Advantage of 140 CCPM?

[ducatiderrick]

What are the advantages to the 140 degree CCPM setup??

[bathmagic]

less interaction is the real reason for it

Dale

[sookainian]

Hmm does it affect the cyclic respon ??

[Peter]

nope , just lets the 3CCPM servos all travel the same amount for a given input .. Servo resolution should be better because of that ...

[BarracudaHockey]

You would have to be a very gifted pilot to tell the difference

[misio]

You would have to be a very gifted pilot to tell the difference - no you don't

I had a chance to test 140 on stratus yesterday, and this is what I have discovered so far.

- no visible interaction on collective
- no interaction on any cyclic input
How you can tell, every flip or roll is strait let say you will do forward flip, you don’t have to correct with aileron after you done with flip. Same with roll

I was very interested on how do 140 will do, and after my test yesterday I can tell you that I like it very much. From now on if I can change all my heli to 140 will do this in a sec.

[Motions]

If your getting enough interaction on a plain forward flip that you actually have to correct, you might want to check your setup, 120, 140 or whatever.

[Dr.Ben]

For those with 12Z/14MZ software, you have enough radio to mix out most of the inherent problems created by 120D eCCPM. You still can't completely resolve the speed differential induced interaction created with rapid elevator commands, though the speed comp function works pretty darn well.

For those without these radios, I promsie you will create a better flying model off the bench if it has 140D eCCCPM, because you just won't be correcting for same the degree of cyclic>pitch interactions. If you can't zero them out with the radio software, then you have to fly with them. If you don't think they can get pretty bad, go up to about 3/4 collective and lay in a hard ele command. Watch how the washout base and swash ball dance. That stuff makes a difference.

For me, it's important to have a control system that requires as little extra programming as possible to keep the model's interactions truly zeroed out. 120 eCCPM requires more time/touch up with the MZ software, and thus I have more work to do over the life of the servos to keep the set-up clean as the servos wear and change over time. IOW, you don't have to do much retweaking on an adjustment that either wasn't needed in the first place or that had little done to it at all. 140D eCCPM cuts those needed adjustment greatly.

Ben Minor

[flyinfool]

The 140° make the elevator more precise at the expense of aileron accuracy.
This is because the balls are moved farther away from the axis of swash rotation for the elevator function and closer together for the aileron function.
So ultimately what you are ending up with the ail and elev closer to each other in accuracy.
With working with levers you NEVER get something for free.
140 vs 120 has zero effect on collective interaction or performance.

Of course all of this is assuming that the heli is mechanically set up correctly in the first place

[Fox222]

Dr. Ben, Well said!
As for the negatives of 140’ leverage, I just don’t see any. How are you losing aileron accuracy when it keeps the same mechanical advantage as with 120’ in respect to roll? The only leverage change is with respect to the elevator. As I see it we are not getting something for free because the 120 ccpm design was not the best design to start with. Just my thoughts.

[sookainian]

Guys, i just ordered my 140 ccpm kit :mrgreen:

[GM1]

Having flown 140CCPM on the prototype Stratus, it is pretty much as Dr Ben described. The collective movements seem to be more pure than on the 120 program, but the biggest difference is in the cyclic pitch commands where the interaction due to speed differential just basically disappear. Roll cyclic commands are pretty much unchanged. With the 14 MZ, I had LOTS of compensations on the 120 model and when I built the 140 CCPM model, I had to take all of that out.
A side note: On the 12Z and 14MZ, when you switch to 140 CCPM, you COMPLETELY start over. You cannot copy a 120 program and adapt as when you switch to 140, it wipes everything out so make sure you back up your 120 program if you think you might ever go back.
Gordie

[JKos]

I was once told that while 140 deg eCCPM fixes the fast elevator input issue, it causes a problem with collective. That doesn't seem logical at first, but the explanation is interesting. The supposed collective problem is that you now have more total force available for collective inputs on the two servo front or rear half of the swash as you do on the single servo rear or front half. This discrepancy would lead to non-level collective swashplate motion under load.

With 120 deg eCCPM, the two servos on the on the front/rear half are half the distance from the center of the main shaft in the longitudinal direction. In terms of lever arms, two times force X at distance Y equals one times force X at distance two times Y.

140 deg eCCPM breaks that balance. I am NOT saying that this actually shows up in real use. Maybe, just maybe with marginal servos; but I doubt it with decent servos. Especially given the super torque servos so commonly used now.

- John