50 SE Pitch alignment

[RaptorMan]

Hi,
Have a 50 SE running BBT carbon blades (TT type black/white).

Problem: -
With link rods and double links all set as per manual I get the desired -10 -> +11 pitch. Now turning the head 180deg (I stay on the same side of the heli) and pitching the other blade it is some 2deg out (-). Why?

Swapping blades (checking for warp etc.) still gives the same result!

Why do I need to adjust the link rod as it should be the same!

Flying with the adjusted rod she does seem in track, but she can do wildly out @ 0deg sometimes.

Dampers and feathering shaft are new.

Any ideas as I just can't see why it needs changing, also is it giving me the 0deg tracking problem.

Please!!

M

[antsis]

Are you sure the swashplate is level?

[Ade_Law]

pitch gauges are notoriously inaccurate. so you will generally get a different reading left and right.

forget the manual,

put the collective servo in with the output shaft of the servo to the front (opposite to manual)

put the ball on the collective lever to the hole closest to the mainshaft.

zero your pitch sub trim, dissable any pitch trimmer nobs/levers in the radio.

collective pitch stick to centre fit the servo horn to the servo so the angle from the pushrod to the servo arm is 90degs.

adjust the length of the pushrod from the servo to the collective tray so that you get the full mechanical travel of the collective lever without binding. increase the end points of the pitch servo if required keep the values the same by adjusting the length of the pushrod. if you find your end points are less than 90 then use a shorter servo horn, over 110 and increase the length of the servo horn.

adjust the length of the rods from the aileron servo to the aileron bellcranks so that the bellcranks sit level. use a vernier calliper to ensure these rods are exactly the same length.

adjust the length of the pushrod from the elevator servo so that the intermidieate lever on the pivot of the collective tray is vertical.

level the swashplate by adjusting the length of the pushrod from the intermidiate lever to the elevator rocker.

adjust the length of the pushrod rods from the aileron bellcranks to the swashplate so its level, again use a vernier to ensure they are exactly the same length.

now with the collective still in at mid stick, adjust the length of the long links from the swash plate to the upper mixer arms so that with the flybar level the mixer arms are parrallel to the flybar. again make the 2 the same length using a vernier.

finally adjust the length of the short links from the upper mixer arms to the blade grips to give you zero pitch. again use a vernier to get them the same length.

to check zero pitch fold both the blades back, hold one with your finger and let the other drop until the weight of the blade is sitting on the linkages and measure the gap between the tips of the 2 blades.

now hold the other blade and let the weight of the other blade rest on the linkages, again measure the distance. if you have zero pitch the measurement will be the same.

this is more accurate than a pitch gauge as you are allowing for any slop or stiffness in the control system.

Ade

[RaptorMan]

Swash plate being level or not will not effect measurments taken from the same side with the blades spun through 180deg.

Ade Law, great instructions and have already done everything you have said, except the folding of the blades back and measuring the distance.

Problem is the blades are not showing the same pitch taking the measurment from the same side. I use one of those pitch gauge that locks the flybar (seems like a good system). With everything level and equal in length, as your great instruction explan why should I be getting 2deg out @ the top end (bottom end is different).

Should this happen with the same blade being used for the measurements? I understand about the pitch gauge being slightly out but not 2deg. You must still be using the gauge to set your p-curves? The pitch on the main frame is meant to be incorrect.

So if everything is level and measured you would not need to adjust the link rods taking the measurment from the same side and the same blade (take the blade off turn the head 180deg and place the blade on the grip now looking @ you) surely?