TM 1-1510-262-10
Table 7-3.
Example Cruise Results
FUEL
3
USED
ESTIMATED
FOR
GROUND SPEED
TIME AT CRUISE
CRUISE
2
KNOTS
ALTITUDE MIN
LBS
ROUTE SEGMENT
DISTANCE NM
1
43
278
9.3
120.34
BIL-SHR
57
318
10.8
139.5
SHR-CZI
20
279
4.3
51.3
CZI-CPR
-
120
24.4
311.14
TOTAL
Distance required to climb or descend has been subtracted from segment distance.
1
Time =Distance divided by Ground Speed.
2
Fuel Used =Distance divided by Ground Speed, multiplied by total Fuel Flow.
3
BT05790
(8) Total fuel requirement. Expected fuel usage + reserve fuel = total fuel requirement. (921 lbs) + (537
lbs) = 1458 lbs.
(9)
Zero-fuel weight limitation. For this example, the following conditions were assumed:
Ramp Weight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16,120 lbs
Weight of Usable Fuel on Board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3631 lbs
Zero Fuel Weight = (16,120 - 3631) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12,489 lbs
Maximum Zero Fuel Weight (from Chapter 5) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13,100 lbs
Maximum zero fuel weight limitation will not be exceeded.
Anytime the zero fuel weight exceeds the maximum zero fuel weight limit, the excess weight must be ofloaded from
payload only (i.e., not from fuel). If desired, additional fuel may then be added. However, the foregoing calculations
will remain unchanged only if the fuel added is equal in weight to the payload ofloaded, since only then will the ramp
weight and takeoff weight remain the same as before.
n. Range and Endurance. Estimates of the effect of fuel load and power setting on aircraft range and endurance
can be determined from the Range and Endurance Proile graphs. The range of a mission at normal cruise power
can be determined by entering the Range Proile - Normal Cruise Power graph at 25,000 feet, reading right to the
anticipated fuel load and down to the resulting range. This chart indicates that a fuel load as low as 1500 pounds
would be suficient for the planned 217 nautical mile mission from Billings to Casper. The available range with full
main and auxiliary tanks (3631 pounds) for a light at 25,000 feet can be determined to be 1010 nautical miles. If
additional range is required, either a higher altitude or a lower power setting could be selected. To determine the
range with a maximum fuel load, enter the Range Proile - Full Main and Aux Tanks graph (Fig. 7-84) at 25,000 feet,
read right to the desired power setting and down to the resulting range. This chart depicts that for a full-fuel mission,
range can be increased from 1010 to 1081 nautical miles by reducing power to maximum range power.
The aircraft endurance can be determined from the various endurance proile graphs in a similar manner.
It should be noted that all of these graphs are based on standard day temperatures, and the range graphs are also
based on zero wind. If forecast temperatures differ from standard values or if headwinds are expected, a more
rigorous mission analysis should be accomplished.
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