The topic of this thesis is performance of helicopter in autorotation as emergency maneuver in case of engine failure. In introduction, a definition of what is autorotation and a computational description of the model of the helicopter with assumption for vertical ight is given. Further, an analytical calculation of helicopter's performance in auto-rotation has been made; this calculation was used as input used in further calculation and analytics for comparison of three configurations of a helicopter. During calculation the following assumptions were taken: parameters of standard atmosphere at 0 m at sea level, the infuence of compressibility has been neglected, the wings of the rotor is considered as a rigid body, the whole weight of the aircraft and not just the main rotor have been taken into account and finally the motion of the rotor blades such as ap,lag and feather were not taken into consideration. After a theoretical consideration of this maneuver and given performance of the helicopter, the procedure on how to construct H/V diagram was explained, as an essential part of a practical application of a helicopter in ight when engine failure occurs.The thesis continues with a description of determining the critical points of the diagram and the procedure for drawing a diagram, which was made with the software package MATLAB. After that, calculation for the H/V diagram for all three types of helicopters was set and were made with MATLAB, followed by the comparison with the actual H/V diagrams. The method used to compare helicopters with each other with respect to their performance in autorotation is given in the description of the characteristics of the authoritative index. The thesis concludes with a comparative analysis of all of the results of the conducted calculation as well as the theoretical view of the results and conclusions made from them.