TM 1-1510-262-10
(b) Cruise power setting. Enter the Normal Cruise Power at 1500 RPM graph at 25,000 feet, and read
the recommended torque settings for ISA -6C (-35C IFAT) and ISA +5C (-24C IFAT):
ISA -6C (-35C IFAT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70% torque per engine
ISA +50C (-25C IFAT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63% torque per engine
NOTE
For light planning, enter the Cruise Power graphs at the forecast ISA condition; for enroute power
settings, enter the graphs at the actual IFAT.
(c) Cruise fuel low. Enter the Fuel Flow At Normal Cruise Power at 1500 RPM graph at 25,000 feet,
and read the fuel low for ISA -6C (-35C IFAT) and ISA +5C (-24C IFAT):
ISA -6C (-35C IFAT)
Fuel Flow Per Engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
392 lbs/hr
Total Fuel Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
784 lbs/hr
ISA +5C (-24C IFAT)
Fuel Flow Per Engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
359 lbs/hr
Total Fuel Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
718 lbs/hr
Time and fuel used were calculated at normal cruise power at 1500 RPM as follows:
Time = distance/ground speed
Fuel used = (time)(total fuel low)
(7)
Flight planning results. Refer to table 7-3 for an example of the light planning procedure.
NOTE
For light planning, enter the Fuel Flow graphs at the forecast ISA condition; for enroute fuel low,
enter the graphs at the actual IFAT.
Refer to table 7-4 for an example of the total light planning results.
(a) Reserve fuel. Reserve Fuel is the amount of fuel required to ly at cruise altitude for 45 minutes at
maximum range power. This example assumes the average cruise weight while using reserve fuel to be 15,000
pounds.
Enter the Maximum Range Power at 1500 RPM tables for ISA and for ISA +10C and interpolate to ind the total
fuel low for 25,000 feet at 16,000 pounds and 14,000 pounds. Interpolate between these values for 15,000 pounds.
Example Cruise Results pounds. In this example it is found that data is presented for MAXIMUM RANGE POWER
at 1500 RPM for ISA and ISA +10C at 24,000 feet and at 26,000 feet for 14,000 pounds, but not for 16,000 pounds.
Consequently, it is not possible to determine a maximum range power torque, airspeed, or fuel low for 15,000
pounds at 25,000 feet, since chart values may not be extrapolated. This means that either a lower altitude must
be selected for the leg of the mission that would be using reserve fuel, or that the Normal Cruise Power At 1500
RPM values must be used to determine power setting and the reserve fuel requirement. If no values are presented
for the given conditions in the Normal Cruise Power at 1500 RPM tables, either select a lower altitude, or use the
maximum cruise power at 1700 RPM table values to determine power setting and the reserve fuel requirement. In
this example it is found that data is presented for the mission conditions in the Normal Cruise Power at 1500 RPM
tables, so that data can be used. Refer to table 7-5 for an example of the reserve fuel determination procedure.
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