Mass stimulator and uses thereof

A mass simulator for determining unbalance of a rotor module in a balancing machine, the mass simulator simulating a mass of an adjacent rotor module to which said rotor module is attached when in use, the mass simulator having:

• a shaft extending along an axis of rotation of the mass simulator, the shaft having at one end an attachment interface for attaching to a corresponding interface of said rotor module, and having at an opposite end a support portion which is rotatably supportable in the balancing machine;
• and
• a mass body mounted to the shaft by a release mechanism which allows the mass body to be repeatably mounted to and dismounted from the shaft;
• wherein the mass simulator can be attached to said rotor module at the attachment interface and an assembly of the attached mass simulator and the rotor module located in the balancing machine to determine unbalance of said rotor module with the mass body mounted to the shaft and to determine unbalance of said rotor module with the mass body dismounted from the shaft.