Mirosław Rodzewicz

Determination and extrapolation of the glider load spectra

Purpose – The purpose of this paper is to present a study on methods for load spectrum (LS) determination and extrapolation, basing on data obtained from experiments.Design/methodology/approach – A sequence of loads registered in flight becomes an object of analysis aimed to calculate full cycles of loads, and on this basis two possible types of LS are determined, i.e. as the transfer array, or in classic form (as the plot presenting appearances of load increments, called “incremental load spectrum”). While the use of incremental LS enables just application of deterministic extrapolation methods, the transfer array enables application of the stochastic method of extrapolation that consists of random redistribution of the transfer array cell values.Findings – The paper presents a comparison between the results of application of deterministic or stochastic extrapolation methods. Attention was focused on the LS registered during thermal flights. The stochastic extrapolation method is less conservative than t...

Design of UAV for photogrammetric mission in Antarctic area

The history of UAVs is relatively long and many such vehicles are in service for different tasks. They can be used even in environments inhospitable for humans, e.g. because of extreme temperature. Moreover, they can perform a task that is difficult or impossible for a manned aircraft because of its size and usually relatively high airspeed. The photogrammetric tasks belong to this group, especially if we need to take high-resolution pictures during low level flight. The advantages of a small UAV for such mission are more evident if we want to investigate the natural environment, where the wild animals are. The paper presents the small UAV designed for a special task, which is counting of the penguins in Antarctica. Inhabited area, extreme weather conditions, the fearfulness of penguins and the goal of the mission put up certain requirements for the UAV. It had to be a reliable, stable platform, which is able to carry photogrammetric equipment and to perform precise flight to cover all investigated areas. The presented UAV was used on such missions in Antarctica in 2014 and 2015. All mentioned tasks were successfully accomplished.

Investigations Into Glider Chassis Load Spectrum

Investigations Into Glider Chassis Load Spectrum The paper describes investigations on load spectrum of a glider chassis during take-off and landing. The experiments were conducted on different kinds of airfield surfaces, and recorded time-courses of loads acting on the main and front gear were used for analysis. The paper shortly describes the tests carried out on a PW-6 glider (description of the measurement system installed on the glider main and front landing gear). There is included a comparison of different methods used for time-courses analysis and full cycle counting. The following methods were used: local extremes count method, level exceeds count method, full cycles count method, rainflow count method, and a method developed by the first author. The outputs generated by application of the above mentioned methods for different test-time-courses of load, and the real time-courses of load observed during take-off and landing, are described. Paper presents also load spectrum for the main gear for take-off and landing on a grassy runway. This load spectrum were used later on an experimental stand, build by the authors for fatigue tests of special shock-absorbing element, made from GFRP composite for a new glider.

Research on the Rotor of a Ducted Fan Propulsion System of MOSUPS Aircraft Taking into Account Self-Balance during Operation

The work concerns the research of a propulsion system for an unmanned aerial vehicle MOSUPS in joined wing configuration. Modeling, analysis and experimental research of a statically unbalanced rotor of a ducted fan propulsion system has been conducted.The aim of the analysis was to determine the critical rotational speeds of the rotor due to the probable excitation of oscillations. Due to the complex geometry, Finite Element Method has been used for the calculations. In the study, the critical frequencies (and also rotational speeds) of the rotor as well as precessional instability, flexibly mounted in the bearings have been calculated. Campbell and SAFE diagrams have been presented.Furthermore, the paper presents the idea for a device for automatic dynamic balancing of the mentioned rotor. A mechanism for changing the position of the correction weights has been developed, allowing for a long term operation of rotating parts without the need to stop the unit and correcting the unbalance.The main motivation for work was to fully understand the working conditions of the propulsion system and dynamic properties of the rotor in order to carry out a proper assessment of their impact on the safe operation of the aircraft.

Fatigue evaluation of high‐loaded aeronautical composite structures

Purpose – The purpose of this paper is to present a study on effective methods for fatigue evaluation of composite structures.Design/methodology/approach – Based on topological correspondence between half‐cycle arrays and the Haig diagrams, the fatigue data for composite structure in the form of array containing numbers of half‐cycles to failure (or in form of unitary damage array) are obtained. Such forms of the fatigue data facilitate significantly calculation of damage produced by any load spectrum (LS), presented as a half‐cycle array.Findings – The loads of highest increments inside the operational range are of crucial importance for the fatigue life of composite structures, therefore it is possible to replace the whole LS with the equivalent loads of significantly reduced cycle numbers, which is very beneficial in the case when the fatigue life evidence is provided in the experimental way.Originality/value – The paper presents novel evaluation methods for equivalent load cycles determination, consis...

