Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates to a landing pylon or pylon
useful for aiding night landing of helicopters or fixed wing
aircraft but also useful as an emergency marker to be carried
in ambulance, or other emergency vehicles.
By 'aircraft' herein I mean fixed wing aircraft. The
invention generally relates to marking the landing area for a
helicopter or aircraft and giving an indication of the desired
approach path.
In this application designated surfaces of the pylon
are reflectant and preferably 'retro-reflectant'. A 'retro-
reflectant' surface is of course specially designed to reflect
back a substantial portion of the incident light in the direction
of the light source. It is important to emphasize however that
an ordinary reflectant surface, not specially designed to be
retroreflectant, still retro-reflects a material portion of the
light back to the source. Where an ordinary reflectant surface
is used with the invention herein it is such retro-reflected
material portion which is visible to the aircraft or helicopter
operator.
The invention comprises means to provide an upwardly
extending column defining a vertical axis. The column will be
laterally defined by a plurality of outwardly facing upwardly
extending surfaces which are highly reflectant and preferably
retro-reflectant.
In one preferred aspect of the invention the surfaces
will be designed, when the axis is vertical to slope at 3° - 10°
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to the vertical. The range includes the sub-range of 8° - 10° to
the vertical in accord with the fact that the preferred angle of
approach of a helicopter to a landing area is along a path about
9° to the horizontal and the sub-range of 3° - 6° to the
vertical
to correspond to aircraft approach angles of 3° - 6° to the
horizontal. It is understood that the helicopter or aircraft will
be provided with lights and a search-light adapted to project a
beam along its approach path so that the helicopter or aircraft
pilot will receive a brighter reflection when located on the
desired approach path than when the helicopter or aircraft is
located above or below the said path.
The side surfaces are collectively arranged in a flat
blank with the side edges of adjacent side surfaces hingedly
connected; with the side surfaces at each end of a connected group
being detachably hingedly connectible to each other. Constructed
in this way the surfaces may be folded at each hinged connection
at equal angles to form the pylon. For storage or transportation
this pylon may have the detachable connection disconnected and be
unfolded flat for convenient stacking.
In its form as a flat blank the pylon is useful for
carrying by ambulances or other emergency vehicles where it will
have many uses in addition to those as a landing pylon. In such
emergency vehicles there is qualities of compact storage and
transportation are of considerable importance.
The preferred means and method of constructing the
connected panels is by constructing them of molded plastic with
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'l,m_ing hinges' that is the side surfaces with connecting thin films
or skins of the same plastic material are molded in a single molding
operation with the free edge connecting means also formed integrally
and in the same molding step. With this arrangement the convenience
of compact stacking is combined with efficiency of manufacture.
The arrangement described in the two previous paragraphs
is preferably arranged, for aircraft or helicopter landing, to provide,
in erected attitude, the desired surface sloping angles of 8° to
10°
or 3° to 6° previously described and will preferably have four
sides
arranged to form a square in section.
The arrangement described in the three previous paragraphs
may preferably be provided with a top panel, also reflectant, and
preferably retro reflectant hingedly connected to the top edge of one
of the side surfaces and connectable (preferably by integrally molded
means) with the top edges of the other side surfaces to form an
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upwardly reflecting top panel in erected attitude.
With a plastic construction each alternative may be
provided with metal weighting means, attachable after molding or
molded in as part of the molding process.
With each alternative, means may be provided to support
the pylon above ground surface for better visibility (for example -
deep snow).
A plurality of such pylons arranged in a suitable pattern
may be used to delineate a landing area or strip in remote areas
which include: national or provincial parks, lumber camps, remote
villages, the grass area in a highway clover-leaf or beside a
highway.
To assist helicopter landing, an array of the pylons will
usually be used to define a square of desired area, for example,
it is desirable to use (for example) 16 of such pylons to define
the outside boundaries of a square of (for example) 86' per side.
The pylons will customarily be separated approximately 20'. A
circular array will sometimes be used.
In its preferred form, the pylon is square in any
horizontal section. Thus 16 such square-plan pylons for a
helicopter, are preferably arranged at the corners and equally
spaced along the sides of an 86' square with the four sides of the
pylon (in plan) parallel and perpendicular to the side of the
square formed by 16 of them. For an aircraft strip the pylons
may be arranged in two rows to border the strip.
