I know that mini servos can be used on the throttle, but how mini can you go? Would a micro servo work? Is there a set amount of torque required? For example, would an HS-55 work?
Thanks

It should probably work. Throttle servos don't need to have much "omph" to them to work. Just make sure you remove and binding or snags in the throttle linkage and you should be fine.

Hope this helps

Ken

If the throttles work smoothly, very little effort is required. I just finished building a Sig Kadet Senior twin engine model that has OS FS .40 Surpass 4 stroke engines on. I used seperate throttle servos in each engine nacelle. The servos were only 17.5 oz.in. torque. These are very light servos, so the there was a great weight savings over a standard servo.

Whatever you use, make sure the carb barrel rotates easy and smooth and no linkage binding.

Rod,

Excellent, that was exactly what I wanted to hear. I thought it wouldn't be a problem since it's not a high stress thing, but just wanted to make sure that people had actually done it with success.

Thanks for the help!

The bigger problem is how long it will last with the vibration that it gets through the throttle pushrod. I use HS 81's for the throttle and they are fine, the 55 doesn't have a good way to rubber mount it and the gears are so tiny, vibration will wear out the servo pretty soon.

I've never seen a statistic for it, but most glow engines would probably be easy on a 15 oz servo. Depends a lot on the smoothness of the carb barrel itself and the resistance or the control linkage. Tight turns with a sleeved rod can be surprisingly hard to cycle.

If vibration is a concern, simply use double sided servo mounting tape or even better, the type of tape we use to mount our gyros with.

Another thing I do is to use a small diameter music wire, such as 1/32" and run it through a piece of ny-rod. The wire is stiff, but flexible enough to smoothly bend around small curves. I even apply some vaseline to th wire to aide smoothness. I've been useing this method for 30 years and it works great for me.

Rod

I use HS81's on most throttles, and I've fitted GWS picos in a couple of sub .15 planes. All work just fine, and have done for some time

As long as the linkage is free and smooth (as it should be) you really dont need much servo to get things going

I've used HS-55's a couple times for a throttle servo. As others have said, it should work great as long as your linkage is smooth.