TM 1-1510-262-10
(3)
Time fuel, and distance to descend. Enter the graph at 25,000 feet, and enter again at 5998 feet,
and ind:
Time to Descend . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 - 4 = 13 min
Fuel Used to Descend . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206 - 58 = 148 lbs
Distance to Descend . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62 - 13 = 49 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. Interpo-
late between these speeds for 25,000-foot values. Refer to table 7-2 for the results.
Interpolate between the 25,000-foot speeds for ISA -6C and ISA +5C at 15,600 pounds.
Cruise True Airspeed (ISA -6C) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257 knots
Cruise True Airspeed (ISA +5C) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 246 knots
Similar computations can be made to interpolate for cruise torque setting and fuel low.
Cruise Torque (ISA -6C) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68.5%
Cruise Total Fuel Flow (ISA -6C) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 778 lbs/hr
Cruise Fuel Flow/Eng (ISA -6C) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 389 lbs/hr
Cruise Torque (ISA+5C) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61.4%
Cruise Total Fuel Flow (ISA +5C) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 716 lbs/hr
Cruise Fuel Flow/Eng (ISA +5C) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 358 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.
Table 7-2.
Example Cruise True Airspeeds
ALT
FEET
16,000 POUNDS
14,000 POUNDS
ISA - 10C
ISA
ISA +10C
ISA - 10C
ISA
ISA +10C
24,000
261
253
242
267
260
250
25,000
259
250.5
238.5
265.5
258
248
26,000
257
248
235
264
256
246
BT05789
NOTE
Use of these graphs for light conditions other than 14,000 pounds gross weight may introduce er-
rors.
(a) Cruise speeds. Enter the Normal Cruise Speeds at 1500 RPM graph at 25,000 feet, and read the
true airspeeds for ISA -6C and ISA +5C:
7-19
