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National Advisory Committee for Aeronautics, Technical Notes - Hydrodynamic and Aerodynamic Tests of a Family of Models of Seaplane Floats with Varying Angles of Dead Rise

Three models of V-bottom floats for twin-float sea—
planes (N. A. G .A. models 057-A6 57-3 , and 57- 0) having an—
gles of dead rise of 20° 25 , and 30° respectively, were
tested in the N-A.G.A. tank and in the N.A.O.Aa 7- by 10-
foot wind tunnel. Within the range investigated, the ef~
feet of angle of dead rise on water resistance was found
to be negligible at speeds up to and including the hump
speed, and water resistance was found to increase with an-
gle of dead rise at planing speeds. The height of the
spray at the hump speed decreased with increase in angle
of dead rise and the aerodynamic drag increased with dead
rise.

Lengthening the forebody of model 57~B decreased the
Water resistance and the spray at speeds below the hump
speed. Spray'strips provided an effective means for the
control of spray with the straight V sections used in the
series but considerably increased the aerodynamic drag.

Chartstor the determination of the water resistance
and the static properties of the model with 25° dead rise
and for the aerodynamic drag of all the models are includ-
ed for use in design.

Seaplane floats are usually of the V-bottom type with
angles of dead rise of from 20° to 50°, angle of dead rise
being defined as the angle with the horifiontal made by a
straight transverse line Joining the keel with the chine.
The N.A.G.A. model~57 series of three float forms was de-
signed to investigate through this range the effect of

dead rise on water resistance, spray. and aerodynamic drag.
The models of the series were tested in the N.A.G.A. tank
and in the 7- by 10-foot wind tunnel at Langley Field. Va.
The results of these tests are combined in this report in
order that they may be useful in the design of twin—float
seaplanes and in the conversion of landplanes for marine
service.