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Hypersonic Morphing for a Cabin Escape System

Final Report Summary - HYPMOCES (Hypersonic Morphing for a Cabin Escape System)

Executive Summary:
Passenger safety is one of the main drivers for the development of future trans-atmospheric transportation systems. The high levels of energy associated hypersonic flights as well as the level of reliability of the enabling technology leads to the need of a passenger escape system in case of flight abort. The implementation of a cabin escape system for a hypersonic aircraft is challenged by the integration within a larger structure, the load factors for the passengers, the ejection propulsion concept, the capability to withstand extreme thermal environment(plasma flow)and the adaptability to a wide range of abort scenario conditions (low and high speed and altitude). This multi-phase nature of the return flight makes morphing an attractive solution for a hypersonic escape system. The abort scenarios cover a wide range of flight conditions and the integration within the mother spacecraft requires compact solutions in terms of shape (ex: capsule adapted to outer mold line). Thus a single shape cannot provide adequate performances and consequently it can be challenging (ex: load factors) for the wellness of the ordinary passengers expected in the cabin. The increase of the lifting capability after ejection of a escape capsule and the increase of aerodynamic control surfaces is a strong requirement in order to safely return to ground the crew – composed by non-trained persons.

Project Context and Objectives:
The implementation of a cabin escape system for a hypersonic aircraft is challenged by the integration within a larger structure, the load factors for the passengers, the ejection propulsion concept, the capability to withstand extreme thermal environment (plasma flow) and the adaptability to a wide range of abort scenario conditions (low and high speed and altitude).
This multi-phase nature of the return flight makes morphing an attractive solution for a hypersonic escape system. The abort scenarios cover a wide range of flight conditions and the integration within the mother spacecraft requires compact solutions in terms of shape (ex: capsule adapted to outer mold line). Thus a single shape cannot provide adequate performances and consequently it can be challenging (ex: load factors) for the wellness of the ordinary passengers expected in the cabin. The increase of the lifting capability after ejection of an escape capsule and the increase of aerodynamic control surfaces is a strong requirement in order to safely return to ground the crew – composed by non-trained persons.
The main goal of HYPMOCES is to investigate and develop the technologies in the area of control, structures, aerothermodynamics, mission and system required to enable the use of morphing in escape systems for hypersonic transport aircrafts. A large cabin escape system able to change its shape and automatically reconfigure during an abort event after ejection will balance the compromise between the constraints for the integration within the mother aircraft (compactness), the adaptability to the unpredicted environment in case of abort and the required flight performance to ensure safe landing.
The HYPMOCES project addresses key technological areas to enable the use of morphing in hypersonic escape systems, namely:
1. Control and Reconfiguration during morphing
2. Structures, materials, actuators and mechanism of the deployed elements
3. System integration within the escape system and within the mother aircraft
4. Aerothermodynamics of the changing external shape
In addition to the technology aspects, the cabin escape concept feasibility from a system and mission standpoint is appraised using a high-energy trans-atmospheric transportation scenario.
Project Results:
In atmospheric space vehicles morphing has been also used to improve performances and to trigger different mission phases: from deployment of hypersonic and subsonic parachutes in entry capsules to folding wings. In suborbital flight, a recent example of morphing is the feathered wing concept implemented in the Space Ship One prototype and foreseen for the Space Ship Two operational vehicle. At design level, morphing has been widely studied either in aeronautics or space application as it is an attractive solution aimed to maximise the system performances for multimission concepts.
An escape system for a passenger transport able to eject the complete cabin in case of abort has not been implemented even if proposed at conceptual level. The achieved levels of reliability in subsonic flight transportation have deemed not necessary the use of such escape systems.
In manned space vehicles, the use of crew escape systems has been considered a compulsory element and concepts like the Launch Escape Tower are of common use mainly to deal with launch abort cases. In the case of the Space Shuttle, it was judged an unnecessary addition and both the Challenger and Columbia accidents have proven it was not a right approach. A trained crew, i.e. professional astronauts, is required to withstand the demanding scenario associated to the use of escape systems in space applications.
Hypersonic flight is an enabler of trans-atmospheric transportation. Two main branches of concepts have been proposed: propulsive cruise using advanced propulsion technology (ex: SCRAMJET), like NASP or Zero Emission Hyper Sonic Transport or gliding flight from a high-altitude injection like the Spaceliner. Thus, hypersonic flight deals not only with high levels of energy (speeds between Mach 7 and 20 and altitudes between 30 and 100 km) but also with the need of propulsion systems able to bring the system to the hypersonic cruise speed or to the gliding entry velocity based on rocket technology. Therefore, launch pad abort or abort during ascent must be tackled. For the concepts requiring flight at high speed (beyond Mach 4), the escape systems are also deemed necessary during the trans-atmospheric gliding descent. High hypersonic applications are additionally challenged by the extreme environment, where surrounding temperatures can easily exceeded 1500K, boundary layer transits from laminar to turbulent increasing heat fluxes and local small geometry “defects” like steps and gaps can change the large scale aerothermodynamic behaviour. In fact, high speed hypersonic flight is characterised by a narrow entry corridor bounded by thermo-mechanical constraints and vehicle flying qualities requiring precise trajectory and attitude control and onboard estimation of the vehicle status and adaptation to the different flight regimes.
Morphing can be qualified as an ideal solution from an airworthiness standpoint. However, the structural implications have been a common showstopper due to the increased complexity which means cost. Movable structures under high thermomechanical loads have severe implications like the transfer of loads, deformability, aero-elasticity, friction, precision of the operation, mass, volume and power. Morphing, hypersonics and escape system require a multidisciplinary approach from a system perspective in order to identify candidate architectures not biased by a single discipline leading to an unrealistic design.
In the frame of the EC FP7 funded FAST20XX project, the implementation of a cabin escape system was addressed, showing challenges and areas for future investigations like the integration within a larger structure, the load factors for the passengers, the propulsion concept and the adaptability of the escape cabin to the different abort scenario conditions.
This multi-phase nature makes morphing an attractive solution for a hypersonic escape system. The abort scenarios cover a wide range of flight conditions and the integration within the mother spacecraft requires compact solutions in terms of shape (ex: capsule adapted to outer mold line). Thus a single shape cannot provide adequate performances and consequently it can be challenging (ex: load factors) for the wellness of the ordinary passengers expected in the cabin. The increase of the lifting capability after ejection of an escape capsule and the increase of aerodynamic control surfaces is a strong requirement in order to safely return to ground the crew – composed by non-trained persons.

