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National Advisory Committee for Aeronautics, Report - A Theoretical and Experimental Study of Planing Surfaces Including Effects of Cross Section and Plan Form

A summary is given of the background and present status of
the pure—planing theory for rectangular flat plates and V-bottom
surfaces. The equations reviewed are compared with experi-
ment. In order to extend the range of available planing data,
the principal planing characteristics for models having sharp
chines have been obtained for a rectangular flat and two V-
bottom surfaces having constant angles of dead rise of 20° and
40°. Planing data were also obtained for flat-plate surfaces
with very slightly rounded chines for which decreased lift and
drag coeficients are obtained. '

A revision of the theory presented in NAC'A Technical Note
3233 is presented for the rectangular flat plate. The revised
theory bases the aerodynamic suction efl’ects on the total lift
rather than solely on the linear component. Also a crossflow
drag coefiicient which is dependent on the shape of the chines
was found from experiment to be constant for a given immersed
cross section; however, for surfaces, such as those having
horizontal chine flare or vertical chine strips, the crossfiow
drag coefficient is constant only for the chine-immersed condi-
tion. The theory is extended to include triangular flat plates
planing with base forward and V-shaped prismatic surfaces
having a constant angle of dead rise, horizontal chine flare, or
vertical chine strips. A method is also presented for estimating
the center of pressure for surfaces having either rectangular or
triangular plan form. The results calculated by the proposed
theory have been correlated only with the data considered to be
pure planing; however, for conditions not considered pure plan-
ing, a method is given for estimating the ejects of buoyancy.
The agreement between the results calculated by the proposed
theory and the emperimental data is, in general, good for
calculations of pure-planing lift and center—of-pressure location
for flat plate, V-bottom, and related planing surfaces.