Table 7-4. Example Time, Fuel, and Distance
Start, Runup, Taxi, and Takeoff Acceleration
Block Speed: 217 NM Divided by 56 9 Minutes = 229 Knots.
Maximum zero fuel weight limitation will not be
Anytime the zero fuel weight exceeds the maximum
zero fuel weight limit, the excess weight must be
offloaded 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 off-
loaded, since only then will the ramp weight and takeoff
weight remain the same as before.
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 Profile graphs. The range of a mission at
normal cruise power can be determined by entering the
RANGE PROFILE 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 sufficient for
the planned 217 nautical mile mission from Billings to
Casper. The available range with full main and auxiliary
tanks (3631 pounds) for a flight at 25,000 feet can be
determined to be 910 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 PROFILE FULL
MAIN AND AUX TANKS graph at 25,000 feet, read right
to the desired power setting and down to the resulting
range. This chart shows that for a full-fuel mission,
range can be increased from 910 to 973 nautical miles
by reducing power to maximum range power.
The aircraft endurance can be determined from the
various endurance profile graphs in a similar manner.
It should be noted that these graphs are all 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.
Landing Example .
Weight. The estimated landing weight is
determined by subtracting the fuel usage expected for
the trip from the ramp weight:
Ramp Weight ...............................................16,120
Fuel Usage Expected for Total Trip ...........(-)916 Ibs
Landing Weight . ................................... 15,204 lbs
Maximum Landing Weight (Chapter 5 - LIMITA-
TIONS) .................................................. 15,400 lbs
Anytime the maximum landing weight limitation would be
exceeded, off-load the excess from useful load prior to
takeoff, or burn off the excess from excess fuel (i e., not
from reserve fuel) before landing.
Normal landing distance flaps down.
Enter the graph at 20°C, 5998 feet, 15,204 pounds,
0.3% uphill runway gradient, 10 knots headwind
component, and read the following:
Landing Distance Over 50-Foot Obstacle ......3437 ft
Table 7-5. Example Fuel Flow (Ibs/hr)
Total Fuel Flow = 718.75 Ibs/hr
Reserve Fuel = 45 minutes x 718.75 Ibs/hr =539 lbs
Change 2 7-11