Page 137 - Theory and Design of Air Cushion Craft

drag
drag
Total
Friction
Method
Remarks
sidewalls
sidewalls
sidewalls
Table 3.3
drag
Drag items
Appendage
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
g) where C w is
Methods for calculating the drag of
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
BJ(p w
3.2 and
+ R
be obtained
g)
I D
R^ is included in R,
3.3
boats
by the
+/ ?
/? a
R m
R^f
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
+ ^
B c)l( Pvi
Method 4
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
trim angle then use C sk as
is at optimum
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
approx
=s a ^
Fig. 3.4
sidewalls is included in
+ R m +
B e p c v
=s b «