Figure 4-3. Wing attach point.
Front collar
Trike mast
Keel nose plate
Control frame apex
Distance from nose
plate to front edge
of front collar
Rear collar adjusted to eliminate gap when
pivot block assembly is against front collar
501/2" to 52
1/2"
example, if the aircraft is flown by a heavy person, the attach
point can be moved farther aft, bringing the wing forward to
compensate for the change in CG. Figure 4-3 shows a close-
up of the wing attach point and the small amount of forward
and aft movement that is available.
Similar to airplanes, sailplanes, and powered parachutes,
increasing weight creates increases in speed and descent
rate. However, the WSC aircraft has a unique characteristic.
Adding weight to a WSC aircraft creates more twist in the
wing because the outboard leading edges flex more. With
less lift at the tips, a nose-up effect is created and the trim
speed lowers. Therefore, adding weight can increase speed
similar to other aircraft, but reduce the trim speed because
of the increased twist unique to the WSC aircraft. Each
manufacturer’s make/model has different effects depending
on the specific design. For detailed weight and balance
information, characteristics, and operating limitations, always
reference the specific manufacturer’s manual or POH for the
make and model. Figure 4-4 shows an example of a weight
and loading sheet that would be issued with a WSC aircraft.
Every aircraft has its own weight and loading data that should
come from the manufacturer. The example in Figure 4-4
comes from Airborne, an Australian company, named
Airborne XT WSC aircraft. For additional information,
refer to the Weight-Shift Control Aircraft Flying Handbook
(FAA-H-8083-5).
Powered Parachutes
Powered parachutes have many of the same characteristics
as WSC aircraft when it comes to weight and balance. They
have the same limited loading, with only one or two seats, and
a fuel tank. A powered parachute acts like a pendulum with
the weight of the aircraft hanging beneath the inflated wing
(parachute). The point at which the inflated wing attaches
to the structure of the aircraft is adjustable to compensate
for pilots and passengers of varying weights. With a
very heavy pilot, the wing attach point would be moved
forward to prevent the aircraft from being too nose heavy.
Figure 4-5 illustrates the structure of a powered parachute
and the location of the wing attachment.
A powered parachute used for sport and private flying must
be registered with an FAA N-number, have an airworthiness
certificate, a POH, and/or limitations with a weight and
balance document aboard. The aircraft must be maintained
properly by the aircraft owner, or other qualified personnel,
and have the aircraft logbooks available for inspection.
Always refer to the POH for weight and balance information
specifi to the powered parachute being fl wn. For additional
information, refer to the Powered Parachute Flying Handbook
(FAA-H-8083-29).
Weight and Balance Computations
(Amateur-Built Aircraft)
A good weight and balance calculation is the keystone
of flight testing an amateur-built aircraft. Accurately
determining the aircraft’s takeoff weight and ensuring that
the CG is within the aircraft’s design for each flight is critical
to conducting a safe flight test
The aircraft should be level when weighed, spanwise and
fore and aft in accordance with the kit manufacturer’s
instructions, and should be in the level flight position. It
is highly recommended that the aircraft be weighed in an
enclosed area using three calibrated scales. Bathroom scales
are not recommended because they are not always accurate.
Figure 4-4. Weight and loading for WSC aircraft.
Hang point
Keel roller
Rear
Front
Keel roller
adjustment holes
U bracket
The effect of changing the hang position is to change the trim speed of the aircraft. Moving the hang point forward
increases trim speed (shorter distances to the datum). The hang point position range may be used on the
applicable wings for the entire weight range of the aircraft. CG limits on the trike base/gondola section of the
aircraft limits are not critical. The defined hang point position and its limits are defined in this document.
The datum point is the forward bolt on
the nose plate (a line between the
leading edge pivot bolts on the nose
plate) referenced to the hang bolt at
the top of the mast for the trike base
(gondola).
Moving hang point position is made by
moving the keel roller forward or
backward along the keel or by moving
the hang point within the U-bracket. A
sticker is used on the keel to show the
standard position for the keel roller. It
lists the keel tube holes used as
standard trim points for each model
wing. The table below shows the
standard keel roller position and the
allowable range of CG position/hang
bolt position referenced to the nose
plate datum.
Diagram of the wing hang point construction, showing
keel, U-bracket, and the top of the control frame.
Wing model and
maximum takeoff
weight
Streak 3
MTO@ 450 kg
Streak 2B
MTOW 450 kg
Cruze
MTOW 450 kg
Wizard
MTOW 430 kg
Standard trim position and range
Distance from the forward keel roller
bolt to forward nose plate bolt
Keel hole 2, second from front
1,340 mm +0 – 20 mm
Keel hole 3, third from front
1,360 mm ±20 mm
Keel hole 3, third from front
1,360 mm ±20 mm
Keel hole 1, at front
1,545 mm +0 – 45 mm
Distance from the hang point to forward
nose-plate bolt
Permissible rear and foremost positions
Permissible U-bracket holes
1,293.5 mm (54.9 in) rear limit
1,353.5 mm (53.3 in) forward limit
Middle U-bracket hole only
1,413.5 mm (55.6 in) rear limit
1,373.5 mm (54.1 in) forward limit
Front and middle U-bracket hole only
1,413.5 mm (55.6 in) rear limit
1,373.5 mm (54.1 in) forward limit
Middle U-bracket hole only
1,578.5 mm (61.2 in) rear limit
1,648.5 mm (64.9 in) forward limit
All U-bracket holes permitted
Date
Empty weight
Maximum takeoff weight
Registration
Wing model
Serial number
Make and (trike) base model Airborne XT series/X series aircraft
Applicable wing models Airborne streak 3/Streak 2B/Cruze/Wizard wing
Figure 4-8. Powered parachute.