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Development and demonstration of materials and manufacturing process for ultra high reliability electric Anti-ice/De-ice thermal layers for high strain rotor blades and helicopter airframe sections

Periodic Reporting for period 3 - NO-ICE-ROTOR (Development and demonstration of materials and manufacturing process for ultra high reliability electric Anti-ice/De-ice thermal layers for high strain rotor blades and helicopter airframe sections)

Reporting period: 2020-01-01 to 2020-12-31

Every icing incident of airplane components may have serious consequences for aircraft flying performance and can even lead to fatal accidents. The statistics on ice- related accidents, reporting of more than 10.000 accidents between 1982 and 2001, make it very clear that ice prevention measures are of great importance.

Ice shapes on aircraft components can have substantial effects on lift, drag, and pitching moment. Even very little surface roughness caused by a thin ice layer generates significant aerodynamic effects, such as a precipitous drop in lift caused by flow separation. Ice accretion can be especially dangerous and fatal on propellers and rotors, significantly reducing propeller or rotor performance.

For tilt rotor aircraft, in-flight icing is an even greater issue - as a balanced and even power output between the two rotors is essential in all phases of flight. Uneven ice accretion between the two rotors, which may be caused by uncontrolled, uneven ice shed, will result in different efficiency and performance output between the two rotors on either side of the centre of gravity, resulting in a severe unbalance of the aircraft.
Furthermore, ballistic shedding of larger ice pieces may cause severe damage on the aircraft fuselage.

Taking all these factors into account, ice protection systems for tilt-rotor aircraft must be designed in a smart way in order to ensure sufficient safety in all weather conditions. Despite a large number of conventional approaches, anti-icing and the removal of existing ice on tilt-rotors are still not completely and satisfactorily solved.

The expected outcome of project NO-ICE-ROTOR is the development, manufacture and environmental test validation of ultra high reliability heater layers for future platforms.

The overall objectives of the project are:
o Design and development of electrically operated heater layers, to be embedded in the rotor blade structure up to a certain TRL
o Definition of test criteria and test matrix
o Manufacturing of suitable test specimens for structural-, and environmental coupon testing and ice wind tunnel testing
o Environmental testing at coupon level
o Structural testing at coupon level
o Ice wind tunnel, in both static-, and rotating configuration at full-scale level with fully functional prop rotor blade section
o Synthesis of testing results
Management including risk management, coordination, and communication within the project team as well as with the TM, is done by Villinger. In order to ensure proper management and coordination of the project, weekly telecons are being held between the TM and the consortium.

Under the framework of WP2, the design and development of the heater layer-based IPS to be incorporated into a prop rotor or panel composite structure will be delivered. AIT has performed CFD simulations in order to determine the requirements for the heater layer in terms of location and arrangement of heating zones on the rotor blade and power density for anti- icing and de-icing strategies. A number of anti-icing and de-icing zones along the rotor blade have been defined to ensure proper ice protection properties.

To guarantee a fair comparison between the current technology and the one employing the Villinger heater layer, the design will proceed by adopting the chord extension of the current heater layer.
Another action conducted in WP2 was the estimation of the parting strip power density requirements.
The parting strip baseline design has been analysed and, based on the constraints provided by the TM, a design for the Villinger heater layer has been proposed.
The anti-icing and de-icing system baseline designs were analysed and a design with the Villinger heater layer will be presented. The IPS developed was numerically simulated and it was verified that the maximum internal temperature of the PropRotor section at R=3175 mm in the most critical condition is below the maximum value indicated by the TM.

The results were very promising and make it clear that the heater layer can withstand the applicable environmental and mechanical hazards.

In WP4, structural element test specimen, representative of the actual system design later applied to a blade specimen, were manufactured for structural testing at Aviatest's facility. 5 coupons, consisting only of the structural laminate base material (Type 0 - Reference Specimen), without electrical elements included, will be tested to establish the laminate strength and failure modes.
Additional Specimens are:
Type 1.1: Specimens with straigth bus bars to analize bus bars only
Type 1.2: Specimens with wolded bus bars
Type 2.1: Specimens with bus bars connected wtih solder points
Type 3.1: Specimens with Chordwise heater layer layout
Type 3.2: Speciemns with Spanwise heater layer layout

WP 5: In period 2, several layup- and manufacturing prototypes were produced. These prototypes were used to investigate material compatibilities and manufacturing processes as well as to analyze parameters such as thickness limitations.
After various improvements were determined and a final layout was defined, a specification describing the demonstrator design was issued. For static testing, two demonstrators were produced, one representing the blade root section with primary and secondary de-icing zones only and one representing the blade tip section with primary and secondary de-icing zones and anti-icing parting strips.

In WP7 the Spin rig test jig was designed. This already happened in RP2. The test stand is manufacrured and first tests are done in beginning of May 2021.

In WP9, additional environmental tests with the final heater mat were carried out to demonstrate maturity of heater layers for ultra high reliability of electric anti-ice/de-ice thermal layers. For that purpose, thermal stability, elasticity and integrity upon harsh induced humidity and temperature close to max. operational temperature of Villinger heater layers applied on GFRP substrates were evaluated.
The heater layers developed in NO-ICE-ROTOR will not only be characterized by high energy efficiency and cost efficiency, but also by increased reliability and lower weight compared to conventional technologies.

The NextGenCTR, capable of generating lift and propulsion with two powered rotating rotors mounted at the ends of a fixed wing, will cover the market need of a civil aircraft that combines the VTOL capabilities of a rotorcraft with the speed and range of a conventional fixed-wing aircraft. The vehicle will expand the EU industry's existing portfolio of heavy multi-engine rotorcraft, providing high-speed, long-range and versatile operation.

Besides the Aviation industry, heater layer- based ice protection measures are of great importance also for all other means of transportation (cars, trains, and vessels), cooling and refrigeration units, for wind energy plants, for bridges, for antennas, and for transmission lines as well. Beyond numerous aeronautical applications, the heater layer technology proposed by NO-ICE-ROTOR has also been successfully applied in the wind energy domain. The further development of this technology pushed by NO-ICE-ROTOR will allow a cross-fertilization between aviation and other technological areas.
Next Generation Civil Tilt Rotor