Seakeeping Characteristics of the XR-5, a High Length-Beam Ratio Manned Surface Effect Testcraft: II. Results of Linearity Investigation, Effects of Changes from Reference Operating Condition and Trim and Draft in Regular Waves,
NAVAL SHIP RESEARCH AND DEVELOPMENT CENTER BETHESDA MD SHIP PERFORMANCE DEPT
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Motion responses in regular head waves for the XR-5 high length-beam ratio surface effect ship are presented. Frequency response functions based on an equivalent amplitude derived from the total energy are presented for pitch, heave, relative bow motion, heave acceleration and bow acceleration. These are compared with responses computed from the first harmonic component of each signal. The results show that the pitch, heave, relative bow motion and bow acceleration exhibit linear behavior for the Froude numbers investigated. Some nonlinear behavior is evident in the heave acceleration at frequencies near the natural frequency in pitch. The effect of varying lift fans and duct valve settings on the response is determined. The pitch magnification is shown to increase when the duct valves are opened beyond the reference settings. Trim angles and drafts for the reference operating condition are presented as a function of encounter frequency for three speeds. The results indicate a moderate variation in trim and draft with frequency.
- Marine Engineering
- Fluid Mechanics