Fuel Required - Cessna SKYHAWK 1976 Pilot Operating Handbook

5-6
SECTION 5
CESSNA
PERFORMANCE
MODEL 172M
FUEL REQUIRED
The total fuel requirement for the flight may be estimated using the
performance information
in
figures 5-6 and 5-7. For this sample prob­
lem, figure 5-6 shows that a climb from 1000 feet to 6000 feet requires
2.0 gallons of fuel and may be used as a conservative estimate for this
problem. This is for a standard temperature (as shown on the climb
chart). The approximate effect of a non-standard temperature is to
in­
crease the time, fuel, and distance by 10% for each lOoC above standard
temperature, due to the lower rate of climb. In this case, assuming a
temperature 16°C above standard, the correction would be:
16
C
C
IO"t:
x 10%
=
16% Increase
With this factor included, the fuel estimate would be calculated as follows:
Fuel to climb, standard temperature 2.0
Increase due to non-standard temperature
(2.0 x 16%) 0.3
Corrected fuel to climb
2.3
Gallons
In addition, the distance to climb, as given in figure 5-6, may be correct­
ed for non-standard temperature as follows:
Distance to climb, standard temperature 14
Increase due to non-standard temperature
(14 nautical miles x 16%)
Corrected distance to climb
2
16 Nautical Miles
The resultant cruise distance is:
Total distance
Climb distance
Cruise distance
420
-16
404 Nautical Miles
With an expected 10 knot headwind, the ground speed for cruise is pre­
dicted to be:
109
-10
99 Knots
Therefore, the time required for the cruise portion of the trip is:
404 Nautical Miles
= 4.1 Hours
99 Knots