Witold Wiśniowski

Multi-disciplinary optimisation approach for a light turboprop aircraft-engine integration and improvement

Purpose The purpose of this paper is to present application of multidisciplinary design optimisation (MDO) in redesign of a small composite aircraft. The redesign process was integration of the turboprop engine in a small composite aircraft. The process requires cooperation of specialists from many disciplines and definition of their tasks. For selected tasks, the authors present results of the calculation. Design/methodology/approach The authors used collaborative optimisation (CO) algorithm to solve the problem. They decomposed this complex process into a set of tasks in different engineering/research disciplines and used techniques and methods specific for each task (research/engineering discipline) to find a proper solution. The computer-aided design (CAD), computational fluid dynamics (CFD) and computational structural mechanics (CSM) commercial software were used as common tools as well as intentionally developed computer programmes were used as basic tools in some tasks, in particular, for aerodynamic optimisation, calculation of load and stability of aircraft. The exchange of data between separate tasks allowed achieving the main goal of complex design process. Findings Selected optimisation algorithm, CO, proved efficient for the authors’ purposes. The effectiveness of multidisciplinary optimisation depends as much on organisational parameters as it does on technical and technology parameters. Practical implications Multidisciplinary optimisation needs to be an integral part of analysis and design process. The successful optimisation results allowed to meet the requirements and to proceed to the next phase of work – preparing technical documentation for manufacturing the components necessary for integration of the airplane with the new engine. Originality/value Presented results of design process are a valuable example of how to achieve the final goal in an ongoing project.

Small air transport aircraft entry requirements evoked by FlightPath 2050

Purpose Europe has adopted the Flight Path 2050 (FP2050) challenge demanding that by 2050, 90 per cent of the travelers are able to reach door-to-door destinations in Europe within four hours. A hypothesis can be formulated that without the Small Air Transport (SAT) system, optimized for short distances and for multiple but narrow passenger flows, this challenge cannot be met. Design/methodology/approach This paper defines design goals and necessary research focused on small aircraft concepts, as a required condition to fulfil the FP2050 challenge “90 per cent d2d 4h”. Findings The new small aircraft concepts have been defined as SAT Aircraft Family Program. Three demonstrators with common modules could be proposed: two using the same turboprop engine (first, one engine, 9 passengers; second, two engines, 19 passengers) and third demonstrator could be with a diesel hybrid engine. Research limitations implications The SAT Aircraft Family Program depends on demand optimized for specific regional features (passenger flows, passenger time value spectrum and infrastructure) and a set of matured technologies as a result of Clean Sky 2 (CS2) devoted to SAT. Practical implications This practical implications consist of developing on SAT technologies in CS2, deploying the demonstrators by the small aviation industry and launching an SAT system pilot phase. Social implications FP2050 has changed the approach to a citizen-oriented from an atomized technologies taxonomy-oriented one. The challenge “90 per cent d2d 4h” also covers the needs of remote regions. This niche could be filled by the SAT system using the small aircrafts family. Originality/value The paper value is in defining entry requirements, answering how to build the SAT Aircraft Family Program satisfying the FP2050 challenge “90 per cent d2d 4h”.

Optimization of small aircraft parameters in the initial phase of the project

Conceptual and preliminary designs of future aircraft have become increasingly complex due to the enlargement of the basic criteria for evaluating emerging solutions. In the past, the basic performance characteristics of an airplane were the only selection criteria. Today, more and more emphasis is placed on factors such as impact on the environment, cost-effectiveness, or comfort of travel. The method for optimization of the key parameters of a small aircraft for use in the initial phase of a project is presented in this paper. It takes into account the requirements of aviation safety imposed by the European Union certification specifications CS-23 and requirements of aircraft competitiveness. Requirements and design assumptions were formulated based on the concept of the Small Air Transport system (SATs). The method is based on the multidisciplinary design optimization and covers the basic areas related to the design of aircraft: aerodynamics, aircraft structure, performance and expected operating costs. The objective function is defined as the value of the direct operating cost per passenger-kilometre. An evolutionary algorithm was applied to solve the optimization problem. As an example of the use of this method, the optimization of design parameters of the two classes of aircraft, 9-seater and 19-seater was carried out. The results were compared with the parameters of aircraft, which are in service. Sensitivity analysis of the objective function with respect to selected parameters of the aircraft was also made. The analysis allowed to select the most important parameters responsible for the operational costs.

FULL-ELECTRIC, HYBRID AND TURBO-ELECTRIC TECHNOLOGIES FOR FUTURE AIRCRAFT PROPULSION SYSTEMS

Recently a huge progress in the field of electrical machines makes them more available for aviation. Assuming a big leap forward of electric technology in the near future, many research institutes around the World examine a revolutionary propulsion system which employs electrical machines. This idea can be a perfect response to a drastically growing air traffic and its demands about emission and fuel consumption reduction. There are already manufactured full electric, ultralight airplanes, which show that the technology is promising and future-proof. What is more it seems to be a key enabler for the development of the other technology that will influence the future of aircraft design and will allow introducing completely new airplane architectures. That is why Institute of Aviation in collaboration with The Ohio State University conducts investigation and analysis on feasibility of using such systems for aircraft propulsion. For this task a completely new tool based on Numerical Propulsion System Simulation (NPSS) environment is being developed. It will enable to analyse the electric devices conjugated with turbine engine as a whole propulsion system in the matter of its performance characteristics. The purpose of this paper is to present some of the most promising ideas and already accomplished analysis of different kinds of architectures. The analysis and optimization of the system, as well as cost effectiveness will be presented.

Identification of main helicopters resonances by ground vibration test

Six resonances of the helicopter body standing on the airport apron and at least two resonances of the free helicopters the frequencies of which are within the range of basic loadings by the helicopter rotor is called (8+) model. It was proposed to identify (8+) model with the use of resonance tests. It was indicated that (8+) model allows for detuning the resonances from the frequency of working loads, tracing the process of moving through resonances as well as taking off and landing. The paper presents: example of a helicopter on a test rig and visible vibrations inductors; induction of resonance vibrations, induction of resonance vibrations with the forms of pitching, yawing, rolling; induction of resonance vibrations with the forms of pitching with opposite pylon yawing and tipping with opposite pylon yawing; model of helicopter resonances; the multiplication of the resonance amplitude for various velocities of moving through with visible growth of the resonance frequency and reduction of vibrations amplitude; change of the frequencies at the taking off and landing.

Structure fatigue crack in the effect of acoustic load : case study

The paper presents a method for detection mechanisms and prevention of the fatigue cracks caused by acoustic loads acting on the aircraft elevator structure. During aircraft inspection, the fatigue cracks in elevator rib caps were discovered. The theory emerged, that cracks were caused by acoustic extortion on elevator sheet covering, caused by jet engine exhaust airstream, engine gas flow expanding in convergent nozzle and acting as the source of the strong acoustic load. To prove this theory, investigations were arranged, in which the strains in the elevator sheet skin, between the ribs area, were determined in harmonic excitation. The results, after frequency analysis, showed strong resonance in 270 Hz area. Mode of this resonance caused drumming of covering, resulting in bending of the ribs caps and causing them to fail from fatigue. Changes in elevator design raised the resonance frequency and lowered strains in modified elevator covering. The changes mainly increased sheet-covering stiffness by increase of thickness and lowering the sheet-metal covering mass in selected places, mainly by technological means metal bonding (gluing) and metal covering chemical milling.