Application of Practical Hydrodynamics to Airship Design.
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION WASHINGTON DC
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The design of a large high-speed airship is primarily a structural problem, in which the most important stresses are those due, directly or indirectly, to aerodynamic forces on the surface of the hull. The force on any small element of the surface is most conveniently divided into two components, respectively tangent and normal to the surface. The tangent or skin-friction forces are so small per unit area that they are structurally almost negligible compared with the normal forces yet their total integrated resultant is responsible for almost the entire drag of the hull, whereas the normal components of pressure are so nearly balanced over a good hull that their net resultant is practically zero. The interreaction of these very substantial forces is, of course, through the medium of stresses in the hull, and in combination with fin and inertia forces they are essential not only from a structural standpoint but also in the consideration of stability and control. The distribution of velocity and skin friction can also be indirectly determined from the normal force distribution. An accurate determination of the latter and its effects is therefore of the very first importance.
- Marine Engineering