What is a Stator Gator and why do I need one?

Because the throttle curve characteristics of a gas helicopter are very different than that of glow models, the setup is greatly simplified by using a governor. However mounting the governor sensors on gas models is usually more difficult because the motor format and cooling system is very different from a typical glow model.

Here's a typical governor and the sensor it uses to sense RPM. The sensor is known as a "hall effect" sensor, which uses the effects of a magnetic field to vary the output voltage it produces.

Typical Governor with Hall Sensor

The key to the system is installing a small magnet and mounting the hall effect sensor close enough for it to measure the field change. Here you can see a typical magnet and where it’s mounted in a fan. This is always accurate because the fan is locked to the crankshaft, but it’s more difficult to get the sensor mounted close to this magnet

Typical sensor magnet and fan

Some of the newer models allow the magnet to be mounted in the clutch bell. It’s easier to get a sensor mounted for this, but if for some reason the clutch is slipping, the governor will start to increase the throttle to compensate for a lower RPM, which of course will probably make the slippage problem worse, and it will continue to add throttle, etc.

In both of these methods, it’s not uncommon for the sensor itself to eventually get loose from the vibrations, which results in the governor failing, at least until the sensor is repaired or replaced.

Some of the newer governors are using crank position sensors, which eliminates the need for magnets because it uses the metal mass on the crankshaft as a trigger. Again, the issue is how to mount the sensor; some of the newer motors come with a special backplate that this sensor will slide into.

Clutch mounted sensor magnet

So a few years ago, a guy named Tom Fiddler found a way to solve this problem for our gas motors. He created a device that reads the pulse from the ignition coils and converts it into a pulse that can be fed into a governor. From the governor, it looks just like the signal coming from the hall effect sensors, but it doesn't require any magnets or sensor to be mounted.

 

Here you can see that there is a sensor wire which connects the Stator Gator to the RPM sensor port on a governor. We'll cover the other connection shortly.

How do I connect my Stator Gator?

Stator Gator connected to a governor

The main part of the Stator Gator is a small plastic case that contains some circuitry.  It’s sealed in epoxy and is not serviceable. This piece gets mounted somewhere on your model; I typically use velcro or two sided tape. It produces no harmful radio emissions so its location is not critical. In some of the early testing they literally wrapped 72mhz rx antennas around the Stator Gator itself and its wires, and it made no difference in control.

 

So in order for it to work, the Stator Gator sensor has to be connected to the ignition system on the motor so it can count the RPMs by the number of times it fires the spark plug.

For more detailed instructions, see our installation page.

Which type of Stator Gator is right for me?

Because the Zenoah/CY motors use 3 different ignition systems, there are 3 different Stator Gator systems and each one connects to the ignition system in a slightly different way. These are the three types:

the Stator Gator RC Series, which is for use on RC format motors,

 

the Stator Gator PUH series, which is for use on PUH format motors,

 

and the Stator Gator 20-26 EI Series which is for use on Electronic Ignition system motors.