It is not thought necessary to provide internal levelling
means for pylons. These in one aspect of the invention are
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preferably each provided with a bubble level mounted to indicate
deviation from a level position and when a level position is
achieved. In the level position, the pylon "vertical" axis will
be truly so. Each pylon is thus placed in location on the field
at the landing area and shimmed or adjusted by objects placed
beneath its base until level attitude is achieved.
In a preferred form of the invention the pylon is
formed as a hollow container so that it may be filled or partially
filled with ballast to weight it in place.
In a preferred form of the invention the top of the
pylon is designed to be perpendicular to the vertical axis and to
provide a highly reflectant (preferably retro-reflectant) surface,
preferably of different colour to the side wall surfaces, directed
upwardly and providing an indication to a helicopter pilot (to a
downwardly directed light) that he is "hovering" over the landing
area. It may be desirable in some instances to provide that
opposite reflecting side walls of the pylon are of different
colours so that a row of pylons may be arranged to indicate which
is the inside and which is the outside of a defined square area.
The side surfaces are provided in a flat blank wherein
side surfaces are collectively arranged in a flat blank with the
side edges of adjacent side surfaces hingedly connected with the
side surfaces at each end of connected group being detachably
hingedly connectible to each other. Constructed in this way the
surfaces may be folded at each hinged connection at equal angles
to form the pylon. For storage or transportation this pylon may
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have the detachable connection disconnected and be unfolded flat
for convenient stacking. Thus the pylon assembled from the blank
may be particularly useful for transport in emergency vehicles,
and when used other than for landing may have different angles
of slope.
The preferred means and method of constructing the
connected panels is by constructing them of molded plastic 'living
hinges' that is the side surfaces with connecting thin films or
skins of the same plastic material are molded in a single molding
operation with the free edge connecting means also formed integrally
and in the same molding step. With this arrangement the convenience
of compact stacking is combined with efficiency of manufacture.
The alternate arrangement described in the two previous
paragraphs is preferably arranged to provide, in erected attitude,
the desired surface sloping angles 3° - 10° including the sub-
range
of 8° to 10° or 3° to 6° previously described and
will preferably
have four sides arranged to form a square in section.
The alternate arrangement described in the three previous
paragraphs may preferably be provided with a top panel, also
reflectant, and preferably retroreflectant hingedly connected to the
top edge of one of the side surfaces and connectable (preferably
by integrally molded means) with the top edges of the other side
surfaces to form an upwardly reflecting top panel in erected attitude.
With a plastic construction each alternative may be
provided with metal weighting means, attachable after molding or
molded in as part of the molding process.
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w With each alternative means may be provided to support the
pylon above ground surface for better visibility (for example -
deep snow).
In drawings which illustrate a preferred embodiment of the
invention:
Figure 1 is a perspective view of a pylon,
Figure 2 is a schematic view showing a preferred arrangement
of the pylons to define a landing spot,
Figure 3 is a side view of a pylon showing the approved
angle of a helicopter approach path,
Figure 4 shows the means allowing the filling of a hollow
pylon with ballasting,
Figure S shows the detachable bottom for the pylon,
Figure 6 shows a blank for the invention,
Figure 7 is an enlarged sectional view along the line 7-7
of figure 6,
Figure 8 is a perspective view of the erected attitude of
the blank of figure 6, and
Figure 9 is a sectional view taken along the lines 9-9 of
figure 6.
Figures 10-12 show the schematic arrangement of retro
reflectant zones on a sheet,
Figure 1-5 show and the accompanying description describes
a pylon its shape and disposition which may or may not be made of the
collapsible type forming this invention,
Figures 6-9 and the accompanying description show the
preferred construction of the collapsible pylon of this invention.
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In the drawings the pylon 10 comprises a base 12 having
four symmetrically arranged upward-inwardly sloping side walls 15
extending upwardly therefrom but preferably inset from the outer
edges of the base to provide a sill 14. The pylon is preferably
symmetrical about a vertical axis. The sloping side walls for
helicopter use are defined by planar outwardly facing surfaces
sloping outwardly between 8° and 10° (preferably 9°) to
the vertical
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axis. For aircraft the side walls will slope at 3° - 6° to the
vertical axis. A cap 16 covers the upper edges of the side walls
and extends slightly outwardly therefrom to prevent rain and dust
from getting into the inside of the pylon which is preferably hollow
as hereinafter described. The cap has four peripheral surfaces 18
sloping inwardly at about 45° to the horizontal, bordering a
horizontal upwardly facing square surface 20.
