The more current you ask the ESC to carry, the hotter it will get. And if you are using the BEC in the ESC to provide power for your receiver and servos, the number and type of servos also has an impact on the heat that will be produced by the ESC.

It's the same story with the battery. The more current you ask it to provide, the more it will heat up. I'm not familiar with the typical current demands for that motor in that type of plane, but my gut feeling is that your battery may have too little capacity (mAh). If so, it will have a short run time and will heat up faster than a battery with a larger capacity.

As a general rule, anytime you operate an ESC or battery (or a motor) near its limits, you run the risk of overheating. Good practice is to use a wattmeter to actually measure the current to learn if your components are being overstressed.

Hopefully, someone who knows more about your motor and plane can provide some specific advice.

- Jeff