The control loading system is the latest addition to the simulator as of 2017. Control loading is a fancy simulator term for force feedback. It’s essential to provide the pilot the most accurate simulation experience.
The system I used is Ian’s BFF Electric Control Loading. The system uses custom hardware and software that drives a large DC servo motor. The system is quite inexpensive however in my setup I use a planetary gearhead that is required to generate the large forces necessary. I picked mine up on ebay for a few hundred dollars but brand new they are quite expensive.
Currently the pitch axis is the only thing that uses active loading. Roll and yaw are next. Below are some pics of the system along with the mechanical interface I made for it.