InsideHeli.com #33: Basic CCPM Setup - HeliFreak
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Old 09-10-2008, 03:04 PM   #1
JustPlaneChris
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Default InsideHeli.com #33: Basic CCPM Setup

InsideHeli #33 is up!

We've got a full house this episode! Join the James' (Northern and Southern), Eeeeky (Aeryk Hurley), and Chris as they chat about CCPM setup basics. Also hear Eeeeky's thoughts about IRCHA and the MSH Protos.

Other Stuff We Talked About:

Video of the Week
MS Heli
Esprit Model
Eeeeky's Protos Vid
Newspaper article about Eeeeky


Listen to the show
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Old 09-10-2008, 04:58 PM   #2
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Great Chris! I'm a big fan of the show and can't wait to relax and listen in on this one!

Keep up the good work

Andy
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Old 09-10-2008, 07:45 PM   #3
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Hmmm listened to the CCPM talk. Gotta make a comment that I feel is incorrect and James had it right but others argued.
Most radios today you can put in subtrim and it will NOT change the end of the servo travel. This has been shown and tested by several people (me included) using accurate measuring.
Futaba 7C, 9C, 9Z, 12mz, and 14mz
JR 9303, X9303, DX7
All of these you can use subtrim and it does not effect the overall servo travel.

So not sure what radio these guys are using but this is an OLD issue with radios made over 5 years ago. Todays radios, subtrim moves the entire range UNLESS you have EPA's maxed out (like 150 on JR) already.

Also I too cannot sometimes get a servo arm 90 without subtrim. In fact more often I cant than not even on $100 servos! So if you insist on not using subtrim then you will have to drill your own wheels.

Also James using a screw driver for 0 pitch is right on! Been showing that in a few of my vids recently.

Bob
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Old 09-10-2008, 08:09 PM   #4
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FYI the redneck night flying that was talked about was Carson from Paso Robles (HF user Sonofcar). He drove out with me and Trooper Sam in a motor home from Ca. Clay and I were the guys holding the spot light. This was at the SWARM party Friday night.
Carson signed up to compete in the night fly Saturday but it didn't go well as one Clay and I were too far away this time and two my spotlight died and he couldn't see the heli A well... Next year....

Also for the guys that took off the gov's off the IRCHA golf carts (Eeeky). I wouldn't advertise that. Mainly because someone drove carts through the corn fields causing thousands in damage so I hope it wasnt you guys! Also if they find the cart was damaged... they know who you are and my understanding is they could come back with a bill to fix it!

Bob
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Old 09-10-2008, 08:24 PM   #5
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Geeze...I'm going to have to go to IRCHA next year just to protect the corn? If you're not mature enough to respect other people's property, you're sure as heck not mature enough to be flying a helicopter near a crowd of people. Not cool at all.
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Old 09-10-2008, 08:47 PM   #6
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Quote:
Originally Posted by Finless View Post
Hmmm listened to the CCPM talk. Gotta make a comment that I feel is incorrect and James had it right but others argued.
Thanks for the clarification, Bob! I guess I was remembering it from the "old days" with my JR X-347
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Old 09-10-2008, 08:51 PM   #7
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No problem.... A lot of us for a long time have been against subtrim and some still say it's a problem but after arguing about it over 2 years ago and then testing myself on my old 9C I found that unless EPA is maxed out subtrim does not effect the ends (overall travel). I was proved wrong and since then have been using subtrim when I cant get arms perfectly 90 as you see in my vids.

Good show by the way... I always like them when there is heli talk

Bob
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Old 09-10-2008, 09:01 PM   #8
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> Today's radios, subtrim moves the entire range UNLESS you have EPA's maxed out
> (like 150 on JR) already.

Bob certainly has this correct. However, I would like to add that on the DX7, XP9303, and X9303 using subtrim while "Swash Exp" is enabled does have negative consequences. Small subtrim values are ok, but anything above maybe 30 starts causing noticeably unequal servo throws. Adjusting the EPAs sort of fixes the issue but does not get it back to the same as with no subtrim.

Besides not being the only one to see this happen on a heli, I have measured and plotted the affect and it is real to say the least.

Thanks,
John
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Old 09-10-2008, 09:22 PM   #9
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Hmmm interesting. I never have swash EXP on as early on I noticed it caused full positive / negative pitch interactions. It stumped me for a while dorking with travel adjust and when I turned off swash Exp, I no longer had top and bottom interactions. Possibly that was because I used subtrims? That explains it thanks!

