Aerial delivery system

An aircraft aerial cargo delivery system for aircraft having a rear cargo receiving and delivery opening and ramp. Cargo is ordinarily secured to pallets which move backwardly and out of the rear cargo delivery opening under either the pull of a parachute when the aircraft is airborne or under the influence of rapid acceleration of the aircraft during a rapid (i.e., combat off-load) discharge of the cargo onto the ground. Locks must be provided (1) which will positively retract (unlock) for ground loading of pallets, (2) which will secure the pallets against forward or aft movement during normal flight conditions, (3) which will permit free aft movement but not forward movement only during combat off-load conditions, and (4) which will permit, through the use of a metallic fuse, aft movement only after a parachute connected to the pallet opens and exerts a predetermined force on the pallet sufficient to overcome the resistance presented by the fuse. The present invention provides locks for the pallets which combine all of the foregoing functions, which can be incorporated into one of two restraint rails on which the pallets are positioned, and which can be controlled by a single control rod at the load master station of the aircraft.

BACKGROUND OF THE INVENTION 
As is known, cargo drops by parachute from aircraft have been extensively 
employed in military operations and disaster relief situations. In the 
usual parachute cargo delivery system, loaded platforms are guided for 
movement along the longitudinal axis of the aircraft between parallel 
rails secured to the aircraft floor. They can be pulled backwardly out of 
a rear cargo receiving and delivery opening by means of a parachute. 
Desirably, such cargo planes must also be capable of discharging cargo 
onto the ground as the aircraft accelerates over the ground surface. 
In certain prior art aerial cargo delivery systems of this type, one of the 
two restraint rails which guide the cargo pallets are provided with aerial 
delivery system locks (i.e., those which permit only aft movement of a 
pallet under the force exerted by a parachute). The logistic locks (i.e., 
those which prevent both forward and aft movement during normal flight 
conditions) are carried on the other rail. In the aerial delivery mode, 
the logistic locks on the left rail, for example, are all disengaged while 
the aerial delivery locks on the right rail provide all forward and aft 
restraint. If it is necessary to return to the logistically locked 
position, the locks on the left rail must be manually reengaged. However, 
the pallets may shift slightly while the logistic locks are disengaged, 
resulting in a skewed condition of the pallets on the rails. This makes 
reengagement by the logistic locks very difficult due to slot 
misalignment. Furthermore, prior art systems wherein locks are deployed on 
both rails are heavy, complex and generally unreliable. 
SUMMARY OF THE INVENTION 
In accordance with the present invention, the disadvantages of prior art 
lock systems for airborne cargo pallets are obviated by combining the 
aerial delivery system and logistic lock functions into one set of locks 
carried on one guide rail and controlled by a single control rod at a load 
master station. By incorporating both lock functions into one lock for 
each pallet and placing the lock on the left-hand rail, for example, the 
lock never has to disengage from the load unless the cargo is actually 
unloaded. This eliminates the necessity of moving pallets which may have 
skewed to reengage the logistic lock function. 
Further, in accordance with the invention, a bending fuse is employed, 
designed to operate in the aerial delivery system mode, which will retain 
a pallet in its proper position until a maximum, predetermined load is 
applied to the pallet by an extended parachute. At this moment, the fuse 
fails in bending, allowing the pallet to be dragged out of the rear cargo 
delivery opening by the parachute. The failure point of the fuse is 
dependent upon the rupture characteristics of the metal used to fabricate 
the fuse. By properly choosing the material, fuses of varying tolerances 
may be employed.

With reference now to the drawings, and particularly to FIG. 1, a cargo 
plane is shown schematically and identified generally by the reference 
numeral 10. It is provided on its underside with a rear cargo receiving 
and delivery opening 12 and ramp 14. Cargo within the aircraft 10 is 
identified by the reference numeral 16 and is carried on pallets which are 
adapted to travel backwardly on restraining guideways or tracks generally 
indicated by the reference numeral 18. Cargo can be discharged from the 
aircraft with the ramp 14 in the open position by causing a parachute, 
attached to the cargo on each pallet, to be released into the slip stream 
below and behind the aircraft. Before the parachute is dereefed and 
expanded to its full drag and load suspension area, the cargo on each 
pallet should be restrained and prevented from movement. However, once the 
full drag force of the parachute is exerted on the cargo, it should "break 
away" from the guide rails 18 such that it can move backwardly through the 
opening 12. This mode of operation is referred to as the aerial delivery 
mode. 
