Since the introduction of the jet engine and its increasing refinement, fuel began to assume a much more prominent role in the overall design of the aircraft [1-1]. Fuel has now reached at least an equal design consideration as the engine and airframe [1-2]. There are several reasons for this increased importance of the fuel in the overall system. In addition to its essential function of providing the energy necessary for flight [1-3], the fuel will act as the primary heat sink required for cooling the aircraft and its equipment [1-4]. In many future systems, the fuel will constitute over fifty percent (50%) of the total weight [1-5] of the system and the fuel cost may well be as high as fifty percent (50%) of the direct operating cost (Figure. 1.1.). The purpose of this mini book is to summarize the progress made to date in the development of these advanced hydrocarbon fuels and to submit the necessary requirements for future hydrocarbon fuels for the aerospace industry. The idea of regular supersonic flight of air-breathing weapon systems has become a reality within previous years and the advancement of even faster systems will continue [1-7]. This incredible boost in flight speed has led to significant increases in the relative value of the fuel to the general system [1-8]. In the period of the piston engine, airplane designers were more concerned with the engine and the airframe rather than with the fuel [1-9]. The choice of fuel to be utilized in the airplane was often of secondary significance [1-9]. All things considered, with the presentation of the jet engine motor and its expanding change, the fuel began to assume significantly more fundamental capacity in the general plan till the point has now achieved where the fuel has obtained at least proportionate status with the motor and the airframe [1-10].

The primary human activities that release carbon dioxide (CO2) into the atmosphere are the combustion of fossil fuels (coal, natural gas, and oil) to generate electricity, the provision of energy for transportation, and as a consequence of some industrial processes. Although aviation CO2 emissions only make up approximately 2.0 to 2.5 percent of total global annual CO2 emissions, research to reduce CO2 emissions is urgent because (1) such reductions may be legislated even as commercial air travel grows, (2) because it takes new technology a long time to propagate into and through the aviation fleet, and (3) because of the ongoing impact of global CO2 emissions. Commercial Aircraft Propulsion and Energy Systems Research develops a national research agenda for reducing CO2 emissions from commercial aviation. This report focuses on propulsion and energy technologies for reducing carbon emissions from large, commercial aircraftâ€" single-aisle and twin-aisle aircraft that carry 100 or more passengersâ€"because such aircraft account for more than 90 percent of global emissions from commercial aircraft. Moreover, while smaller aircraft also emit CO2, they make only a minor contribution to global emissions, and many technologies that reduce CO2 emissions for large aircraft also apply to smaller aircraft. As commercial aviation continues to grow in terms of revenue-passenger miles and cargo ton miles, CO2 emissions are expected to increase. To reduce the contribution of aviation to climate change, it is essential to improve the effectiveness of ongoing efforts to reduce emissions and initiate research into new approaches.