Also yes to amount of subtrim. If you have to go more than 20 in either direction then you should have been able to find an arm closer. Usually my subtrim adjustments are 10 or below. Now that said... the subtrim steps on a DX7 are larger than a X9303. e.g. 10 on a DX7 is more movement than 10 on a X9303. Be aware of that for those migrating from a DX7 to a X9303 and scratch their head when trying to resetup.

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Old 09-10-2008, 10:14 PM   #10
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Great stuff, guys! This definitely will get a mention (and link) on the next show.
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Old 09-11-2008, 12:32 AM   #11
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You should invite JKOS to a "session" with you guys! Get into radio latency and stuff. This guy know his STUFF and I think it would be an interesting podcast!

Bob
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Old 09-11-2008, 10:57 AM   #12
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I found a quick and dirty way of measuring the pitch on a flybarless heli. Pull the head button off and take some thing you know is straight and flat and set it on top of the flat section. I happened to have one of those small 6" metal rulers handy that I drilled a hole in and attached it with the headbutton screw. This gave me a known plane that was 90 degrees to the shaft to sight off of. Of course this will only work if the head you are working with has a flat spot on top to work with as like the Mikado head. Looking at my Trex 600 head it is slightly rounded so not sure how well it would work. Won't have to worry about that one anytime soon though since it's still flybar'd.
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Old 09-12-2008, 09:36 PM   #13
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Great show guys. I listen to it while I'm driving for work and wishing I could be flying. I have a question about setup. It's my understanding that most helis lean slightly to the right in a hover because the tail rotor pushes it to the left. Am I correct? So does the swash have to be trimmed a little to the right to get a steady hover or does it lean to the right with the swash level?

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Old 09-12-2008, 11:02 PM   #14
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They will still lean.
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Old 09-13-2008, 08:21 AM   #15
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In general, it isn't a good idea to tilt your swash to trim out the heli for a steady hands-off hover. You should get the CG correct and level the swash and be done with it. You will soon learn to compensate for things like tail rotor thrust and wind without even thinking about it.

This was a topic of discussion on this thread recently:
https://www.helifreak.com/showthread.php?t=91995
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Old 09-13-2008, 09:40 AM   #16
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Quote:
Originally Posted by JKos View Post
> Today's radios, subtrim moves the entire range UNLESS you have EPA's maxed out
> (like 150 on JR) already.

Bob certainly has this correct. However, I would like to add that on the DX7, XP9303, and X9303 using subtrim while "Swash Exp" is enabled does have negative consequences. Small subtrim values are ok, but anything above maybe 30 starts causing noticeably unequal servo throws. Adjusting the EPAs sort of fixes the issue but does not get it back to the same as with no subtrim.

Besides not being the only one to see this happen on a heli, I have measured and plotted the affect and it is real to say the least.

Thanks,
John

What about digital servos that are programmable for a much wider range of motion? How does the subtrim affect those servos??? Does the TX EPA have to be maxed-out regardless of total servo travel to have end points NOT affected by subtrim??? Thanks.
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Old 09-13-2008, 11:34 AM   #17
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RMG2,
The issue with the DX7, XP9303, and X9303 when using subtrim while Swash Exp is active is that the servo commands become nonlinear within the radio itself. No amount of playing with EPA or programmable endpoints on the servo itself will bring it back to linear.

- John
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Old 09-13-2008, 09:11 PM   #18
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Quote:
Originally Posted by JKos View Post
RMG2,
The issue with the DX7, XP9303, and X9303 when using subtrim while Swash Exp is active is that the servo commands become nonlinear within the radio itself. No amount of playing with EPA or programmable endpoints on the servo itself will bring it back to linear.

- John
When you say "swash exp" does that mean elevator and aileron expo? I have original Esky servos in a Honey Bee King 2 that require subtrim with a DX7. If I use subtrim and expo will the collective, cyclic, or both be nonlinear?

Chris
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Old 09-13-2008, 11:40 PM   #19
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> When you say "swash exp" does that mean elevator and aileron expo?

No, it is the "Swash Exp" on the Swash Mix page (which is to correct for non-linear servo throw away from center). Expo on aileron, elevator, or rudder (which reduces sensitivity around center) and expo on pitch and throttle curves (which smooths the curves) work fine and are not negatively influenced by subtrim.

- John
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Old 09-14-2008, 01:58 PM   #20
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I have some bad news... The JR 12X suffers from the same problem. I have one in my hands right now and, unfortunately, confirmed this problem on it. I can't believe that didn't fix it!!!

- John
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