Søgning i bogen
Den bedste måde at søge i bogen er ved at downloade PDF'en og søge i den.
Derved får du fremhævet ordene visuelt direkte på billedet af siden.
Digitaliseret bog
Bogens tekst er maskinlæst, så der kan være en del fejl og mangler.
78
THE SUBMARINE TORPEDO BOAT
5. Variations of Power with Speed
P: P^ Sa : St®
This may be assumed to be correct for occasions where
the difference of speed is small but at very high speeds the
exponent may go as high as 4 or greater.
6. Variation of Power with Displacement for small
changes in draught
P:P1= IP : D13 for large ships of moderate speeds,
and,
P:P1= D:D* for ships of high speed.
A third method of computing the resistance when no
other data is at hand is called the independent method.
By this method the total resistance is divided into two
parts, the surface or frictional resistance, and the residual
or wave making resistance.
The formula for the calculation of the frictional resist-
ance is
Ry= f.S.Vn in which
V is the speed in knots,
S is the wetted surface in square feet,
f and n are the quantities deduced from Froude’s
experiments and found in any standard work, I able 2.
The wave making resistance is found by the formula
„ b.D.3 V. ,
L — where
D is displacement in tons,
V is the speed in knots per hour,
L is the length in feet on the L.W.L.
b is a value ranging from .35 for fine ships; .40 for