Report

Teaser, summary, work performed and final results

Periodic Reporting for period 1 - FLEXOP (Flutter Free FLight Envelope eXpansion for ecOnomical Performance improvement)

Teaser

The FLEXOP project is about developing multidisciplinary design capabilities for Europe that will increase competitiveness with emerging markets, particularly in terms of aircraft development costs. A closer coupling of wing aeroelasticity and flight control systems in the...

Summary

The FLEXOP project is about developing multidisciplinary design capabilities for Europe that will increase competitiveness with emerging markets, particularly in terms of aircraft development costs. A closer coupling of wing aeroelasticity and flight control systems in the design process opens new opportunities to explore previously unviable designs. Common methods and tools across the disciplines also provide a way to rapidly adapt existing designs into derivative aircraft, at a reduced technological risk (e.g. using control to solve a flutter problem discovered during development). The goal will be achieved by: (a) improving efficiency of currently existing wing, by increased span at no excess structural weight, while establishing modifications by aeroelastic tailoring to carry the redesigned derivative wing; (b) developing methods and tools for very accurate flutter modelling and flutter control synthesis, to enable improved flutter management during development, certification, and operation, enabling to fly with the stretched wing at same airspeed as the baseline aircraft; (c) validating the accuracy of developed tools and methods on an affordable experimental platform, followed by a scale-up study, demonstrating the interdisciplinary development cycle. Manufacturers will gain cost efficient methods, tools and demonstrators for enhancing aircraft performance by integrated development of flutter control and aeroelastic tailoring. Flight test data will be posted on the project website to provide a benchmark for the EU aerospace community. The project’s results will serve as a preliminary outlining of certification standards for future EU flexible transport aircraft. The project is divided into four technical and one management work packages. Within WP1 the consortium designs the demonstrator applicable for scale-up and designs the different sets of wings and develops the suitable mathematical models of these designs, which can be used for performance validation and model based control synthesis. Within WP2 the flutter prediction and control design methods are addressed including 3 tasks: control oriented modelling, flutter analysis and prediction and flexible aircraft control methodologies. The demonstrator specific tasks are within WP3 where the air vehicle is designed, manufactured and integrated with the different sets of wings. The theoretical claims and the real world implementation meets in WP4 where the demonstrator is prepared for flight testing (including implementation of flight control laws and ground testing) and than flight tested. Based on the experimental results the methods and tools are validated which serves as a baseline for scale up studies. Supporting the ambitious work plan WP5 deals with coordination, exploitation & dissemination.

Work performed

Since most of the partners have worked together in previous projects the initial pace was already high to generate results. Several iterations about the wing planform were followed by laying down the draft specifications for the demonstrator aircraft. This unusual order was unavoidable since very limited literature and prior experience exists about designing a wing, which will flutter at relatively low airspeed. In summary within the WPs the following achievements have been reached in the period:
WP1
requirements for wing-1 & overall A/C
wing section design & 3D wing shape design
generation of aerodynamic data
CFD Calculations on D1.1 A/C planform
trim calculations for D1.1 configuration
overall A/C configuration definition
strain & monitoring system requirement specification
structural concept
flutter calculations for structural concepts
parameter sensitivity study for wing-1 Flutter characteristic
condensed modelling trials
material selection
actuator selection investigations
performance specifications for the -2 wing
detailed design of the different wing configurations (-0,-1,-2) and fuselage
WP2
studies on flutter LFT/LPV modelling & analysis
modelling interfaces
reduced order draft aircraft models
control investigation to account for actuator and control system limitations
baseline rigid body control law
theoretical studies on model order reduction and flutter prediction
modelling, reduction, control synthesis toolchains of several partners
WP3
CATIA design model of the entire aircraft with all components
propulsion and airbrake functional prototyping
control surface actuation testing of servos and design of surfaces
rescue system redundancy concept
engine bench testing
mission simulation
ground control station, control link and data storage design
load and shape monitoring system, including physical interfaces and number of measurement point
flight control hardware selection and manufacturing and functional integration
detailed design plan for tooling
WP4
Overall test procedure, flight test regulations
Choice of measurement strategy (Sensors, Data, etc.) completed for validation
Preliminary results for rigid derivative aircraft configuration
WP5
Workflow, GANTT chart and timetable updated regularly
Deliverables submitted or their delay is justified by parners
Project management site
Regular WP and Consortium Webexes
Financial data preparation tested
Declaration and reporting under control

Final results

The consortium members have already achieved results which are significantly beyond the state-of-art and it is expected that these will have significant socio-economic impact.
FACC started to experiment and investigate very thin ply technology to manufacture aircraft structural components from both carbon fiber and glass fiber reinforced plastic.
TUM gained significant expertise in designing wings especially for flutter, including tuning masses and joint structural/aerodynamical optimization.
TUD have gained significant insight in maturing the theoretical aeroelastic tailoring methods into manufacturable aircraft structures.
AGI-UK gained significant insight on the aerodynamical and structural properties of aircraft wings using different design criteria (tailored vs. non-tailored wings), especially with respect to different points of the flight envelope.
AGI-G gained insight on the characteristics of flutter frequency and modes, caused by adding tuning masses on the wing.
INASCO gained insight on the real time, embedded implementation of fibre brag sensing on small-scale instrumentation.
SZTAKI gained insight on the performance trade-offs with respect to actuator limits on the achievable control performance and also in model order reduction of large scale LPV systems.
DLR gained significant insight in controllability of flexible structures with pre-defined control layout, where large scale FEM and aerodynamic models have to be included in the design.
RWTH and AGI-G gained insight in the potential ways of scaling up results and the required abstraction level.

Website & more info

More info: https://flexop.eu.