Problem with setting up CCPM head on CDE trex 450

[sireric]

Hey.

I've viewed all the videos multiple times. I've built up the Trex 450 CDE following the directions in the manual (for link lengths) and the videos. Things are trim and level at centered throttle.

However, if I push the throttle all the way up, the top of the washout base and bottom of the main rotor housing touch each other at around 90% of maximum. I've reduced some of the middle links, but it didn't help that much.

If I reduce the throttle to 0, the swashplate drops nearly to touching the bottom (~4 mm clearance), which seems ok height-wise

Should I continue to adjust the links or should I limite the end points in the transmitter to reduce the movement?

(Using HS55 servos and Futaba 6exh transmitter + 146 receiver)

Aside from setting the trim and making sure that everything is level at the midpoint, I haven't done anything else.

Thanks!!

[sireric]

Added info:
Throttle amount angle of blades to flybar
~90% (hits) >12 deg
50% +10 deg
~30% 0 deg
0% -7 deg

Don't know if this helps, but I was hoping for 0 @ 0%, 6 @ 50%, 10@ 100% -- I haven't tried to adjust this yet, but I'm wondering if it's related to my other problem.

[Bayou Talker]

Looks like you have too much total travel. You can move the links closer to center on the servo arms to reduce the overall throw for a rough setting and then do the final setting with the end points. Set a temp pitch curve for 0 @ 50%. Put the stick in the middle and then adjust the links so that you have 0 degrees. You should then have equal travel in both directions and be mechanically centered. Then set your pitch curves for the way you want to fly. In normal I would suggest -6 @ 0%, 0 @ 50%, 10 @ 100%. That way you will hover at about 3/4 stick and still have a little negative in case you get in an updraft and need to power back down. If you want to hover at mid-stick, then set 6 @ 50%. The advantage of 0 @ 50% in all modes is that you will become accustomed to the feel of the collective at the setting you will want for 3D flying. A common setting for Idle 1 is -10 @ 0%, 0 @ 50%, 10 @ 100%.

Why start one way and then have to get used to new settings as you progress? I am talking from experience. I started with a mid-stick hover and then had to re-learn a new feeling as I advanced.

[sireric]

Thanks. I have the servo arms at 10 mm from the center of the servo. This is a hole at ~7.5 mm which I can use. I just worried that the links would get stuck on things, but I can switch. Would that be the correct advice?

[Bayou Talker]

Try them in the other holes and see what the total travel is. Also make sure that they cannot get stuck on anything. If either of these things won't allow them to be moved, then put them back and adjust the end points. I just prefer to make adjustments mechanically before electronically. Make sure that the swash does not bind at the limits and moves the same amount in both directions.

Something else that would help get the swash centered is to purchase a swash leveling tool. Just put it under the swash and it will be centered. Then adjust the links as necessary and connect. There is a link on the HeliFreak main page where you can get one for donating to HeliFreak.

Here is the link to the guy that makes them.

http://web.tampabay.rr.com/helipad/

[sireric]

Oops -- I see that the closer hole doesn't have the clearance for the ball on the "inside" which is where I've put the top ball for the aileron and pitch.

[Bayou Talker]

Then you will have to use the outer holes and adjust the end points.

[sireric]

Thanks. I adjusted the end points to around 72% to prevent hitting the top (I set all 3 to be the same before leveling).

I then tried arranging the ccpm interactions, and those are not trivial! I ended up remembering that I had purchased a swashplate leveler per suggestion, and I must admit that it made it much easier to set the end points and level the plate. I hadn't realized it wasn't level at mid throttle.

After all that, I have +9.5 degrees at max throttle and ~-0.5deg at mid throttle. I'll tune some more in a few days. Thanks for the help!

[Bayou Talker]

That sounds real close to me. How much do you have on negative? It should be close to equal with the positive side if all is centered.

Good luck.

[Seeker]

In the CCPM setup for the radio, you can control the total swash travel (AFR I think?). Use those settings to adjust the total travel if you can. They represent the total travel for stick movement... or I missed that you've done this already?

[sireric]

Really? I have a futaba 6ex transmitter -- I haven't seen that anywhere. I've seen the collective swash control settings, but not the total swash travel, but perhaps I missed it?

I ended up setting a basic ~72% for all 3 servos and using that as a base.

I'm on a business trip so I can't check right now, but will try to check this weekend -- But the futaba docs aren't that great. Any advice is appreciated.

