Note: Descriptions are shown in the official language in which they were submitted.
' 2055516
This invention relates to a landing pylon useful for
aiding night landing of helicopters or fixed wing aircraft but
also useful as an emergency marker to be carried in ambulances,
or other emergency vehicles.
By 'aircraft' herein I mean fixed wing aircraft. The
invention generally relates to marking the landing area for s
helicopter or aircraft and giving an indication of the desired
approach path.
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 side panels which are highly retro reflectant. In
one preferred aspect of~the invention the side panels will be
designed, when the axis is vertical, to slope (for helicopters)
at 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. For aircraft the
side panels slope at 3° - 6° to the vertical to correspond to
uircraf t approach angles of 3°-6° to the horizontal. Thus the
side panels preferably slope at between 3° and 10° to the
vertical
It is understood that the helicopter or aircraft will be provided
with lights and a searchlight 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
30 below the said path.
In one form the pylon is provided in permanently
erected form.
In an alternate preferred form of the invention the
side panels are provided in a flat blank wherein side surfaces
are collectively arranged in a flat blank with the side edges of
adjacent side panels hingedly connected; with the side surfaces
at each end of a connected group being detachably hingedly con-
nectable to each other. Constructed in this way the panels
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 its qualities of compact storage and traps-
portation are of considerable importance.
In the alternative discussed in the two previous para-
graphs, the preferred means and method of constructing the connected
panels is by constructing them of molded plastic with '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, 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.
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The alternate arrangement described in the three previous
paragraphs may preferably be provided with a top panel, also 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 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.
1U 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, or circle of desired
diameter 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.
2p In its preferred form, the pylon is square in any hori-
zontal 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 level-
ling means for py2ons. However, these in one aspect the pylons are
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2055516
preferably each pxoyided 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.
The side surfaces or panels are preferably covered
with retro-reflecting material. By 'retro-reflecting' I mean
a surface that will reflect light back in the incident direction
over a wide range of angles to the normal.
The invention preferably makes use of retro-reflectant
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, 81U, 8U4 Rowland
4,025,159
4,202,600 Burke
In particular the invention preferably makes use of
cube corner retro-reflective 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 in such 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
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20~551~
triads. A 'zone' is the area occupied by such an array.
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 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.
In a preferred form of the invention the bottom of the
pylon is made detachable so that when not in use the bottom may
be removed and the sloping side panels of a number of pylons
nested for compact packing or transport.
In a preferred form the pylon is provided with an out-
wardly directed flange at the base which is preferably made hollow
so that it may be filled with ballasting sand or other material.
Anchors for anchoring the pylon on the ground may also be provided.
With the ballasting and anchoring means the goal with
pylons for helicopter landing areas is to ensure that they are
capable of withstanding a down draft from the helicopter rotor
or wind gusts, up to 75 kilometres per hour.
In a preferred embodiment the pylon is provided with
side panels and a top panel, as described; differently colored
upper panels are provided sloping between the side panels and the
top panel at an angle of 30° to 60° to the vertical. The upper
panels are narrower in their sloping than in their horizonta l
direction and covered with retroreflectant material to provide
through retroreflection a horizontal line which acts as an artificial
horizon to the helicopter pilot which acts as a safety feature
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to lessen the likelihood of dynamic roll-over.
A critical point in flying a helicopter is the arrival
or departure from the site. During this operation a certain
portion of time is spent in the hover mode. Whilst in this position
it is essential that the pilot have access to a horizontal reference
datum to present the possibility of dynamic roll-over. To this
end the top bevel or sloping lid of the pylon has been designed to
provide a horizontal band of alternatively colored retroreflective
material. The choice of angle for this feature is 45° which
ensures that the pilot is not blinded by reflection.
In one alternative form of the permanently erected form
of the pylon it is designed to be downwardly opening and to nest
with a pylon above end below. The pylons in this alternative are
provided at the base with an outwardly extending flange. The
geometry of the flange is chosen, relative to the sloping walls
of the pylon, so that in nesting arrangement the flanges of each
pylon contact the flanges of the next pylon above or below but
maintain spaced the side, upper and top panel surfaces of adjacent
pylons. In this way the retroreflectant surfaces of the panels
are not damaged by nesting the pylons and removing them from
nested arrangement.
