Air sock

An air sock for indicating wind speed as well as direction is the subject of the present invention. A fabric type sock member is mounted on an upright standard for pivotal movement about its longitudinal axis. A spring is provided for existing pivotal movement and an arrangement is also provided for effecting pivotal movement in response to wind speed. The air sock is divided into equal quadrants of different colors so that, as the wind speed increases, a different color will be visible from an aircraft overhead. In one form of the invention, a torsion spring is utilized to resist the pivotal movement and an impeller is provided for effecting the pivotal movement. In an alternative form of the invention, a single tension spring is utilized to resist the pivotal movement and also effect the movement in response to increases in wind speed.

This invention relates generally to instrumentation for determining wind 
speed and direction and, more particularly, to an air sock for use in 
conjunction with air fields. 
Air socks have long been used in conjunction with airfields to provide 
aircraft pilots with an indication of wind direction. While a conventional 
air sock will also provide some indication of wind velocity, its accuracy 
in this regard is limited largely to determining whether the wind is 
blowing "hard" or not at all. 
An improvement in the basic air sock design is disclosed in U.S. Pat. No. 
3,696,672, issued to John Lindsay, Oct. 10, 1972. The device shown in the 
referenced patent is a freely rotatable sock which, in rotating about its 
axis, provides an indication of wind speed. While the device disclosed in 
the referenced patent does represent an improvement over earlier devices, 
it still does not provide the degree of certainty in indicating wind speed 
which is necessary for safe and reliable aircraft operation. 
Particularly in the case of small airfields where radio contact with the 
ground is not always possible, it is extremely important for a pilot to 
have the best possible information with regard to ground wind speed. 
Especially when a cross wind is blowing, it is unsafe for a small aircraft 
to land if the cross wind is blowing at too high a speed. 
It is, therefore, the primary object of the present invention to provide an 
air sock which indicates wind direction and also provides a visual 
indicator of wind speed in incremental units. 
Another primary objective of the invention is to provide an air sock of the 
type indicated in the foregoing object which provides an indication of 
wind speed in incremental units wherein the indicator is accurate to 
within a few miles-per-hour up to the design maximum. 
It is an important aim of the invention to provide an air sock as indicated 
in the foregoing objects which mounts on the existing approved staff 
support of the Federal Aviation Administration. 
Another objective of the present invention is to provide an air sock which 
visually indicates both wind direction and speed in incremental units and 
which does not require any external power source. 
Still another object of the invention is to provide an air sock of the type 
described in the foregoing objects which is economical to build and easily 
installed using existing technology.

Referring initially to FIG. 1, the air sock of the present invention is 
designated generally by the numeral 10. The air sock 10 is mounted on an 
upright staff support 12 of a conventional nature. Staff support 12 is 
provided with upper and lower sealed bearings 14 and 16 which are free to 
rotate about the staff. The bearings are rigid with upper and lower 
bracket mounts 18 and 20 which in turn hold a vertical bracket support 22. 
The air sock 10 of the present invention is mounted on support 22 and 
comprises a rigid horizontally extending member 24 which is rigid with 
support 22. 
First and second bearing housings 26 are carried by member 24 and serve to 
mount sleeve 28 which is keyed to the bearings. A cap 30 covers the 
exposed end of member 24 and receives a pin 32 which passes through the 
cap and the member to lock the sleeve and bearing assembly in place. 
Sleeve 28 serves to rotatably mount a framework and impeller assembly which 
will now be described. The framework is designated generally by the 
numeral 34 and is disposed in the shape of a truncated cone. A plurality 
of spoke members 36 extend radially outward from the sleeve 28 at each end 
of the latter and are located in circumferentially spaced relationship. 
Each set of spokes 36 is circumferentially enclosed by a rim 38. A 
plurality of longitudinally extending parallel cross braces 40 span the 
distance between the two rims 38 and are rigid with the latter to complete 
the framework. 
