Effect of uncertainties on UCAV trajectory optimisation using evolutionary programming

There is a recognised need for an automated trajectory planning to guide manned or unmanned aircraft against an agile adversary such as a missile. Evolutionary programming approaches provide an alternative to classical functional optimisation methods with the capability of incorporating multiple optimisation goals and in the same time tolerating aircraft constraints. In this study, an evolutionary flight path planning algorithm capable of mapping aircraft trajectories in three dimensions under several aerodynamics constraints is developed. The task of the trajectory was to guide the aircraft away from interception. The calculations assumes that the aircraft states are accurate. Good trajectories were found under this assumption. But in reality, states are measured in an environment that has uncertainties, such as instrument error, atmospheric disturbances, etc. This paper studies the effect of the presence of errors to the accuracy of the algorithm. Two state variables were studied, i.e. altitude and velocity for both players. From the simulation, the effect of noises and interception radius can influence the sensitivity of the optimiser

THE APPLICATION OF CONSTRAINT PROPAGATION TECHNIQUE FOR CONCEPTUAL AIRCRAFT DESIGN

In conceptual aircraft design phase, the aircraft configuration and several design variables are frequently changed and starting points are depended on any most probable design conditions. Therefore, it is required a design tool having flexibility to response to different starting points. The implementation of the constraint propagation supported by an object-oriented programming could result in a computer application that considerably accommodates the need of flexibilities.  Moreover, the implementation of some graphical user-interfaces and filter are not only to make it become user-friendly but also it may perform good filters to validate all inputs from the user. Use case diagram and class diagram are utilized as tools for designing the computer application using Microsoft Visual C++ 6. For a case study, some relations of basic aircraft geometry are implemented by selecting the six constraints and fourteen design variables. The result of this work shows that the application of constraint propagation is right and proper to handle any frequent changes during the conceptual design phase

Intelligent Data Storage and Retrieval for Design Optimisation – an Overview

This paper documents the findings of a literature review conducted by the Sir Lawrence Wackett Centre for Aerospace Design Technology at RMIT University. The review investigates aspects of a proposed system for intelligent design optimisation. Such a system would be capable of efficiently storing (and compressing if required) a range of types of design data into an intelligent database. This database would be accessed by the system during subsequent design processes, allowing for search of relevant design data for re-use in later designs, allowing it to become very efficient in reducing the time for later designs as the database grows in size. Extensive research has been performed, in both theoretical aspects of the project, and practical examples of current similar systems. This research covers the areas of database systems, database queries, representation and compression of design data, geometric representation and heuristic methods for design applications.

Ship motion prediction for launch and recovery of air vehicles

Due to the random nature of the ship's motion in an open water environment, the deployment and the landing of air vehicles from a ship can often be difficult and even dangerous. The ability to reliably predict the motion will allow improvements in safety on board ships and facilitate more accurate deployment of vehicles off ships. This paper presents an investigation into the application of artificial neural network methods trained using singular value decomposition and genetic algorithms for the prediction of ship motion. It is shown that the artificial neural network produces excellent predictions and is able to predict the ship motion satisfactorily for up to 7 seconds

Assessing organisational factors in aircraft accidents using a hybrid Reason and AcciMap model

Despite the use of high safety standards in aircraft design and operations, accidents do occur. In a process of continuous improvement it is essential that we learn from each accident so we can take measures to prevent such accidents from happening in the future. It is often the case that an accident is the result of a sequence of, seemingly minor and often unrelated, events. The challenge is to identify the major causes, which can include deficiencies in organisational processes which may have been present well before the accident itself. This paper discusses tools which can be used to identify key organisational factors which contribute to aviation accidents. The research uses a thoroughly-investigated helicopter accident as a case study, to determine the extent to which analytical and visualisation tools can be used to assess maintenance organisational issues which contributed to the accident

Maintenance in aeronautics in an Industry 4.0 context: The role of Augmented Reality and Additive Manufacturing

