Sizing of a Fully Integrated Hypersonic Commercial Airliner

Abstract

S TUDIES on hypersonic vehicles date back to the 1960s [1–4], when due to the NASAAdvancedManned Interceptor X Planes (AMI-X) program [5], it was realized that the approach of integrating individually optimized system elements (as routinely done in designing subsonic and supersonic aircraft) yielded a significant reduction in performance: in practice, the sum of individually optimized subsystems did not result in a system optimum [6,7]. Thus, the starting point for hypersonic vehicle design was a first-order analysis of the entire vehicle configuration [7]. In this Note, the approach to hypersonic vehicle sizing is based on the parametric sizing methodology, identified by Czysz and Vanderkerckhove [7], consisting of defining a set of equations that relates mission requirements to geometry, aerodynamic, and propulsion efficiencies, and that are solved simultaneously. The Vanderkerckhove sizing methodology is based on the coupled solution for the overall weight empty (OWE) and planform area Spln equations, ensuring that the separately calculated available and required weights and total volumes Vtot converge for a given slenderness parameter [8], defined as ( Vtot=S pln). This approach has demonstrated the ability to screen, identify, and visualize the design to the first order in the solution space. In this context, the airliner assumed in the European Union (EU) Long-Term Advanced Propulsion Concepts and Technologies II (LAPCAT 2) project is a case in point. Its mission requirements are those of a long-haul commercial airliner burning hydrogen [9] and flying at Mach 8 (M8), with 300 passengers and an unrefueled 18,728 km range (constraints imposed are those of existing airliners). The first step of this approach is to define a convergence space solution at the cruise design point (see [10,11] by Ingenito et al.). Once a feasible cruise space solution [10], the second step [11] is the integration of the overall mission, i.e., from takeoff (TO) to landing. The flight trajectory in [11] is based on an ejector ramjet (EJR) propulsion system with an engine thrust to weight ETW 22 switching to a dual-mode ramjet (DMR) at M 3:8: the solutions were preliminary, i.e., simple elliptical cone configurations, with no control surfaces [12] and no engine–vehicle integration [13]. The next step, reported here, is to identify the final configuration of a wholly integrated hypersonic vehicle with trimming, control surfaces, and an integrated propulsion system. Vehicle weights (including those of trimming and control surfaces), volumes, and aerodynamic efficiencies are iterated until all weights converge and the thrust required to climb and cruise ismet by engines specification. In Sec. II, final configurations for two different propulsion systems are identified and compared. In Sec. III, a sensitivity analysis to the industrial structural capability index (ISTR) and the ETWparameters is carried out. Section IV shows a fully integrated vehicle configuration.