Reactive compositions for making a polyurethane-based rain-erosion protective coating for rotor blades, the reactive composition comprising an isocyanate-reactive component and an isocyanatefunctional component and wherein the isocyanate-reactive component comprises a first component i) being a short chain hydroxyl-functional compound having two terminal (alpha-omega)hydroxyl groups, a molecular weight of less than 250 g/mole and containing at least 2 carbon atoms and a second component ii) comprising a high molecular weight hydroxyl-functional compound having two terminal (alpha-omega) hydroxyl groups and a molecular weight of at least 250 g/mol and comprising one or more units selected from oxyalkylene units and polyoxyalkylene units and wherein the isocyanate¬ functional component is an isocyanate prepolymer of the general formula NCO-Z- NCO, wherein Z is a linking group comprising at least two urethane (-NH-CO-O-) units and additionally one or more units selected from alkylenes, oxyalkylenes, polyoxyalkylenes, alkylene esters, oxyalkylene esters, polyoxyalkylene esters and combinations thereof.