Jabiru Aircraft
Pilot Operating Handbook
Model J230-D
JP-FM-09
Revision:
0
12 April 2007
Page 10
Weight and Balance Terminology
•
Datum –
An imaginary vertical plane from which all horizontal distances are measured for
balance purposes.
•
Station –
A location along the aircraft fuselage usually given in terms of distance from the
reference datum.
•
Arm –
The horizontal distance from the reference datum to the centre of gravity (C of G) of
an item.
•
Moment
– The product of the weight of an item multiplied by its arm.
•
Index Unit
– Moment divided by a constant. Used to simplify balance calculations by
reducing the number of digits.
•
Centre of Gravity
(C of G) – The point at which an aircraft would balance if suspended.
The distance from the C of G to the reference datum can be found by dividing the total
moment by the total weight of the aircraft.
•
C of G Arm
– The arm obtained by adding the aircraft's individual moments and dividing
the sum by the total weight.
•
C of G Limits –
The extreme centre of gravity locations within which the aircraft must be
operated at a given weight.
•
Useable Fuel –
The quantity of fuel available for flight planning purposes.
•
Unusable Fuel –
The quantity of fuel (determined under adverse fuel flow conditions) that
is not available for flight.
•
Empty Weight –
Weight of aircraft with unusable fuel and full oil.
•
Useful Load –
Difference between take-off weight, and basic empty weight.
•
Maximum Take-Off Weight –
Maximum weight approved for take-off.
•
Maximum Landing Weight
– Maximum weight approved for the landing.
•
Header Tank –
Fuel tank plumbed between the wing tanks and the engine. Also known as
Collector Tank
or
Sump Tank.
