Device for protecting parked aircraft

A removeable spoiler is described for reducing the wing lift of parked aircraft. It includes a spoiler member in the form of a strip temporarily mountable to stand upright and project into the airstream on the top of the wing. It extends parallel to the wing axis and is supported by a clamp contacting the outer surface of the wing for securing the spoiler to the wing.

FIELD OF THE INVENTION 
The present invention relates to fixed wing aircraft and more particularly 
to the protection of parked aircraft from high winds. 
BACKGROUND OF THE INVENTION 
Wind damage to light aircraft stored in the open is notoriously common in 
part because the flying speed of a light plane is easily achieved in the 
winds of most thunderstorms. An aircraft that is tied down may even break 
its anchor cables during a storm because wings produce too much lift for 
the anchors to withstand. The lifting force on the wings may also cause 
the wings to suffer internal damage. Thus, aircraft are needlessly damaged 
or lost every year due to a failure of the tie-down cables. The problem is 
made worse since empty aircraft are especially vulnerable to damage 
because the weight of the empty aircraft is only a fraction of the gross 
weight. Moreover, adequate protection is often difficult to provide when 
the aircraft is not at its home base. To overcome these problems a 
development effort was undertaken to provide a removable device for 
reducing wing lift in the presence of a high wind. It was found that for 
such a device to be successful, it should be portable, collapsable, easily 
transported, inexpensive and should be highly effective if the wind is 
from the front of the wing, but preferably should become inactive when the 
wind is from the trailing edge of the wing. This is because a wind from 
the rear produces no lift. In addition, the device used for protecting the 
aircraft may be more subject to damage when the wind is from the rear. The 
major objective of the present invention is to provide a portable and low 
cost, yet effective system for reducing the opportunity for damage to 
parked aircraft during a windstorm while achieving the other 
aforementioned design objectives. 
These and other more detailed specific objects and advantages of the 
invention will become apparent during the course of the following 
description of the invention and in the figures which illustrate the 
invention by way of example. 
SUMMARY OF THE INVENTION 
In accordance with the invention a removable spoiler member is provided. 
The spoiler is adapted to be temporarily mounted on the wing of a parked 
aircraft to protect the aircraft from high winds. The invention preferably 
includes a mounting means for securing the spoiler member to the aircraft 
and in one preferred form of the invention, a hinge is provided between 
the spoiler and the mounting means to enable the spoiler to pivot 
forwardly about the hinge but resist rearward pivotal motion so that the 
spoiler is held in an upright position when the wind strikes the front of 
the spoiler. The mounting means can be removably mounted on each aircraft 
wing, for example by means of tie-down cords and clasps engaging the front 
and rear edge of the wing. The spoiler member is preferably an elongated 
plate or strip formed from either rigid or flexible sheet material having 
a longitudinal and transverse axis. The mounting means is preferably 
constructed for removably securing the strip to the top of the wing and 
orienting the transverse axis of the strip normal to the top surface of 
the wing and the longitudinal axis parallel with the wing axis. 
In a preferred form of the invention the spoiler strip consists of a 
flexible and foldable sheet such as a sheet of strong fabric reinforced as 
required by means of a reinforcing strut framework connected to it, for 
example by being mounted in pockets extending transversely to the strip of 
fabric.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Shown in the figures is a light aircraft 10 which illustrates a typical 
application of the invention. While the invention is most useful in 
connection with light aircraft it is not limited to such an application. 
The airplane 10 is of the fixed wing type suited for one to eight 
passengers. It includes the usual fuselage 12, tail 14 wings 16 and 18 
cabin 20 and propeller 22. When parked the aircraft is held in place by 
means of tie-down cables 24 and 28 secured to the wings which are fastened 
to the ground at 26 and 30 respectively. The tail 14 is also tied to the 
ground by means of a tie-down cable 32 secured to the ground at 34. 
In accordance with the present invention, a portable spoiler is mounted on 
each wing the one on the left wing being designated 42 and the one on the 
right wing being designated 44 in FIG. 1. Each spoiler is identical and 
therefore only one will be described in detail. Spoiler 42 is composed of 
an elongated strip or band of rigid or flexible sheet material, in this 
case strong fabric such as nylon fabric which is easily folded for 
storage. The strip has a longitudinal axis running horizontially as seen 
in FIG. 5 and a transverse axis which extends vertically. The transverse 
dimension of the spoiler 46 can be from say 3 to 6 inches and its length 
along the longitudinal axis typically 4 to 6 feet. Spaced apart along the 
length of the spoiler strip 46 are transversely extending longitudinally 
spaced apart pockets 48, 50, 52, 54 adapted to receive reinforcing struts 
56, 58, 60, 62 respectively of a reinforcing framework 64 which holds the 
spoiler in a flat spread-out i.e. extended condition. The framework 64 
also helps to hold the spoiler 46 in an upright position on the top of the 
wing 16 as shown in FIGS. 5, 6, 7. The reinforcing framework comprises a 
stiff semi-flexible longitudinally extending frame member composed of 
three tubular sections 64a, 64b and 64c each connected telescopically 
within an elbow tube section T at the base of one of the reinforcing 
struts 56-62. Upright struts 58 and 60 can be glued directly to section 
64a. Alternatively, rotation can be prevented by the provision of pins 66 
which are connected rigidly to the struts 58 and 60 and extend 
horizontally through suitable slots 65 at each end of the framework 
sections 64a-64c. In this way the framework 64 can be broken down into 
pieces whenever desired by withdrawing the ends sections 64a-64c from the 
sliding fit within the T sections at the end of the struts. A stretched 
band of rubber 70 in the nature of a bungi cord extending through it and 
connected to its ends will hold the framework in the assembled condition 
shown in FIGS. 5 and 6. Once the framework 64 is assembled, the fabric 
strip which forms the spoiler is mounted on the framework with the struts 
located in the pockets. 
