Accession Number : ADA307698

Title :   Stochastic Modeling of Antisymmetric Buffet Loads on Horizontal Stabilizers in Massively Separated Flows.

Descriptive Note : Final rept.,

Corporate Author : AEROTECH ENGINEERING AND RESEARCH LAWRENCE KS

Personal Author(s) : Farokhi, Saeed ; Mauk, Clay S. ; Locke, James E.

PDF Url : ADA307698

Report Date : MAR 1996

Pagination or Media Count : 78

Abstract : Federal Aviation Regulation (FAR) 25 has been revised to clearly identify buffet loading as a structural design load. A modem method was developed to model antisymmetric buffet design loads on horizontal stabilizers with a known probability, utilizing a rigid wind tunnel model. The surface pressure was measured for a large number of test conditions, including the most severe buffeting environment for this type of aircraft: the tail immersed in the massively separated wake of the wing. Modifications to the Beech King Air 200 one-sixth scale wind tunnel model included the construction of a new horizontal stabilizer instrumented with 12 miniature pressure transducers. Structural characteristics of the full-scale aircraft were estimated using the Automated STRuctural Optimization System (ASTROS) program. ASTROS, while not directly supporting buffet calculations, is written in a flexible high-level language and thus easily adaptable. Motion-dependent aerodynamics (stiffness and damping) were computed using the proven doublet lattice method, which is incorporated into ASTROS. Due to difficulties with the data acquisition system, the current approach was validated with buffet pressure power spectral densities from an existing reference. Based on the results, the methodology is sound. Future work would include more detailed investigations of the buffet phenomenon and integration of software programs to build a multidisciplinary design tool. This would allow aircraft manufacturers to predict the horizontal stabilizer antisymmetric buffet loads early in the certification program.

Descriptors :   *HORIZONTAL STABILIZERS, COMPUTER PROGRAMS, MATHEMATICAL MODELS, UNITED STATES, OPTIMIZATION, COMPUTATIONS, STOCHASTIC PROCESSES, AUTOMATION, ENVIRONMENTS, AIRCRAFT INDUSTRY, MANUFACTURING, STRUCTURAL PROPERTIES, LOADS(FORCES), STIFFNESS, DAMPING, AERONAUTICS, INTEGRATION, SURFACE PROPERTIES, BUFFETING, PRESSURE, WAKE, DATA ACQUISITION, SEPARATION, WINGS, MODEMS, FAILURE(MECHANICS), FLOW SEPARATION, RIGIDITY, HIGH LEVEL LANGUAGES, WIND TUNNEL MODELS, STRUCTURAL ENGINEERING.

Subject Categories : Aerodynamics

Distribution Statement : APPROVED FOR PUBLIC RELEASE