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Radio - Servo - Gyro - Gov - Batt > RD8000 and CCPM Setup
 
 
Trace
Senior Heliman
Location: Wildwood, MO

I have a question regarding the RD8000 and setting up eCCPM.

At full pos. collective I get an unwanted pitch up interaction. It is well documented how to dial this out with other radios by setting the ATV's on all 3 channels to level the swash plate at -100/0/+100. However, the RD8000 does not allow you to set the ATV's of the individual servo channels, it only allows you to set the ATV's of the individual functions (ele, ail, pitch). It seems like the only setting which affects the individual servo channels is the centering, but that doesn't help set end points in 2 different directions. If possible I would like to dial this out without using the mixes, since the RD8000 only has 2 programmable mixes which I am currently using to mix throttle to cyclic.

Does anyone know of a way to set this up, or am I just going to have to buy a governor and use the mixes to dial it out?

Thanks,
Trace
09-14-2004 Over year old.
 
 
TMoore
rrProfessor
Location: Cookeville, TN

Quote 
However, the RD8000 does not allow you to set the ATV's of the individual servo channels, it only allows you to set the ATV's of the individual functions (ele, ail, pitch). It seems like the only setting which affects the individual servo channels is the centering, but that doesn't help set end points in 2 different directions.


Look in the manual on page 36 covering EPA's. Of course the RD 8K has ATV's on each servo channel. The problem you have is probably a geometry problem. I'm using an RD8K on a Caliber and I don't have any problem with the swashplate pitching up at either extreme of collective pitch because the geometry is correct for the type of motion that I need.

What it sounds like is the servo arms are too small and you are using more servo travel than you need. There could be a geometry issue with the heli as well, depending on where the arms are and how they sweep through their respective travels. The CCPM software in the RD doesn't work like other systems, ie, the Futaba or JR. ATX doesn't use AFR or anything similar. The Stylus give you more adjustment flexibility than the RD and hence costs more. The RD's aren't in that price class.

My suggestion is to use longer arms and less servo travel.

TM
09-14-2004 Over year old.
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staraero1
Key Veteran
Location: Atlantic City, New Jersey

Many are using the RD 8000 with CCPM helicopters. The radio is trouble free and the CCPM features they have work very well.

The RD 8000 system works well in any helicopter, airplane, and sailplane application.

I agree with Tmoore. you have missed something in the setup somewhere.


Staraero1
09-14-2004 Over year old.
 
 
Trace
Senior Heliman
Location: Wildwood, MO

TMoore, I believe you are incorrect regarding ATV's on each channel when using CCPM. I will try to explain what I mean a little more thoroughly.

Using standard mix the ATV's properly affect each servo independently, because on standard mix they are independent.

However if you are running 120 deg. CCPM the ATV on the Ele. channel affects all 3 servos not just the one servo. So if you have a servo which travels slightly more or less than the other 2 from 0 to full collective you cannot with the RD change the ATV on that one servo, so that it has the same range as the other 2, unless it is buried somewhere I cannot find.

This is on a Raven 50 which has all 3 servos connected directly to the swashplate using 25mm metal servo arms. The epa on pitch is at about 75% each way which is about +/-10.5 deg. Everything was built up from 0 deg. Servo arms level and perpendicular to the pushrods. Pushrods adjusted until swashplate was level. Mixing arms, bell mixers, fly bar, blade grips, all level at 0 deg.

I believe the crux of the problem probably lies with the subtrim. The raven ccpm requires the use of half arms, so you only get one choice for fitting on the splines and of course it is never perfect. So you have to adjust the subtrims to line them up. I used the centering on the RD to square the arms up, as this still allows full throw in each direction, whereas using the trim function would skew the ATV range to one side.

I just thought someone might have run across this and maybe have a setup trick which compensates for servo fine tuning using the RD software.
09-14-2004 Over year old.
 
 
TMoore
rrProfessor
Location: Cookeville, TN

Trace,

Try a set of plastic wheels instead of the metal arms. I don't recommend metal arms. They don't bend in a crash. Plastic wheels will work better for this application if they are big enough.

As far as the EPA's are concerned, when CCPM is turned on the ATV's don't work in the conventional way. You won't have individual control of each servo. The Stylus has this but the RD doesn't.

The EPA's on the RD don't work like AFR on other radios.

Terry
09-14-2004 Over year old.
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Radio - Servo - Gyro - Gov - Batt > RD8000 and CCPM Setup
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