THE EFFECT OF CAMBER ON THE NEAR-SURFACE FORCE, CENTER-OF-PRESSURE, AND VERTICAL STABILITY CHARACTERISTICS OF A RECTANGULAR -PLANFORM HYDROSKI.
DAVIDSON LAB STEVENS INST OF TECH HOBOKEN N J
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The hydrodynamic force characteristics of a cambered rectangular planform, 15-degree deadrise hydroski are shown to be similar to those of an equivalent uncambered ski with the exceptions that, for a cambered ski 1 the zero lift angle is shifted to lower angle of attack for the same wetted area and aspect ratio and 2 the center of pressure is shifted aft. Comparison at the same draft -- or wetted area and aspect ratio -- show similar submerged lift-drag ratios for both cambered and uncambered skis in the range of trim angles tested. The region of pre-emergence vertical instability is shown to be caused by the loss in lift as a hydroski runs in the range of drafts just below the planing boundary down to drafts sufficiently deep to preclude ventilation and surface effects, where a ski can run stable fully-wetted with approximately double the planing lift. Increased forward acceleration at unporting was found to shift the pre -emergence instability range to higher speeds and to reduce the time interval spent in this unstable region. Author
- Fluid Mechanics