450 450 Tail Centering with pitch at zero

[sts41]

My question may be mute since I do not see a way to adjust this no matter what. With the tail collar centered, I would imagine that the tail blade pitch should be zero. That way, there would be an equal pitch deflection on either side of the collar.

Does this make sense?

However... With the blades at zero pitch, the collar is way closer to one side than the other.

Anyone ever see this before? ... Does it make a difference?

Next question is... Do I trim for zero pitch, or center collar?

This is my first build, and yes, it is one of those Chinese copters (HK 450 Pro, TT), but I just find it funny that it is out by that much.

I have 2 other copters... one Align v1 and the other a HK pro, and neither have this issue.

As always... Thanks for the much needed help.

Steve

 

[Tony]

YOu will always trim for the collar centered on teh shaft. There is always going to be torque on the tail from the head, so you always want some right thrust coming out of the tail when the stick is centered.

 

[Lee]

The torque from the main blades will always try to turn the heli.
So a lot of helis now, have the tail blades set so when the pitch slider is in the middle, the blades are producing counter torque to keep the heli from turning on the yaw axis.
This means you will still have equal turning capability left and right.

 

[sts41]

Thanks for the quick response.... I will give it a try and see how it flies... I normally run the heli on the floor without main blades to check that the gyro is properly setup. I will give it a try this morning and see how it goes.... By all rights, the gyro should still try and keep it pointed in the right direction.

Thanks Steve

 

[Lee]

The gyro will always try to do its job, but by having it mechanically set up, your easing the stress on the gyro having to keep the tail in line.
Good luck
Do check my tail servo and gyro set up video to be sure you have it all set up correctly before spooling up.
You can find it in my RC tips and tricks link below.

 

[sts41]

That was extremely helpful... and easy to remember.... I have seen it explained a dozen different ways... But You are the winner...

Thanks Very Much.

Steve

 

[Lee]

You are very welcome.

 

[orbi]

YES.... I know what you mean , the slider is off centre when the blades are zero. I added a new twin armed slider and found this compounded the problem. The link arms that control the blade pitch on the new slider mechanism were longer and thus pushed the position of the slider towards the boom a tad more, this reduced the amount of room on the slider bar for right hand manoevering.

To position the correct degree of positive pitch I do the following which is easier to do than it is to edit.
1. looking at the heli from the rear fold the blades at 90 pointing towards you.
2. The top blade should be parallel to the bottom blade when viewed from above. and the servo centred .
3. Now simply adjust the linkage rod eye till the top blade moves left by 3/4 inch. This 3/4 inch difference in blades ,is the amount of positive pitch that is a real good starting point .

I have set my gyro at 70 and 30

This works on all my 450 models obviously the larger tail blades on bigger models will be different, but this method has always done it for me.

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With this degree of positive pitch I am finding too that I only have a minimal 4mm left for clockwise heli movement, I have tons of pitch the other way.

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Tail blades at zero pitch will automatically put the slider where it is supposed to go on the tail bar. The tail grips may be longer in the newer twin armed slider which places the slider more off centre towards the boom side. Mine does this. I have measured the distance of the old slider and the new one and there is a bigger difference there in the links.

 

[Slobberdog]

The new double armed slider has longer links so when you have the slider set to centre it will put some pitch on the blades to help with the torque of the main rotor,

Most new heli's are set up with this pre set amount of pitch on them.

 

[orbi]

I had my answer today, my cheapy dual arm stuck solid and almost burned out my servo. Ive reverted back to a single arm as I have equal amounts of pitch either way. Centering the servo with horn at 90 is vital. Every arm has a different angle of throw so keep trying till you get the right one.!

Align 450 models should have no more than 9mm from the centre of the servo to the ball link. They say that the further throw you have, the more it can lead to vibrations and over sensitivity, which makes sense.

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I had my answer today, my cheapy dual arm stuck solid and almost burned out my servo. Ive reverted back to a single arm as I have equal amounts of pitch either way. Centering the servo with horn at 90 is vital. Every arm has a different angle of throw so keep trying till you get the right one.!

Align 450 models should have no more than 9mm from the centre of the servo to the ball link. They say that the further throw you have, the more it can lead to vibrations and over sensitivity, which makes sense.