Mounting means for securing the spoiler of the aircraft will now be 
described. As shown in FIGS. 5 and 8, flexible retaining members such as 
fabric gussets 80 and 82 of generally triangular shape extend from each 
end of the spoiler 46 forwardly and include lower edges secured by means 
of stitching or adhesive to generally C shaped front mounting anchor hooks 
or clasps designated 86 and 88 respectively located at opposite ends of 
the spoiler. Each of the mountings clasps has the same shape as the 
leading edge of the wing as seen in FIGS. 3 and 4 can be formed from a 
lightweight strip of sheet aluminum or other suitable material. The clasps 
86 and 88 thus extend from the lower surface of the wing forwardly around 
the leading edge of the wing and upwardly across the top surface of the 
wing. Each includes an upwardly bent tab at the center designated 90 which 
serves as a hinge for the framework 64 to allow the framework 64 and the 
spoiler 46 itself to pivot forwardly about a longitudinal axis at the top 
of the wing (FIG. 4). The clasps 86 and 88 also include upwardly bent 
sections 92 and 94 which are in turn secured to a tie cord 96 by means of 
a removable pin 98 extending between them. The rear end of the tie cord 96 
is secured to a removable rear edge clasp 98 which as shown in FIG. 8 is 
secured over the aileron 99 and flap 97 locking them in place. The locking 
of the aileron by means of the clasp 98 acts as a reminder which serves as 
an extra safety measure by locking the controls to prevent the spoiler 
from being inadvertently left in place before a flight. Secured to the 
rear end of the front mounting clasp 88 at the left end of the spoiler is 
a similar tie cord 100 which is secured to a rear edge clasp 102 identical 
with clasp 98. Each of the clasps 98 and 102 is made from lightweight 
metal or plastic sheet material folded at its center to the shape of a V 
of the appropriate size to fit over the rear edge of the wing. At the 
center of the spoiler is provided a supporting strap 104 which is 
connected at its upper end to the center of the framework 64 as shown in 
FIGS. 2 and 8. From the framework 64, the strap 104 extends forwardly 
around leading edge of the wing and from that point rearwardly beneath the 
wing and is connected at its rear end to a third rear mounting clasp 106 
which is engaged over the rear edge wing. Both of the clasps 106 and 102 
are secured to the flap 97. The deployment of the spoiler device will now 
be described. 
To use the spoiler, the strip 46 is unfolded and mounted on the framework 
64 as shown in FIG. 5. The clasps 86 and 88 are then slid rearwardly over 
the leading edge of the wing with the spoiler 46 in an upright position as 
shown in FIG. 3. The clasps 98 102 and 106 are then placed over the rear 
edge of the wing and the tie cords 96 and 100 and strap 104 are tightened 
until the spoiler is held firmly and securely in place. The spoiler 44 is 
similarly mounted on the left wing of the plane and the invention is ready 
for use. It will be seen that the spoilers will normally lie flat as shown 
in FIG. 43. Any wind from the front will cause the spoiler 46 to pivot 
about the axis of tube 64a-64c to an upright position where it is held by 
the gussets 80 and 82. However, if the wind comes from the rear of the 
plane, the spoilers will pivot forwardly about longitudinal axis of the 
framework 64 i.e. a line of joining the tabs 90 at the rear edges of the 
clasp 86 and 88 which act as hinges allowing the spoilers to pivot 
forwardly as shown in FIG. 4. Whenever the wind comes from the front of 
the wing the spoilers will again take their active upright position as 
shown in FIGS. 1-4 & 8 drastically reducing the lift provided by each wing 
thereby lessening the stress produced by the wind and reducing the chance 
for damage or possible breakage of the tie-down cables 24, 28, 32. It will 
also be seen that the strap 104 functions to reinforce the framework 64 
while the spoiler is operating. 
The invention is highly effective in reducing lift by up to 40% or more 
even though wing design varies greatly from one aircraft to another. It is 
adaptable to a variety of aircraft and need not extend all the way to the 
wing tips since much of the lift produced by each wing is provided by the 
half of the wing closest to the fuselage. The invention thus helps to 
prevent storm damage to the aircraft by reducing the wing lift developed 
in a high wind traveling from front to rear across the wing. The invention 
is inexpensive, lightweight, collapsable and can be easily stored on board 
the aircraft. Spoilers are attached temporarily in a matter of minutes and 
function by keeping large sections of the wing in a stalled condition. If 
one or more of the trailing edge clasps lock the aileron it will serve as 
a reminder to the pilot that the spoiler is in place. 
The invention provides an important advantage over simply strengthening the 
tie-down cables; namely, a drastic reduction in the upward force on the 
wing. Thus, while Federal Aviation Administration reports have shown that 
chains will hold stored aircraft in place during almost any windstorm, the 
wind can still damage the wings internally. For this reason, the FAA has 
recommended the use of nylon cords rather than chains for tying down 
aircraft. The invention is an improvement over such cords or any other 
type of external restraint since it attacks the problem directly by 
reducing lift and thereby lessening both internal and external stresses 
that might damage the aircraft during a storm. 
Many variations in the invention within the scope of the appended claims 
will be apparent to those skilled in the art once the principles of the 
invention described above are understood.