Cessna 172N - Page 68

SECTION
5
PERFORMANCE
CESSNA
MODEL
172N
performance
information
in
figure
5-6
and
5-7.
For ths
sample
prob-
Iem, figure 5-6
shows that a climb
from
2000 feet
to
6000
feet requires
1.3
gallons
of fuel.
The corresponding
distance
during
the climb
is I
nautical miles.
These
values
are
for a
standard
temperature
and
are
sufficiently
accurate
for most
flight
planning
purposes.
However,
a
further
correction
for
the effect of
temperature
may be
made as
noted
on the climb chart.
The
approximate
effect
of
a
non-standard
tempera-
ture is to increase
the
time,
fuel,
and distance
by
IOVo
for
each
10'C
above standard
temperature,
due
to the
lower
rate of climb.
In
this
case, assuming
a
temperature
16oC above
standard,
the
correction
would
be:
+9;9
^
rovo
=
l6vo
Increase
100c
With
this
factor
included.
the fuel
estimate
would
be calculated
as
fol-
Iows:
Fuel
to
climb,
standard
temperature
1.3
Increase due to
non-standard temperature
(1.3
'
tGVo)
O.2
Corrected
fuel to
climb
1'5 Gallons
Using a similar
procedure
for
the
distance
to climb
results
in
10 nauti-
cal miles.
The
resultant
cruise distance is:
Total distance
460
Climb
distance
-10
Cruise
distanee
4ffi-Nautical
Miles
With
an expected
10
knot headwind, the
ground
speed
for cruise
is
predicted
to
be:
Lt4
-10
104
Knots
Therefore, the time required
for
the eruise
portion
of
the
trip
is:
450 Nautical Miles
=
4.3 Hours
104 Knots
The
fuel required
for cruise
is:
4.3 hours
'
7.1
gallons/hour
=
30.5 Gallons
5-6