TM 1-1520-240-10
7-7-6
CRUISE EXAMPLE
EXAMPLE 1 (DUAL ENGINE)
WANTED:
SPEED FOR MAXIMUM ENDURANCE
SPEED FOR MAXIMUM RANGE
MAX. SPEED AT CONTINUOUS TORQUE RATING
ESTIMATED AIRSPEED LIMIT WITH CRUISE
GUIDE INDICATOR OPERATIVE
KNOWN:
GROSS WEIGHT = 50,000 LB.
PRESSURE ALTITUDE = SEA LEVEL
FAT = 30_C
METHOD:
READ SPEEDS WHERE GROSS WEIGHT LINE
INTERSECTS PERFORMANCE OR LIMIT LINE
MAXIMUM ENDURANCE: TAS = 89 KN, IAS = 83
MAXIMUM RANGE: TAS = 144 KN, IAS = 140 KN
(REQUIRES POWER IN EXCESS OF MAX
CONTINUOUS POWER)
MAX SPEED (CONTINUOUS TORQUE RATING):
TAS = 130 KN, IAS = 127 KN
ESTIMATED AIRSPEED LIMIT (VCGI): 152 KN
IAS = 148 KN
EXAMPLE 2 (DUAL ENGINE)
(DASH LINE)
WANTED:
TORQUE REQUIRED FOR LEVEL FLIGHT, FUEL
FLOW, AND INDICATED AIRSPEED AT TAS = 120
KN.
KNOWN:
GROSS WEIGHT = 45,000 LB.
PRESSURE ALTITUDE = SEA LEVEL
FAT = 35_C
TRUE AIRSPEED = 120KN
METHOD 1 (SIMPLEST)
USE NEXT HIGHER TEMPERATURE (40_C)
ENTER TAS, MOVE RIGHT TO GROSS WEIGHT
MOVE DOWN READ TORQUE REQ’D = 55%
(PER ENGINE 0
MOVE UP READ FUEL FLOW = 2670 LB/HR
(TOTAL)
MOVE RIGHT READ IAS = 114 KN
METHOD 2 (INTERPOLATE)
READ TORQUE REQ’D, FUEL FLOW, AND IAS AT
EACH ADJACENT TEMPERATURE THEN INTER-
POLATE BETWEEN TEMPERATURES
(REFER TO TABLE BELOW)
PRESSURE ALTITUDE
SEA LEVEL
SEA LEVEL
SEA LEVEL
FAT
30_C
40_C
35_C
TORQUE REQ’D (%)
54.7%
55%
54.9%
FUEL FLOW (LB/HR)
2620
2670
2645
IAS (KNOTS)
117
114
115.5
Figure 7-7-1. Example Cruise Chart (Sheet 1 of 2)
