
kingair

rrKey Veteran

Utah - USA

My Posts: All  Forum  Topic

I found the picture at rchelimag.com and gave them credit in my post. I wish I could've come up with the picture on my own.

There is a very fine line between "hobby" and "mental illness."

PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
12-01-2007 02:34 AM  10 years agoPost 36
Matt-Drummer

rrApprentice

Suffolk, United Kingdom

My Posts: All  Forum  Topic

Discussions about eCCPM are fine when the servos are level but what about the interactions that occur when you have say 10 degrees of positve collective pitch, 5 degrees of forward cyclic and you go to give some lateral cyclic?

The flaw in these systems is that our servos work in an arc and therefore in the above situation some collective pitch will be applied because one aileron servo will move the swashplate more than the other, they both move the same number of degrees but one will be moving towards its neutral position and the other away, the one moving towards its neutral position will move the swashplate more.

I would agree that 140 degree eCCPM gives less interaction around the neutral postion but I don't know if it does at the extremes or the closer you get to them? Its clear to me that the aileron servos need a greater overall travel in a 140 degree system, at full collective and fore/aft pitch the aileron servos will be displaced further from the neutral position than those in a 120 degree system, either that or the servo arms need to be longer in the 140 degree system therefore losing torque compared to a 120 degree system.

I am sure we could all agree that its most important to buy the best (fastest, strongest, etc) servos we can afford to ensure the best results with either system.

I am also of the opinion that mechanial mixing offers several advantages at the expense of shared loads beteen the servos. I always rather liked the Kalt system of a fixed swashplate with collective pitch changes being acomplished by moving the washout unit.

The cost of fast and powerful collective/cyclic pitch changes is interaction issues and they will be present in both systems, fast and strong servos minimise how noticeable they are.

How long will it be before decent linear servos are available? They were around many years ago but I don't know of any suitable servos of that type availabe now? They would solve all the problems I think?

PM  EMAIL  GALLERY  Attn:RR  Quote
12-01-2007 04:37 AM  10 years agoPost 37
JKos

rrProfessor

Redondo Beach, CA

My Posts: All  Forum  Topic

> The flaw in these systems is that our servos work in an arc

This can be accounted for in the math. Some radios and CycLock do this.

- John

RR rules!

PM  EMAIL  GALLERY  Attn:RR  Quote
12-01-2007 11:20 AM  10 years agoPost 38
Jeff polisena

rrElite Veteran

westpalmbeachflorida usa

My Posts: All  Forum  Topic

All I can say is 140 makes it easier/faster to roll and flip just to keep it simple

PM  EMAIL  GALLERY  Attn:RR  Quote
12-01-2007 11:20 AM  10 years agoPost 39
Brovic777

rrElite Veteran

Los Angeles, CA

My Posts: All  Forum  Topic

I just got a heli that offers 140 swash option.

Could I setup my DX7 to use this setup? And if so, how would I go about to do it.

Thanks

Killer Beam E4 450
Check out my HD Gallery

PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
12-01-2007 12:07 PM  10 years agoPost 40
colsy

rrElite Veteran

Cambridge, UK

My Posts: All  Forum  Topic

140 Degree mix, i quoted earlier in the thread.

Its elev to pitch 23% each side works out on my VIBE/DX7

Col.

Only Quote From Experience.

PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
WATCH
 5 pages [ <<    <     1     ( 2 )     3      4     NEXT    >> ] 9061 views
HelicopterMain Discussion › 120 or 140 CCPM
 Print TOPIC  Make Suggestion 

 16  Topic Subscribe

Tuesday, December 12 - 6:09 pm - Copyright © 2000-2017 RunRyder   EMAILEnable Cookies

Login Here
 New Subscriptions 
 Buddies Online