K110: Why is the ZERO pitch different when I turn both main blades 180 degree

[Thomas.Heiss]

Hello,

I think ZERO blade pitch (when both blades are folded into the same direction) is a general topic so I also want to place it in the 100er forum.

My thread from the K110 sub forum: https://www.helifreak.com/showthread.php?t=861265

I don't remember that I have made this test on the Blade 4503D.
On the 450 I just measure one blade in the normal (spinning) position and use a pitch gauge.

And when I measure the pitch at the back over the tail boom to adjust it for ZERO pitch, then I know that I have to spin the whole head 180 degree so the other blade (in normal position) is again measured at the same spot.
You can probably also fold both 325mm blades back to roughly check for ZERO pitch; other videos suggest to do this with the heli lying on its side both blades looking to the left (or right), so 90 degree and not over the tail boom.

For micro helis a good trick also is to lift the heli with the nose up, so both main blades (into the same back direction) can freely fall (there might be some slop in the blade holder) and the servos do not have to work that hard and that there is not much swashplate slop.

Usually I do both.

Q: Do you have to tigthen the main blades or is the strength at the point enough where you fly the blades?
First I tigthen them and then I loose the screw slightly until the main blade can freely fall down.
Can't I use this setup for ZERO pitch measurements when I fold both blades back?

..(...)..

Of course, you can also measure at the front (both times), instead over the tail boom.

I am not sure what pitch measurements you get or should get if you turn one blade 90 degree from the back to the left side, then front side, than right side.

For example:
On the B450 the main shaft is not 100% vertical (it slightly leans to one direction)....so to do any fency swashplate leveling (e.g. with bubbles on this flybar heli) I first have to use some papers below the landing gear and correctly level the heli on the nick and roll axis.

I am not sure if you guys additionally check for left/right side of the rotor head or if you put two main blades (folded both back = same direction) from the back to the front to see if they are even or not.

This is what is now happening with the K110 that I get different ZERO pitch measurements at the tail vs the front.

I have no idea....

How the heck shall I correctly fine tune on the K110 the ZERO pitch with subtrim (collective channel) and also check for roughly correct blade tracking (to see if there are nasty vibrations, something is wrong with the head) when I get different measurements depending how what direction I align both main blades in the blade holders: Front vs back?


Can someone help me and push me into the right direction?
What part of the head might be wrong?

As I do have no pitch gauge for the K110, I have to use the main blade folding technique.

Thanks.

Best regards from Germany

[ridge-runner]

Check if the main blade itself is bent near the root. The blades must themselves be straight for the folding back the blades zero pitch technique to be accurate - i.e. centerline of blade must be perpendicular to main shaft.

A bend in a main blade becomes apparent by installing it upside down. If the tip locates in the same place right side up and upside down, then the blade is straight, otherwise it is not.

[BobHyatt]

Another thing. At zero pitch is the swash plate dead level? If, as you rotate the blades, they slowly separate and then slowly return together as you rotate through 360, you probably need to check this...

[CrashyCrashy]

^^^Good advice above. Also take in to account the low quality swashplate, slop in the linkage, and servos. The swashplate servo link arms can be off or bent from crashing. After mechanical setup I fine tune pitch travel in the TX. Zero pitch with sloppy components just isn't going to be precise. It's a micro. You will go crazy chasing it. Also one crash can change things. Bent linkage or a ball link jumping a thread or two. Bent swashplate arm as mentioned.

CrashyCrashy

[Thomas.Heiss]

Originally Posted by CrashyCrashy

Also take in to account the low quality swashplate

Well, I have done all my tests with the black and red aluminium swashplates.

They usually are made (if they work, one red does not not) of better quality and with the additional brass ring on the inside there is way less slop than with the plastic stuff (where the inner whole is too big for the main shaft).

[CrashyCrashy]

Yes, I prefer the aluminum swash. The plastic seems more forgiving when the main shaft is bent.

CrashyCrashy