Innovative Method for Aircraft Gross Weight and Center of Gravity Estimation

The objective of this proposal is to develop a physics based model for determining the center of gravity of both fixed and rotary wing aircraft. The location of the center of gravity is critical for the ability of an aircraft to take off and sustain flight. When an aircraft is loaded improperly, its center of gravity (CG) will shift creating instability during takeoff, flight and landings. If the aircraft is properly instrumented, the effects of the loading process can be monitored to ensure that the center of gravity location remains within an acceptable region of the aircraft. In aircraft applications, any additional weight or maintenance time represent an unacceptable increase in operational costs and decrease in availability. To limit the measurement burden of the required load sensing system, several commercially available wireless strain gages will be used to properly identify the location of the center of gravity of the unloaded and loaded aircraft. Due to their small size and weight, a telemetry system will eliminate the need for wires. Various techniques (inductive coupling, solar cell, etc.) will be investigated to eliminate the need for batteries in the telemetry system. With the batteries removed, the required upkeep of the sensing system will be nearly eliminated. The sensing of distributed load through the use of strain gages will be demonstrated via the use of a custom made aircraft fuselage simulator test rig (FSTR). Strain gages will be installed on supports which serve as the landing gear of the aircraft. A finite element model of the FSTR will be created to corroborate the experimental and analytical results, as well as to aid in the determination of physics based algorithms for the estimation of the center of gravity location. ID & T expects that the results will show that commercially available telemetry systems can be an effective means for measuring strain and that array strain measurements can be used to accurately identify the location and magnitude of the aircraft center of gravity. The system can also be used to monitor the drift in the location of the center of gravity during the loading process of an aircraft.