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Windshield with improved bird-strike, erosion, de-fogging, de-icing and IR performance

Periodic Reporting for period 3 - Wimper (Windshield with improved bird-strike, erosion, de-fogging, de-icing and IR performance)

Reporting period: 2020-06-01 to 2021-07-31

The ambition of the project is the developing, testing and manufacturing of a complete set of pilot windshield and lower cockpit windows for the new developed high-speed helicopter of Airbus Helicopters called RACER (Rapid And Cost-Effective Rotorcraft).
The requirements for a High Speed Helicopter (min. impact on drag & max. operational performance) and the requirements for bird-strike resistance have to be fulfilled.
The windshields will be mainly designed to have a lightweight design with superior optical quality, which withstands bird-strikes and is resistant to erosion.
Furthermore, anti-fogging and anti-icing functional passive coatings will feature effective inflight requirements, which are critical safety features of modern rotorcraft.
These coatings on the inside and outside of the windshields will help increasing the performance of the designed windshield. The operation time can be increased and preparation time reduced.
Further advantage of a passive water repellent fog and ice protection is a significant reduction in air conditioning devices and therefore a reduction in weight and power consumption.
The power consumption of the system can be reduced, too, which has an additional impact to the engine of the helicopter performance itself.
Preparation time under icing conditions will be same as under normal conditions, because no special de-icing pre-flight activities need to be carried out.
Another main objective is the development of a fast installation and replacement technique of all the windshields resulting in a reduction of the down time of the helicopter during maintenance.
These specific objectives have been verified by testing and simulations to enable the production of the windshields.
Conclusion of the action:
The WIMPER consortium successfully implemented the action, which was achieved by passing critical milestones, submitting of all deliverables, documents and FEM simulations in collaboration with the core partner Airbus Helicopters.
The developed windshield and lower cockpit windows fulfil the requirements bird-strike at high speed, lightweight, high optical quality and it can be assumed that the functional coating lower the power consumption of the RACER.
Work Package 1 was the definition of the Technology specification. The definition of the requirements and the later discussion about the specification lead to the start of the development phase.
The development of the new windshield design (Work package 2) comprised the upper windshield (base and fall-back solution), the lower cockpit windows, the assembly and the coating development (Anti-ice,-fog, IR). The planned designing activities were finished in the second reporting period and all the results from simulation and testing tasks have been included in reports necessary for Permit to fly. The windshield design was successfully fixed at the Milestone critical design review (CDR).
The simulation tasks (Work package 3) were carried out for several windshield design developments. This includes various frame and screw materials, windshield shapes, sizes, thicknesses, position and quantity of bolts, adhesive properties, thermal properties and impact requirements. A detailed substantiation report of the RACER windshield was finalized in the 3rd period, which is required for the permit to flight approval of the RACER demonstrator.
The testing activities (Work package 4) were concluded early 2019 with the bird-strike test of prototypes (windshield). A successful lower cockpit window bird-strike test already lead to the acceptance of the developed lower cockpit window design. The “permit to fly” demands numerous testing and documentations, which were performed within this work package. The testing included material testing, coating testing, adhesive testing and impact testing with artificial birds.
The work package 5 - Production started after the critical design review with the first production of sets of windshields and test articles for mock-up.
The lower cockpit windows and the windshield for the RACER demonstrator were manufactured at the end of the project and will be shipped to Airbus Helicopters in Marignane, France for the final assembly of the RACER.
The tasks of the project coordinator in Work package 6 – Project management included the communication towards the JU-Project Officer and the Topic manager. With this work package 6 the accurate submission of the deliverables was monitored within the consortium.

Overview of results:
- Design of windshield and lower cockpit windows validated
- Design of interface connection to canopy validated
- Assembly definition completed
- Test activities completed: Material testing; coating testing, climate tests, weathering tests, high-speed bird strike tests
- CAD drawings released
- Tooling production completed
- FEA Model validated with test results
- Supporting documentation for permit to flight approved
- Milestones successfully passed
- Prototypes manufactured

Publications and presentations of bird strike testing with a substitute bird contributed to any future standards for bird-strike testing and impact simulation.
Bird-strike tests were effective performed for the canopy partner of the RACER during WIMPER’s project duration and increased the acceptance of substitute birds for aeronautical impact tests.
FEA-simulation of polymeric materials generated knowledge for the university education, resulted in dissertations in this technology and lead to follow-up national SME-research projects.
The Coating technologies of functional coatings launched new businesses in other helicopters and fixed wing aircrafts.
The consortium demonstrated lightweight glazing solutions, which withstand bird strikes at high speeds. The resulting technology can be implemented in airframes where structural weight together with increased optical and mechanical performance is a relevant factor. 
• Rising safety standards of crew and air traffic (better visibility in fog or icing conditions)
• Less / no iced windshield over night
• Weight impact by effective design for windshield and canopy
• No active or less active systems needed, with this, a reduction of power consumption of heating and air conditioning (power and weight)
• New testing and constitutive modelling for low temperature composites damage/failure
• Advances in strain rate modelling for ply and delamination failure of both windshield and frame
• Advances in state-of-the-art for bird-strike test fragmentation modelling
• Enhancement and assessment of a simplified analytical tool for design purposes to estimate damage tolerant hybrid composite laminates
• Validation of advanced finite element methods for bird-strike simulation of transparency and composite structures
• Reduction of animal testing by substitute bird with improved reproducibility
• Marketing issue cause of outstanding better visibility
• Technology transfer possibilities to other and future helicopter models or even other vehicles with comparable requirements

Procedures and standardisation for testing and modelling:
• Currently, there are no standardised test procedures for materials strain rate testing.
• Similarly, there is no applied standard for testing and modelling bird-strike for windshields. Results will be published that this work can usefully contribute to any future standards for bird-strike testing and simulation
Wimper - Lower Cockpit Window Bird Strike Simulation