Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02484119 2004-10-07
"SYSTEM, APPARATUS AND METHOD TO IMPROVE THE AERODYNAMICS
OF A FLOATPLANE"
FIELD OF THE INVENTION
The field of present invention relates generally to the field of lift
producing aerofoils or wings extending between the floats of a floatplane and,
more
particularly, to providing a retro-fit aerofoil or wing which can be easily
mounted in
place over a float spacer or spreader bar.
BACKGROUND OF THE INVENTION
It is well known that, during operation, floatplanes, sea planes and
amphibious aircraft suffer from an undesirable aerodynamic drag due to the
float
structure and the floats, the struts and the spreader or spacer bars; said
drag
generally causing the aircraft to pull nose down.
U.S patent 2,964,271 to Strawn provides one solution to this problem
of aerodynamic drag, by disclosing an amphibious aircraft having a float
structure
with an integrated aerofoil or stub wing.
However, the design of Strawn does not provide a solution for existing
airplanes having a traditional float structure; since Strawn discloses an
entire
amphibious airplane. Furthermore, Strawn's float structure incorporates
landing
gear, a pair of floats and a stub wing as one integrated unit.
CA 02484119 2004-10-07
Accordingly, there still exists a need to improve the aerodynamics of
existing floatplanes, sea planes and amphibious aircraft without resorting to
a
replacement of the entire aircraft or of the existing float structure.
BRIEF DESCRIPTION OF THE DRAWINGS
Figures 1a - 1f are a perspective views of one embodiment of an
apparatus for improving the aerodynamics of a floatplane, sea plane or
amphibious
aircraft (shown mounted an a floatplane in Figures 1d - 1f);
Figures 2a - 2c are additional perspective views of the embodiment
of Figures 1a -1f;
Figures 3a - 3c are a perspective views of a second embodiment of
an apparatus for improving the aerodynamics of a floatplane, sea plane or
amphibious aircraft;
Figures 4a - 4d are perspective; exploded perspective, bottom
perspective and top views respectively of one embodiment of a pair of
fairings, the
right sided version is shown, the left sided version (not shown) being a
mirror image
of the right sided version;
Figure 4e is a perspective view of a pair of fairings of the embodiment
of Figures 4a - 4d shown mounted against the second embodiment of the
apparatus;
Figure 4f is a perspective view of the second embodiment of the
apparatus, and a left sided fairing of the embodiment of Figures 4a - 4d,
shown
mounted on a floatplane;
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CA 02484119 2004-10-07
Figures 5a - 5b are perspective views of a second embodiment of a
pair of fairings, the right sided version is shown, the left sided version
(not shown)
being a mirror image of the right sided version;
Figures 6a - 6f are perspective views of various stages or steps of
installation of the second embodiment of the apparatus, and a left sided
fairing of
the embodiment of Figures 4a - 4d, onto a floatplane;
Figures 7a - 7b are perspective and side views, respectively, of a third
embodiment of the apparatus;
Figures 8a - 8b are perspective views ~of a fourth embodiment of the
apparatus (shown mounted on a fioatplane in Figure 8b);
Figures 9a - 9b are perspective views of a fifth embodiment of the
apparatus (shown mounted on a floatpiane in Figure Ob); and
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Reference is to be had to the Figures in which identical reference
numbers identify similar components.
FIGS. 1 a - 2c show a first embodiment of an apparatus 1 for
improving the aerodynamics of a floatplane, sea plane or amphibious aircraft
2, said
aircraft 2 having a float structure 3 with floats or pontoons 8a and a front
spreader
or spacer bar 4 between the floats 3a. The apparatus 1 comprises a stub wing
or
aerofoil 6 removably mounted on the front spreader bar 4 between the floats
3a,
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and torque-restraining means 7 to prevent the wing 6 from rotating or torquing
around the front spreader bar 4 during operation.
Preferably, the apparatus 1 further comprises a pair of left and right
fairings 8a, 8b (see FIGS 1e - 1f and 5a - 5b). Advantageously the fairing's
8a, 8b
shape and dimensions are customized to a particular installation of the
apparatus 1
between a particular set of floats 3a, thereby eliminating the need for the
wing's 6
sides to be contoured to the particular three-dimensional profile of the
particular set
of floats 3a. More preferably the fairings 8a, 8b are comprised of a plurality
of
pieces so as to facilitate installation (see FIGS 5a - 5b). Another, two-
piece,
embodiment of the fairings 8a can be seen in FIGS 4a - 4f.
