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Question about rudder delay

Posted: Mon 31. Mar 2025 8:56:59
by Michldigital
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

Re: Question about rudder delay

Posted: Mon 31. Mar 2025 11:13:39
by Mona
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.

Re: Question about rudder delay

Posted: Mon 31. Mar 2025 11:56:20
by ZeXx86
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.

Re: Question about rudder delay

Posted: Mon 31. Mar 2025 21:39:26
by Michldigital
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

Re: Question about rudder delay

Posted: Thu 10. Apr 2025 8:51:43
by Michldigital
May i ask for an answer?

Re: Question about rudder delay

Posted: Thu 10. Apr 2025 16:11:33
by curmudgeon
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.