6.2. Servos

6.2.1. Swashplate (cyclic) servos

Torque, speed, and precision should be considered for swashplate servos.


All servos controlling the swashplate MUST be the same type. Do not mix servo types otherwise cyclic control will be erratic. Corona/ECO 8/16 choices

The servo generally recommended for the Corona is the HS-85MG because these last longer then the HS-81MG when abused by beginners.

The ECO 8/16 require a servo no taller than 1.1 inches, so this limits servo choices considerably.

  • JR 341 (0.22 secs/60 degrees, 32 oz-in)

  • JR 351 (0.22 secs/60 degrees, 32 oz-in)

  • HS-81 (0.11 secs/60 degrees, 36 oz-in)

  • HS-85MG/BB+ (0.16 secs/60 degrees, 42 oz-in)

  • GWS Micro 2BBMG (0.17 secs/60 degrees, 75 oz-in)

  • Futaba S3102 (0.22 secs/60 degrees, 63 oz-in)

  • Volz Micro-Maxx (0.16 secs/60 degrees, 55 oz-in)

  • Volz Micro-Maxx XP (0.16 secs/60 degrees, 66 oz-in)

  • JR DS368

  • Multiplex Mini Polo Digi 4 (0.10 sec/60 degrees, 39 oz/in) Logo 10 choices

The Logo 10 uses servos from 1.1 inches to 1.3 inches tall, so it can use all the servos used in the ECO 8/16 except the servos with less torque are not suitable. Probably 42 oz-in of torque is a reasonable minimum requirement for a Logo 10.

  • HS-85MG/BB+ (0.16 secs/60 degrees, 42 oz-in)

  • JR 341 (0.23 secs/60 degrees, 42 oz-in)

  • JR DS368

  • Multiplex Micro BB? Summary

I've been told the Volz servos are too deep to fit into the Logo 10 frame, so they are supposedly not usable for the Logo 10.

For the Piccolos, the most popular choices seem to be the Hitec HS-50 and the HS-55.

If you use ANY digital servos, see the BEC section for more info.

The HS-81s and HS-85BBs can be upgraded HS-81MGs and HS-85MGs by replacing the plastic gears with the metal gears from the MG version, which are available at many places (Servocity, etc).

6.2.2. Tail (rudder) servo

The tail servo for a helicopter needs to be very fast to respond quickly to small random tail movements. The tail servo should have a specification of 0.12 sec / 60 degrees of travel or better.

For the Corona, Logo 10, and ECO 8/16, some usable tail servos are:

  • Hitec HS-81

  • JR DS368 (do not use in DS mode, will burn out)

  • Volz Speed-Maxx XP (DS mode compat, will be released about Oct 2003)

  • Multiplex Micro BB Speed (DS mode compat)

  • Hitec HS-5245MG (DS mode compat)

  • Hobby Electonics HDS-577 (DS mode compat)

  • Multiplex Mini Polo digi 4 (DS mode compat)

The Multiplex Micro BB Speed is slightly larger than the HS-81/DS368 so some modification may be required to use it.

For the Logo 10 or larger, the Futaba S9253 is very popular used with the GY401, although the S9253 is rather heavy for the Logo 10.

Some servo mounts will allow you to use high-speed micro servos for the tail pitch servo, such as the Precision Model Products tail servo mount for the ECO 8/16.

For micro helis such as the Hornet, Shogun, and T-rex which use tail servos, some usable tail servos are:

  • Hitec HS-55

  • Hitec HS-56

  • Hobby Electronics HDS-877 (DS mode compat)

The Hitec HS-50 is not recommended for a tail servo because it has excessive slop in the gears and may cause tail wag when used with a heading hold gyro.

The metal gear servos are not recommended for the tail because the metal gear servos wear faster and have more backlash than plastic gear servos, which will result in less precise tail control (with the exception of the Volz Speed-Maxx XP which is specifically designed for tail pitch control)

The slower digital servos (such as the JR DS368, 0.21 sec/60 degrees) do not work well as a tail servo unless the stock servo arms are replaced by extra-long servo arms (Du-bro, Servo City, etc). This sacrifices some precision for extra speed.

JR does not recommend the DS3421 for tail gyros because the servo motor is too small to handle the frequent movement required.

Gyros are sensitive to temperature changes. If you car is warm, the weather is cold and you take your heli out of the car and immediately try to fly, the gyro will not work well. You should allow a few minutes for the gyro temperature to settle before flying.