In other embodiments (not shown), the sides of the wing 6 are
contoured or canted to provide an aerodynamic fit when the wing 6 is mounted
on
the spreader bar 4 and between a particular set of floats 3a.
The stub wing 6 comprises a plurality of ribs 10 spaced along the
wing's 6 axis and a skin, sheet or sheeting 12 covering the ribs 10 creating
an
aerofoil. Each rib 10 has a recess 14, sized and located so as to accept the
front
spreader bar 4 at a substantially perpendicular angle across the ribs 10. The
front
spreader bar 4 is thus acting as the wing's 6 main or front spar. The sheeting
12 is
mounted to, and generally covers, the ribs 10; as is customary in the field of
aeronautical wing construction. In this embodiment, a sectian of sheeting 12a
over
the recess 14 is flexible and removably attached to the ribs 10, so as to
facilitate
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installation and removal of the wing 6 onto the front spreader bar 4 (see
FIGS. 2a -
2b). This is of particular advantage during a retro-fit of the apparatus 1
onto an
aircraft's 2 existing float structure 3.
Preferably the recess 14 is located along the top of each rib 10; so
that, when the wing 6 is mounted on the front spreader bar 4 and float
structure 3
and the aircraft 2 is in operation, the upward force, as generated by the
wing's 6 lift,
will be transferred efficiently to the front spreader bar 4 via the ribs 10
without
requiring any additional structural elements. Advantageously, the flexible and
removable section of sheeting 12a is likewise located on the top of the wing 6
over
the recesses 14 and the underside of the sheeting 12b can therefore be
constructed
as an uninterrupted surface or covering, so as to minimize water entry that
may
occur from any splashing generated by the floats 3a during operation of
aircraft 2.
In another embodiment (not shown), the recess 14 in each rib 10 is
located on the bottom of each rib 10 and the wing 6 further comprises
additional
structural elements (not shown) to ensure that the force, as generated by the
wing's
6 lift, will be transferred efficiently to the spreader bar 4. Such additional
structural
elements are know to those skilled in the art and can include filler blocks
(filler
blocks are further described below).
In the first embodiment (see FIGS. 1 a - 2c) the torque-restraining
means 7 comprises a pair of brackets 7a mounted on the top surface of the wing
6
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and a pair of struts 7b connecting the brackets 7a and the float structure 3
(see
FIGS 1d -1f).
Preferably, the apparatus 1 is mounted on the front spreader bar 4
such that the wing 6 is at substantially the same angle as the main wing of
the
aircraft 2. However, the angle of the wing 6 may be adjusted so as to provide
more
or less lift as may be desired. This may be accomplished by adjusting the
torque-
restraining means 7 and/or the shaping of the recess 14. More preferably, the
apparatus 1 is mounted on the front spreader bar 4 such that the wing 6 and
the
main wing of the aircraft 2 are in a stagger wing configuration, thereby
providing
increased stability to the aircraft.
Suitable materials for construction of the fairings 8a, 8b and the
sheeting 12 include aluminum, aluminum alloy or fiberglass. Suitable materials
for
construction of the ribs 10 include composite materials, closed cell foam,
metal,
aluminum, aluminum allow or wood. A suitable aluminum alloy for the fairings
8a,
8b and sheeting is 2024-T3.
Second Embodiment
Now referring to FIGS 3a - 3c a second embodiment of the apparatus
1 is shown. The second embodiment is subsfiantially similar to the first
embodiment, with the primary difference being the torque-restraining means 7,
which in this embodiment comprise a rear spar 20, mounted perpendicular to the
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ribs 10 and rearward of the front spreader bar 4 inside a second recess 14b in
the
ribs 10, and a pair of rear spar brackets (not show). One rear spar bracket is
mounted on either float 3a and the rear spar 20 connect between the pair of
brackets; that is, each rear spar bracket connects an end of the rear spar 20
to the
floats 3a. Preferably the rear spar brackets are positioned so as to be inside
the
fairings 8a, 8b, so as to reduce any aerodynamic drag that the brackets may
create.
Preferably, the second embodiment of the apparatus 1 further
comprises filler blocks 18 positioned over the spreader bar 4 and underneath
the
sheeting 12 so as to fill in the remaining space of the recess 14 after the
spreader
bar is has been placed in said recess 14 (see FIG. 3b and 3c). Advantageously,
the
filler blocks 18 provide additional structural support to the apparatus 1 and
assist to
keep the apparatus 1 in place while the aircraft 2 is not in operation and the
only
force acting on the apparatus 1 is gravity.
