Christopher Jouannet

Distributed Aircraft Analysis Using Web Service Technology

The design of modern aircraft requires the integration of multidisciplinary mouels for analysis in the early design phase to increase the chances of a successful project. In this paper, a framework ...

A Framework for Aerodynamic and Structural Optimization in Conceptual Design

Aircraft design is an inherently multidisciplinary activity that requires different models and tools for various aspects of the design. At Linkoping University a novel design framework is being dev ...

Use of Panel Code Modeling in a Framework for Aircraft Concept Optimization

In this study the use of a high-order panel code within a framework for aircraft concept design is discussed. The framework is intended to be a multidisciplinary optimization tool to be adopted from the very beginning of the conceptual design phase in order to define and refine the aircraft design, with respect to its aerodynamic, stability and control, structure and basic aircraft systems. The presented work is aimed at developing a module for aerodynamic analysis of concepts as a basis for a direct search optimization of the concept layout. The design criterion, used in the example presented here, is to minimize the maximum take-off weight required to fulfil the mission. Classic and simple equations are used together with the data generated by the panel code solver to calculate the aircraft’s performances. Weights are calculated by means of statistical group weight equations, but the weight could also be calculated from a CAD-model. The design of an Unmanned Combat Air Vehicle is used as test case for three different optimization algorithms: one gradient method based (Fmincon), one non-gradient based (Complex) and one Genetic Algorithm (GA). Comparison of results and performances shows that the Genetic Algorithm is best fitted for the specific problem, having the by far best hit rate, even if it is at a cost of longer computing time. The Complex algorithm requires less iterations and is also able to find the optimum solution, but with a worse hit rate, while Fmincon can not reach to a global optimum. The suggested optimized configuration for the aircraft is very similar to the Boeing X-45C and Northrop Grumman X-47B.

Unsteady aerodynamic modelling : a simple state-space approach

A simple mathematical prediction model for high angles of attack aerodynamics, including dynamic effect over delta wings, and an extension to full configuration is presented. The model presented is ...

Lift Coefficient Predictions for Delta Wing Under Pitching Motions

This thesis present a simple mathematical prediction model for high angles of attack aerodynamics, including dynamic effects over delta wings, and an extension to full configuration. The model presented is intended for application in conceptual design and is extended to parameters identifications in preliminary design with validation against experimental data.The aerodynamic model is based on leading edge suction analogy. In order to extend it to high angles of attack and dynamic motions, internal state variables are used to describe the different flow conditions, or state, over the wing/aircraft.In conceptual design the parameters used are determined from geometrical considerations and analogies with delta wings. For slender delta wings, the parameters are determined from flow visualisation, determining the three transition states used here; potential, vortex and fully separated. Results from conceptual design have shown good agreement with published data and demonstrates the usefulness of integration of dynamic effects in aerodynamic predictions. To extend the mathematical model to later design phases and augment the accuracy, the parameters were determined from wind tunnel data. The results obtained then showed high accuracy in both static and dynamic cases.The results obtained both in conceptual design and from parameters identifications are suitable for flight simulation and stability analyses, and will allow the aircraft designer to increase his knowledge of the behaviour at high angles of attack and large pitch motions. The present model allows to keep the same mathematical structure through the entire design, the parameters being refined when new data is available from wind tunnel tests or CDF or flight tests.The present model will be included in a distributed aircraft analyse to simulate the whole aircraft including systems and sub-systems.

Subscale flight testing used in conceptual design

Purpose - The purpose of this paper is to present the latest subscale demonstrator aircraft developed at Linkoping University. It has been built as part of a study initiated by the Swedish Material ...

Design and Flight Testing of an ECO-Sport Aircraft

The presented work is centered on different concept studies for “greener” sport aircraft. The goal is to show the possibility to manufacture a sport aircraft based on different environmental friendly propulsion systems. A first theoretical part consists of creating a sizing program for studying different concepts. Then the gathered knowledge will result in the realization of two flying down-scaled demonstrators. This study was realized during a student project over a 5 month period.

Direct Simulation Based Optimization for Aircraft Conceptual Design.

Evolution of computational power offer new possibilities for Aircraft Conceptual Design, allowing multidisciplinary optimisation to be used in a broader manner, than what is done with classical aircraft conceptual design methods. In order to show those new possibilities, sizing, flight dynamic and hydraulic systems are combined in the same optimisation loop. A distributed modelling approach is used, makes it possible to simulate faster than real time on a standard PC. This means that complete aircraft, including general sizing and system optimization can be performed in reasonable time. Limitation and benefit of classical aircraft design methods are discussed and a new framework for is presented and illustrated by an example.

Modelling of High Angle of Attack Aerodynamic, a State-Space Approach

This paper presents a mathematical prediction model for high angles of attack aerodynamics, including dynamic effect over delta wings, and an extension to full configuration. The model presented is intended for application in conceptual design and is extended to parameter identifications in preliminary design with validation against experimental data. In conceptual design, the parameters used are determined from geometrical considerations and analogies with delta wings. To extend the mathematical model to later design phases and increase accuracy, the parameters can be determined from panel code, CFD or wind tunnel data. In static case, the presented model has been extended to sideslip. The results obtained show high accuracy in both static and dynamic cases.

Whole Mission Simulation for Aircraft Preliminary Design

Developments in computational hardware and simulation software have come to a point where it is possible to use whole mission simulation in the preliminary design. This paper address some key issues needed to realize this. These are, system simulation using distributed solvers for robust large scale simulation, time scale compression to deal with the widely different time scales involved, e.g. the transient behaviour of control surface actuators, to the tracking of fuel consumption. The application is a flight simulation model with subsystems such as control surface actuators. In this way it is possible to do real time simulation (RTS) and faster than real time simulation (FRTS) of rather complex systems. Using such models it is possible to do design analysis, e.g sensitivity analysis and trade of analysis, as well as design optimisation, In this paper this is demonstrated on a flight simulation model with subsystems, such as control surface actuators.