On the other hand, it is sometimes desirable or necessary to unload the 
cargo on the pallets while the aircraft is taxiing on the ground and 
accelerating. In this mode, called the combat off-load mode, the pallets 
are restrained against forward movement but must be free to move aft of 
the aircraft. In still another mode of operation, referred to as the 
logistically locked mode, the pallets are locked to the guide rails 18 
during normal flight of the aircraft and can move neither forward nor aft. 
In FIGS. 2 and 3, a typical pallet is identified by the reference numeral 
20 while the guide rails are identified by the reference numerals 18A and 
18B. Guide rail 18A will be referred to as the left-hand guide rail while 
guide rail 18B will be referred to as the right-hand guide rail. The two 
guide rails 18A and 18B are interconnected by an aircraft floor structure 
22 provided with rollers 24 on which the pallets 20 can move. Formed in 
the floor structure 22 are two troughs 26 and 28 each having a plurality 
of upstanding brackets 30 spaced along its length (see FIGS. 3 and 4). The 
brackets 30, in turn, are connected through a hinge connection to brackets 
32 on the guide rails 18A and 18B, the arrangement being such that the 
guide rail 18A, for example, can pivot about axis 34A (FIG. 3) from the 
upright position shown to the horizontal dotted-line position shown 
wherein its top surface is essentially flush with the upper surface 36 of 
the floor structure 22. Similarly, the guide rail 18B can rotate about 
axis 34B from the upright position shown in FIG. 3, for example, to the 
dotted-line position where it is also flush with the floor surface 36. As 
will be appreciated, when the aircraft is carrying no palletized cargo, 
the rails 18A and 18B will be rotated downwardly into the horizontal 
dotted-line positions so as to eliminate any discontinuities in the floor 
surface. 
Extending along the entire length of the guide rail 18A, at the bottom 
thereof (FIGS. 3 and 4) is an actuator bar 38 which extends through 
openings 40 (FIG. 3) in the brackets 30. In this manner, it will be 
appreciated that the actuator bar 38 can slide backwardly or forwardly 
along the direction of arrow 42 shown in FIG. 4. Carried on the bar 38, 
and slidable therewith, are brackets 44 (FIG. 4) pivotally connected to 
brackets 46. Each of the brackets 46, in turn, is secured to an associated 
slidable bar 48 which carries two cam rollers 50 and 52. Each of the bars 
48 is slidable within and is supported on a generally U-shaped bracket 54 
formed on the inside surface of the guide rail 18A. The pivotal axis of 
the brackets 30, 32 is aligned with that of brackets 44, 46 such that the 
bars 48 and the cams 50, 52 carried thereby will rotate downwardly into 
trough 28 when rail 18A is rotated into the broken-line position shown in 
FIG. 3. 
The guide rail 18A is provided along its length with a series of openings 
56. Only one of such openings is shown in FIG. 4; however, it should be 
understood that the openings 56 are spaced apart on rail 18A such that at 
least two of the openings are adjacent each of the respective pallets. 
Pivotally carried within each of the openings 56, about an axis 58, is a 
locking mechanism, the details of which are shown in FIGS. 5A and 5B. FIG. 
5A is a bottom view of the locking mechanism; whereas FIG. 5B is a view of 
the locking mechanism from the side opposite that of FIG. 4. 
The locking mechanism includes an upper body portion 60 having a horizontal 
slot 62 (see also FIG. 4) which carries a pair of rollers 64 and 66 
rotatable about axes 67 and 69, respectively. Projecting downwardly from 
the bottom of the body portion 60 is a vertical cam surface 68 on one side 
of the body portion 60 and a downwardly-depending projection 70 on the 
other side of the body portion. Also carried beneath the body portion 60 
is an elongated member 72 pivotal about the axis 58. The member 72 is 
provided with a slot 74; and fitted into the slot 74 is a generally 
T-shaped fuse member 76 secured in place by means of screw 78. The fuse 
member 76 has a portion 76A which overlies the body of member 72 so as to 
rotate therewith and a portion 76B which extends beyond the member 72 and 
is in engagement with a knife-edge 70A on the projection 70. Member 72 is 
not connected to body portion 60 and can rotate about axis 58 with respect 
to body portion 60 in the direction of arrow 71 (FIG. 5A) assuming that 
the turning force is great enough to cause portion 76B to bend outwardly 
against knife-edge 70A. As shown in FIG. 3, the rollers 64 and 66 are 
adapted to fit into slots or notches 80 formed in flanges on the pallets 
20. 
