Cozy III
Pilot’s Operating Handbook Page 46
WEIGHT AND BALANCE
Your final weighing before initial flight tests is very important and
should be done carefully. The measurements taken should be
recorded in the airframe log book and used in the weight and
balance data kept aboard your airplane.
You will need three scales. Platform scales are preferred with
enough capacity for the anticipated load on the mains. Bathroom
scales are unsuitable, except perhaps for the nosewheel, and
only then if you have calibrated them at about the same weight
being measured. The platform scales under the mains must be
aligned with their wheels perpendicular to the center line of the
airplane so the gear doesn't side-load the scales. You will also
need a level, a 12 ft. decimal tape measure, a plumb bob and
line, chalk-and chalk line to mark the hangar floor, and some
ballast weight to keep the nose down on the scales with
nosegear extended. Check accuracy of the scales by weighing
an item you already know the weight of.
Position the airplane on the scales with the W.L. reference (top
longerons) level fore and aft and side to side. If you have only
one scale and plan to measure just one gear at a time, the other
gear must be propped up so the airplane is level. Put the ballast
in the nose ballast compartment (F.S. approx. 8, measure
yours). Close the canopy. Record the scale readings with the
airplane alone (no fuel, no pilot, no baggage, etc.).
After weighing, with the airplane off the scales but still level, use
your plumb bob and line to mark the aircraft centerline on the
floor, and then the position of the nose, ballast compartment,
nosewheel axle, canard leading edge (both sides), front face of
instrument panel, main gear axles (both sides), wing root L.E.
(both sides), firewall, and propellor hub flange. Then roll the·
airplane out of the way, translate the plumb bob points to the
aircraft centerline, assign F.S. 113.9 to the wing root leading
edge, and measure and record all of the other points (see
example, next page).
Note that the reference point for all c.g. calculations and limits is
the wing root L.E., which is set at F.S. 113.9 in. The forward face
of the instrument panel should be approximately F.S. 41.25.
Record the exact location in the airplane. The main gear should
be at F.S. 109.5 ± 0.5 to allow correct rotation speed and ground
handling. Canard L.E. should be at F.S. 18.6 ± 0.5 for · correct
flying qualities.
When ballasting the aircraft for the initial flight testing, and for
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