Ground resonance is an unbalance of the helicopter main rotor rotation caused by its asymmetry. Whilst the helicopter is in contact with the ground this asymmetry generates a divergent and often destructive oscillations of the helicopter structure. These oscillations are self-excited. This paper present results of both theoretical and experimental investigations of this phenomenon. They were dedicated to the new polish UAV helicopter ILX-27. The theoretical analysis were done with commercial software ANSYS using Finite Element Method. The virtual model of the helicopter model accurately reproduced the geometry of all elements of the helicopter and was easy to modify to simulate various kinds of damages. Calculations were done for the following cases: C1 – the helicopter standing on the ground with zero thrust of the rotor, C2 = C1 + helicopter with additional support of the rotor mast, C3 = C2 + thrust of the rotor equal to the total mass of the helicopter, C4 = C2 + fixing the helicopter to the ground, C5 = C2 + helicopter with additional mass. At the beginning the modal analysis for all cases was done – natural frequencies and modes of the structure were identified. Next, for selected cases, harmonic analysis was performed – the structure of the helicopter was loaded with concentrated harmonic forces. Finally the dynamic analysis gave time courses of blades and the hub center motions in the case of structural damages. All phases of simulations were correlated with ground tests of the helicopter prototype. This allowed to compare results of theoretical investigations. These results also supported tests of the prototype.
The need to quickly provide assistance to victims of accidents or seriously ill has created the need for the construction of helipads at selected hospitals. Their operation and the conditions of use are governed by regulation of the Ministry of Health on Hospital Emergency Ward (SOR) and rules required by the Civil Aviation Authority.
The direct vicinity of the helipads causes impact of landing and departing helicopters on buildings, people and hospital equipment as well as the construction of the airfield. This article presents vibroacoustic impact of helicopters on helipads’ measurement methods and the results of the preliminary measurements to estimate the impact of Helicopter Air Rescue (LPR) on adjacent buildings and surroundings.
 Golak K.: Method of regulation condition assessment of turbine jet engine in flight basing on signals recorded during groundtests, Journal of KONES, Vol.19, nr 3 (2012).
 Golak K.: Validity Check of the Assessment of a Jet Turbine Engine Regulation in Flight Using a Computer Simulation, Solid State Phenomena, Durnten-Zurich 2013.
 Lindstedt P., Praktyczna regulacja maszyn i jej teoretyczne podstawy, Wydawnictwo Instytutu Technicznego Wojsk Lotniczych, Warszawa 2010.
 Osiowski J., Zarys rachunku
Comparison of Computer-Simulation Results for a Jet Engine with Half-Ideal Gas and Ideal Gas as a Working Medium
Two simulative models for the same jet engine, plus simulation results of deceleration, acceleration and steady states of engine operation during ground tests, are presented in the article. The models differ from each other just with the working medium flowing through the engine. In the first model it was assumed that, while the working medium is flowing through the compressor, the isentropic exponent and average specific heat are functions of average total temperature, whereas, while it is flowing through the combustion chamber, turbine, and nozzle, these are functions of corresponding average temperatures of total pressure and combustion air factor. In the second model the working medium is treated as an ideal gas, with constant values of isentropic exponent and specific heat in some parts of the flow being analyzed.
Maciej Słowik, Daniel Ołdziej and Zdzisław Gosiewski
In the paper the implementation process of commercial flight and navigational controller in own aircraft is shown. The process of autopilot integration were performed for the fixed-wing type of unmanned aerial vehicle designed in high-wing and pull configuration of the drive. The above equipment were integrated and proper software control algorithms were chosen. The correctness of chosen hardware and software solution were verified in ground tests and experimental flights. The PID controllers for longitude and latitude controller channels were selected. The proper deflections of control surfaces and stabilization of roll, pitch and yaw angles were tested. In the next stage operation of telecommunication link and flight stabilization were verified. In the last part of investigations the preliminary control gains and configuration parameters for roll angle control loop were chosen. This enable better behavior of UAV during turns. Also it affected other modes of flight such as loiter (circle around designated point) and auto mode where the plane executed a pre-programmed mission.
Jerzy Lewitowicz, Mirosław Kowalski and Andrzej Żyluk
, Warszawa 2010 (in Polish).
 Kułaszka A., Błachnio J.: A non-destructive thermography-based method to assess gas-turbine blade condition. The Problems of Studying, Testing and Operating Aeronautical Systems. Vol. 8, Chapter 8. AFIT, Warszawa 2012 (in Polish).
 Lindstedt P., Golak K., Borowczyk H.: A complex method to predict in-flight functional properties of an aircraft turbine engine on the basis of groundtests. The Problems of Studying, Testing and Operating Aeronautical Systems. Vol. 8, Chapter 11, AFIT, Warszawa 2012 (in Polish
Zhang Qing-Zhe, Yan Bing, Dai Jing-Liang and Yang Bao-Gui
Processing, 37(12): 2091-2110, 1989
5. C hang Y un - hua , L i Z ong - wei , Y in D a - juan , Non-stationary Vibration Signals Of The Wavelet Analysis Method, Noise And Vibration Control,5, 98-101, 2008.
6. L i J ian - feng , S hi G uang - fu , Z hang P ing , Noise-reducing of vibration signal in SRM groundtest by using wavelet analysis, Journal of Solid Rocket Technology, 25(4), 63-66, 2002
7. W ang N an , D u J in - song , Wavelet De-noising In The Application Of Vibration Signal Processing, Chinese Journal of Scientific Instrument, 22(4), 225
., Sabatini, M., Palmerini, G., Groundtests for vision based determination and control of , Acta Astronaut, 2014.
 Ruel, S., Luu, T., Anctil, M., Gagnon, S., Target localization from 3D data for onorbit autonomous rendezvous and docking , Proceedings of the IEEE Aerospace Conference, Big Sky, MT, USA 2008.
 Fischler, M., Random Sample Consensus: A Paradigm for Model Fitting with Applications toImage Analysis and Automated Cartography , Comm. of ACM, Vol. 24, No. 6, pp. 381-395, 1988.
 Quan, L., Lan, Z-D., Linear N4point pose
Conference (CCDC 2009).
 HUANG, Y.—CHEN, K.—WEI, J. : Robust Controller Design and Experiment for Electric Load Simulator, 2010 3rd International Conference on Advanced Computer Theory and Engineering (lCACTE).
 XIN, W.—ZHU, F. D. : Load Simulator Design and GroundTest of Near Space Hypersonic Vehicle, Journal of System Simulation 21 No. 19 (Oct 2009).
 YONG, H.—LU, X.—JIE, Y.—LI, S. : The Controller Designed for Motor Servo Loading System based on ITAE, 1994-2010 China academic Journal.
 PENG, L.—HUI, L. : Controller Design for
missile engines. Groundtests.)
12. Romasewicz W.F., Samojłow G.A.: Практическая аэродинамика вертолетов . Военное Издательство Министерства Обороны СССР, Москва, 1980 (Practical aerodynamics of helicopters), Military Publishing House of the Ministry of Defense USSR, Moscow, 1980)
13. Silnik turbinowy TWD-10B, Instrukcja Eksploatacji Technicznej, Nr dok 19.0.646 (10B.00.030.RE2), (TWD-10B turbine engine. Operation and maintenance manual No. 19.0.646 (10B.00.030.RE2), WSK-Rzeszów, 1984.
14. Śmigłowiec Mi-24A, Mi-24D