The paper broadly addresses how Industry 4.0 program drivers will impact maintenance in aviation. Specifically, Industry 4.0 practices most suitable to aeronautical maintenance are selected, and a detailed exposure is provided. Advantages and open issues are widely discussed and case studies dealing with realistic scenarios are illustrated to support what has been proposed by authors. The attention has been oriented towards Augmented Reality and Additive Manufacturing technologies, which can support maintenance tasks and spare parts production, respectively. The intention is to demonstrate that Augmented Reality and Additive Manufacturing are viable tools in aviation maintenance, and while a strong effort is necessary to develop an appropriate regulatory framework, mandatory before the wide-spread introduction of these technologies in the aerospace systems maintenance process, there has been a great interest and pull from the industry sector

Observations on CFD Verification and Validation from the AIAA Drag Prediction Workshops

The authors provide observations from the AIAA Drag Prediction Workshops that have spanned over a decade and from a recent validation experiment at NASA Langley. These workshops provide an assessment of the predictive capability of forces and moments, focused on drag, for transonic transports. It is very difficult to manage the consistency of results in a workshop setting to perform verification and validation at the scientific level, but it may be sufficient to assess it at the level of practice. Observations thus far: 1) due to simplifications in the workshop test cases, wind tunnel data are not necessarily the correct results that CFD should match, 2) an average of core CFD data are not necessarily a better estimate of the true solution as it is merely an average of other solutions and has many coupled sources of variation, 3) outlier solutions should be investigated and understood, and 4) the DPW series does not have the systematic build up and definition on both the computational and experimental side that is required for detailed verification and validation. Several observations regarding the importance of the grid, effects of physical modeling, benefits of open forums, and guidance for validation experiments are discussed. The increased variation in results when predicting regions of flow separation and increased variation due to interaction effects, e.g., fuselage and horizontal tail, point out the need for validation data sets for these important flow phenomena. Experiences with a recent validation experiment at NASA Langley are included to provide guidance on validation experiments

Prospects for liquefied natural gas and other alternative fuels for future civil air transportation

Fundamental issues related to the possible introduction of liquid methane, propane or butane fuelled civil passenger transport aircraft are addressed. It is proposed that partial transition to one, or a mixture, of these alternative fuels may provide an operational interim option when supplies of Avtur become prohibitively expensive. Preliminary criteria to determine the suitability of alternative fuels are also included

Assessing organisational factors in aircraft accidents: Methodologies and limitations

This paper discusses tools which can be used to identify key organisational factors which contribute to aviation accidents. The research uses a thoroughly-investigated helicopter accident as a case study, to determine the extent to which analytical and visualisation tools could be used to assess maintenance organisational issues which contributed to an accident

Mortality Rates above Emergency Threshold in Population Affected by Conflict in North Kivu, Democratic Republic of Congo, July 2012-April 2013

The area of Walikale in North Kivu, Democratic Republic of Congo, is intensely affected by conflict and population displacement. Médecins-Sans-Frontières (MSF) returned to provide primary healthcare in July 2012. To better understand the impact of the ongoing conflict and displacement on the population, a retrospective mortality survey was conducted in April 2013. A two-stage randomized cluster survey using 31 clusters of 21 households was conducted. Heads of households provided information on their household make-up, ownership of non-food items (NFIs), access to healthcare and information on deaths and occurrence of self-reported disease in the household during the recall period. The recall period was of 325 days (July 2012-April 2013). In total, 173 deaths were reported during the recall period. The crude mortality rate (CMR) was of 1.4/10,000 persons/day (CI95%: 1.2-1.7) and the under-five- mortality rate (U5MR) of 1.9/10,000 persons per day (CI95%: 1.3-2.5). The most frequently reported cause of death was fever/malaria 34.1% (CI95%: 25.4-42.9). Thirteen deaths were due to intentional violence. Over 70% of all households had been displaced at some time during the recall period. Out of households with someone sick in the last two weeks, 63.8% sought health care; the main reason not to seek health care was the lack of money (n = 134, 63.8%, CI95%: 52.2-75.4). Non Food Items (NFI) ownership was low: 69.0% (CI95%: 53.1-79.7) at least one 10 liter jerry can, 30.1% (CI95%: 24.3-36.5) of households with visible soap available and 1.6 bednets per household. The results from this survey in Walikale clearly illustrate the impact that ongoing conflict and displacement are having on the population in this part of DRC. The gravity of their health status was highlighted by a CMR that was well above the emergency threshold of 1 person/10,000/day and an U5MR that approaches the 2 children/10,000/day threshold for the recall period