Question about rudder delay

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Michldigital
Posts: 13
Joined: Sun 23. May 2021 9:13:35

Hi,

I'm currently building a RAW580 with an MKS HBL880 servo for the tail. I'm setting it to 760us and 560Hz.
The servo isn't listed in the servo list. However, the almost identical HBL990 is included. Here the list says: Delay = 0 - 3

For a Futaba BLS276, the list says: Delay = 0.
So why should I set up to 3 for an MKS servo, which is almost twice as fast as the Futaba servo?

What effect does rudder delay have on tail performance? What figures can I fly to determine the ideal delay for the servo in flight?

Greetings
Maik
Mona
Posts: 42
Joined: Wed 15. May 2024 11:00:21

Would like to know this too. The manual gives some guidelines on what the value should be in relation to servo speed, and there is the servo list. But the actual tuning procedure is not described. If the range is 0-4 how to we find the optimal value? What issues to look for?


From what I understand with the info available:
It's some type of damping on the tail servo that prevents problems in case the servo isn't fast enough to keep up with the corrections. Manufacturer specs can't necessarily be trusted so you probably can't make assumptions comparing to a different brand. Behavior largely depends on the servo controller programming as well. Lower values are more taxing on the servo. My servo wasn't on the list at the time (KST 0.035s/60°) so I just started with 3, then lowered to 0, noticed no difference and the servo never gets even slightly warm so I guess it's fine. I'm assuming lower is more precise if the servo can handle it.
ZeXx86
Site Admin
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Difference is that BLS servos are working better always with low Rudder Delay. While other could work also with higher Rudder Delay.
It is due to a different algorithm used to control servo motor that is programmed by servo manufacturer.

Difference between 0 - 3 is very small. Almost all really fast tail servos should work well with 0.
Spirit System developer
Michldigital
Posts: 13
Joined: Sun 23. May 2021 9:13:35

Thank you. Ok, i understand.

But is there a chance to find the best value for my servo? Or just set it to 0 and thats it??

Greetings
Maik
Michldigital
Posts: 13
Joined: Sun 23. May 2021 9:13:35

May i ask for an answer?
curmudgeon
Posts: 219
Joined: Thu 01. Oct 2015 15:13:29

The MKS HBL880 X8 tail servo is among the fastest servos in the market today. Treat it as a very fast tail servo, meaning a Delay of “0” should be good for it.
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