The paper deals with a single-spool single-jet turbo engine with variable area exhaust nozzle for aircraft use. Based on engine’s non-linear motion equations, its mathematical model was established; a new form of the model was issued, by using the finite differences method to bring it to a linear form, which was brought to a dimensionless form after convenient equations’ processing and then the Laplace transformation was applied. The final form of the model was determined by a matrix description and using an algebraic solving method; two equations, concerning the main outputs, were selected and studied. Two essential coefficients (engine’s time constant and stability constant) were identified and their variations inside the range of engine’s rotational speed and flight altitude were studied. Engine’s quality was estimated performing engine’s step response studies. Some conclusions regarding engine’s stability and its idle speed establishing was also presented.

The paper deals with an exhaust nozzle control unit for aircraft engines, based on combined pneumatic/hydraulic operating principles. From controller's non-linear motion equations one has obtained its mathematical model; one has applied the finite differences method in order to bring them to linear adimensional forms, then one has applied the Laplace transformation. Based on this mathematical model, controller's block diagram with transfer functions was built and its quality (its step response) was evaluated. A possible using of the nozzle's controller inside complex control architecture of a jet-engine was also studied; one has performed simulations (using Simulink-Matlab) concerning engine's output parameters' time behavior (their step responses), which lead to some conclusions, about controller's pre-design, further using possibilities as well as possibilities to continue and expand the carried out studies.

The paper deals with a supersonic air inlet for a supersonic drone, considered as controlled object The author has determined inlet's optimal architecture based on its efficiency (total pressure recovery) maximization, using the carpet search method. Inlet's characteristics were also determined and (based on same algorithm) one has determined the effective inlet control law with respect to the flight Mach number. A simple control system was proposed for the adapting of the inlet to the drone's flight regime and one has identified its main parts and described by their linearised adimensional mathematical model; the block diagram with transfer functions was built A study about system's quality (its step response) was performed which lead to some conclusions, concerning system's using possibilities, as well as for its pre-design.