Riblets are micro-grooves capable of decreasing skin-friction drag, but recent work suggests that additional benefits possible for other components aerodynamic drag. The effect riblets on a fixed-wing, low-speed Unmanned Aerial Vehicle (UAV) the total drag assessed here first time by means RANS simulations. Since microscopic scale precludes their direct representation in geometric model UAV, we...

The objective of this paper is to study the effect of an unsteady moving heat source on the aerodynamic performance of an NACA 0012 airfoil section, with particular focus on the lift and drag coefficients. The compressible Navier–Stokes equations are solved using a finite volume method as well as Spalart-Allmaras Model for turbulence simulation. The heat source periodically moves over the lower...

Small-winged drones can face highly varied aerodynamic requirements, such as high manoeuvrability for flight among obstacles and high wind resistance for constant ground speed against strong headwinds that cannot all be optimally addressed by a single aerodynamic profile. Several bird species solve this problem by changing the shape of their wings to adapt to the different aerodynamic requireme...

The results presented in this paper apply to a generic vehicle that makes use of geometry changes to modulate the heat, drag, and acceleration loads while entering a planetary atmosphere. Two structural concepts for implementing the cone angle variation, namely a segmented shell and a corrugated shell, are presented. A structural analysis of the corrugated shell configuration shows that the str...

This paper introduces a novel Lyapunov-based adaptive control strategy for spacecraft maneuvers using atmospheric differential drag. The control forces required for rendezvous maneuvers at low Earth orbits can be generated by varying the aerodynamic drag affecting each spacecraft. This can be accomplished, for example, by rotating dedicated sets of drag panels. Thus, the relative spacecraft mot...

A moving model test method based on stagnation pressure measurements is proposed to measure the train aerodynamic drag coefficient. Because the front tip of a high-speed train has a high pressure area and because a stagnation point occurs in the center of this region, the pressure of the stagnation point is equal to the dynamic pressure of the sensor tube based on the obtained train velocity. T...

This paper addresses the aerodynamic performance of Busemann-type supersonic biplanes at both design and offdesign conditions. An adjoint-based optimization technique is used to optimize the aerodynamic shape of the biplane to reduce the wave drag at a series of Mach numbers ranging from 1.1 to 1.7, at both acceleration and deceleration conditions. The optimized biplane airfoils dramatically re...