Airfoil leading edge coatings

A polyurethane or polyurea coating composition for protecting a leading edge substrate on an airfoil against liquid and solid particle erosion, comprising:

• a polyisocyanate elastomer formed by the reaction of a curing agent and a polyisocyanate selected from the group consisting of hexamethylene diisocyanate (HDI), 2,2,4- and/or 2,4,4-trimethyl-1,6-hexamethylene diisocyanate, dodecamethylene diisocyanate, 1,4-diisocyanatocyclohexane, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (IPDI), 2,4′- and/or 4,4′-diisocyanato-dicyclohexyl methane, 2,4- and/or 4,4′-diisocyanato-diphenyl methane and mixtures of these isomers with their higher homologues which are obtained by the phosgenation of aniline/formaldehyde condensates, 2,4- and/or 2,6-diisocyanatotoluene and mixtures thereof, said curing agent being selected from the group consisting of an aldimine, a ketimine, a polyaspartic ester, a polyamine, a polyol and mixtures thereof, said polyurethane or polyurea rain erosion resistant coating composition in dry cured form having a tensile strength greater than 1000 psi (70 kg/cm2), an elongation at break greater than 350%, a tensile set after break of less than 150%, and a Shore A hardness of 44A to 95A as measured at 68° F. and having a rain erosion resistance of greater than or equal to 70 minutes.