Tail servo question

[supamansuper]

I've been trying to centre the tail servo and cant seem to get the arm centred without using a lot of sub-trim.Is it ok to use sub trim as all the vids i've watched say not to use subtrim on the tail servo?Do you think it might just be the servo need changed,i'm just using the ones that came with the flasher 450.
cheers.

-40sub trim

Also there isn't a lot of movement in the tail servo,only moves a bout 5mm full

[coptermanic]

You don't really not want to use any main trim or sub-trim on the rudder servo. Try flipping the horn 180 degrees or 90 degrees to see if you can get a close 90 degrees at neutral. It is not critical to be exactly 90 degrees to the push rod, but realistically as close as you can. My 450 is certainly not 90 degrees!!

[Tom Burgess]

What radio? You can use sub-trim on Spektrum radios on the tail. You will need to flip the gyro into rate mode, then use sub trim to get the servo 90. You "HAVE" to rebind after you have got it at 90 otherwise the gyro will see the sub-trim as an input and will drive the servo to its endpoint.

[supamansuper]

thanks for the replies.Its dx6i radio.What settings should I use for gyro?Its the gt400 that came with the heli.Next time I think i'll just buy a ready to fly heli.

[Mutley]

Depends on a lot of factors - no point in listing them all if you've mounted the tail servo the opposite way.

Generally .
DX6I servo reverse - N
Gyro reverse - Normal (not reversed)
Set DX6I to rate mode (49%)
and hover

Look at where the servo horn is once you get it to hover at whatever sub-trim.

If its not vertical adjust the subtrim and move the horn until it is. Note at this point you might be restricted by where the servo is along the boom so adjust as required.

What you want to get to is : You can hover - zero subtrim - not holding rudder stick either left or right and that the mecanical links are all aligned 45/90 degrees.

Only at this point can you up your gain out of rate into heading hold. If its not mechanically set in rate mode first you'll always be compensating in heading hold.

Hope this helps.





*Note - its a guide, settings may very etc like the servo reverse - mine is N (normal) yours might not be.

[scallybert]

One thing to remember about tails is that depending on your gyro mode, the 'rudder' input means two different things.

'Rate Mode': rudder input sets tail pitch - gyro modifies this to reduce yaw rate at any time. (Like rate damping.)

'Heading Hold mode': Gyro controls tail pitch to maintain heading. Rudder input to gyro specifies a yaw rate.

In HH mode, centre stick is going to be 'no yaw' - so sub-trim or trim is going to mess this up. Probably.

The set-up for the two modes is likely to be at odds - unless you're very careful.

Personally, I'd go for a good HH gyro, and forget rate mode (for now). No rudder trim. Mechanical set-up so that zero input to tail servo gives the tail pitch that the gyro manual says. (This may be something like 8 deg. It may also not matter too much for basic flying with a decent gyro. My Spartans seem to tolerate almost anything.)