## 1 Introduction  
The Italian Aerospace Research Centre (CIRA) is involved in several programs to develop new technologies, material, and structural concepts to speed up the process of designing and manufacturing the next European System for in-orbit-experimentation with re-entry capability, known as Space Rider, after the successful heritage of the IXV program [1, 2]. For such vehicles, one of the key points is the need for a hot primary structure that can withstand the severe thermo-structural challenges that are typical of the re-entry phase aero-thermal environment. Ceramic matrix composites (CMC) are widely used and have been developed for this purpose in the last few decades [3, 4, 5, 6]. CIRA is also developing new CMC for space applications, for the design of control surfaces and thermal protection systems [7, 8, 9]. Another key point is represented by the development of key technologies applicable to future unmanned spacecraft, for re-entry from LEO orbits w.r.t structural optimization. In this framework, CIRA was the primary contractor on the Unmanned Space Vehicle 3 project, named USV3 [10]. The CIRA Unmanned Space Vehicle (USV3) concept must respect a set of technical guidelines, in particular, the objective is to perform an autonomous orbital and suborbital with enhanced flying capability and conventional landing on a runway. A typical atmospheric re-entry flight consists of three phases: a hypersonic phase, a transition phase from supersonic to subsonic flight, and a landing phase. During the hypersonic phase, aero-braking decelerates the vehicle from near-orbital velocity while cross-range maneuvering and down-range energy management are used to reach the desired landing area. The transition phase requires only stable, controllable flight. The landing phase consists of intercepting the approach path, and holding an established glide slope with the correct excess speed to enable a flare maneuver for landing. The selected aerodynamic shape is based on a winged body concept [11; 12]. The advantages of using a winged body that relies on improved low-speed flight, landing performance, and hypersonic maneuverability must be weighed against the complexity of the design by aerodynamics, aerothermodynamics, and structural point of view. Moreover, the need for housing in operative existing launchers, such as the VEGA-C fairing of a winged vehicle, leads to the adoption of very stretched vehicle configurations, with consequent penalties in terms of volume and weight to be dedicated to the payload. Therefore, a deployable wing solution could overcome difficulties in the launcher accommodation offering, at the same time, the opportunity to keep the winged layout [13]. The \"USV3 DWS\" is a 2500 kg re-entry vehicle, equipped with deployable wings housed in the fairing of the VEGA C launcher. The vehicle conceptual design equipped with a deployable wing is the output of a trade-off study (phase 0/A study, ECSS standard) that aimed to define a possible system concept design and related high-level system requirements, taking into account the following criteria: global weight minimization; payload maximization; optimization of aerodynamic efficiency over all the flight regimes; mass minimization of wing thermal shields; maximization of mechanisms simplicity and reliability. In particular, two different concepts, each one with a different re-entry strategy, have been identified by exploiting the experience acquired during USV1, USV3, and IXV programs and the ongoing activity on the Space Rider European program. The first concept (IXV-based) is expected to operate a re-entry mission based on the following three phases: atmospheric re-entry without wing (lifting body) and controlled flight up to the low supersonic or transonic regime; deceleration using a parachute (if needed) and deployment of the wing; controlled flight through transonic and subsonic regimes up to landing.