Continuous Runway Load-Deflection Evaluation Methodology

The deployment of US military forces often requires aircraft operations on runways of unknown construction, roughness, and load carrying capacities not only in UAS but also in foreign countries. Current FWD, DCP and RWD cannot satisfy the mission requirement. The air force is looking for an air droppable lighter weight RWD that can rapidly collect continuous data using sensor technologies. In this proposal, a lightweight RWD with same tire pressure as the big RWD is proposed. Instead of using a rotating mirror an innovative sensor array using linear IR laser diode array and detector array sharing a common optical axis is designed. One sensor array will be put at a location under truck before loading and the other will be put after loading to measure the perpendicular distance from the laser to the runway. Two arrays will be mounted on a H-shape suspension platform with the same height and will be aligned each other precisely. By subtracting the data from two sensor arrays we not only can quantitatively measure the deflection of the runway but also can eliminate all systematic errors caused by vibration etc. If we use our unique parabolic LED array to replace the laser diode array, the total saving will be over $10,000 and the system reliability can be largely increased. In addition to the above sensor arrays, a stereo camera using linear CCD & LIR fused arrays is also designed to not only visualize the runway deformation after loading but also detect the void underneath the runway. Since all optical sensors cannot penetrate the runway, simple microwave impulse radar is also designed to show the void and construction under the runway. Because the RWD is air droppable it should not use a driver, therefore a novel robot is designed to operate the sensors in the RWD and drive the RWD to any place on the runway, and the data will be wirelessly sent to a remote computer for analysis. After finishing the runway survey the RWD will return to the start point and wait for pickup by the helicopter. In order to calibrate the RWD data, our automatic FWD and DCP operated by the robot and developed in one phase-I and two phase-II projects for Army and SOF will be used to measure the runway stiffness and CBR at certain points, thus the relationship between the RWD deflection and the runway strength can be established. Not only all above new sensor prototypes but also a bench scale RWD prototype will be delivered to the Air Force in phase-I.