Air rescue net

A net is mounted to hang freely from the end of a pair of pivotally secured arms extending from the underside of a helicopter. The arms and net hang down in a vertical position when the helicopter is in flight and a motorized lifting mechanism raises the arms and net into a forward horizontal position for particular rescue missions or on land. A movable weight is guided along a tube extending adjacent the rear of the helicopter to balance the weight of the arms and net. A resilient bumper is mounted on the front of the net and a locking mechanism secures the arms in the horizontal position. The lifting mechanism is mounted close to the center of gravity of the helicopter to avoid balance problems.

The present invention relates to helicopter rescue devices and particularly 
to a net and support arrangement pivotally secured to the underside of a 
helicopter in a balanced manner. 
DESCRIPTION OF THE PRIOR ART 
Presently available air rescue devices are generally in the form of nets or 
supports which hang down vertically from a boom mounted on an upper side 
of a helicopter. The nets cannot be supported rigidly in a forward 
position and the weight of a load at a distance from the center of gravity 
causes an undesired tilting of the helicopter. Examples of such devices 
are shown in U.S. Pat. Nos. 2,738,939, issued Mar. 20, 1956 and 3,228,044, 
issued Jan. 11, 1966. 
SUMMARY OF THE INVENTION 
It is therefore the primary object of the present invention to provide a 
rescue net for a helicopter which can be raised from a vertical to a 
horizontal position and which is supported in a substantially continuously 
balanced manner on the underside of the aircraft during such raising 
operation. 
This is achieved by a pair of arms pivotally secured under the helicopter 
adjacent the center of gravity, with the net hanging freely at the end of 
the arms. When the helicopter is in flight, the arms and net hang 
vertically, while a motor operated lifting mechanism raises the arms and 
net into a horizontal forwardly extending position when the helicopter is 
on land or for particular rescue missions. A locking mechanism secures the 
arms in the horizontal position and the net includes a resilient bumper on 
the front end. A longitudinal tube having a slidable weight extends 
adjacent the rear of the helicopter to balance the weight of the arms and 
net. Other objects and advantages will become apparent from the following 
description taken in conjunction with the accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
As shown in FIGS. 1 through 5 a helicopter 10 employs net 30 secured to arm 
26 by way of yoke 28. Axle 32 permits net 30 to pivot there-around. The 
forward edge of the net includes a resilient bumper guard 34, such as of 
soft rubber, secured to the net by spring members 36 which provide 
vibration damping. A curved metal or plastic arm 38 at the ends of the 
bumper provide a guide which moves from the angled position to a vertical 
position when an object contacts the front of the bumper. Skids 12 are 
shown secured to the helicopter utilizing strut 84 therefor. Cable 88 is 
shown extending upwardly from drum 78. Arm 26 is shown attached to shaft 
18 so that upon the rotation of shaft 18 net 30 may move in the direction 
of arrow 60. Cable 88 passes over pulleys 90 and 92 and enters an opening, 
not shown, in hollow tubular spar 40. Such opening, adjacent uppermost end 
110 of spar 40, is located in an upper and forwardmost position relative 
to end 112 of the spar. End 110 of spar 40 is located above arm 26, a the 
end thereof adjacent shaft 18. The rearmost end of cable 88 is connected 
to weight 48 which utilized gravity to pull weight 48 in the direction of 
arrow 102. Brackets 94 and 96 secure spar 40 to the fuselage as does spar 
98, adjacent tail section 100. Housing 50 contains a gear train which 
couples drum 78 and shaft 18 together. 
Hollow tubular spar 104 is shown disposed on an opposite side of the 
fuselage, opposite to spar 40. A weight, not shown, slideably engaged in 
spar 104 as is weight 48. Spar 40 is provided with elongated opening 42 
which has slots 44 and 46 communicating thereto. Weight 48 slides along 
the passageway communicating with opening 42 having a portion thereof 
extending downwardly and outwardly from spar 40. End 86, of cable 88, is 
secured to weight 48 controlling the position of the weight along the 
length of the passageway. Plate 14 is shown mounted on skids 12 and is 
used to support housing 50 thereon. Shaft 18 is shown journalled to plate 
14 utilizing bearing 22 therefor. The end of shaft 18 is journalled into a 
bearing, not shown, housed within tube 20. Arm 24 is also secured to shaft 
18 and is shown coupled to yoke 28 having axles 32 extending inwardly from 
the ends thereof so as to support net 30 pivotably. Shafts 80 and 82 
extend outwardly from housing 50 and carry drums 76 and 78 thereon. End 
84, of cable 88, is shown secured to drum 78, having the adjacent portions 
thereof wrapped about the surface of drum 78. Thus, when shaft 82 rotates 
cable 88 may be caused to move upwardly or downwardly, dependent upon the 
direction of rotation of the drum. Another cable, not shown, is similarly 
fastened to drum 76 which is coupled to the weight residing in slideable 
engagement with spar 104. When shaft 18 turns some 90 degrees, arms 24 
and 26 pivot between the horizontal position, shown in FIG. 1, and a 
vertical position, not shown, as net 30 moves downwardly in the direction 
of arrow 16. 
