TM 1-1510-224-10
NOTE
Use
of
these
graphs
for
flight
conditions other than 14,000 pounds
gross weight may introduce errors.
(a)
Cruise speeds. Enter the Normal
Cruise Speeds at 1500 RPM graph at 25,000 feet, and
read the true airspeeds for ISA -60C and ISA +5°C:
Cruise True Air Speed (ISA -6°C)..............261 KTAS
Cruise True Air Speed (ISA +5°C).............252 KTAS
(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 -6°C
(-34°C IFAT) and ISA +5°C (-24°C IFAT):
ISA -6°C (-34°C IFAT) ........... 69% torque per engine
ISA +5°C (-24°C IFAT) .......... 62% torque per engine
NOTE
For flight 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 flow. Enter the Fuel
Flow At Normal Cruise Power at 1500 RPM graph at
25,000 feet, and read the fuel flow for ISA -6°C (-34C
IFAT) and ISA +5°C (-24C IFAT):
ISA -6°C (-34°C IFAT)
Fuel Flow Per Engine............................... 392 lbs/hr
Total Fuel Flow ........................................ 784 Ibs/hr
ISA +5°C (-24°C 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 flow)
(7)
Flight planning results. Refer to table 7A-
3 for an example of the flight planning procedure.
NOTE
For flight planning, enter the Fuel
Flow graphs at the forecast ISA
condition; for enroute fuel flow, enter
the graphs at the actual IFAT. Refer
to table 7A-4 for an example of the
total flight planning results.
(a)
Reserve fuel. Reserve Fuel is the
amount of fuel required to fly 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 +10°C and interpolate to find
the total fuel flow for 25,000 feet at 16,000 pounds and
14,000 pounds. Interpolate between these values for
15,000
Table 7A-3. Example Cruise Results
ROUTE
SEGMENT
1
DISTANCE
ESTIMATED
GROUND
SPEED
2
TIME AT
CRUISE
ALTITUDE
3FUEL
USED FOR
CRUISE
NM
KNOTS
MIN
LBS
BIL-SHR
42
276
9.1
118.4
SHR-CZI
57
316
10.8
140.3
CZI-CPR
18
278
3.9
46.4
TOTAL
117
---
23.8
305.1
1 Distance required to climb or descend has been subtracted from segment distance.
2 Time =Distance divided by Ground Speed.
3 Fuel Used =Distance divided by Ground Speed, multiplied by total Fuel Flow.
BT0D883
7A-15
