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Post by edintexas on Mar 10, 2013 15:16:49 GMT -4
I have a question about how to setup my head. I set my servo wheels so that the linkage is perfectly square (I have the slanted "A" style control arms. This puts the linkage balls in line with the elevator control arm shaft centerline. The elevator control arm is level (both pivot points are in line with the elevator servo output shaft and the pivot is centered in the viewing hole in the frame). It only took a little sub-trim on two servos to get everything lined up perfectly so to this point I'm sure everything is correct. I have all the linkage rods at the exact lengths shown in the manuals (both the Chaos and T-Rex manuals show the same lengths). I leveled the swashplate with a swash leveling tool. Minor adjustments to the aileron and pitch links required here (one turn each). When I mount the head, the control arms (both the washout and the upper) are several degrees out of horizontal at mid-stick. I followed the sequence ala Finless Bob (and others) to get them in allignment but it meant shortening the rods in some cases as much as 2 or 3 mm. It bothers me that it takes this much adjustment from the factory recommendations. Once I have everything lined up I can only get 9 degrees of positive pitch before the washout block hits the headblock. I need to shorten the swashplate links to pull everything down a bit. The problem is the elevator link length is not adjustable. The only way to adjust it is with subtrim. Any suggestions?
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Post by chitty024 on Mar 10, 2013 23:31:15 GMT -4
I remember having this same issue. The big thing to remember is the rod lengths in the manual are only suggestions. If I remember right what I had to do was adjust the servo to swash links to get everything to line up. Could you post some pics of what exactly is going on?
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Post by edintexas on Mar 11, 2013 7:51:03 GMT -4
Chitty, I removed the head and re-leveled the swash with just a little "down" subtrim on the elevator (maybe equal to about 1mm). Just enough to pull the washout block down a bit. I'll have to live with whatever interaction that creates. But it gave me enough travel to get to 10 degrees at full positive collective. In the process however I discovered something strange. I had to tighten the lower control arm to see-saw links about three turns each to get the control arms level. When I did this it threw the see-saw cage way out of level. What the *&%$?! (see the attached photo). How can this happen??? I thought I was going crazy! If you look closely at the link rods you can see threads exposed on the one on the right but no exposed threads on the one on the left. I took the cage apart then removed and disassembled the links. I found that the rods are both 19mm but they have different threaded lengths and different thread pitches! One turn on one of them made more change in length than one turn on the other. I had bought a spare set of linkage rods so I re-made the links with new, identical rods and ball links and now everything is squared up and perfect. I now have +10 to -10 degrees and the washout block is just kissing the head block. No servo buzzing. Whew! Hope that wasn't too long winded. Attachments:
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Post by edintexas on Mar 11, 2013 8:01:57 GMT -4
Picture of the servo links. I hadn't adjusted the aileron link lengths yet so the swash was out of level when I took this photo. Attachments:
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Post by chitty024 on Mar 11, 2013 9:37:06 GMT -4
I am glad you got it to work out, however, something is still wrong. You should not be hitting the head block and only be getting 10 degrees of pitch. I am getting 14 and not hitting it. When the swash travels down are you still a ways off of hitting anything? Sounds like the swash still needs to drop more and be centered between points. Then you can adjust the pitch up or down with endpoints in your tx. How long are your links going from the swash down?
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Post by edintexas on Mar 11, 2013 9:46:03 GMT -4
I made the swash links 60.5mm per the manual. I've adjusted them a turn or two one way or the other in order to level the swash. The first photo shows the swash position at mid-stick.
Looking at the RCA website's Chaos 600 parts list there is a "Radius Arm/New". Was there a Radius Arm/old? And if so, what is the difference?
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Post by chitty024 on Mar 11, 2013 11:29:46 GMT -4
I made the swash links 60.5mm per the manual. I've adjusted them a turn or two one way or the other in order to level the swash. The first photo shows the swash position at mid-stick. Looking at the RCA website's Chaos 600 parts list there is a "Radius Arm/New". Was there a Radius Arm/old? And if so, what is the difference? Just checked mine and they are at 59mm, not sure how much difference that would make but it would be lower. The old arm I believe did not have the bearings or a spot for them. I accidentally ordered some before.
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Post by edintexas on Mar 11, 2013 12:36:42 GMT -4
Chitty, There's not much difference in the lengths of your swash links and mine. Are the control arms on your bird level at mid-stick? Did you have to make large adjustments to the linkages to get them level or just minor tweaks?
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Post by chitty024 on Mar 11, 2013 12:50:30 GMT -4
Chitty, There's not much difference in the lengths of your swash links and mine. Are the control arms on your bird level at mid-stick? Did you have to make large adjustments to the linkages to get them level or just minor tweaks? Yes everything is perfectly level at mid stick. I make small adjustments.
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Post by edintexas on Mar 11, 2013 17:18:13 GMT -4
Guess I'll start over again. I had to shorten the flybar cage links 3-4 full turns each to get the control arms level.
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Post by chitty024 on Mar 11, 2013 17:23:56 GMT -4
I remember starting over a couple times during my build. If I remember right the trick is to get the swash level and centered and then work your way up to the top with the links making things level as you go.
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Post by edintexas on Mar 11, 2013 17:37:35 GMT -4
If the elevator link was adjustable it wouldn't be a problem. I just don't see how I can get the swash where it needs to be unless I drop the elevator link to where the arm is well below level.
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Post by chitty024 on Mar 11, 2013 17:43:58 GMT -4
If the elevator link was adjustable it wouldn't be a problem. I just don't see how I can get the swash where it needs to be unless I drop the elevator link to where the arm is well below level. I think my elevator arm is below level now that I think about it
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Post by edintexas on Mar 11, 2013 20:41:39 GMT -4
Do you notice any interactions?
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Post by chitty024 on Mar 11, 2013 20:51:53 GMT -4
Do you notice any interactions? Not at all
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