Estimation of Fatigue Properties of Composite Structures

Estimation of Fatigue Properties of Composite Structures The paper presents the proposal of a simplified method of fatigue properties estimation for polymer composite structures.

Structural dynamics of a girocopter: numerical approach in some emergency cases

Purpose This paper aims to present the assumptions, analysis and sample results of numerical modeling and analysis of dynamic events encountered in emergency cases during deployment of parachute rescue system (PRS) and hard landing of a small gyrocopter. The optimal design requires knowledge of structural loads and structural response – the information obtained often from experiment. Numerical simulation is presented as an alternative tool for estimating these data. Design/methodology/approach Structural analyses were performed using MSC.Nastran. Multibody simulations were done using MADYMO system. Findings Initial design parameters were evaluated and verified in numerical simulations. Some of the resulting conclusions were proven during the test flights. Practical implications Some chosen results of simulation of dynamic problems are presented. They can be useful as reference values for similar cases for light aircraft analysis. Originality/value The paper presents an alternative way of assessing structural response parameters in the case of emergency dynamic events of usage of PRS. The results can be used in other projects.

Experimental investigations into Parachute Rescue Systems

Purpose The purpose of this paper is to describe the results of investigations of parachute rescue systems (PRS) for light gyrocopters. Design/methodology/approach Although the investigations were conducted in both stages simultaneously, i.e. experimental mechanics approach and numerical simulations, the paper is focussed mainly on the experimental part of the work. To ensure the safety of experimental works (i.e. for both experimenters and bystanders), the authors applied unmanned, remotely controlled scale models of autogyro for the PRS testing in the air. Findings The critical problem for successful use of the PRS is that the rotation of the rotor blades must be stopped when the main parachute opens, otherwise the influence of the rotor on the improper opening process of the parachute may cause the whole PRS to become useless. Research limitations/implications The existing regulations for the use of unmanned aircraft impose the limitation upon the organisation of in-flight tests of PRS, i.e. the maximum take-off mass of the tested gyrocopter models is limited, and a full-scale test needs the approval of European Aviation Safety Agency (EASA). Practical implications The research contributes to increasing the safety level for gyrocopter users. The authors elaborated the original PRS, which currently is in the process of patenting. Originality/value Originality of the work consists of both an innovative PRS, which has never been tested before, and the results of experimental investigations, which cover both ground tests carried on static or moving stands and in-flight testing.

The Elaboration of the Method of Fatigue Testing of the Rotor of the Mosups Plane Propulsion System

Abstract This paper concerns fatigue testing of the rotor of the propulsion system for the MOSUPS – an unmanned aircraft designed in a joint wing configuration, and equipped with a ducted propeller. The work presents the analysis of the stresses and deformations of the rotor structure as well as the form of the loading cycle. The aim of the paper is to introduce the concept of a simplified method of fatigue testing of multi-blade rotors. With the sophisticated geometry of the rotor in mind – the authors applied the FEM tools and implemented the ANSYS and nCode programs. The prototype of the fatigue stand built by the authors is also presented in the paper.

Synthesis and Structural Analysis of High Strength Composite Flexible Landing Gear Legs

The problem considered was to develop, synthesize and design a flexible landing gear leg, subject to some restrictions resulting from requested loads and boundary conditions. The problem was already undertaken by many researchers, e.g. in monographs written by Currey (Aircraft Landing Gear Design: Principles and Practices, 2004, 1) and Thuis (The development of composite landing gear components for aerospace applications, 2004, 2) and in journals and conference papers (Ganorkar and Deshbhratar, Design Optimization of landing gear of an aircraft, 2014, 3; Goyal and Laksminarayan, Design, Analysis and Simulation of a composite main landing gear for a light aircraft, 2002, 4; Yu-xiu et al., The dynamics research on the composite undercarriage of the Unmanned Aerial Vehicle, 2015, 5; Niezgoda et al., Selection of dynamics characteristics for landing gear with the use of numerical model, 2002, 6). It was assumed that two roving “concentrated constant cross-section booms” would be created. FE simulations allowed to determine the flexible leg deformations, stress distribution and Failure Indices (using maximum stress theory) (Spencer, Novel Optimization Strategy for Composite Beam Type Landing Gear for Light Aircraft, 2013, 7). The foam core inset was tested as a means of mass reduction. FE program ANSYS was used for the analysis (Ansys Theory Reference, 2013, 8).