Hello,
I'm doing quite a bit of servo research right now trying to decide on the "right" servos for my new 1/4 scale Laser 200. My question is, "How fast is fast enough?" with respect to manufacturer stated servo travel times.

Does anyone really feel a difference in flight between say 0.18 s and 0.13 s? I'm looking at digital servos and the the range of times and dollars I'm seeing is 0.18 for $36 to 0.08 for $80.

Any thoughts or personal observations?

Thanks,
John Kos

I guess it depends. Are you an extremely experienced aerobatic flyer? Will you be flying in IMAAC type competitions?

If you're sport flying, I wouldn't worry about it. Be more concerned with servo "torque".

I have a friend that fly's tight, fast aerobatics. He says he can tell the difference between them. I doubt that I could.
Dennis-

Ditto, .2 sec is plenty for me.

Hey Mike......

You know if Roger sees this he will make comments about the servos you had on the plane that you sold him...

John,

Another factor that enters is the "gear" ratio between the servo and the control surface. A servo wheel that rotates 60 deg in .2 seconds will move the surface at half that rate if the control horn is twice as long as the servo horn. If your servo horn is longer that the control horn, the surface moves faster than the servo.

This is very apparent with 3D setups which have extreme control throws. The surfaces move faster due to the gear ratio. This also accounts for the higher torque needed.

Bottom line; standard speed servos work just fine.

Tom

I built a plane one time and used fast servos.
then I bought a computer radio and programed expodential.

bugsiegel,

Please tell us how your story ends!!! Did your plane crash instantly, or did girls start hanging around your plane, or what?

Fast servos don't create the need for exponential because you can move the sticks as slow as you want to.

Fast servos are only useful if you are moving the sticks back and forth so fast that a slow servo can't keep up. As far as I know, the only really useful application is on the tail rotor of a helicopter where a computer is making rapid tail movements.

Tom

I put some .14 speed digitals in a profile plane where most folks just use standard servos. They are quick and precise, but probably not necessary.

I let a 3D master fly it..this guy is amazing, one of the best I've seen (who BTW runs Std servos in his plane AFAIK) and the very first words out of his mouth:

"Wow..you've got some good servos!"

So if you are experienced enough to tell the difference, I guess you can tell but I run .21 speed servos on a different profile (on 6v however) and they seem just fine to me.

As for the exponential...I use it so I can run radical throws and still fly "normal"..and I use dual rates also, but my low rates are still pretty touchy without EXP. Just my $.02

I fly funfly's with exagerated control throws and over sized control surfaces that weigh just over three pounds. on high rates with out expo the plane can be a hand full.

I just use futaba s3004. they are plenty fast, ball bearing, except i have a coreless servo on my rudder, and it moves that thing in a hurry. i guess "fast enough" is as fast as you move yoru sticks around.