A fluid foil has a fixed main portion 3 with a moveable tip 11 mounted at one end, both portions having upper 12 and lower surfaces. The foil is operable from a first configuration (fig.3), where the tips upper surface is angled downwardly with respect to the main portions upper surface, into a second configuration (fig.4), where the upper surfaces of both portions are continuous surfaces; the tip is exclusively passively actuated to rotate upward by movement of the foil with respect to a surrounding fluid. A third configuration (fig.4) may angle the tips upper surface upwardly. The tip may remain in its downward position when forward motion of the foil through the fluid is below a predetermined forward speed; to reduce a taxiing/stationary aircraft’s wingspan, for example. Preferably, the tip is mounted by a hinge or flexible element 16, biased towards the downward position using a spring, which imparts a variable force as the tip is rotated upward, and/or under its own weight. The tip may rotate about a pitch axis so that its angle of incidence reduces as it rotates upward. The tip may include one or more fixed or rotating secondary lifting surfaces (fig.12a,31).
Passively actuated fluid foil
2019-06-26
Patent
Elektronische Ressource
Englisch
IPC: | B64C AEROPLANES , Flugzeuge / B63B Schiffe oder sonstige Wasserfahrzeuge , SHIPS OR OTHER WATERBORNE VESSELS / F01D Strömungsmaschinen [Kraft- und Arbeitsmaschinen oder Kraftmaschinen], z.B. Dampfturbinen , NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES / F03D Windkraftmaschinen , WIND MOTORS |