Specifications

gers before mounting in the frame.
6.4.2. Pinion
For more details see Section 30.4, “Pinion selection guide” in Chapter 31, Glossary
Most helicopter manufacturers supply a range of pinions for their helicopters. You may require
pinions with more teeth for some reason. The most common reason is for running outrunner
motors which usually have a fairly low Kv and therefore require a pinion with a higher tooth
count.
Some helicopters use metric pinions, and some use English pinions.
The smaller brass press-on pinions (1 and 1.5mm) can be very difficult to remove from motors.
I do not recommend the GWS pinion puller for these - I have personally destroyed two GWS
pinion pullers trying to remove this type of pinion. The Maxx products pinion puller (ACC650) is
much sturdier than the GWS pinion puller. Also, many brass pinions can be pulled off motor
shafts by using heat since brass has a high coefficient of thermal expansion.
The best way to remove these brass pinions is to clamp the motor in a vise, then press a hot
blunt tip soldering iron on the end of the pinion (for maximum heat transfer), wait about four
seconds to allow the pinion to become hot and expand, then pry off the pinion using needle
nose pliers. Do not skip the soldering iron step, because otherwise you will pull the shaft out of
the motor.
The best way to install a brass pinion on a motor is to use a vise. Put the motor and pinion
between the jaws, and screw the vise shut to push the pinion onto the shaft. Be sure the back
end of the shaft is pressed against the jaw otherwise you may damage the motor bearings.
When selecting pinions, be sure to check your helicopter manufacturer's pinions first. The pin-
ions from the helicopter manufacturer usually work best for most models.
6.4.3. Motor connectors
The standard connector for nonmicro helis is the 3.5mm bullet-style connector. These work
well for up to 70 amps and are supplied with Schulze controllers.
For the main motor of FP micro helicopters and for tail rotors of micro helicopters, the most
commonly used connector is the crimp pin from a D-sub connector. These are good up to
about 4 amps and are available from Jameco Electronics; the female pins are part #43369 and
the males are part #43377
For the main motor of CP micro helicopters there really is no standard. I personally use the MP
Jet 1.8mm gold connectors, which are available from Aircraft World.
6.4.4. Main motor ESC
(See Chapter 31, Glossary for a definition of ESC)
If you plan to use a brushed motor, you will need a brushed motor ESC. If you plan to use a
sensored brushless motor (like the X-250-4H) then you can use either a sensorless or
sensored brushless motor controller. For the sensorless brushless motor controller, the sensor
wires (connector) from the motor will not be connected to anything because the sensors are
not required by the controller.
The sensored brushless motors may need to be sent back to the motor factory to reverse the
Helicopter Parts Selection
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