Textron Cessna C172S PIM, Pilot Operating Handbook

Page: 172 / 322

SECTION 5 CESSNA
PERFORMANCE MODEL 172S NAV III
GFC 700 AFCS
U.S.
SAMPLE PROBLEM
(Continued)
CRUISE
The cruising altitude should be selected based on a consideration of
trip length, winds aloft and the airplane's performance. A typical
cruising altitude and the expected wind enroute have been given for
this sample problem. However, the power setting selection for cruise
must be determined based on several considerations. These include
the cruise performance characteristics presented in Figure 5-8, the
range profile chart presented in Figure 5-9, and the endurance profile
chart presented in Figure 5-10.
The relationship between power and range is illustrated by the range
profile chart. Considerable fuel savings and longer range result when
lower power settings are used. For this sample problem, a cruise power
of approximately 65% will be used.
The cruise performance chart, Figure 5-8, is entered at 8000 feet
pressure altitude and 20°C above standard temperature. These values
most nearly correspond to the planned altitude and expected
temperature conditions. The engine speed chosen is 2600 RPM, which
results in the following:
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Power 64%
True airspeed 117 Knots
Cruise fuel flow 8.9 GPH
172SPHBUS-00
5-6