Brushless servo


Thread Starter


Need three Servos for control surfaces on an experimental aircraft I am building. Need help to find the right part:

1. 20W+600%-20% 24V continous (
2. lightweight brushless DC motor (Stepper?)
3. Geared down to 0.5 rev/sec
4. Electric clutch to disengage servo from control
You'd probaly want a dc or brushless motor with neodimion [spelling?] magnets. These types of motors can give you extra torque for same size motor with traditional magnets. However, they can get pretty hot if used continously at max torque and would need cooling. Steppers could work but I would guess that the dc servo motor would give you more torque for the size. Have you tried Micromo or Pittman? Maxon is another. Magmotor is a custom house that would make custom motors for fairly reasonable quantities.

Why would you need a clutch when you can just stop the motor with the servo controller?
If I was building an auto-pilot for my airplane... I would want a mechanical disconnect (clutch).


Jack Eskew
Microsmith, Inc.
301 W. Deer Valley Road # 3
Phoenix, AZ 85027
V: 623-587-6473
F: 623-587-0612
[email protected]
Yaskawa has some very small 24 vdc brushless drives and motors. 20 watts sounds about right. Up to several 1000 RPMs. They are called their MiniDrives.

You will need to obtain any needed reducers and clutches someplace else.

Phill Jackson

Micromo or Pittman are a good starter for development demonstrators only.

The problem you are going to come across is the use of rare-earth magnets and the localised electronics to control the commutation.

We have started to develop an optically commutated brushless for fuel valve operation. NdFe magnets will not give you your temperature ranges (-55 deg.C to +125 deg.C) I would suggest starting with SmCo. Kollmorgen are a good supplier.

Any electronics that you use. Keep these as simple as possible, aiming for passive components as much as possible. Your main problem is getting the electronics to work reliably at +125 deg.C. Further to this, the estimated MTBF (mean time before failure) will be reduced with the complication of all the additional electronics. We are trying to hide the electronics in the electrical connectors though price then comes mind, since you will have to consider lightning and EMI protection. Solder joints are our main concern with the reliability of the electronics together with the prices for Silicon-on-insulator devices required to allow for the electronic commutation at the elevated temperatures.

Not too sure how much you have managed to progress since August? Developing the technology is one thing. Flying it commercially seems to require more of a push-me-pull-you.