From Rise: The Vieneo Province - The Space Simulator MMO from Unistellar Industries, LLC
Elevator trim balances the control force necessary to maintain the aerodynamic down force on the tail. Whilst carrying out certain flight exercises a lot of trim could be required in order to maintain the desired angle of attack. This mainly applies to slow flight, where a lot of trim is required to maintain the nose-up attitude. Elevator trim is correlated with IAS, thus airspeed changes to the aircraft or aerospace vehicle require re-trimming. An important design parameter for a vehicle is the stability when trimmed for level flight. Any disturbances such as gusts or turbulence will be dampened over a short period of time and the pitch attitude will return to its level flight trimmed airspeed.
The operation of the trim can be actuated using the ";" and "/" keys. When autoflyte is engaged, the trim is commanded by the autoflyte system. One method of disconnecting the autoflyte coupling is to actuate the trim.
In the Rise universe, trim adjusts the control surface directly (as opposed to a trim tab on more conventional aircraft) and will limit the control authority the pilot has over the elevator.
There is no aileron or rudder trim available in the Rise universe at the writing of this article.