Housing 50 contains electrically operated motor 56 which is adapted with a 
slip clutch. Thus, output shaft 62 will rotate only when forces exerted on 
shaft 62 do not overcome the slipping tendencies of clutch 58. Clutch 58 
may be of the frictional variety or, if desired, of a hydraulic nature. 
Clutch 58 is a frictional clutch that may consist of, if desired, two 
plates engaging one another, having a common surface adapted for 
frictional coupling, but being able to slip relative one to another when 
the drag forces exerted on shaft 62 differ from the forces produced by 
motor 56. Brake 60 is shown coupling shaft 62 to shaft 64. The housing of 
brake 60 is shown connected to block 114. Block 114 is secured to plate 
14. Thus, brake 60, being of any conventional variety, such as an 
electrically operated brake, when locked, prevents rotation of shaft 64, 
as well as shaft 62. In the locked position, brake 60 will prevent motor 
56, if operated, from further movement of arms 24 and 26. This is due to 
the slipping action of clutch 58. Spur gear 66 is coupled to larger spur 
gear 68. Larger spur gear is secured to shaft 18 and is coaxially aligned 
therewith. Thus, when brake 60 is locked, shaft 18 is not free to rotate. 
When brake 60 is unlocked, motor 56 is capable of driving shaft 18 at 
slower speeds than the operational speed of the motor, because of the 
ratio between spur gear 66 and gear 68, to which it is coupled. However, 
when brake 60 is locked, despite the operation of motor 56, shaft 18 will 
not turn at all. This provides a safe and secure positioning for net 30, 
at any desired location, when brake 60 is locked. When the brake is 
released, the amount of friction coupling of clutch 58 determines the 
amount of force exerted on net 30 required to move net 30 in a downward 
position, in the direction of arrow 16. A suitable electrical control 
circuit, comprising a series electrical circuit involving a switch, the 
helicopter battery, each not shown, and the brake, controls the operation 
of brake 60. In likewise fashion, a suitable another switch and the 
helicopter battery, each not shown, in another series electrical circuit 
with motor 56, may be employed to operate same at times other than the 
period of time that brake 60 is locked. If desired, a hydraulically 
operated frictional slipping clutch may be employed for clutch 58, a 
hydraulically operated motor may be employed for motor 56, and a 
hydraulically operated brake mechanism may be employed for brake 60, each 
of well known design, operated from a convenient source of hydraulic 
power, not shown, carried within helicopter 10. Spur gears 70 engage 
smaller spur gears 72 and 74. Spur gears 70 are secured for concurrent 
rotation with shaft 18. Shafts 80 and 82, each carry drums 76 and 78 
secured to the ends thereof. Thus, when motor 56 is made operational in a 
preferred direction, shaft 18 is operating at slower speeds so as to cause 
arms 24 and 26 to pivot about the longitudinal axis of shaft 18. Net 30 is 
permitted to be lowered to a vertical position or raised to a horizontal 
position only when brake 60 is unlocked and motor 56 is operated in the 
proper direction. Forces exerted on drums 76 and 78 are modified and 
applied to shaft 18 in accordance with the ratio of the diameters of gear 
70 to gear 74 and gear 70 to gear 72. End 84 of cable 88, as applied to 
drum 78, permits a force to be exerted on drum 78 so as to enable arms 24 
and 26 to be pivoted in a horizontal direction. When net 30 comes 
downwardly to a position beneath the fuselage, then weight 48 ascends 
upwardly along tube 40 so as to reside closer to the center of the 
helicopter. This set of motions causes net 30 to hang directly downwardly 
from helicopter 10 whilst weight 48 assumes a position close to the center 
of gravity of the aircraft, tending to minimize the unbalancing effects 
that would occur by changing the angle of elevation of arm 26 alone. 
Obviously, the ratio of diameter of gears 74 and 70, the diameter of the 
portion of drum 78 upon which end 84 of cable 88 is attached and the angle 
and length of hollow spar 40 will determine the effectiveness of achieving 
a perfectly balanced condition for all angular positions of arms 26 and 
24. Though gears 70 and 72 and gears 70 and 74 are shown as spur gears, 
each pair in a two gear gear train, each pair of gears may be replaced by 
a gear train, not shown, whose gear ratios are such that shafts 80 and 82 
turn many times more than the number of turns that shaft 18 would rotate 
upon the operation of motor 56. This fact, coupled with a large diameter 
construction for drums 76 and 78 permits cable 88 to move a substantial 
distance upon only a 90 degree rotation of arms 24 and 26. 
Thus, there is disclosed in the above description and in the drawings, an 
embodiment of the invention which fully and effectively accomplishes the 
objects thereof. However, it will become apparent to those skilled in the 
art, how to make variations and modifications to the instant invention. 
Therefore, this invention is to be limited, not by the specific disclosure 
herein, but only by the appending claims. 
The embodiment of the invention in which an exclusive privilege or property 
is claimed are defined as follows: