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Conceptual Design of a New Generation JAS 39 Gripen Aircraft
Linköping University, Department of Management and Engineering, Machine Design. Linköping University, The Institute of Technology.
Linköping University, Department of Management and Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
Saab Aerostructures, Linköping, Sweden.
2006 (English)Conference paper (Refereed)
Abstract [en]

This paper describes the conceptual phase of a modification proposal for Saab Gripen, which aims to create the best possible basis for future aircraft development. One of the main tasks in this respect is to investigate different means to extend range. This paper describes the technical outcome from the concept generation, concept selection, and concept refinement at system and airframe level. The chosen concept involves relocation and redesign of the main landing gear. The original main landing gear bay is converted into fuel tanks. The relocation of the main gear enables a new ventral twin store carriage with supersonic jettison capability to be introduced. The concept proposal yields the following improvements:

· Increased range due to increased fuel capability

· Increased maximum allowed takeoff weight due to beefe d-up main gear

· Increased weapon flexibility and capability due to introduction of two new ventral store

· Introducing supersonic jettison capability

The paper also includes a description of how the work is related to the overall design process in general and the conceptual phase in particular, as described in design methodology literature.

Place, publisher, year, edition, pages
2006. no AIAA-2006-0031
National Category
Engineering and Technology
URN: urn:nbn:se:liu:diva-12980DOI: 10.2514/6.2006-31OAI: diva2:17584
44th AIAA Aerospace Sciences Meeting and Exhibit, Reno, USA
Available from: 2008-04-01 Created: 2008-04-01 Last updated: 2013-11-07
In thesis
1. On aircraft fuel systems: conceptual design and modeling
Open this publication in new window or tab >>On aircraft fuel systems: conceptual design and modeling
2007 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The largest and most important fluid system in an aircraft is the fuel system. Obviously, future aircraft projects involve the design of fuel system to some degree. In this project design methodologies for aircraft fuel systems are studied, with the aim to shortening the system development time.

This is done by means of illustrative examples of how optimization and the use of matrix methods, such as the morphological matrix, house of quality and the design structure matrix, have been developed and implemented at Saab Aerospace in the conceptual design of aircraft fuel systems. The methods introduce automation early in the development process and increase understanding of how top requirements regarding the aircraft level impact low-level engineering parameters such as pipe diameter, pump size, etc. The morphological matrix and the house of quality matrix are quantified, which opens up for use of design optimization and probabilistic design.

The thesis also discusses a systematic approach when building a large simulation model of a fluid system where the objective is to minimize the development time by applying a strategy that enables parallel development and collaborative engineering, and also by building the model to the correct level of detail. By correct level of detail is meant the level that yields a simulation outcome that meets the stakeholders’ expectations. The experienced gained at Saab in building a simulation model, mainly from the Gripen fuel system, but also the accumulated experience from other system models, is condensed and fitted into an overall process.

Place, publisher, year, edition, pages
Institutionen för ekonomisk och industriell utveckling, 2007
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1067
Aircraft, morphological matrix, simulation, Saab, Gripen
National Category
Reliability and Maintenance
urn:nbn:se:liu:diva-11146 (URN)978-91-85643-04-2 (ISBN)
Public defence
2007-02-23, C3, Hus C, Campus Valla, Linköpings universitet, Linköping, 10:15 (English)
Available from: 2008-04-01 Created: 2008-04-01 Last updated: 2009-04-08
2. Aircraft conceptual design methods
Open this publication in new window or tab >>Aircraft conceptual design methods
2005 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Generally aircraft conceptual design is defined as the starting point for concept sketcing and evaluation, but before that work can start an even earlier stage has to be covered.

This is the stage where different scenarios are being worked through in which the aircraft as a platform is supposed to work. The scenarios will differ between civil and military use of course. but will have to fit well inside both customers and manufacturers strategic plans for the future.

In planning for the future it's vital to think and plan in broader terms, i.e. not only creating single products but rather create families of aircraft. This way of thinking and planning is usual amongst civil manufacturers. Creating a family based product line means better economics, better market coverage and of course lesser risk taking if and when the market changes. On the military side this way of thinking and planning is still quite unusual, mainly because customers are governments which usually only ask for single products.

The manufacturer from his point of view must think differently, he needs to spread his risk taking, especially as orders from the govemment are becoming scarcer. Therefore a modular product line would be of economic interest and would probably interest more customers.

The basic idea behind Saab Gripen (three roles merged into one single platform), or the US Joint Strike Fighter (JSF) idea of a modular aircraft, could be seen as the start of some kind of new family planning, but family planning on the military side could reach further than that. Probably military manufacturers can learn a lot from their civil counterparts.

Conceptual design might be a one man job in the early stages, but will very soon develop into team work. This development is only natural since the conceptual designer can't be expected to have detailed knowledge or experience which will cover every item. Conceptual design introduces a holistic viewpoint into the aircraft design process and it's vital to keep this viewpoint as long as possible. This becomes even more important over time, since the more detailed the project gets, the overall goal tends to drown into details.

Conceptual design phase offers the only occasion when design changes still can be made quite easily. Design freeze is not only a simple freeze of aircraft layout and geometry, it also sets the fmal prize tag on the aircraft. So in a way it is what you did (and what you forgot to do) in the conceptual design phase which fmally decides the faith of the end product. Hence conceptual design needs all the time it takes to be able to develop successful future products.

Generally there are two sides to conceptual design: either you develop a brand new design or make changes to an already existing one. Either way has its own needs and can't be run in the same manner, since different tools are needed in both cases. A new design needs a good conceptual design program, while in the latter case only minor parts of it might be used. A new design starts off fresh; everything is possible and nothing is sacred, but changing on an existing design means working with hands tied, you do not change things that easily.

Aircraft Conceptual Design takes long time to learn. It requires more than just being able to run a conceptual design program. Previous experience in a number of different aircraft design disciplines is a must; so is the ability to be able to humbly listen to experienced people's knowledge and advice.

This paper describes methods for aircraft conceptual design at two basic levels. At the top level there's a method described for conceptual design of civil jet transport aircraft.

On the second level different methods for conceptual design of core aircraft systems such as landing gear, environmental control and hydraulic are presented.

Place, publisher, year, edition, pages
Linköping: Linköpings universitet, 2005. 72 p.
Linköping Studies in Science and Technology. Thesis, ISSN 0280-7971 ; 1197
National Category
Engineering and Technology
urn:nbn:se:liu:diva-31439 (URN)17222 (Local ID)91-85457-32-9 (ISBN)17222 (Archive number)17222 (OAI)
Available from: 2009-10-09 Created: 2009-10-09 Last updated: 2013-11-07

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