1.)
The takeoff gross weight is the operat-
ing weight plus the variable and expendable load
items which vary with the mission.
(2.)
The landing gross weight is the take-
off gross weight minus the expended load items.
6-8. BALANCE DEFINITIONS.
Balance definitions are as follows:
a. Reference Datum. The reference datum is
an imaginary vertical plane at, or forward of, the
nose of the aircraft from which all horizontal dis-
tances are measured for balance purposes. Diagrams
of each aircraft show this reference datum as fuse-
lage station zero.
b.
Arm. Arm, for balance purposes, is the hor-
izontal distance in inches from the reference datum
to the center of gravity of the item. Arm may be
determined from the Aircraft Compartment and Sta-
tion Diagram (fig. 6-l).
c.
Moment. Moment is the product of a
weight multiplied by its arm. Moment divided by a
constant is generally used to simplify balance calcu-
lations by reducing the number of digits. For this
aircraft, inches and moment/100 have been used.
d. Average Arm. Average arm is the arm
obtained by adding the weights and the moments of
a number of items and dividing the total moment by
the total weight.
e.
Basic Moment. Basic moment is the sum of
the moments of all items making up the basic
weight. When using data from an actual weighing of
an aircraft, the basic moment is the total moment of
the basic aircraft with respect to the reference
datum.
f
Center of Gravity (CG). Center of gravity is
the point about which an aircraft would balance if
suspended. Its distance from the reference datum is
found by dividing the total moment by the total
weight of the aircraft.
g.
CG Limits. CG limits are the extremes of
movement which the CG can have without making
the aircraft unsafe to fly. The CG of the loaded air-
craft must be within these limits at takeoff, in the
air, and on landing.
6-9.
CHART C - BASIC WEIGHT AND BALANCE
RECORD.
Chart C is a continuous history of the basic
weight and moment resulting from structural and
equipment changes made in service. At all times, the
TM 55-1510-221-10
last weight and moment/100 entry is considered the
current weight and balance status of the basic air-
craft (fig. 6-2).
6-10. WEIGHT AND BALANCE CLEARANCE
FORM F, DD FORM 365-4 (TACTICAL).
Form F (fig. 6-3) is a summary of the actual dis-
position of load in the aircraft. It records the bal-
ance status of the aircraft step by step. It serves as
a work sheet to record weight and balance calcula-
tions and any corrections that must be made to
insure that the aircraft will be within weight and CG
limits. It is necessary to complete a Form F prior to
flight when an aircraft is loaded in a manner for
which no previous valid Form F is available. A copy
must remain in the aircraft for the duration of the
flight. Form F (Tactical) is completed as follows:
1.
2.
3.
4.
Insert necessary identifying information at
t o p o f f o r m . I n b l a n k s p a c e s o f
LIMITATIONS table, enter gross weights
for takeoff and landing obtained from the
WEIGHT LIMITATIONS paragraph in
Chapter 5.
Ref 1. Enter aircraft basic weight and index
or mom/100 figure. Obtain this information
from last entry on Chart C (fig. 6-2).
Ref 2. Leave blank (oil is included in basic
weight).
Ref
3.
Using
compartment
letter
designations as
s h o w n i n
Aircraft
Compartment and Station Diagram (fig.
6-1) enter number, weight, and mom/100
figures of crew at their takeoff positions. Use
actual crew weights if available. Enter total
of each compartment in WEIGHT and
MOM/100 columns. To determine MOM/
100 of crew use Table 6-1, Occupants Useful
Load, Weights and Moments.
NOTE
The maximum baggage compartment
weight is 410 pounds. Also the floor load-
ing limit of 100 Lbs/Sq Ft shall not be
exceeded.
5. Ref 4. Enter sum of weights and sum of
mom/100 figures for Ref 1 through Ref 3 to
obtain OPERATING WEIGHT and corre-
sponding mom/ 100 figure.
6. Ref 5. Enter the item description (flare/
chaff), total amount, weight, and MOM/100
of all expendable stores.
6-3
