Zdobysław Goraj

Design concept of a high-altitude long-endurance unmanned aerial vehicle

Abstract This paper presents a conceptual project of a high-altitude long-endurance unmanned aerial vehicle. It describes a number of historical, current and prospective HALE aircraft and considers existing four serious obstacles, to overcome them can mean the successful building of HALE aircraft. Among these obstacles there are very special aerodynamic (low Reynolds numbers together with transonic speeds), very light structures usually of high aspect ratio, propulsion technology (usually propeller driven by turbocharged piston engines) and flight control system (usually combining the best features of preprogrammed and hand-flown modes). Four aerodynamic design concepts are presented and their performances are compared. Among them is a biplane, considered mainly because of its moderate wing span, which can be obtained for a relatively big wing area and a high effective wing aspect ratio, a relatively stiff wing structure, and lower induced drag being possible to be obtained at the same lift and wing area as for the equivalent monoplane. It is shown that an attentively designed biplane can be efficient aerodynamically for high altitude patrol missions having almost the same endurance, using the same fuel to reach a service ceiling and having the take-off mass (and the payload) considerably bigger than a corresponding, equivalent monoplane. The paper is completed with selected considerations about dynamic stability.

MALE UAV design of an increased reliability level

Purpose – This study seeks to present the initial requirements for medium altitude long endurance (MALE) UAV design of an increased reliability.Design/methodology/approach – Shows and describes the successive design phases of PW‐103 MALE UAV.Findings – The analysis of the performances of the PW‐103 UAV, powered by either a main or an auxiliary engine, demonstrated that auxiliary power unit improved flight safety significantly.Originality/value – Successive MALE UAV configurations developed in the design process were aerodynamically more efficient than their predecessors.

Flight dynamics models used in different national and international projects

Purpose – The present study aimed to demonstrate different computational models, data and stability results obtained in a wide number of projects of various aircrafts such as unmanned aerial vehicles (UAVs), general aviation and big passenger flying airliners in blended wing body (BWB) configurations. Many details of modeling and computing are shown for unconventional configurations, namely, for a BWB aircraft and for tailless UAVs. Design/methodology/approach – Mathematical models for analysis of static and dynamic stability were built and investigated based on equations of motion in the linearized form using the so-called state variable model for a steady-state disturbed, generally asymmetric, flight. Findings – Flight dynamics models and associated computational procedures appeared to be useful, both in a preliminary design phase and during the final assessment of the configuration at flight tests. It was also found that the difference between thresholds for static and dynamic stability conditions was ...

Design challenges associated with development of a new generation UAV

Purpose – To provide an overview of design activity undertaken within the CAPECON Project supported by European Commission and devoted to development of HALE UAV being proposed for long endurance flights.Design/methodology/approach – Selected research methods devoted mainly to the improvement of dynamic stability of unmanned aerial vehicles have been described and their application into design optimisation are shown. The main goal of this research was to improve an economic effectiveness, safety and a modular arrangement of on‐board systems, especially with respect to sensors being easy replaceable for different missions.Findings – The research and design process included an aerodynamic optimisation of swept wing, stability analysis, weight balance, some on‐board redundant systems, reliability and maintability analysis, safety improvement, cost and performance optimisation. A number of design iterations were performed to achieve the required aircraft performances and characteristics. This iteration number...

Analysis and optimisation of a MALE UAV loaded structure

Purpose – To provide an effective design methodology focused on loading structure of unmanned aerial vehicles with a special emphasis on MALE class platform.Design/methodology/approach – Selected design methods and numerical calculations used during the development of two different class (MALE PW‐103 and HALE PW‐114) unmanned aerial vehicles have been described and discussed. The initial loading structure was set‐up coming from a steady state level flight condition.Findings – Aeroelastic analysis showed that the wing torsional rigidity is not sufficient. To increase the critical flutter speed the wing sandwich skin has been reinforced adding extra layers of carbon fibres. This procedure is iterative by nature, because adding the new layers changes the weight and stiffness of aircraft and the critical flutter speed has to be computed again.Research limitations/implications – Analysis and design methodology is limited to surveillance and monitoring platforms, where the design objectives are long endurance, ...

