1. Establishing the link between hemolymph modification (under atmospheric conditions) and interaction with the surface: A comprehensive study on the biochemical modification of hemolymph allowed to determine the main proteins undergoing chemical transformation and the related physico-chemical properties. The laboratory experiments further focused on the evaluation of impact velocity and UV exposure on the biochemical modifciation of hemolymph and the consequent interaction with the surface. The main outcomes from this part of the project is the definition of critical parameters for the design of anticontamination of coating and cleaning solutions; the unexpected and crucial role of chemical composition on coagulation kinetics and the influence of exposure to aircraft environment on the transformation of hemolymph and the consequent increased adhesion on the surface (especially under UV exposure). Part of this work was published ESPCI and CNRS. CIDETEC and UMONS have patented the coating chemical composition.
2. Formulation of smart eco-friendly anticontamination coatings
The coatings are based on several chemistries and include slippery effect and self-healing properties. The formulations were optimized and their durability evaluated. This led to the selection of 3 candidates which were tested following a set of aeronautic requirements (impact and erosion resistance, UV, etc). Several communications (conferences, general publications) were carried out these developments.
3. Development of eco-friendly cleaning solution
SOPURA developed solvent and enzyme-based formulas providing very good detergency effect. The application process was evaluated at laboratory scale and the best solution was tested in real conditions on the test aicraft of SONAIR. Life cycle assessment was carried out on the developed solution and allows to reveal hot spots which might be used for further optimization.
4. Development of a test device for wind tunnel and short flight tests
Fuel tank of the S200 Sonaca Aircraft, selected to be used for testing the 3 coatings, equipped with sensors and cameras by LMSM. The test device was evaluted in wind tunnel, than revised and adapted to satisfy secure flight tests with S200 aircraft.
5. Wind tunnel and short flight tests on selected coatings
The 3 selected coatings were tested in wind tunnel (combined or not with water injection to evaluate self-cleaning under rain) and further tested on the S200 aircraft. Many communication (general press, etc) were carried out during the short flight test campaign.
6. Application of the final selected coating on a slat of a commercial A319/320 aircraft operating for 6 months : the coating was successfully applied on a real slat at SONACA and then installed on the aircraft. Easy to clean properties were verified and maintained during the flying period (with no modification of coating aspect).
A full day workshop has been organized at the end of the project at VKI allowing to present an oveview of the main results obtained in STELLAR and some related projects. Exploitation opportunities are evaluated for the coatings developed, the cleaning solution (for aeronautics sector but also other sectors where similar properties are requested), the testing material and protocols. Collaboration with airlines and aircraft manufacturer for coating evaluation has also been identified as an opportunity for the future.
