Specifications

Therefore, it is best to use metal geared servos for swashplate control, where the crash resist-
ance is desirable. The plastic geared servos work better for tail control because tail control
slop will cause tail wag with a heading hold gyro.
30.6.2.6. Replacement gear availability
Servo gears are sometimes destroyed in heli crashes, so you should consider the availability
of replacement servo gears when selecting a servo.
30.6.2.7. Geartrain slop
Slop is undesirable for both swashplate and tail control servos. SOme servos, such as the HS-
50, have excessive amounts of mechanical slop, which make them undesirable for helicopter
use.
30.6.2.8. Overall quality
The two best servo manufacturers are probably Volz and Multiplex. They have a history of
manufacturing servos with extremely good geartrains and very tight deadbands.
The next best servo manufacturers are probably Futaba, JR, and Hitec. All three manufacture
good quality servos.
30.7. Electronics modification guide
30.7.1. Adding a brushless motor to a brushed 3-in-1 controller
You may want to use a brushless motor with an existing 3-in-1 controller without converting the
helicopter to separate electronics. There are a few different ways to do this.
Note: A 4-in-1 controller is the same as a 3-in-1 controller with a receiver, so these techniques
will work with a 4-in-1 controller as well.
30.7.1.1. Using a Y-lead
A brushless main motor ESC can be added to an brushed 3-in-1 controller by simply using a
Y-lead servo connector on the throttle channel. This will allow both the 3-in-1 and brushless
motor controller to receive the throttle signal. This will not work for a brushless tail motor be-
cause a Y-lead on the rudder channel will bypass the revo mixing capability of the 3-in-1 con-
troller.
30.7.1.2. Using a PowerZone adapter board
A PowerZone adapter board converts a brushed motor signal back into a servo signal (variable
width pulse) so the brushless ESC can plug into the PowerZone. This works for a brushless
main and tail motors, although a Y-lead is much cheaper for a brushless main motor. However,
if the 4-in-1 board has both the receiver and controller on a single board, then using a
PowerZone may be easier than trying to trace the receiver's throttle channel to connect a servo
connector.
Search the RCgroups micro heli forum for more info on the PowerZone.
30.7.1.3. Use transmitter mixing to slave channel 5 to the throttle channel
If you are using a six or more channel transmitter, then channel 5 should be unused when us-
ing the 4-in-1 board. You can slave the unused channel 5 to the throttle channel (usually chan-
Technical Appendix
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