Aerodynamic calculation of unmanned aircraft

Purpose – To provide an effective numerical method for analysis and design of aerodynamic characteristics of unmanned aerial vehicles basing on commercial package VSAERO.Design/methodology/approach – Calculation was made by VSAERO package, which is based on a classical panel method enhanced on boundary layer method. Paper explains how to use efficiently VSAERO package, which utilizes advanced CAD techniques, in modern designing of unmanned aircraft.Findings – During aerodynamic analysis of unmanned aircraft the computing cycle is repeated many times until the required accuracy is obtained and when the best performance of an aircraft is achieved. Design process depends on the number of iterations. If the preliminary configuration (the so‐called starting design point) is well selected and the aerodynamic analysis is completed in a relatively short time, then the overall design time will be shortened.Research limitations/implications – The panel method is very useful tool in spite of different limitations. F...

Security analysis of uav radio communication system

Abstract This paper presents analyzed questions of the safety of the information transferred by the radio connection link of the Polish UAV project “Aircraft for monitoring” SAMONIT. This safety is especially important for the design and use of unmanned aerial vehicles (UAV). This paper also presents the structure of the SAMONIT communication system, security threats to the radio connection system, and possible measures to ensure secure information.

Dynamics of a light aircraft in spin

This paper focuses mainly on the experimental and in‐flight spin investigations for an executive light airplane, named I‐23 and built in the Institute of Aviation (Warsaw, Poland). It is a single‐engine, all composite, straight wing, retractable undercarriage, conventional configuration and flight control system airplane. In‐flight spin tests confirmed good rudder and elevator effectiveness for spin recovery in a wide range of positions of the center of gravity. A typical time history of a spin entry and the developed spin and recovery is shown as well.

Influence of weak and strong gyroscopic effects on light aircraft dynamics

Purpose The purpose of this study is to investigate the influence of gyroscopic effects on the dynamic stability and the response of light aircraft to manoeuvres following either a rapid deflection of the control surfaces or wind gust. Design/methodology/approach The analyses were conducted for several different mathematical models of aircraft motion, which allowed for the investigation of the relationship between introduced simplifying assumptions and the aircraft response, including non-linear terms in equations of motion expressing the influence of inertial coupling. The analytical and experimental methods (measurements in the wind tunnel for the scaled model and during flight tests of I-31T prototype aircraft) were used. Findings It was found that gyroscopic moments are induced mainly by the propeller, and their influence on dynamic stability of a light aircraft is negligible. However, these phenomena in manoeuvring flight investigation should not be excluded, although for general aviation (GA) aircraft, they are not strong. Hence, two types of gyroscopic effects depending on the level of steady flight disturbances were distinguished. The authors differentiated weak gyroscopic effects, corresponding to classical dynamic stability, and strong gyroscopic effects, corresponding to rapid manoeuvres. Practical implications Conclusions include some findings on the nature of gyroscopic effects (i.e. sensitivity of flight stability versus turboprop power unit parameters) and practical recommendations for aircraft designers dealing with new configurations of GA aircraft. Originality/value The analysis focuses on the assessment of the flight dynamics of light aircraft with a novel, compact, lightweight, fast-rotating turbopropeller engine and strong/weak gyroscopic effects.

Aeroelastic analysis of remotely controlled research vehicles with numerous control surfaces

Purpose – The purpose of this paper is to find an influence of the reduced stiffness of actuators, located on the most outer parts of ailerons, flaperons, rudders, elevators and elevons on the excitation of flutter. This phenomenon is especially important for unmanned aerial vehicles because they continuously use all these control surfaces for trimming and stabilisation and on the other hand, the numerous statistics show that failure of elements of flight control systems are still the most probable reasons of aircraft critical failure.Design/methodology/approach – Flutter calculations were performed by use of the classical modal approach. The normal vibrations of the free aircraft were measured in the ground vibration test (GVT). Test results were used either for verification of the FEM model of the structure – in this case for flutter calculation the MSC.Nastran software was used, or directly for flutter calculation. Based on the flutter analysis, the control surfaces critical for flutter were determined...