1. A system for real-time adjustment of radial clearances between rotor and stator elements of a gas turbine engine having an air compressor comprising; (a) conduit means directing air onto at least one of the rotor and stator elements so as to vary the radial clearance therebetween; (b) valve means regulating the air flowing through the conduit means; and (c) electronic computer means generating a first output control signal operatively connected to the valve means, the computer means having: means to sense and determine thermal and mechanical expansion parameters of the rotor and stator elements at a time T during operation of the gas turbine engine; means to calculate the actual radial clearance between the rotor and stator elements at time T based upon the thermal and mechanical expansion parameters; means to determine a desired radial clearance at time T based upon thermal and mechanical parameters of the rotor and stator elements as a function of thermodynamic and geometric characteristics of the gas turbine engine; means to compare the desired radial clearance with the actual radial clearance; and means to generate a first output control signal to the valve means so as to regulate the air flowing through the conduit based upon the comparison of the desired radial clearance with the actual radial clearance.