Another milestone for the ATTILA project! The DLR-Institut für Aeroelastik from the German Aerospace Center (DLR) and Royal NLR recently completed a comprehensive ground vibration test (GVT) of the ATTILA tiltrotor wind tunnel model at the large low-speed facility (LLF) of DNW – German-Dutch Wind Tunnels.

The GVTs are aimed at the dynamic characterization of the ATTILA model prior to whirl flutter testing in the LLF later this year. Tiltrotor whirl flutter is a complex aeroelastic instability involving coupled rotor, pylon and wing motion. The GVTs and subsequent model scale wind tunnel tests are part of a comprehensive analysis and testing effort that is taking place within the ATTILA project.

The GVT team from DLR Göttingen brought their mobile suite of dedicated instrumentation, shakers and data processing tools to test and characterize the vibration response of the tilt rotor model. The data generated from this test will be used to update the simulation models. Furthermore, the internal acceleration and strain instrumentation in the ATTILA model were measured and compared to the GVT results for verification purposes. These sensors will be used by DLR for online assessment of the aeroelastic stability during wind tunnel testing by real-time operational modal analysis. Engineers from Leonardo Helicopters Division assisted during the test activities, lending their expertise on tiltrotor dynamics.

The test activities took place over a period of 5 days and provided valuable information on the dynamic characteristics of the ATTILA model. The validity of the aeroelastic design was assessed and the tests confirmed low levels of structural damping and minimal nonlinearity in the primary modes of interest. Next steps after data processing will involve updating the numerical structural dynamics models that support the ATTILA design, as well as the related whirl flutter predictions, prior to tunnel entry.

For additional information: https://reports.nlr.nl/items/092c5cd3-72b1-4a07-a52b-de37d32e76f0

Case: ATTILA: Advanced Testbed for Tiltrotor Aeroelastics

An article about the ATTILA project was published on the NRL website.

News link:
https://www.nlr.org/case/case-attila-advanced-testbed-for-tiltrotor-aeroelastics/

We are all excited to share that Alessandro Cocco, who has been working at the multibody and coupled fluid-structure simulations of ATTILA for Politecnico di Milano since the beginning of the project, successfully defended his Ph.D. thesis cum laude on tiltrotor aeroelasticity.

Alessandro made the best possible use of our multibody solver, MBDyn, and vortex particle solver, DUST, and substantially contributed to their development, creating an outstanding suite of tools for the aeroelastic analysis of tiltrotor aircraft.

At the same time, he gave substantial contributions to aeroelastic simulations of ATTILA, in support of the design of the wind-tunnel model. He will soon move to the University of Maryland as a postdoctoral researcher.

Congratulations for your achievements, Alessandro, and good luck for the continuation of your career.

AIAA’s Aerospace America Year in Review (YIR) describes the ATTILA project and its status in a December 2022 article about Aerospace Design and Structures, “Advancing a new generation of tiltrotors”.

See the full article here:

https://aerospaceamerica.aiaa.org/year-in-review/advancing-a-new-generation-of-tiltrotors/

The ATTILA Team presented a paper at the 47th European Rotorcraft Forum, recently held online (September 7-9, 2021) by ERF’s UK representatives.  The paper illustrates the results of the whirl flutter simulations performed so far by NLR and POLIMI in support of the development of the wind tunnel model.  Two independent multibody dynamics solvers, FlightLab and MBDyn, are used, with sophisticated stability analysis techniques like Matrix Pencil Estimation (MPE) and Periodic Operational Modal Analysis (POMA).  Results show good correlation with the expected stability characteristics, suggesting that the project is on the right track for obtaining a wind tunnel model that meets the expectations.

Link: https://re.public.polimi.it/retrieve/handle/11311/1183862/653030/COCCA03-21.pdf

To enable fast and focused growth, the integrated photonics sensing activities of Technobis, a member of the ATTILA Consortium, have changed their name to PhotonFirst, which now operates independently from its ‘mothership’ Technobis Group since January 1st.

PhotonFirst is a leading integrated photonics sensing systems supplier for advanced applications in aerospace, automotive, medical, high-tech equipment, energy and infrastructure.

ATTILA project News

Ten months from the Kick-Off meeting, in September 2020, WP1 of the ATTILA project has been closed by two online design review meetings that have involved all the consortium partners.

The conceptual design of the wind tunnel model as carried out by NLR aims for minimum complexity and structural nonlinearity to ensure that the dynamic characteristics are well-defined.

As an important outcome of WP1 we can mention that the two multibody models developed by NLR using FLIGHTLAB (https://www.flightlab.com/) and by POLIMI with MBDyn (https://www.mbdyn.org/) showed a good correlation with the reference data provided by LHD, as well as in terms of preliminary whirl flutter predictions.

The next period will be entirely dedicated to the detailed design of the model, with the objective to close the CDR by the end of 2021.