The side walls and the upwardly square surface are
designed to be reflectant and preferably retroreflectant and
preferably to reflect most brightly to a helicopter or aircraft which
is projecting its light perpendicular to the plane of a side wall,
and to reflect to a substantial but lesser extent to a helicopter
or aircraft shining its light obliquely on the surface.
Figure 3 shows a helicopter approaching at 9° to the
horizontal and designed to have its light directed at 9° to the
horizontal and in the travel direction of the helicopter so that
the pilot will receive a brighter retro reflection than if he is
above or below the 9° approach path or to the right or left of the
perpendicular to the retro reflecting surface. Thus the pilot will
be warned that he is off path by the decreased retro reflected
brightness.
Figure 1 shows a bubble level 22 designed to indicate
when the vertical axis of the pylon is truly vertical. Thus with
the pylon in place shims or supports are located and adjusted under
the base until the bubble is centered indicating that the axis is
vertical. The bubble level may preferably be located midway along
a side of sill 14.
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Sill 14 is preferably provided with vertical mounting
holes 23 at each corner. Holes 23 may be used to mount the pylon
on a concrete slab or otherwise anchor it.
Figure,4 shows that the device may be made a hollow
container and filled with ballast to hold it in place. The opening
for filling may be provided in any of a number of different ways
and one way is having the cap 16 removable as shown in Figure 4.
Preferably the upper surface 20 is made reflectant and
preferably retro-reflectant but of a contrasting colour to the
side walls so that the pilot (with a downwardly directed light)
may tell when he is directly over an array of pylons. For such
applications it is believed most effective to make the side walls
of yellow reflectant material and the top wall of red reflectant
material.
As Figure 5 shows the bottom 12 may be made detachable
from the four side walls 15 which side walls form a single unit.
The bottom 12 may be made detachably attachable in any desired
manner. Figure 5 shows a base 12 provided with L-shaped flanges
which rest inside the corners of the side walls and hold them
20 in place. Bolts or screws may be used to attach the flanges to
the side walls if desired. For packing and transportation therefore
the bottoms 15 may be removed from the side walls and separately
stacked while the side wall assembly may be conveniently and
compactly nested.
In Figure 2, sixteen pylons 10 are shown defining a
square preferably 86' with pylon spacing of approximately 20'. If
desired and as shown three or more extra pylons l0E may be provided
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lttesding into the centre of one side of the square and thus indicating
the desired approach direction. In some cases a second row of pylons
10E may be provided leading out of another side of the square. This
arrangement would be suitable where the entrance and exit paths for
a helicopter are to be different. In such case each row 10E of
pylons would have distinctively coloured reflectant material on
opposite sides facing toward and away from the desired travel
direction to indicate it to the pilot.
As shown the pylons 10 are oriented in the array so
their side walls are (in section) perpendicular to and parallel to
the square sides. If desired opposite~pylon walls may have opposite
coloured reflectant material to distinguish between the inside and
outside of the array or between a desirable and undesirable approach
direction.
In operation the pylons are preferably arranged as shown.
The side surfaces are designed to give lesser reflections to a
helicopter located above, below or to the side of the perpendicular
to the surfaces plane but the lesser reflections are designed to be
sufficient to allow the pilot to locate the array. Having located
the array, the pilot descends and locates his craft until the brighter
reflection tells him that he is on the 9° flight path. He then
descends on this flight path to landing. In addition a hovering
helicopter with a vertically directed light can determine when it is
directly over the array because of the brighter reflection,from the
top surface 20.
Although not shown it is understood that, for aircraft
use, the pylons with 3° - 6° side wall slope will be arranged in
two
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li ~ on opposite sides of the desired landing path and may be
differently coloured on opposite sides to indicate the desired
landing and take-off directions.
