Liquid hydrogen has been proposed as an alternate fuel for aircraft to supplant our dwindling and increasingly costly and insecure hydrocarbon fuels. It is plentiful in supply, recyclable after combustion, low in pollutant and toxic products, high energy content per unit mass, and compatible with state-of-the-art engine technology. Its low density, storage and handling problems, uncertain costs, and safety aspects are facets that have to be dealt with before widespread application is accepted.
This paper outlines some of the airplane design problems and economic aspects of subsonic commercial transports that might be evolved using liquid hydrogen as fuel. Both short and medium haul applications are considered and it will be shown that whatever the category in terms of size and range, these aircraft can compete with equivalent concepts utilizing conventional hydrocarbon jet fuels.