Evaluation of Trapezoidal Shaped Grooves

Figure 37. Illustration of Water Dispersal Difference This portion of the evaluation, combined with the results of the earlier braking coefficient research, shows that the trapezoidal-shaped grooves were able to displace water faster than the standard grooves which, in heavy downpours, could significantly enhance an aircraft’s ability to resist hydroplaning and lead to better stopping capability and reduced runway closures. Friction Characteristics. During periodic visits to MCAF Quantico, researchers were able to conduct friction-measurements of the entire runway surface using an FAA-owned and -operated surface friction measuring equipment (SFME). The SFME that was used for this evaluation was a Dynatest ® 6850 Slip Friction Tester, commonly called the Runway Friction Tester (RFT). This model SFME is approved for use by the FAA and is listed in the FAA AC 5320-12C [1]. Data collection runs for this project were conducted at 40 mph with data collection starting about 700 ft from the threshold of Runway 02. Tests were performed with the vehicle aligned about 10 ft from the center of the runway. On July 19, 2007, researchers were allowed to collect friction data over the full length of the runway. The runway contains several different surfaces including grooved concrete, ungrooved asphalt, and ungrooved concrete areas where an arresting cable is installed in the runway. Figure 38 shows a sample of the data collected from the RFT during one of the first runs, titled run 1R, with a dry runway surface, and the vehicle using its own self-contained wetting system. With the self-watering system, a calibrated amount of water is applied to the pavement at a 1.0-mm thickness in front of an ASTM E1551 test tire, as installed on the SFME. The locations for all


Made with FlippingBook - professional solution for displaying marketing and sales documents online