The pylons may be made of any material, but ultra violet
stabilized plastic is preferred. The reflectant and preferably
retro-reflectant surface may be laminated on the outside of a top
or side wall in any desired manner.
The preferred qualities and type of the retro-reflectant
material are described hereafter in connection with Figure 10, 11 and 12.
Figures 6-9 show the blank of the invention wherein the
four side walls 115 are defined by side edges 116, top edge 118 and
bottom edge 120 and arranged to be made of molded plastic in a single
molding step. In the flat blank the middle side walls 115M are each
joined to the adjacent side wall at initially adjacent side edges by
a thin film or skin 122 of the same plastic forming the side wall,
known as a "living hinge" and molded with the four side walls in a
single molding step.
In the flat blank the outer side walls 115E are joined to
the adjacent wall 115M by a living hinge 122 as described and form as
shown in Figure 8 a pylon body 110 geometrically similar to that of
body 10 of Figure 1. The panel walls are covered with a preferred
reflectant material 121, preferably laminated on as described hereafter.
The angle selected for the sloping
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side will be less than 20° and for the use described for the
ap~r~ication of Figures 1-5 the sloping sides will define an angle
of 8° - 10° or 3° - 6° for use in landing
helicopters or fixed wing
aircraft, respectively.
A top panel 134 may be hinged by a "living hinge" 136 to
one of the panel 115 top edges. For ease of construction and use it
is preferred to hinge the top panel to one of the end panels 115E
above. The free side edges 116E of the side walls 115E are provided
with mutually cooperating hinged connection means for hingedly
connecting these side walls in the erected position of the pylon.
These mutually cooperating means may be of any desired form but I
prefer to use one (or more) tabs 124 connected to the free side edge
of one of the walls 115E by a living hinge 122 and a strip 128 with a
complementary slot 130, the strip being connected to the other side
wall by a living hinge 122.
Thus the blank as (partially) described so far may be erected
by folding the four side panels so that each is at the same angle to
its neighbour panel with tabs) 124 inserted in slots) 130. In
erected form therefore with the folded panels so hinged the top panel
and each of the top edges of the other three sides are provided with
complementary tabs and slot strips with living hinges 122 similar in
arrangement and use to those on the side panels.
Thus when the blank is folded for erection the top panel is
attached to the side top edges (Figure 8) a pylon very similar except
for the levels 18 to the pylon of Figure 5 is provided. The top panel
will be laminated with reflectant material and the provision of selected
colours on the sides. The attached top panel 134 may be omitted a
separated top 20 may be provided as with the embodiment of Figures 1-5.
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A bottom 131 connected by living hinging 122 and tabs, in a similar
man't~"er to the top, may be provided and is shown
However in many applications it may be preferred to have an open bottom.
With an open bottom the pylon folded from a blank may be provided
with the detachable bottom shown in Figure 5.
The pylon of Figure 6 to 9 may be provided with weight bars
133 attached to the inside of the side panels near to their lower
edges. Such bars will customarily be made of iron or steel and may
be molded into the panels during the single molding process.
Alternatively 'keepers' of plastic may be formed in the side wall panels
during the molding process adapted to detachably receive the weighting
bars put in place with the pylon erected.
In operation, the pylon blanks of Figures 6-9 may be compactly
stored or transported in flat attitude. For use each pylon is erected
by applying weights, if not already in place, folding the sides and
attaching the free edges and folding the top into place. The erected
pylons will preferably be arranged as shown and described in connection
with the embodiment of Figures 1 - 5 with particular reference to
Figures 2 - 3. They will be designed for helicopter or fixed wing
aircraft approaches, as previously described.
The pylon Figures 6 to 9 may be provided with leveling means
if desired. For example two adjacent side panels may be molded each
to support a level so that the two levels together will indicate a
level attitude in the pylon.
If desired the pylons may be molded to receive support stakes
so that the pylons may be supported clear of the ground for better
visibility - for example in drifting snow.
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Although the most common application of the invention
will be to use the pylons in square, circular or other array,
the pylons may be used singly, where desired.
As previously stated, the pylon of Figures 6-9 is useful
for other purposes than for landing aircraft or helicopters.