[eeeyal]

Adjusting the end point for the servos will solve your pitch problem. However, if your heli reposes are sluggish (because you don’t have enough cyclic throw) I would adjust the limit for pitch with the PIT curve. (Don’t forget to do the same adjustments for idle ups and hold)

[Bayou Talker]

If you change the value, either up or down, for the "ch P" setting you will increase or decrease the total collective travel. Go back to 100% on end points and then adjust pitch travel there. You will probably see a quicker response that way than using the end points. After that use end points to correct any interactions.

I was not thinking correctly on my earlier advice. Sorry.

[Seeker]

If you change the value, either up or down, for the "ch P" setting you will increase or decrease the total collective travel. Go back to 100% on end points and then adjust pitch travel there. You will probably see a quicker response that way than using the end points. After that use end points to correct any interactions.

I was not thinking correctly on my earlier advice. Sorry.

That's the ticket!

[sireric]

Ok, sorry if I'm dumb, but to recap: on the SWSH AFR "Pitch" setting, I should use that to limit the total travel and then set the End points back to a base of 100% (and adjust to keep things level from there)?

How about the other SWSH AFR settings? (Aileron / Elevator)

Thanks a lot!

[Bayou Talker]

First set the end points back to 100%. Then adjust the SWSH AFR "Pitch" setting to achieve the total travel that you need. It should default to 50% so if you go above or below that, you will increase or decrease total travel. I am not familiar with this radio so bear with me. Most Futaba heli radios will start at 50% on all of the AFR's so I am assuming this one does too. In any case increasing or decreasing the AFR for pitch will change the total travel. After that is done, you can adjust end points slightly to correct any interactions.

As for the other AFR's, they too should start off at 50%. If you want more or less throw on either or both, then they can be adjusted in the same manner.

[Seeker]

I have the 9CHP so it's a little different as far as the menus... keep asking questions until we get it worked out or someone with that radio jumps in.

There's no dumb questions :)

[sireric]

Guys, thanks a lot!

So, I ended up setting the SWSH pitch setting down from 50% (default) to around 36%. With that setting, with throttle at max, I see a sliver of the main shaft. I left the aileron/elevator AFR at 50%, which matches the description of good AFR in the videos (the top part of the swashplate just reaches the flat part of the bearing inside when at full elevator)

I had to re-tune all the end points and even the mid point swashplate level, but they all started off at 100%, and are in the 90~105% range. I'm surprised how out of tune they were after the AFR change.

I now have a pitch of ~1 degree at middle throttle, +10 deg at max throttle, -9 deg at min. Does that sound reasonable?

Now I need to start looking at installing the 401 gyro. I don't know if I'll fly this guy, but it's sure a blast to put together!

Thanks again!!

[Bayou Talker]

That pitch sounds good enough to fly. If you wanted to make it perfect, you could re-adjust the servo links and add back a little to AFR to get +10, -10 but I would just fly it as is until you need to do some more work on it. Eventually you will crash (we all do) and you will need to re-do it anyway.

Good luck on the gyro. If you need help just ask and we will try to help.

[sireric]

Ok.

Actually flew a little!! Big problem: My left/right collective is flipped!! I tried flipping channels 1 and 6, but then they are high on low pitch! What's the easiest way?

Thanks!

[Bayou Talker]

Go into the Swash AFR and change the AIL channel to -50% and it should change the direction. Make sure to change the #1 & 6 channels back to the way they were. That is the way it works on CCPM. You change the direction and travel with the Swash menu.

Hope this helps.

[sireric]

I have the channels back to normal (i.e. reverse). In the Swash AFR, all I have are the Aileron, Elevator and Pitch settings. Currently, they are A:+50%, E:+50%, P:+36%.

If I switch aileron to -50%, It does seem to switch things, but the swashplate is completely unlevel, with the right side (from the rear) is much lower than the left side. Do I need to re-level the whole thing (sigh)?

[Bayou Talker]

That should not have made the swash unlevel, just reverse the aileron. Does the swash move up and down in the correct direction or does one side go up while the other goes down? Does the left/right work properly now?

[sireric]

Yes, left/right are ok. Also, if I move up the throttle, the whole swashplate goes up equaly. It's only level if I give full left stick. Basically, I can't even get the plate to tilt left at all. Only right or level (from rear).

[Bayou Talker]

Are you sure the servos are plugged into the correct channels? It is easy to make a mistake that can cause all sorts of odd problems.