Rudder servo

Rcsailing.net General Discussion
1

Hi all

There 's usually lots of talk about sails servo, but here I’d like to get some info on the rudder side. Is there some minimum requirements ?

My first IOM was built to be reliable rather than “utimately competive”. For the rudder I bought a Futaba S3010 which is “torquey” 65 N.cm and ball raced. I have to say it works fine, but maybe this is a bit overkill ?

For the next one I’m wondering if I could not use the Standard S3003 that is usually supplied in the RC kit.

What’s your experience ?

2

I’m using the 3003 on mine without problem - but have never expected it to be fully up to the task and will get around to upgrading at some stage. I think there are several servos that are better suited to the job.

3

A strong servo mount, or bracket, and the correctly working steering linkage are just as important as the servo itself. floppy mount and loose links will not allow one to steer precisely, and the servo will need to work harder.

4

seems to me that a “standard” S3003 has enough “power” to handle a rudder…

Control System: +Pulse Width Control 1520usec Neutral
Required Pulse: 3-5 Volt Peak to Peak Square Wave
Operating Speed (4.8V): 0.23sec/60 degrees at no load
Operating Speed (6.0V): 0.19sec/60 degrees at no load
Stall Torque (4.8V): 44 oz/in. (3.2kg.cm)
Stall Torque (6.0V): 56.8 oz/in. (4.1kg.cm)
Operating Angle: 45 Deg. one side pulse traveling 400usec
360 Modifiable: Yes
Direction: Counter Clockwise/Pulse Traveling 1520-1900usec
Current Drain (4.8V): 7.2mA/idle
Current Drain (6.0V): 8mA/idle
Motor Type: 3 Pole Ferrite
Potentiometer Drive: Indirect Drive
Bearing Type: Plastic Bearing
Gear Type: All Nylon Gears
Connector Wire Length: 12"
Dimensions: 1.6" x 0.8"x 1.4" (41 x 20 x 36mm)
Weight: 1.3oz. (37.2g)

I use mine with 6v…
I also must add that I prefer the S3004 (it has ball bearing)

my 0.2 Yen

5

What are you trying to move, that you need so much torque? There’s no need to make snap turns in an r/c sailboat.

6

The comments above re no slop are spot on. I have just changed a standard servo for a hitec HS-645MG servo, running on regulated 5V via 280 D Smartwinch. Also used an alloy servo arm with a good control horn for movement free rod connection.
Then used a ball link on rudder arm. Still have some minor movement in plastic rudder arm and am looking for better unit.
This made steering absolutely positive, and a bit too quick so moved pivot hole on servo arm to reduce rudder movement and it now steers with ease and precision.
The strong servo is not about moving large loads, its about having control, it centres consistently and moves with minimal stick to allow small adjustments.
Check out www.kbits.co.uk for more info on servos, winches and steering setup

7

Your moving in the right direction by using a standard servo. A well designed boat will steer really good on standard servos. If it doesn’t then there is something wrong in the design, big time. You can talk about the torque etc , till the cows come home but the probs are not in the servo but the boat. Get the boat right and it should turn easily.

If the boat is not turning on a standard servo then there are other probs too.
Go look.
Steve