AEROTHERMAL ENVIRONMENT METHODOLOGY OF THE HEXAFLY-INT EXPERIMENTAL FLIGHT TEST VEHICLE (EFTV) Giuseppe Pezzella (1) , Valerio Carandente (2) , Roberto Scigliano (3) , Marco Marini (4) , Johan Steelant (5) (1) Italian Aerospace Research Centre (CIRA), Via Maiorise snc, 81043 Capua, Italy, Email: g.pezzella@cira.it (2) Italian Aerospace Research Centre (CIRA), Via Maiorise snc, 81043 Capua, Italy, Email: v.carandente@cira.it (3) Italian Aerospace Research Centre (CIRA), Via Maiorise snc, 81043 Capua, Italy, Email: r.scigliano@cira.it (4) Italian Aerospace Research Centre (CIRA), Via Maiorise snc, 81043 Capua, Italy, Email: m.marini@cira.it (5) European Space Agency (ESA), Keplerlaan 1, 2201 AZ Noordwijk, Netherlands, Email: johan.steelant@esa.int ABSTRACT Over the last years, innovative concepts of civil high- speed transportation vehicles and the development of related technologies were proposed in EC co-funded projects like ATLLAS, LAPCAT and HEXAFLY [1-3]. These vehicles have a strong potential to increase the cruise range efficiency at high Mach numbers, thanks to efficient propulsion units combined with high-lifting vehicle concepts. Nonetheless, performing a flight test will be the only and ultimate proof to demonstrate the technical feasibility of these new promising concepts and technologies and would result into a major breakthrough in high-speed flight. In this frame the Hexafly-INT project intends to test in free-flight conditions an innovative gliding vehicle with several breakthrough technologies on-board. This approach will create the basis to gradually increase the readiness level of a consistent number of technologies suitable for high-speed flying systems. This work describes the methodology and the implementation of tools for thermal analysis of the Hexafly-INT Experimental Flight Test Vehicle, namely EFTV, during a preliminarily considered test window. The paper will present the environment during the test window at cruise Mach numbers, in particular regarding aerothermodynamic loads acting on the vehicle along the flight path. Then, preliminary results of a Finite Element thermal analysis, useful to perform a proper material selection, will be presented and discussed. 1. INTRODUCTION Over the last years, innovative concepts of civil high- speed transportation vehicles were proposed. These vehicles have a strong potential to increase the cruise range efficiency at high Mach numbers, thanks to efficient propulsion units (turbojets based on air-turbo- rocket cycle for take-off and landing, and dual-mode ramjet/scramjet for cruise) combined with high-lifting vehicle concepts [4,5]. Nonetheless, performing a flight test will be the only and ultimate proof to demonstrate the technical feasibility of these new promising concepts and would result into a major breakthrough in high-speed flight. At present, the expected performances are usually demonstrated by numerical simulations and partly experimentally. As high-speed wind tunnels are intrinsically limited in size or test duration, it is nearly impossible to fit even modest vehicle plan-form completely into a tunnel. Therefore experiments are limited either to the internal propulsive flow-path with combustion, but without the presence of high-lifting surfaces, or to complete small-scaled aero-models, but without the presence of a combusting propulsion unit. Though numerical simulations are less restrictive in geometrical size, they struggle however with accumulated uncertainties in their modelling, making predictions doubtful without in-flight validation. As a consequence, the obtained technology developments are now limited to a technology readiness level of TRL equal to 4 (components validated in laboratory). The HEXAFLY-INT project aims at the free flight testing of an innovative high-speed vehicle with several breakthrough technologies on board. This approach will create the basis to gradually increase TRL. The vehicle design, manufacturing, assembly and verification will be the main driver and challenge in this project, in combination with a mission tuned sounding rocket. The prime objectives of this free-flying high- speed cruise vehicle shall aim at [4]: • a conceptual design demonstrating a high aerodynamic efficiency at cruise with a high volumetric efficiency; • a positive aerodynamic balance at a controlled cruise Mach numbers from 7 to 8; • a good gliding performance from Mach 7 to 2; • an optimal use of advanced high-temperature materials and/or structures. The main preliminary flight sequence profile and events are shown and listed in Fig. 1 and in Tab. 1, respectively. Then, the EFTV configuration under consideration is depicted in Fig. 2. In the present work the methodology and the implementation of tools for thermal analysis of the EFTV, during a preliminarily considered test window, is presented. Thermal analyses are performed in the most critical phase of the mission, on the basis of the trajectory provided by Gas Dynamics Limited (GDL). In particular, the calculations show a first feasibility analysis for the preliminarily selected materials.