The equations that describe component performance are summarized, including non-dimensional parameters, such as corrected mass flow, Mach number total/static ratios. The isentropic and polytropic efficiency definitions for compressors and turbines are compared. We then follow with a detailed hand calculation through the cycle of a turbojet engine in-flight. We cover each component from the inlet to the nozzle and evaluate the differences caused by using the mean specific heat rather than the entropy function (as used in GasTurb). ItSpreadsheet calculation is recommended that students refrain from using gas turbine performance software until they have hand-calculated a turbojet cycle and are proficient in accounting for efficiencies and work balance.