The operation of the locking mechanism can best be understood by reference 
to FIGS. 6A-6F. In FIGS. 6A and 6B, the position of the actuating bar 38 
and cam rollers 50 and 52 is shown for the combat off-load and unlocked 
positions, respectively. Upon aft movement of a pallet 20 (i.e., to the 
right in FIG. 6A), the rollers 64 and 66 will be forced out of slot 80 in 
the pallet 20 with the entire locking mechanism being caused to rotate in 
a clockwise direction about the axis 58 and into the position shown in 
FIG. 6B. Should the pallet attempt to move forward, however, roller 64 
will attempt to rotate in a counterclockwise direction as viewed in FIG. 
6A. This tends to rotate the locking mechanism about axis 58 in a 
counterclockwise direction also, holding it in the locked position. Thus, 
under these conditions, the pallets can move aft but not forward. In FIG. 
6B, the lock is shown in its unlocked position. After the pallets are 
loaded onto the rollers 24 and the notches 80 aligned with rollers 64 and 
66 on the respective locking mechanisms, each locking mechanism may be 
simply kicked so as to rotate it about its axis 58 in a counterclockwise 
direction whereby the rollers 64 and 66 will be moved back into an 
associated notch 80 in a pallet 20. However, by moving the actuating bar 
38 and the cam rollers 50 and 52 forward so that roller 52 engages cam 
surface 82 on member 72, it will be appreciated that the locking assembly 
is prevented from moving about axis 58 from its open position and into the 
locked position. This condition is shown in FIG. 6C. 
In FIG. 6D, the actuating rod 38 and cam rollers 50 and 52 are shown in the 
logistically locked position. In this position, roller 52 engages cam 
surface 84 and the lock mechanism cannot move in a clockwise direction 
about axis 58 with the result that the rollers 64 and 66 must remain 
within a notch 80 in a pallet 20. FIG. 6D thus shows the positions of the 
cam rollers 50 and 52 during normal flight, under which conditions the 
pallets can move neither forward nor aft. 
In FIG. 6E, the cam rollers 50 and 52 are moved to their extreme rearward 
positions. Roller 50 now engages surface 86 on member 72. Under these 
circumstances, member 72 is blocked against rotation; however the upper 
body portion 60, including lower elements 64, 66 and 68, can still rotate 
about the axis 58, assuming that enough force is applied to it to bend the 
fuse 76 as shown in FIG. 6F. This will occur, for example, when a 
parachute to which cargo on a pallet is attached is deployed to the rear 
of the aircraft and opens. The force exerted on the pallet, which will be 
approximately 5,000 to 55,000 pounds, depending on parachute size, will 
force the rollers 64 and 66 out of their associated slot 80 in a pallet. 
Roller 64 will rotate in a clockwise direction as the pallet moves 
backwardly, causing clockwise rotation of the lock mechanism (but not 
member 72) about axis 58. At the same time, the portion 76B of the fuse 76 
will bend outwardly as shown in FIG. 6F. This releases the pallet in order 
that it can be dragged out of the rear opening in the aircraft under the 
force of the parachute. At the same time, the fuse 76 is of sufficient 
strength to prevent aft movement of the pallet under nominal flight 
conditions. It will be appreciated, of course, that once a pallet has 
ejected from the rear of the aircraft with the use of a parachute, the 
fuse 76 must be replaced by a new fuse. This can be accomplished by simply 
loosening the screw 78, removing the bent fuse, inserting a new fuse, and 
tightening the screw 78. Fuses of several different load ratings are used 
to accommodate the various parachute forces. 
It can thus be seen that the present invention provides a means whereby 
logistic locking, combat off-load release and aerial delivery via a 
parachute can be provided by locks at only one side of each pallet. 
Although the invention has been shown in connection with a certain 
specific embodiment, it will be readily apparent to those skilled in the 
art that various changes in form and arrangement of parts may be made 
without departing from the spirit and scope of the invention.