TM 1-1520-240-10
7A-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 (CGI) 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 KN
MAXIMUM RANGE: TAS = 144 KN, IAS = 140 KN
MAX SPEED (CONTINUOUS TORQUE RATING):
TAS = 152 KN, IAS = 149 KN
AIRSPEED LIMITED BY VCGI.
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)
MOVE UP READ FUEL FLOW = 2,600 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 INTERPOLATE
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/H)
2,570
2,600
2,585
IAS (KNOTS)
117
114
115.5
Figure 7A-7-1. Example Cruise Chart (Sheet 1 of 2)
