THE BRAKING PERFORMANCE OF AN AIRCRAFT TIRE ON GROOVED PORTLAND CEMENT CONCRETE SURFACES

Abstract : Introduction of transverse grooves on runways improves braking and cornering performance of aircraft during operations in wet weather conditions and helps to alleviate hydroplaning. The Federal Aviation Administration (FAA) has recommended 1/4-inch square grooves spaced at 1-1/4 inches for installation on runways where the potential of hydroplaning exists. However, a large number of runways remain nongrooved. The major reasons are the high cost of groove installation and limited evidence as to the effectiveness of the grooved surfaces at the touchdown speeds of modern aircraft. The findings of the research described in this report indicate that by increasing the spacing of the conventional saw-cut grooves (in the portland cement concrete surfaces) up to 3 inches, groove installation cost can be reduced by up to 25 percent compared to the installation cost of grooves spaced at 1-1/4 inches. The results further show that the friction levels available on these grooves under wet operating conditions are not significantly below those attained on grooves spaced at 1-1/4 inches. These results are valid for operating speeds of up to 150 knots. The results also show that a reflex-percussive cutting process is an alternative groove installation technique that produces V-grooves which provide braking performance comparable to that of conventional saw-cut grooves. The installation cost of these alternative grooves can be substantially less than that of saw-cut grooves. (Author)