TM 1-1510-223-10
CPR
Pressure Altitude .....................................5998 feet
FAT................................................................20C
ISA Condition ........................................ ISA +17C
(2)
Time, fuel, and distance to cruise climb.
Enter the graph at 15 C, to 3499 feet pressure altitude,
and to 16,000 pounds. Enter again at -40 C to 25,000
feet pressure altitude, and to 16,000 pounds. The
following results are obtained:
Time to Climb ..................................24 - 2 = 22 min
Fuel to Climb ..............................389 - 48 = 341 lbs
Distance Traveled ............................63 - 6 = 57 nm
(3)
Time fuel, and distance to descend. Enter
the graph at 25,000 feet, and enter again at 5998 feet,
and find:
Time to Descend
17 - 4 = 13 min
Fuel Used to Descend
234 - 63 = 171 lbs
Distance to Descend
74 - 15 = 59 nm
(4)
Cruise weight (estimated).
For
the
following cruise segment examples, the estimated
average cruise weight used was 15,600 pounds.
(5)
Cruise tables. Enter the tables for
NORMAL CRUISE POWER AT 1500 RPM for ISA -
10C, ISA, and ISA +10C, and read the cruise speeds
for 24,000 feet and 26,000 feet at 16,000 pounds and
14,000 pounds. Interpolate between these speeds for
25,000-foot values. Refer to table 7-2 (EXAMPLE
CRUISE TRUE AIRSPEEDS) for the results.
Interpolate between the 25,000-foot speeds for ISA -6 C
and ISA +50C at 15,600 pounds.
Cruise True Airspeed (ISA -6 C) .............. 233 knots
Cruise True Airspeed (ISA +5C) ............. 223 knots
Similar computations can be made to interpolate for
cruise torque setting and fuel flow.
Cruise Torque (ISA -6C) ..............................68.9%
Cruise Total Fuel Flow (ISA -6C) ............ 780 Ibs/hr
Cruise Fuel Flow/Eng (ISA -6C) ..............390 Ibs/hr
Cruise Torque (ISA +5C) ................................61%
Cruise Total Fuel Flow (ISA +5C) ............ 718 Ibs/hr
Cruise Fuel Flow/Eng (ISA +5C) .............359 lbs/hr
(6)
Cruise graphs. In addition to the cruise
performance
presented
in
tabular
form,
data
representing a cruise weight of 14,000 pounds is
presented in graphical form for quick reference.
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 -6 C and ISA +5C:
Cruise True Air Speed (ISA -6 C) .............239 KTAS
Cruise True Air Speed (ISA +5C) ............231 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 -6C (-34C IFAT) and ISA +5C (-25C IFAT):
ISA -60C (-35C IFAT)
69%torque per engine
ISA +5C (-25C 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 -6C
IFAT) and ISA +5C (-24C IFAT):
Table 7-2. Example Cruise True Airspeeds
ALT
FEET
16,000 POUNDS
14,000 POUNDS
ISA - 10°C
ISA
ISA + 10°C
ISA - 10°C
ISA
ISA + 10°C
24,000
238
230
219
243
237
228
25,000
235.5
227
215.5
241.5
235
226
26,000
233
224
212
240
233
224
BT03867
Change 2 7-9