The spokes 36 at the large end of framework 34 also serve to mount 
curvilinear impeller vanes 42 best illustrated in FIG. 1. Further suport 
for vanes 42 may be provided by welding the base of each vane to sleeve 
28. 
As best understood from referring to FIGS. 1 and 2, rigid horizontal 
support member 24 also serves to mount a coil spring 44. A locking pin 46 
extends laterally from member 24 and is rigid therewith to hold one end 
44a of the spring. The other end 44b of the spring is received in an 
opening provided in sleeve 28. 
A housing 48 is secured to bracket support 22 and extends away from the 
latter to enclose spring 44. An O-ring 50 is sandwiched between sleeve 28 
and housing 48 to seal the interior of the housing from moisture and dirt. 
A rigid tab stop 52 is rigid with housing 48 and is designed and 
positioned to be engaged by a movable stop member 54 carried by one of the 
spokes 36. 
A generally flexible fabric sock is designated by the numeral 56 and 
extends over framework 34 and beyond to complete air sock 10. Sock 56 is 
divided into four equal quadrants designated in FIG. 1 by the numerals 58 
through 64. Each of the quadrants 58 through 64 is identical, except for 
color, and comprises a generally wedge shaped segment of the conically 
shaped sock 56. Any readily distinguishable color scheme may be used, for 
example, red in one quadrant, white in another, blue in another, and black 
and white striping (as indicated for the segment 64) in another. It is 
also to be understood that while sock 56 is illustrated as being divided 
into four equal quadrants, a smaller or greater number of sections could 
be utilized. 
In operation, air sock 10 is mounted in an unobstructed location where it 
is free to respond to changes in wind speed and direction. Air enters the 
large end of framework 34 and strikes vanes 42 thereby causing pivotal 
movement of the vanes and the sleeve 28. This pivotal movement is resisted 
by coil spring 44 which is designed to exert a uniform resistance force as 
it is coiled more and more tightly around support member 24. For example, 
coil spring may be designed so that for winds of from 0 to approximately 7 
m.p.h., the strength of the spring will be sufficient to resist any 
pivotal movement of sleeve 28. Thus, the quadrant 58 will remain at the 
top of the air sock and will be visible from an aircraft to indicate a 
wind speed of 7 m.p.h. or less. 
As the wind speed increases from say 7 m.p.h. to 14 m.p.h., impellers 42 
will impart a torsional force sufficient to rotate sleeve 28 approximately 
90.degree. in a counter-clockwise direction so as to bring quadrant 60 of 
sock 56 to the location previously occupied by quadrant 58. Since quadrant 
60 is of a different color, it will provide a readily apparent visual 
indication to a pilot that the wind speed is between 7 and 14 m.p.h. As 
the velocity of the wind continues to increase, for example from 14 to 21 
m.p.h., coil spring 44 will be wound still tighter on support member 24 
thereby causing quadrant 62 to move to the top location. Finally, when the 
wind speed advances beyond 21 m.p.h., the fourth quadrant 64 will move to 
the top location to provide a further visual indictor of the wind speed. 
As the wind speed reaches and excedes the design maximum of the unit 34, 
stop member 54 will engage stop tab 52 to prevent further pivotal 
movement. Thus, the unit will be held in position indicating maximum wind 
velocity until the speed of the wind is reduced. 
As wind speed decreases, the torsional forces inherent in spring member 44 
will cause the spring to unwind relative to support member 24, turning 
sleeve 28 and the associated framework and sock 56 in the opposite 
direction. Thus, the device will continue to provide an accurate 
indication of wind speed whether the speed is changing in a positive or 
negative direction. 
As indicated in FIG. 5, the air sock 10 also provides an accurate 
indication of wind direction by virtue of the pivotal mounting on staff 
support 12. As the direction of the wind changes, the circumferential 
location of air sock 10 will change so as to always face the large end of 
framework 34 toward the direction from which the wind is blowing. 
