Military aircraft face several contemporary challenges. From a thermal management perspective, they include the more extensive use of electrically driven technologies and more power-hungry tactical systems. These systems demand more cooling power from the aircraft thermal management system. Thermal management systems of modern aircraft face another challenge with shrinking heat sink capability. This is because of platform design aspects. Increasing use of composite materials for airframe skin over traditional metals impedes the dissipation of waste heat through skin. Infrared and radar cross-section signatures are minimised to improve aircraft stealth by minimising the cross-sectional areas of ram air intakes. This reduces the amount of waste heat that can be dumped over-board through ram air. And there are only two options for heat sinks, air (ram or engine fan) and fuel. All these contemporary challenges create a strong need to carry out thermal management design effectively at the aircraft concept stage.

A framework is presented in this thesis that demonstrates how effective thermal management design at the concept stage can be conducted at an aircraft developer like Saab. The framework was created with data collection through workshops, document studies, interviews, and group discussions conducted at Saab. Therefore, the framework is based on industrial reality. It can be tested for application at the aircraft concept stage of Saab projects. Further, the methods created in this thesis can be used in a broader context that transcend their primary application in thermal management design. They can also complement other methods presented in literature on aircraft thermal management. Thus, this thesis makes industrial and scientific contributions to aircraft thermal management design.