Cgy750 Neutral points and Atv's

[Paul'os]

Hi
I have setup my cgy750 on my Trex550 pro.
The 550 uses metal horns of which none line up perfectly at 90 deg, i've tried swapping them all around with no luck. I have had to use some neutral trim in the cyg750 to get all of my servo arms at 90 degrees as per the manual. The downside of doing this is that it alters the servo's travel, i get more movement one way than another. This gives me unequal pitch and cyclic, which feels weird to fly. Do you just dial this out using the transmitters ATV. Any info would be appreciated.

Thanks

Paul

[Steve Evans]

Originally Posted by Paul'os

Hi
I have setup my cgy750 on my Trex550 pro.
The 550 uses metal horns of which none line up perfectly at 90 deg, i've tried swapping them all around with no luck. I have had to use some neutral trim in the cyg750 to get all of my servo arms at 90 degrees as per the manual. The downside of doing this is that it alters the servo's travel, i get more movement one way than another. This gives me unequal pitch and cyclic, which feels weird to fly. Do you just dial this out using the transmitters ATV. Any info would be appreciated.

Thanks

Paul

Adjusting the sub-trim or neutral point to get 90deg is fine. Sure this will limit the absolute max extreme of movement in one direction compared to the other, but I'd not expect you to hit that limit, even with full collective and pitch. If you do, you need to move the ball out a hole on the servo arms.

Steve

[Paul'os]

Hi Steve

Thanks for the reply, my observation was that when i looked at my servo monitor and applied say 20% aileron i had a pitch discrepency of may be 3/4 of a degree between each side, this gets exponentially worse to about a degree and a bit at full stick. I just thought that this was too much, i can see visually the servos moving more one way than the other. I can dial it out with a few clicks of atv on the tranny but didnt know whether this would be a problem for the gyro?

Thanks

Paul

[quantummodz]

just recently had to set mine up

dont use end points

set up servo arms and 90 to the link rods not 90 to the servo shell.

lower the swash link length by a turn or half a turn

on the trex 600N LE is has a solid elevator bar i has to lower that arm slightly off 90 to get the correct pitch

handy tip i use to get a ruff bearing is say you have pitch of -11 and +12 then just go to low pitch as adjust tell you have 11.5 bottom. then re ajust 0 pitch and you should get even pitch

the theory is if you have the same pitch top and bottom with 0 pitch at centre also. Your servos will be centred as you have even travel both ways

[Paul'os]

Thanks people for your advise. I have re-set up all the linkages and servos. I now get equal pitch neg and pos and equal aileron but the elevator is 1 degree out for and aft. I think i am going to give up and just keep flying it as is, i just wanted it to be.equal all the way round but im sure there must be something going on with the 550 geometry. :-)

[quantummodz]

yep your right

when you setup your pitches and the swashplate is flat for elevator put the blades at 90 to the boom
then put the blade alon the boom for aileron the pitch should be same top bottom a 0 ish middle

the cyclic pitch can or is normally only checked one side as the gyro is compensating for movement - you can tell this by the pitch gauge giving a different centre reading when returned

any way the key points for you now are to do the link compensation setup ( from page 121 on manuel ) key word to remeber reduce interaction not eliminate it

then do a trim flight fly with HH off and trim the 3 axis then land flick in and out of hh 3 times then put hh on and your off

then DONT go back to the bench and recheck pitches cos they will be all different again as the swash is not NOT level it cannot be as it is compensating for rotational forces just like the tail does

lastley check your centre of gravity ( hold rotor arms and tail should balance at 90 )

good luck

[Paul'os]

Thanks
Still playing with the setup, but the weather is so rubbish at the moment I havent had time to do much testing. I am getting to the point where I am so rusty I'm to sure whether its my flying or the heli setup which needs tweaking. Roll on summer when we can get some flying in.