TM 55-1510-220-10
Then interpolate for the fuel flow at ISA + 17 °C as
follows:
Change in Fuel Flow = 466 - 454 = 12 Lbs/hr
Change in Temperature = (ISA + 20°C) - (ISA + 10°C) =
10°C
Rate of Change in Fuel Flow = Change in Fuel Flow +
Change in Temperature
Rate of Change in Fuel Flow = (12 Lbs/hr) + (10°C)
Rate of Change in Fuel Flow = 1.2 Lbs/hr increase per
1°C increase
Temperature increase from ISA + 100C to ISA + 17°C =
7°C
Total Change in Fuel Flow = 7 x 1.2 Lbs/hr = 8.4 Lbs/hr
Total Fuel Flow = (ISA + 100C Fuel Flow) + (Total
Change in Fuel Flow)
Total Fuel Flow = (454) + (8.4) = 462.4 Lbs/hr
Reserve Fuel = 45 minutes x Total Fuel Flow
Reserve Fuel = (0.75) x (462.4 Lbs/hr) = 349.112 = 350
Lbs/hr.:
a.
Total Fuel Requirement.
1937 + 350 = 2287 pounds
7-14. Zero Fuel Weight Limitation.
For this example, the following conditions were
assumed:
Ramp Weight ......................................... 12,090 pounds
Weight of Usable Fuel Onboard ................2287 pounds
Zero Fuel Weight = Ramp Weight - Weight of Usable
Fuel Onboard
Zero Fuel Weight = (12,090) - (2287) = 9803 pounds
Maximum
zero
fuel
weight
limitation
(from
LIMITATIONS section) = 11,500 pounds.
Maximum Zero Fuel Weight Limitation has not been
exceeded.
Anytime the Zero Fuel Weight exceeds the Maximum
Zero Fuel Weight Limit, the excess must be off-loaded
from PAYLOAD. If desired, additional FUEL ONLY may
then be added until the ramp weight equals the
Maximum Ramp Weight Limit of 15,090 Lbs.
7-15. Landing Information.
The estimated Landing Weight is determined by
subtracting the fuel required for the trip from the Ramp
Weight:
Ramp Weight ................................................ 12,090 Lbs
Fuel Required for Total Trip ....................... 1937 pounds
Landing Weight (12,090-1937) ................ 10,153 pounds
NOTE
Some graph examples use 10,300
pounds for the landing weight.
Enter the NORMAL LANDING DISTANCE WITHOUT
PROPELLER REVERSING - FLAPS 100'/( Graph at
32°C, 4732 feet, 10,153 pounds, and 10 knots head
wind component:
Ground Roll......................................................1215 feet
Total Distance Over 50-foot
Obstacle ....................................................2120 feet
Approach Speed ............................................. 100 knots
Enter the CLIMB - BALKED LANDING Graph at 320C,
4732 feet, and 10,153 pounds:
Rate of Climb ................................................1340 ft/min
Climb Gradient..................................................... 10.7%
7-16. Comments Pertinent To The Use Of
Performance Graphs.
a.
In addition to presenting the answer for a
particular set of conditions, the example on a graph also
presents the order in which the various scales on the
graph should be used. For instance, if the first item in
the example is FAT, then enter the graph at the existing
FAT.
b.
The reference lines indicate where to begin
following the guidelines. Always project to the reference
line first, then follow the guidelines to the next known
item by maintaining the same PROPORTIONAL
DISTANCE between the guide line above and the guide
line below the projected line. For instance, if the
projected line intersects the reference line in the ratio of
30% down/70% up between the guidelines, then
maintain this same 30%/70% relationship between the
guidelines and follow them to the next known item.
7-6