Third Embodiment
Now referring to FIGS 7a - 7b a third embodiment of the apparatus 1
is shown. The third embodiment is substantially similar to the second
embodiment,
with the primary difference being that the sheeting 12, although flexible, is
continuous; including the section over the recess '14. In this embodiment the
sheeting 12 is removably attached to the ribs 10 by folding it over the ribs
and
having the opposite ends of the sheeting 12c, 12d meet at the rear-most point
of the
ribs at point R.
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Fourth Embodiment
Now referring to FIGS 8a - 8b a fourth embodiment of the apparatus 1
is shown. The fourth embodiment is substantially similar to the second
embodiment, with the primary difference being that the sheeting 12 includes
openings 22 to facilitate passage of boxing wires 24 that may need to be
connected
between the spacer bar 4 and other structural components of the aircraft 2 as
bracing.
Fifth Embodiment
Now referring to FIGS 9a - 9b a fifth embodiment of the apparatus 1 is
shown. The fifth embodiment is substantially similar to the second embodiment,
with the primary difference being that the flexible and removable section of
sheeting
12a over the recesses 14 has been replaced with a removable cap strip, cover
plate
or stress panel 26. Preferably the panel 26 is removably mounted to the wing
6,
and over the spreader bar 4, by means of pitched screws 28.
Sixth Embodiment
A sixth embodiment (not show) is substantially similar to the second
embodiment, with the primary difference being that the rear spar and the rear
spar
mounting brackets further comprise variable incidence means to raise or lower
the
rear spar relative to the float structure, thereby adjusting the incidence or
angle of
the wing 6 so as to provide more or less lift as may be desired.
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One embodiment ofi the variable incidence means comprises a track
with a slot mechanism, connected between the rear spar and rear spar mounting
brackets and actuated by a linear actuator, similar to the electric flap
mechanism in
a Cessna. Another embodiment of the variable incidence means comprises a
mechanism similar to the stabilizer trim jacks of a Cessna 180 or 185.
Installation
In a method aspect, the second embodiment of the apparatus 1 may
be installed by moving the wing 6 from a position in front of the firont
spreader bar 4
(see FlG 6a) to a position underneath the firont spreader bar 4 (see FIG 6b),
filexing
the section ofi sheeting 12a temporarily out of the way (see FIG 2a), fitting
the front
spreader bar 4 into the ribs 10 recess 14 (see FIG 6c - 6e), securing the
section of
sheeting 12a in place over the front spreader bar 4 and connecting the torque-
restraining means 7 to the filoat structure 3. Preferably, fairings 8a, 8b are
also
installed.
The other embodiments of the apparatus 1 may be installed in a
similar manner as described above. For example the fifth embodiment of the
apparatus 1 may be installed by moving the wing 6 from a position in front of
the
front spreader bar 4 to a position underneath the front spreader bar 4,
removing the
panel 26, fitting the front spreader bar 4 into the ribs 10 recesses 14,
securing the
panel 26 in place over the firont spreader bar 4 (preferably with pitched
screws 28)
and connecting the torque-restraining means 7 to the float structure 3.
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The apparatus 1 may also be installed in a number of other ways,
such as by removing one of the floats 3a and sliding the wing 6 in place over
the
front spreader bar 4 or by building the wing 6 in place around the front
spreader bar
4.
Examples of Dimensions
Depending on the particular aircraft 2 on which the apparatus 1 is to
be used, the dimensions of the apparatus 1 will vary. For example, the table
below
illustrates chard measurements of the apparatus 1 which are suitable for
particular
types or models of aircraft 2:
Chord Measurement Aircraft model
23 - 30 inches Superc~hamp, Scout, Supercub
1 meter Cessna 180, 185, 206
4 '/2 - 5 foot Beaver
5 foot Norseman and Otter
6 foot or more Fire Boss
Depending on the exact aerodynamic qualities desired, the chord
measurements may vary from the above examples. Likewise the aerofoil, or
surface shape of the wing, will be determined according to conventional
aeronautic
and aerodynamic principles and the exact aerodynamic qualities desired. A NACA
23012 aerofoil is a suitable aerofoil.
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Advantages
Advantages of the apparatus 1 includes improved aerodynamics of
the aircraft 2 onto which the apparatus 1 is mounted, the ability to be
retrofit onto
existing float structures 3, minimal damage to the float structure 3 upon
removal of
the apparatus 1 (e.g. removal of rear spar mounting brackets would leave only
small
holes in the floats 3a which can be easily patched) and increased load rating
for the
aircraft 2 due to the improved aerodynamics and increase in aircraft total
wing
surface area.
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