Table of Contents
Advertisement
CESSNA
MODEL
172N
SECTION
5
PERFORMANCE
CRUISE
The
cruising altitude
should be
selected based
on
a
consideration of
trip
length, winds aloft,
and
the
airplane',s performance.
A
typical cruising
attltudJand the
expected
wind
enroute have
been
given for this
sample
problem. However, the power setting selection for cruise must
be
deter-
mined
based
on severafconsiderations.
These
include the cruise perfor-
mance characteristics presented
in
figure
5-7,
t]rle
range
profile
chart
presented
in figure
5-8,
andthe
endurance
profile chartpresentedinfigure
5-9.
The
relationship
between
power
and
range is illustrated
by the
lange
profile
chart. cons-iderable fuel savings and longer range result when
io*",
po*ur
settings
are used.
For
this
sample
problem,
a
cruise
power
of
approximately
65Vo
will
be used.
The
cruise performance chart, figure
5-7,
is entered
at
6000
feet
altitude
and
20oC
above
standard temperature.
These
values most nearly corres-
pond
to the planned altitude
and
expected
temperature conditions.
The
Lngine
"peed
chosen
is
2500
RPM,
which results in the following:
Power
True
airspeed
Cruise fuel flow
64qo
114
Knots
7.1
GPH
The
power computer may
be used
to
determine power
and
fuel
consump-
tion more accurately during the flight.
1
July
1979
5-5
FUEL REOUIRED
The
total fuel requirement for
the
flight
may
be
estimated using
the
performance information in figures
5-6
and
5-7.
For this
sample
problem'
iigrr"
5-6
shows
that
a
climb from
2000
feet to
6000
feet
requires
1.3
gallons
oifuel.
The
corresponding distance during the climb
is-9
nautical miles.
These
values
are
for
a
standard
temperature
and are
sufficiently acculate
for most
flight
planning purposes. However,
a
further correction for
the
effect
of
temperature
miy
be made as noted on the climb chart.
The
approximate
effect of
a
non-standard temperature is to
increase the
time,
tuet,
ana
distance
by
loTo
for
each
10oc above
standard
temperature,
due
to
the lower rate of
cl1mb.
In this
case,
assuming
a
temperature
16oC
above
standard.
the correction would
be:
1S8
,
lovo
=
r67a
Increase
Advertisement
Chapters
Table of Contents
