IXV Venting System Design and Testing

The Intermediate eXperimental Vehicle (IXV) is a non-pressurized lifting-body shaped re-entry vehicle committed by ESA to TAS-I as prime contractor (on June 2009) in a synergic approach with industrial partnerships. The flight element is currently under integration at TAS-I premises (in Turin, Italy) and planned to be shipped for testing to ESA/ESTEAC by Mid-2014 and subsequently to Launch Facility. IXV mission target (whose flight is scheduled by End 2014, launch site Kourou) is basically addressed to the demonstration of advanced technologies capable of sustaining an atmospheric re-entry after a 1-hr orbital arch ranging from 120 km to 400 km of altitude. In this perspective, innovative design solutions suitable to the IXV mission have been designed and manufactured for the flight element after the completion of focused development tests and qualification campaign. Testing allowed to increase the design maturity at component, sub-systems and system Element level (technology readiness level, TRL) up to a robust design compliant with mission success criteria and ESA ECSS directed prototype demonstration requirements. To provide adequate depressurization and repressurization levels during ascent and re-entry, a dedicated venting system was accurately designed against mission-dependent environments and requirements dictated by structural and avionics constraints to preclude catastrophic effects or equipment malfunctions / damages. The scope of this paper is to present the IXV de-press/re-press venting system design, its major constituents, the analysis / test-based end-to-end development and qualification approach. The latter was adopted to achieve an adequate TRL at element / system level, reduced risks and sufficient margins for mission success. The IXV venting system, which is under responsibility of the IXV Thermal Control System (TCS), basically consists of venting ports which allow quick de-pressurization under the fairing during ascent and preclude re-entry overheating. The latter I due to the fluxes entering the internal volumes when IXV is passing across the plasma layers down to 27 km altitude. The overheating of the IXV external structures due to the high temperature of the low gas concentration mesosphere layer combined to the molecular plasma have been attentively evaluated for the venting ports design and performance optimization. The venting system architecture is discussed with reference to the driving requirements, the thermal- hydraulic behavior at element level, the performed development and qualification tests (at element and system level), the tools used to perform test predictions / post-test correlations, and finally, the test-based analysis outcomes to give evidence of functional verification. In addition, this paper intends also to present an overview of the qualified hardware manufactured and integrated in IXV for flight.