TM 55-1510-215-10
Section XIV. CRUISE
7-50. Description.
NOTE
The Cruise Charts (fig. 7-18 thru fig. 7-70), show
Fuel flow values should be doubled
the horsepower per engine for various airspeeds and
for two engine operation.
weights at selected combinations of altitude and
temperature. Cruise and climb fuel flows are shown
f. Horsepower Per Engine.
Horsepower per
corresponding to engine power. Maximum performance
engine, although not readable in the cockpit is utilized in
conjunction with the Climb/Descent Chart (fig. 7-71), to
and engine horsepower are shown. Two engine and
obtain rate of climb or descent.
single-engine data are presented on the chart. Each
individual chart is for a single pressure altitude and FAT.
7-52. Conditions.
7-51. Use of Chart.
a. Configuration - All cruise data are based on the
aircraft in a clean configuration.
The primary use of the Cruise Chart is shown in the
Cruise Example (fig. 7-18). Other uses for the chart are
b. Fuel - Fuel flow is based on use of JP-4 aviation
described under "Other uses for Chart" (para. 7-53).
fuel.
The Cruise charts are for use in determining power
settings to obtain a desired level of performance for a
c. Operation - Areas not recommended for cruise
known set of conditions of altitude, temperature, weight
operation are shown in yellow.
and number of operating engines. Normally, sufficient
accuracy can be obtained by selecting the chart nearest
7-53. Other uses for Chart.
to the planned cruising altitude and temperature. If
greater accuracy is desired, interpolation between two or
a. Selected True Airspeed
more charts should be used. The power setting is
obtained by adjusting torque and propeller speed.
Wanted
Indicated airspeed, horsepower per engine.
a. Maximum Range. The maximum range line
Fuel flow, and torque for a selected cruise
shows the airspeed which will provide the maximum
true airspeed.
range for a given aircraft weight at the chart conditions.
Known
b. Maximum
Endurance.
The
maximum
Pressure altitude
endurance line shows the airspeed which will provide
FAT
maximum endurance for a given aircraft weight at the
Weight
chart conditions.
Prop RPM
c. Maximum Rate-of-Climb . The maximum rate of
Method
climb line shows the airspeed which would provide
Enter chart for true airspeed
maximum rate of climb for a given aircraft weight if
Move right
maximum horsepower was used at the chart conditions.
Read indicated airspeed
Move down from weight line
d. Airspeed. The relationship between indicated
Read horsepower per engine
and true airspeed is shown for the specific chart
Move down
conditions of altitude and temperature.
Conversion
Read fuel flow
between the two airspeeds can be accomplished without
Move left from prop RPM
regard to other chart information.
Read torque
e. Fuel Flow.
The fuel flow for cruise and climb
b. Climb Conditions
settings is shown.
Wanted
Maximum rate-of-climb airspeed.
Horsepower required for level flight at
MAX R/C airspeed.
7-38
