DEVELOPMENT OF A FAST RESPONSE FIBER-OPTIC FLEXURE BALANCE

A fast response aerodynamic balance will be developed for force and moment measurements under non-steady-state flight conditions. A cylindrical balance 2 inches in diameter and 6 inches long that uses a set of X-flexures will be considered as a candidate design. To satisfy the requirement for achieving a natural frequency of 100 Hz, the balance must be designed with very stiff flexures. The displacement of the sensing elements due to the loads imposed on them will be sensed with a fiber-optic sensing technique. Because the flexures are stiff, the displacements are small and require amplification. We will take advantage of mechanical leverage incorporated into the balance design to provide the amplification. The small displacements of the fiber-optic flexure balance will be sensed with a modified and upgraded commercial fiber-optic sensor, which is currently being used in a fiber-optic transducer under development at QUEST. During Phase I, we will develop and test a two-component laboratory balance. A six component prototype balance will then be designed and tested in Phase II. To strengthen our capability in the proposed R&D, we have invited the participation of two Boeing engineers specialized in sting-mounted balance design, fabrication, and operations. Their specialized knowledge complements well our capabilities for the proposed research and development.