Continuous Aerodynamic Modelling of Entry Shapes

Abstract

During the conceptual design phase of a re-entry vehicle, the vehicle shape can be varied and its impact on performance evaluated. To this end, the continuous modeling of the aerodynamic characteristics as a function of the shape is useful in exploring the full design space. Local inclination methods for aerodynamic analysis have proven sufficiently accurate for use at such a design stage, but manual selection of methods over the vehicle is inefficient for the exploration of a large number of design possibilities. This paper describes the model of an aerodynamic analysis code, written for use in conceptual vehicle shape optimization, which includes an automatic method selection algorithm. Panel shielding is also included in the analysis code to allow for the analysis of more complex geometries. The models used for the shape and aerodynamics are described and results for the Space Shuttle and Apollo are compared to wind tunnel data. They show an accuracy of better than 15% for most cases, which is sufficient for the use in conceptual design. Panel shielding is shown to be important in the prediction of control derivatives at low angle of attack, as well as the prediction of lateral stability derivatives. Finally, a simple guidance algorithm is used to assess the impact of the errors in the aerodynamic coefficients on the vehicle heat load and ground track length. Both show discrepancies of less than 10%.

Removal notice

“…The rationale behind these methods, as well as their specific execution and validation, has been presented previously. 13,19 In this paper, we use modified Newtonian method as compression method and Prandtl-Meyer method as expansion method. These methods were coded to specify the aerodynamic quantities for a given shape of the re-entry capsule.…”

“…For the standard local inclination methods, every panel with a positive inclination angle acted as a compression panel. 13 Generally, different methods are applicable for windward and leeward sides. The rationale behind these methods, as well as their specific execution and validation, has been presented previously.…”

“…The viscous effect on the aerodynamic forces and moments will be neglected in these methods. 13 Local surface inclination methods find wide use in the conceptual analysis of hypersonic vehicles and are very suitable for use in the conceptual design optimization process. Even though such methods are clearly highly simplified and appropriate results can be obtained using them.…”

“…By connecting every point to neighbor points on the same contour and connecting points with the same indices on subsequent contours, a wireframe of quadrilaterals is got. 13,14 Aero-thermodynamic models…”

“…Even though such methods are clearly highly simplified and appropriate results can be obtained using them. 13,[15][16][17][18] In general, two types of methods are used: compression methods for the windward sides of vehicle and expansion methods for the leeward sides of vehicle. For the standard local inclination methods, every panel with a positive inclination angle acted as a compression panel.…”