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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 in accord
with the invention,
Figure 2 is a schematic view showing a preferred
arrangement of the pylons to define a landing spot,
Figure 3 is a side 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 5 shows the detachable bottom for the pylon,
Figure 6 shows a blank for an alternate form of the
invention,
Figure 7 is an enlarged sectional view along the lines
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 of retroreflectant material,
Figure 13 shows an alternative form of pylon in accord
with the invention,
Figure 14 is a vertical section of the pylon of Figure 13.
In the drawings the pylon 10 comprises a base 12
having four symmetrically arranged upward-inwardly sloping side
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walls or panels 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 axis. For a; rr.,-af~ ~~,o ~: a..
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 panels and the upper square panel are designed
to be retro-reflectant and preferably to reflect most brightly to
a helicopter or aircraft which is projecting its light normal
to the plane of a side panel, and to reflect to a substantial but
lesser extent to a helicopter shining its light obliquely on the
surface. Preferably a sheet of retro-reflecting material is
laminated on the outer surface of the panels to provide its
reflectivity.
The pylons may be made from any material. I prefer to
use ultra violet stabilized plastic. Plywood and other materials
may be used.
Figure 3 shows a helicopter approaching at 9° to the
horizontal and in the travel direction of the helicopter so that
preferably the pilot will receive a brighter reflection than if
he is above or below the 9° approach path or to the right or left
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of the perpendicular to the reflecting surface. (This is a
quality of retro-reflecting surfaces). Thus the pilot will
be warned that he is off path by the decreased 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 plyon 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 con-
tainer 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 panel 20 is made 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 effect-
ive to make the side walls 15 of yellow retro-reflectant material
and the top wall of red retro-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 S shows a base 12 provided with L-shaped flanges 25 which
rest inside the corners of the side walls and hold them 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 leading
into the centre of one side of the square and thus indicating the
desired approach direction. In some cases a second row of pylons
l0E may be provided leading out.of another side of the square. This
arrangement would be suitable where the entrance and exit paths for
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a helicopter are to be different. In such case row l0E of pylons
would have distinctively coloured retro-reflectant material on
opposite sides facing toward and away from the desired travel direc-
tion 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 retro-reflectant material to distinguish between the in-
side and outside of the array or between a desirable and undesirable
approach direction.
In operation the pylons are preferably arranged as shown.
The side panels are designed to give lesser retro-reflections to a
helicopter located above, below or to the side of the normal to the
panel plane but the lesser retro-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
retro-reflection along the.normal to the panel 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
lines
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 retro-reflectant surface side panels 15, as well as
for top pane120 is made up of cube corner reflectant material
reflectors. Preferably the cube corner reflectors in such material are
laminated on a sheet and attached by adhesion to the outer surface
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of the panel. Thus each panel is preferably of molded plastic with
the cube corner reflectant layer on the outside. Preferably the
retro-reflectant layer is that provided by Reflexite Corporation
of Vew Britain, Connecticut under the model number AP1000. Other
cube corner reflector arrays for rays at large angles to the normal
show a wider variation in retro-reflective intensities for varying
azimutnal angles. As explained in U.S. Patent 4,202,600 it is possibl
to arrange small zones of regular arrays of cube corner reflectors
so that each zone is at an angle of 90° to adjacent zones (but effect-
ively at 30° since the regular array has 60° symmetry). It is
pre-
ferred to use cube corner reflectant material arranged in this way
since less variation with azimuthal angle is encountered in the retro-
reflection wide angles to the normal. The pattern of each array zone
and the zones themselves are made too small to be distinguishable
at normal, minimum viewing distances.
Thus, it is preferred to use Reflexite, a product of
Reflexite Corporation, of 'New Britain, Connecticut and, of their
products preferred to use their Reflexite model number AP1000 as
embodying the use of cube corner array zones at 90° to adjacent
zones as described in the preceding paragraph.
Figures. l0-12 are taken from U.S. Patent2,202,600 pre-
viously referred to. In Figure 10 the preferred retro-reflective
sheeting is schematically illustrated from the non-retroreflecting
side. The array as oriented in Figure 10 may be thought of as hav-
ing 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 alter-
nating pattern, such as a checkerboard pattern, in a random pattern
or in any other pattern that provides sufficient mixing of different
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orientations. to give the sheet an appearance of uniform brightness
when viewed at a high angle of incidence from the minimum.
Figures 11 and 12 show two preferred methods of combining
arrays in zones with orientations at 90° to each other. Since the
arrays have 60° symnetry (90° - 60° - 30°) each
zone has its cube
corner reflectors oriented 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 11 or 12 is Reflexite, AP1000 of the Reflexite
Corporation. The zones are indistinguishable at nornal cainimum ~riew-
ing distances.
