Journal of Aerospace Science and Technology
Volume:2 Issue: 3, Autumn 2005

This work is an example of application of nonlinear programming to a problem of three-dimensional trajectory optimization for multistage launch vehicles for geostationary orbit missions. The main objective is to minimize fuel consumption or equivalently to maximize the payload. The launch vehicle considered here, Europa-II, consists of 5 thrust phases and 2 coast phases. Major parameters of the coast arcs such as inclination, eccentricity and true anomaly of attachment points are not prespecified and should be found in optimization problem. The fairing should be jettisoned whenever aerothermal flux falls below a certain value. An aerodynamic heating constraint for atmospheric part of the flight is also considered. The problem is solved by direct collocation method and results are compared with those in Ref. [1] where an indirect multiple shooting method with an inner loop for parameter optimization is used. Advantages of present work with respect to methods used in that reference are then discussed.

This study investigates geometrical non-linear analysis of composite circular cylindrical shells under external pressure over part of their surfaces and also shells subjected to combined axial compression and triangular external pressure. Donnell non-linear shell theory along with first order shear deformation theory (FOSD) are adopted in the analysis. In the case of combined axial compression and triangular external pressure post-buckling curves for various shell stacking sequences and different load interaction parameter are traced. Comparison of the results for uniform and triangular external pressures in combination with axial compression applied to the laminated cylindrical shells is carried out in terms of interaction buckling curves and load-deflection and load-shortening diagrams.

From Wright Brothers 1903 to present day 2003, aeronautical technology has made a profound progress. This paper demonstrates the outcome of this progress in weight, wing area, and engine thrust in three categories of transport aircraft of short to long range, regional jets, and turbo-prop commuter aircraft. Also the paper includes those aircraft with distinct jump in aeronautical technology. Few of the technologies that have contributed to this progress are elaborated too. An average of four to three times progress in aerodynamic sciences, three to four times in weight reduction for material science, and system design, and two to one and half times progress in propulsion of turbo-fan, and turbo-prop engines are concluded.