jzinckgra

My Feedback: (11)

I want a dedicated nose gear steering servo for my 1/6th trojan t28. I was looking at the futaba micro (3103) servo, which has 17oz torque at 4.8V. Would this be enough or should I get something a little stronger>?

FHHuber

That size bird... steering (being the beast it is...) you don't want that servo unless you like replacing gears.

If you never bounce a landing and never hit a rock on the smooth paved runway its fine.[&:] (anyone who can claim they NEVER bounce and never hit a rock?) its not the servo power... its the shock loads it can encounter.

Flypaper 2

You might look at the GWS micro's with the metal gears and ball brgs.

Highflight

My Feedback: (4)

I'll go against the flow here and suggest that you're OK with that servo for nose wheel steering only, but with a big exception.
If you hook it up directly to the nose wheel steering control arm, you'll strip the gears every time you taxi.
The way around that is to set up a dual spring system where the nose wheel is only "encouraged" to move by the use of spring tension between the servo and the nose gear.
That way, the nose wheel can bounce and move all it wants and the springs will take up most of the impact forces. Since you want to get by with such a small servo, be sure to use weak springs, be be aware that you won't actually be "turning" the aircraft, you'll be "suggesting" that it turn so be patient as it works it's way around to the direction that you want.

Highflight

jzinckgra

My Feedback: (11)

Well, maybe I'll go to a bigger servo, but do I really need a full size servo, like the ones I'll be using on the control surfaces? I guess I am trying to keep the weight down and thought a micro would be ok. I also thought of just hooking it to the same servo as my rudder, but that might overload the servo.

Highflight

My Feedback: (4)

No, you're thinking in the right direction because you'll "obviously" save weight by using the same servo to drive the nose wheel as you do the rudder, but I'd still say to use intermediate springs up to the nose wheel to protect the rudder servo.
Look at a bunch of the giant size taildraggers you come across, and you'll see that (the smart buildiers) use a spring/spring setup on their tail wheels in the same way that I suggest doing it for the nose gear. That's how you keep servos from stripping a gear every time you hit a bump or land a little hard.
I wouldn't worry about overloading that servo because if you think about it, the rudder doesn't "load up" from flight loads until just before rotation so it's no big deal for the same servo to drive the nosewheel when it's taxiing. It could even be argued that there is a transition point where the servo really ONLY drives EITHER the nosewheel OR the rudder but not really both at the same time (with respect to torque loading and resistance).
Just don't confuse "overloading" with abuse. Driving both the nosewheel and the rudder with the same servo is NOT overloading, but hooking up the nosewheel DIRECTLY to the servo (with no spring buffer) is ABUSE that will trash any servo at some point.

Highflight