The preferred material, to produce a retroreflection for
a wide range of angles about a normal to a panel, although brighter
along the normal, is Reflexite (trade mark), part number AP1000 a
product of the Reflexite Corporation of New Britain, Connecticut.
Reflexite may be obtained in various colours including the red and
yellow preferred.
The pylon panels may be made of any material, but ultra
violet stabilized plastic is preferred. The reflectant surface may
be laminated on an inner top or side wall in any desired manner.
Figure 6-9 show an alternative embodiment 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
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2p~~~1~
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 retro-reflectant material 121, preferably
laminated on and preferably Reflexite (trade mark), part number
AP1000 as with the principal embodiment. The angle selected for the
sloping side will be less than 20° and, for the use described for
the application of Figure 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 con-
necting 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.
14
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 retroreflectant material and the
provision of selected colours on the sides and the top may be pro-
vided as with the embodiment of Figures 1-5. A bottom 131 connected
by living hinging 122 and tabs, in a similar manner to the top, may
be provided and is shown in dotted form. However in many applications
it may be preferred to have an open bottom.
The pylon of Figures 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. (Such weighted
bars may similiarily be molded on or used, instead of the ballasting,
with the pylon shown in Figures 1-5).
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 des-
cribed.
The pylons of Figures.6 to 9 may be provided with level-
ing means if desired. For example two adjacent side panels may be
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2~~~~~6
molded each to support a level so that the two levels together
will indicate a level attitude in the pylon.
If desired the pylons of either embodiment 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.
Although the most common application of the invention
will be to set 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 then 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°.
Figure 13 shows an alternative form of pylon having
side panels 115, top panel 120 and upper panels 118 sloping
from the upper edge of each side panel to the outer edge of the
top panel. To assist in molding and nesting the panels this
alternative avoids the overhang of upper panels 18 in Figure 1.
The pylon is permanently erected rather than collapsible
and preferably molded from ultra-voilet stabilized plastic. The
side panels slope at 3°-10° to the vertical being at 3°-
6° for
helicopters and 8°-10° for aircraft. The upper panels 118 slope
at about 45° to the vertical and provide a narrow vertical and
extended horizontal reflection which forms an artificial horizon
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for a pilot. The angle of 45° is shown so that this artificial
horizon will be visible to the pilot without blinding him which
would be the risk if the retro reflected light were normal to.
the upper panel surfaces.
The bottom edges of the side walls extend, preferably
integrally, into an outwardly extending peripheral flange 112.
The flange 112 is preferably made hollow so that it may be filled
with ballasting material, preferably sand. An opening 113 with
closure 115°of any suitable type is provided. As shown in dotted
form,spikes 117 may be bolted to the corners of the flange to
be driven into the ground to fix the pylon in position. The pylon
is preferably mounted to withstand 75 Km/hr ground winds or
helicopter downdrafts. The body of the pylon is preferably made
sufficiently yieldable that it will deflect on accidental contact
with an aircraft or helicopter so that frangible ground mountings
are not necessary.
As shown in Figure 14 the pylon of Figure 14 has a
bottom opening and is designed to nest with a pylon above and
below. The geometry of the flange and the panels of the pylon
are selected so that in nested arrangement the flanges 112 contact
and position the pylons relative to each other so that the
side, upper, and top panels of each pylon are spared from the
one above. This avoids friction and scuffing of the retro
reflectant surface of one pylon by the one above so that the
reflectant surface is not affected by friction or scuffing when
nested or removal from nested position.
The pylon of Figures 13 and 14 has retro reflectant
side, upper and top panels and preferably uses retroreflectant
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2~~~51fi
Reflexite (trademark) as discussed in connection with the
other alternatives).
The layout of heliport and spacing of pylons using
the circular and square format to define the helipad boundary.
HELIPAD
Landing Pylon Layout
Circular Format
Diameter of Helipad Retro- Equal Spacing Pylons
flective Perimeter Pylons Between Pylons Required
115'-0 30'.1 12
115'-0 ~ 27'.7 13
115'-0 25'.8 14
115'-0 24'.0 15
115'-0 22'.5. 16
115'-0 21'.2' 17
115'-0 20'.0 18
Square Format
Length of Each Side Equal Spacing Pylons Total Pylons
Between Pylons Per Side Required
115'-0 28'.7; 5 16
115'-0 23' .0~ 6 20
115'-0 19'.1 7 24
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