Page 136 - Theory and Design of Air Cushion Craft

drag
drag
Total
Friction
Method
sidewalls
sidewalls
sidewalls
Remarks
Table 3.3
drag
Appendage
Drag items
Skirt drag or
to air cushion
drag of
drag
Residual drag of
the
Aerodynamic profile
residual
Wetted surface area of
Wave-making drag due
(p v
R w
+ R^
Method
+
according
= 0.05
1
Estimation
Figs 3.2 and
to
7? sww
3.3
+
C w (pi
Methods for calculating the drag of
g) where C w is
5 C)/
Fig. 3.19
from
/?„„) or
/? w
from
=
WIW m
R. dp can
Method
Fig.
2
C w pi
model tests
SES over calm water
R.
?
Conversion from
as for high-speed
3.2 and
BJ(p w
+ R
be obtained
g)
I D
R^ is included in R,
3.3
boats
by the
+/ ?
/? a
R^f
R m
NPL
=
=
Method
p. A
+/ ?
0.5p
= (C {
3
Q v
C a
C w can be obtained
Method
+
same methods
S. A v
+ AC f) S t q w
If
C f
(pi
^sk
=
fl sww =
is from
C sk from
+ ^
Method 4
B c)l( Pvi
the craft
0.05 C w
+ ^
= 0.455 / [/ g
Qk B, h,. # w
Fig. 3.17
shown in Fig. 3.17,
+
Figs 3.2 and
otherwise increment.
Re] 2 ' 58
g) where C w
3.3
is at optimum
trim angle then use C sk as
Kf t
R. k
AC f
g 4)
/? sww
=
=
0.0087
=
from
(a
Kf t
Method 5
+
+
C w from
W
0.0004
R a
where 0.00225
appendage drag
b Fr d)
Residual drag for
0.021, and 0.0015
Kolezaev Method
Fig. 3.30
Fig. 3.4
approx
=s a ^
+ R m +
sidewalls is included in
B e p c v
=s b «