Referring now to FIGS. 6 and 7, an alternative form of the invention is 
shown. The alternative form of the invention utilizes the same upright 
staff as with the preferred embodiment and a bracket support 22 is mounted 
for 360.degree. rotation as previously described. A horizontal rigid 
support member 124 extends at a right angle from support 22 and mounts 
bearing housings 26 which are disposed in spaced apart relationship. 
Support member 124 is provided with a circumferentially extending 
curvilinear groove track 125 for purposes to be described hereinafter. 
Rigid with bearing housings 26 so as to rotate therewith is elongated 
sleeve 28. 
Mounted on sleeve 28 is a framework 134 similar to the framework 34 
previously described. Framework 134 is provided with a plurality of 
radially extending spokes 36 which are circumferentially spaced around 
sleeve 28 and rigid with the latter. Each of the spokes 36 is in turn 
rigid with a circumferential rim 38 which encloses the spokes. Cross 
braces 40 extend between the two rims 38 and angle braces 41 extend from 
the base of one set of spokes to the opposite rim 38. 
A coiled tension spring member 144 has one end secured to member 24 and the 
other end secured to sleeve 28 as previously described for the spring 44. 
A housing 148 encases spring 144 and is sealed by an O-ring 150. 
A stop tab 152 is rigid with housing 148 and a stop member 154 is rigid 
with one of spokes 36. The stop tab and the stop member are disposed in 
perpendicular relationship for interengagement as previously described for 
tab 52 and stop member 54. A bracket 66 is secured to sleeve 28 and mounts 
a follower pin 68 which extends through the side wall of sleeve 28. 
Follower pin 68 is received by groove track 125. 
As will be described more fully hereinafter, the alternative form of the 
invention is designed so that framework 134 moves longitudinally relative 
to support member 124, to a limited degree, and to this end support 124 is 
slightly longer than the corresponding support 24. Accordingly, an end cap 
130 is provided at the end of support member 124 and a locking pin 132 
extends through the end cap and the support member 124 so as to limit the 
extent of movement of framework 134. 
Spring 144 is of a type such that while it resists pivotal movement or 
unwinding at any one longitudinal position, as a force is applied 
sufficient to overcome the resistance of the spring and elongate it, the 
spring will also exert a torsional force partially unwinding until an 
equilibrium condition is reached. Stated differently, spring 144 is of a 
design such that for any given threshold force it will resist both 
elongation and pivotal movement. When the force on the spring exceeds the 
threshold force, however, the spring will both elongate and unwind thereby 
exerting a moment force. The unwinding continues until the resistance of 
the spring is in equilibrium with the force tending to unwind it. 
Thus, in operation, the alternative form of the invention functions similar 
to the preferred form above described. It is to be understood that the 
flexible sock 56 is not shown in FIG. 6 but would be fastened to frame 134 
in the same manner as previously described for the framework 34. When the 
wind blows through the sock from the large end of the framework, the 
spring 144 will hold one quadrant of the sock in the upper position until 
the wind velocity reaches a level where the spring tends to unwind and 
elongate. When this occurs, sleeve 28 will rotate and track 125 along with 
pin 68 will guide pivotal movement of the sleeve relative to support 
member 124. 
As with the preferred embodiment described above, continued rotation of 
sleeve 28 will expose a different quadrant of the sock 56 to indicate a 
different wind speed. Rotation of the entire assembly more than one 
revolution is precluded by interengagement of tab 152 with stop 154 as 
well as by pin 68 reaching the end of track 125. 
It is also possible to apply the principles of the alternative embodiment 
above described to an air sock which eliminates the supporting framework. 
That is, support 124 and the framework 134 could be eliminated and an air 
sock secured directly to a spring of the same type as the spring 144 above 
described. The sock would be pivoted by the spring in response to 
increases in wind velocity, the same as sleeve 28 for the alternative 
embodiment described above.