Potential Impact:
Accordingly to the FP7 Work Programme 2012 the proposals under this call should investigate breakthrough technologies and concepts that have the capacity to cause a step change in aeronautics and air transport in the second half of this century (AAT.2012.6.3-1).
Rescue systems for modern civil air transportation have been considered and discarded since the gain in safety is marginal with respect to the achieved level of reliability. This reliability is a result of decades of constant technological development and is owed to the enormous amount of acquired experience that has been continuously taken into consideration for new developments. This basis of experience is completely lacking for hypersonic aircraft for which no system is currently in operation. Due to this lack of experience and because of the complexity of the system and other risk sources inherent to this kind of system it is deemed essential to provide an escape system in order to bolster the reduced level of reliability. The safety feature is considered essential in order to increase acceptance of this kind of trans-atmospheric transportation by potential customers.
HYPMOCES main goal is (as mentioned before), to investigate and assess the feasibility of a group of technologies needed to develop a novel escape system for hypersonic transportation. Such escape system will require a new concept, hypersonic morphing, and breakthrough technological developments to enable it.
Morphing structures on a hypersonic rescue capsule has the potential to increase safety for passengers for hypersonic flight through increased mission flexibility and may thus act as an enabler for this kind of future transportation which itself represents a step change with respect to current air transportation systems that are subsonic without exception.
This new approach in hypersonic flight for an escape system will require a breakthrough in a set of nowadays technologies in the area of control, structures, aerothermodynamics, mission and system required to enable the use of morphing in escape systems for hypersonic transport aircrafts. Thus, HYPMOCES addresses the breakthrough technologies (AAT.2012.6.3-1) required to enable a radical new concept for air transportation (AAT.2012.6.3-2). Addressing concept and technology will ensure higher reliability in the conclusions and the identification of the next steps to increase the technology readiness level.
The breakthrough proposed is only possible if we bring together renowned experts in each field. Thus, the proposed consortium has been sought out in order to join the best competences and required facilities all throughout Europe while maximizing the restrictions of L0 type of proposal and taking advantage of the developments already performed at National and European.

Dissemination activities have been implemented across the whole duration of the project to plan and facilitate the transfer of knowledge to the aeronautics community.
The achieved results are:
• Hypmoces project website: http://hypmoces.deimos-space.com/
• Presentation of 6 papers at 4 international conferences:
o IAC 2014: “CONCURRENT ENGINEERING APPROACH FOR THE PRELIMINARY STUDY OF HYPERSONIC MORPHING FOR A CABIN ESCAPE SYSTEM”. DLR-DMS-ONR-AVS
o IAC 2014: “HYPERSONIC MORPHING FOR A CABIN ESCAPE SYSTEM”. DMS-DLR-AVS-ONR
o EURO GNC 2015: “Analytical and simulation-based V&V techniques applied to hypersonic vehicles”. DMS
o 8th ATD 2015: “Aerothermodynamics analysis of the Spaceliner Cabin Escape System modified via a morphing system”. ONR-DMS
o 8th ATD 2015: “Hypersonic Morphing for a Cabin Escape System: results of Design Loop 1”. DMS-DLR-AVS-ONR
o Aerodays2015: “HYPersonic MOrphing for a Cabin Escape System”. DMS-DLR-AVS-ONR. Included 2 posters at the project stand with the 3d printed mockup.
• Two project stands at international conferences:
o Aerodays2015, London, October 2015. Included 2 posters, brochures and a 3D printed vehicle mockup (baseline concept).
o AIDAA, Turin, November 2015. Included a 3D printed vehicle mockup (backup concept).
• Publication of a dedicated article on Aviation Week (web and paper magazine), following the Aerodays2015 conference with echo on multiple websites worldwide.
• Organization of the HYPMOCES workshop to disseminate the project results to a wide audience of European experts (from agencies, industry, research centers, universities) and post-graduate students. It has been a full day event with HYPMOCES project presentations and 4 invited presenters (ESA, DLR, AeroSekur, IST Lisbon). Included brochures and a 3D printed vehicle mockup (baseline concept) exposition.
• Twitter account: https://twitter.com/HYPMOCES

List of Websites:
http://hypmoces.deimos-space.com/