View Full Version : Unequal Pitch
In trying to get the head set up I am having some problems that I can't seem to find the answer for. After watching the videos I have setup the head a dozen times, watching the videos numerous times throught each setup. Everytime I am coming up with the same problem, unequal pitch. The pitch always ends up around -12 +8.
Trex 450 SA with some metal upgrades and DX7
Current set up is:
Swash is level at mid - high - low stick (checked with micrometer, endpoints adjusted to get level at top and bottom)
Pitch Curve is linear
Washout and Mixing Arms are level at midstick
0 pitch at midstick
Throttle hold is off
No Subtrim or Trim
Pitch measured with the flybar level
I just watched the finless videos again, and searched the forums for the last 45 minutes. I see where other people have had similar problems, but never really any answer as to what fixed it. Any Ideas guys?
Thank you very much for any info!
shaggybirdman
03-19-2008, 12:53 AM
only thing i can see is that you used end point adjustment to level the swash. now i'm a no0b myself, but the swash should be leveled via the 3 links, and not the end point adjustments. that mite be the prob. invest the $16 at rchover.com and get there swash leveler.
remember i'm a no0b too so wait for the experienced guys to chime in.
Skarn
03-19-2008, 09:54 AM
What pitch percentage do you have your radio set up for in your swash menu? You can mess with that to get more postive pitch, but watch for binding.
Skarn
BarracudaHockey
03-19-2008, 10:54 AM
only thing i can see is that you used end point adjustment to level the swash. now i'm a no0b myself, but the swash should be leveled via the 3 links, and not the end point adjustments. that mite be the prob. invest the $16 at rchover.com and get there swash leveler.
remember i'm a no0b too so wait for the experienced guys to chime in.
You use the end points to tweak the swash level at high and low stick, he is correct.
Something to check, set point 2, 3, and 4 to 50 and make sure you have zero pitch at mid stick, this way if the stick is anywhere near the middle the servos will be centered.
I have all the swash percentages around 60%, but if I move them up to get more positive pitch don't I get more negative pitch at the bottom end as well? I will try setting the middle three pitch curve points to 50 just to make sure. Maybe I need to adjust the endpoints to take out some negative pitch and add some positive. This doesn't seem like the correct way to fix it, but it might get me close to equal pitch.
Ok,
I think I may have figured out what I was doing wrong after reading another post in the Trex 450 forum. I leveled and setup the swash plate with the swash mix on the radio set at 60%. So in otherwords the swash isn't centered in its travel up and down the mainshaft, correct? That 10% difference is causing the servos to be centered above their actual true center of travel if I am thinking about it correctly. Any thoughts?
BarracudaHockey
03-19-2008, 05:14 PM
No the swash percentage is added or subtracted symetrically.
Figured it out last night finally. The swash plate was too high. After lowering the swash with about 2.5 turns of the links and then adjusting the rest of the links to match, Everything started to measure up in the pitch. With just a quick test hover everthing seems to be very nice. I still need to get the blades to track a little better, you can just barely see one above the other. Other than that, ready to fly (or in my case crash) again.
geoff200
05-20-2008, 06:59 AM
Just out of interest, what height did your Swash end up at mid stick?
aucmax
05-23-2008, 09:41 PM
Figured it out last night finally. The swash plate was too high. After lowering the swash with about 2.5 turns of the links and then adjusting the rest of the links to match, Everything started to measure up in the pitch. With just a quick test hover everthing seems to be very nice. I still need to get the blades to track a little better, you can just barely see one above the other. Other than that, ready to fly (or in my case crash) again.
Don't forget to check both blades for max and min pitch, one side may slightly differ from the other. This is another way to fine tune tracking from the bench. My 2 cents.
Sorry guys, just realized that this thread popped back up. I originally set the swash at 10mm but it just didn't work. Honestly I didn't measure the distance once it was setup for equal pitch. Now I just eyeball the height, check my pitch at top and bottom on both blades and make sure they are equal. Works and Flies awesome. Probably would be quicker to get one of those swash levelers, but my Rex might be going to a new home.