Aerospace Engineering Commons^™

Aerodynamic Forces On Flight Crew Helmets, Timothy A. Sestak, Richard M. Howard, Chester A. Heard

Publications

Wind tunnel tests were conducted to deter- mine the aerodynamic forces generated on aircrew flight helmets. Three helmets were tested: two used by aircrews flying ejection seat aircraft in the U.S. military, the Navy HGU-33/P and the Air Force HGU-53/P; and one prototype helmet of significantly different shape and volume. Axial and normal forces were measured through a range of pitch and yaw angles. It was found that large forces exist tending to promote helmet loss during ejection, and that simple modifications to the current helmet configurations can reduce those forces by as much as 40%. It is demonstrated that …

Calculations Of Three-Dimensional Transonic Flows Using The Implicit Formulation Of The Isenthalpic Euler Equations With Flux Vector Splitting, Frank E. Cannizzaro

Mechanical & Aerospace Engineering Theses & Dissertations

A numerical method for solving three-dimensional transonic flows using the isenthalpic formulation of the Euler equations is developed. The method uses van Leer's flux vector splitting to solve the implicit formulation of the governing equations, which are applied to a cell centered finite-volume scheme. A three factor spatial approximate factorization is implemented in solving the implicit part of the governing equations. Time marching to a steady state solution requires short computational times due to the relative efficiency of the basic method. Computational times are further reduced by the implementation of the multigrid acceleration technique, which provided converged solutions in approximately …

Analysis And Optimal Design Of Wind Tunnel Balances, Sung-Ling Twu

Mechanical & Aerospace Engineering Theses & Dissertations

The problem of finding the optimal cross-sectional shape of the elastic cage in wind tunnel balance is formulated and solved numerically. A mathematical model to implement the boundary condition associated with the elastic rigid connection into the finite element method is discussed. Numerical results show that the rigid connection at the end of the elastic cage has significant effect on the stress distribution.

The finite dimensional approach for a three dimensional design sensitivity analysis is derived. Using both the free and rigid boundary conditions, numerical examples are performed and comparisons of the accuracy of design sensitivity analysis between the proposed …