Crashworthiness of the Flying-V Aircraft Concept with VerticalDrop Test SimulationsM. Desiderio, M.J. Schuurman, R.C. Alderliesten and S.G.P. Castro∗.Department of Aerospace Structures and Materials, Faculty of Aerospace Engineering, Delft University of Technology,Kluyverweg Street No. 1, 2629HS, Delft, The Netherlands.The following presents a preliminary assessment on the crash characteristics of the Flying-Vaircraft, an unconventional configuration consisting of a V-shaped flying wing with an oval cabincross section, currently being actively researched at TU Delft. Successively, the preliminaryassessment is carried out by means of design of experiments, where four crash structureconcepts are defined and evaluated. Virtual drop tests of the Flying-V typical fuselage sectionare performed while measuring the energy absorption of the fuselage, and the dynamic responseindex (DRI) and selected locations. The finite element modeling scheme is validated using theFokker F-28 Fellowship typical section, for which physical drop test data is available. Whilea crashworthy typical section for the Flying-V could not be designed, it has been found thata conventional crash concept with a total of four oblique floor struts is able to absorb 72%of the total kinetic energy, with a DRI reaching 18.2 units. A sensitivity analysis shows thatthe bending stiffness of the frames has a critical role in the crashworthiness of the Flying-V,due to the increase in rigidity following pressurization loads of the oval fuselage section andthat, additionally, the structural simplifications applied in the context of the research likelyrendered the results overly-conservative. A 16% frame thickness reduction resulted in a DRIof 16.2 units, just above the 16 units typically required by regulators. Recommendations forfuture work include a structural sizing optimization where requirements from crashworthinessand airworthiness can be evaluated simultaneously as design constraints, enabling design forcrashworthiness at the preliminary design.

The Flying-V (FV) represents a novel aircraft configuration that integrates the cabin and two half-wings into a V-shaped structure, promising increased aerodynamic efficiency and an estimated 20% reduction in fuel consumption. Unlike conventional aircraft or other blended wing-body designs, the FV can be scaled to generate a family of aircraft models, which enhances its commercial viability. However, the V-shaped cabin introduces significant eccentricity in the fuselage section, creating unique challenges for crashworthiness.

Aircraft crashworthiness refers to the capability of the airframe to protect occupants during an impact. Regulatory standards for large passenger aircraft (CS-25) require verification of four key criteria: maintaining a survivable volume for occupants, limiting accelerations and loads, retaining items of mass, and preserving occupant egress paths. Historical accident data highlight the importance of these criteria: between 2011 and 2020, 54% of fatal crashes occurred during landing or final approach, accounting for roughly 40% of casualties, emphasizing the vulnerability during these phases. Typically, crashworthiness is assessed via drop tests on a representative fuselage section, focusing on loads and accelerations transmitted to occupants.

To understand how fuselage ovalization and the vertical position of the floor structure affect crash performance, parametric studies were conducted on a conventional aircraft, the Fokker F-28. A parametric CAD model of the F-28’s fuselage section was created and linked to a finite element model (FEM) in Abaqus. Virtual drop tests were performed at 9.1 m/s to evaluate occupant accelerations, dynamic response index, and energy absorption. Ovalization studies varied the fuselage eccentricity from 0 (circular) to 0.75 (approximating the FV’s eccentricity), while floor beam height was varied in 50 mm increments. Results indicated that increasing fuselage eccentricity and floor height generally led to higher occupant accelerations due to reduced crushable volume and shorter impact durations.

For the FV, a preliminary FEM was constructed using previous structural optimization results, which assumed constant frame height and thickness. Four crash concepts were assessed: two conventional designs with four and six floor struts and two unconventional designs featuring vertical crushable elements. The unconventional concepts failed to absorb sufficient energy, leading to high occupant accelerations due to the absence of plastic hinges in the frames. The six-strut conventional concept was overly stiff, also increasing occupant accelerations. The four-strut conventional concept appeared most promising but did not achieve full crashworthiness in this initial study.

Overall, the research shows that the FV’s eccentric fuselage presents unique crashworthiness challenges. Future work should focus on coupled static-dynamic optimization, incorporating both quasi-static operational loads and crashworthiness criteria. This approach will allow designers to iteratively adjust structural parameters such as frame height, thickness, and floor beam placement to improve energy absorption while maintaining stiffness for operational loads. Developing crashworthy designs early in the preliminary design phase is essential to ensure occupant safety without compromising the aerodynamic benefits of the FV configuration.