On the Stability of Flight Vehicles in the Low Reynolds Number Non-Linear Regime

The first part consists of a literature survey in external fluid mechanics, (i.e., flow over wings and bodies) in the Reynolds number range of 20,000 to 200,000. The second part was a technical review of the material presented at Low Reynolds Numbers Flow. The third part was a trajectory study for a vehicle flying in the low Reynolds number regime. The trajectory study was initiated as a means of accessing the stability of a vehicle flying under circumstances where (a) the aerodynamic characteristics are non-linear and (b) there is coupling between lateral motion (which can induced local stalling) and pitching motion. It is found that for the case studied a modified from of the Liapunov Stability Criteria using a phase-plane, provided a suitable description of the motion. The unstable lateral motion of the vehicle chosen for analysis is shown. The instability is indicated by steady growth of the curve away from any particular point shown on the plane. This work is incomplete in that time did not permit study of reverse interesting features; like the effect of lift curves hystersis on the motion.