Thus it may be carried in emergency vehicles for any use to
which a reflectant pylon could be put and where its flat blank
form for storing and transportation is a great advantage over
prior pylons or markers. When used for other purposes than
landing helicopters or aircraft the pylon may have any slope
to its sides although they will preferably slope at less than
20°.
The preferred retro-reflectant material for being
laminated onto or otherwise placed on the pylon, will now be
described.
The invention preferably makes use of surfaces made
up of cube corner reflectors as described in the following
U.S. Patents .
2,380,447 Jungerson
3,712,706 Stamm
3,684,348 Rowland
3,810,804 Rowland
4,025,159
4,202,600 Burke
In particular the invention preferably makes use of
cube corner ref lective sheeting as described in the Burke Patent
4,202,600 where regular arrays of cube corner sheets are arrayed in
zones (indistinguishable to the user) oriented relative to adjacent zones
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in ~ich a way that retroreflective intensity variation with azimuthal
angle is reduced at high angles of incidence to the normal to the sheet.
By an array is meant an ordered group of cube corner triads.
A 'zone' is the area occupied by such an array.
The invention takes advantage of the fact that retroreflectant
material composed of arrays of cube corner reflectors (which are not
individually distinguishable at minimum expected viewing distances)
customarily retroreflect incident light more strongly at a normal angle
of incidence and at an angle of incidence at 60° to the normal than at
angles in between. It is sometimes convenient herein to refer to
retroreflection along the normal as primary reflection and retroreflection
at 60° to the normal as a secondary reflection.
It is noted that with all cube corner reflector arrays there
is some directivity in the strength of the secondary reflection. That
is for a given array zone the secondary reflection will be stronger in
some azimuthal directions relative to the normal than others. This is
of course more noticeable with a single array where all triads have an
ordered orientation relative to each other. It will also be noted that
the cube corner reflector array zones which are taught by Patent
4, 202, 600 and preferred for use with the invention, are too small for
resolution by the viewer so that the actual orientation of individual
zones of the reflecting surface is not known when a sheet bearing the
reflectant coating is applied. Thus it is preferable if the cube corner
reflector sheet is divided into zones (indistinguishable at usual
viewing distances) which are differently oriented relative to each other
tending to give a more uniform reflection at large angles to the normal
and at varying azimuthal angles about the normal.
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Preferably the cube corner cavity material is that sold under
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the trade mark REFLEXITE, a product of the Reflexite Corporation of
New Britain, Connecticut. In such product the cube corner cavities
are arranged in windows formed by triads of mutually perpendicular cube
faces in an ordered array with a predetermined orientation. Such
ordered arrays are in zones small enough to be indistinguishable to the
viewer at minimum normal viewing distances. The zones are preferably
arranged to have two orientations at 90° to each other arranged in a
checkerboard or other pattern. The characteristics of the ordered
array is to give stronger secondary reflections at 60° angular azimuth
intervals and the result is that the 90° rotation between adjacent
zones achieves an effective 30° rotation giving stronger azimuthal
reflectivity at 30° intervals but relatively similar reflection
intensity
at angles in between.
Figures 10-12 are taken from U.S. Patent 2, 202, 600
previously referred to. In Figure 10 the preferred retroreflective
sheeting is schematically illustrated from the non-retroreflecting
side. The array as oriented in Figure 10 may be thought of as having
an orientation corresponding to a horizontal directional arrow. As
stated in Patent 4, 202, 600 the orientation of an array with an
orientation as shown in Figure 10 can be varied in a regularly alternating
pattern, such as a checkerboard pattern, in a random pattern or in any
other pattern that provides sufficient mixing of different orientations
to give the sheet an appearance of uniform brightness when viewed at
a high angle of incidence from the minimum.
Figures ll andl2 show two preferred methods of combining arrays
in zones with orientations at 90° to each other. Since the arrays have
60° symmetry (90° - 60° - 30°) each zone has its
cube corner reflectors
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or rated at 30° to adjacent zones. The result is reflective sheeting
which for retroreflected rays at 60° to the normal, has relatively even
reflectivity at different azimuthal angles about the normal.
As previously stated the preferred sheeting having the
arrangements of Figures ll or 12 is Reflexite, AP1000 of the Reflexite
Corporation of New Britain Connecticut. The zones are indistinguishable
at normal minimum viewing distance.
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