Sizing of TBCC Hypersonic Airbreathing Vehicles

Abstract

This paper provides a methodology to identify, for current technology levels (TRL), a airliner configuration capable of flying over the anti podal range Brussels -Sydney (~ 18000 km) in about 2 hours at Mach 8. This work is performed within the LAPCAT 2 European project, whose mission requirements are: 300 passengers, 18,728 km of range, un-refueled, Mach 8 as nominal speed at cruise, hydrogen as fuel and an airbreathing propulsion system. Critical parameters for sizing of such vehicles are identified by means of a sensitivity analysis to the structural index (Istr), the payload weight (Wpay), the propulsion system and the engine thrust to weight (ETW). This analysis shows that for a fuel-dominated aircraft, such as this, TOGW and vehicle scaling are driven primarily by fuel weight and volume: in fact, the fuel weight and volume requirements in conjunction with the emergency take-off (TO) and landing wing area requirements are among the primary drivers for these aircrafts. Structural and payload weights are of secondary order in comparison: thus, a conservative structural technology level may be selected without a dramatic impact on vehicle size. This is true if the propulsion system is not a critical point. In fact, above an ETW 4.5, the vehicle weights and volumes decrease slightly, while below this value, the solution has a drastic increase in weights leading to a solution divergence. This means that attention must be posed on the engines technology level.