POLYURETHANE COATINGS FOR RAIN EROSION PROTECTION.
Abstract:
Advancements in polyurethane coatings for subsonic rain erosion protection of metallic and plastic laminate substrates are described. Polyurethane coatings have been developed which offer protection for up to two hours at 500 MPH in two inches per hour simulated rainfall on a whirling arm apparatus by comparison the specification neoprene coating lasts five to eight minutes under the same conditions. Flight tests on an F-100 aircraft and a UH-1 helicopter flying in heavy rain have confirmed the protectiveness of the coatings. Experimental studies of polyurethane have indicated that a low modulus vehicle with good tensile strength and elongation yields the most erosion resistant coatings. Whirling arm evaluations, abrasion data, and hysteresis measurements have proven vital in determining these factors. Microwave power transmission tests have indicated 94 to 96 percent transmission for polyurethane coatings as compared to 90 percent for the neoprene coatings. Author