Inflatable Decelerator

When a retarding mechanism and a body suspended therefrom are launched from an aircraft or missile, the high speed at the time of dispersal causes a severe shock to the package due to sudden retardation. The sudden shock is frequently sufficient to cause general mechanical failure to the retarding device or damage to the load which increases the incidence of duds. The prior art retarding devices utilized parachutes, metal fin stabilizers and ballute technology to retard the impact upon dispersal and descent to reduce incidences of damage. A common difficulty with such devices has been that excessive speeds at the time of dispersal often results in mechanical failure. For example, parachutes used individually would provide drag at speeds below 1500 feet per second but at higher speeds the lines would tangle, become disoriented or break. Parachutes also prove disadvantageous in wooded areas since they would be hung up in branches and shrubs preventing the load to penetrate to the target.

Metal fin stabilizers perform satisfactorily where release velocities are under 1600 feet per second but encounter structural failure operating above 2000 feet per second. A combination of a parachute and balloon referred to as ballute technology requires air ports at its extremeties to provide the proper orientation to inflate the ballute. However, none of the present designs available would assure proper operation or structural integrity at speeds above 2000 feet per second.

The present invention relates to ballute technology which will permit successful dispersion at speeds above 2600 feet per second by providing rigid air scoops which will assure proper inflation of the device and structural integrity. In addition, upon deceleration to a pre-selected terminal velocity the ballute becomes a streamer to allow the munition to impact at a high energy level.

It is, therefore, an object of this invention to provide a novel high drag stabilizer attached to a munition so that a greater reliability of operation is possible than in the prior art.

Another object of this invention is to provide a high drag stabilizer which can be economically constructed and can operate at speeds of 2600 feet per second.

Still another object of this invention is to provide a high drag stabilizer, which is attached to a munition and upon deceleration to a pre-selected terminal velocity becomes a streamer providing a high energy impact.

A further object of this invention is to provide a high drag stabilizer attached to a munition which is affected by means entirely responsive to acceleration and deceleration forces.

These and other objects and many of the attendant advantages of the present invention will become apparent as the same becomes better understood from the following detail description, taken in conjunction with accompanying drawings.

FIG. 1 is an exploded view of the inflatable decelerator.

FIG. 2 is a central longitudinal section through an embodiment of the invention showing the arrangement of the device in a fully inflated condition.

FIG. 2a is a fragmentary view of FIG. 2 showing an enlarged view of the seam.

FIG. 3 is a view similar to FIG. 2 but with the inflatable decelerator collapsed forming a streamer prior to impact.

Referring now more particularly to the drawings, the number 10 designates the inflatable decelerator of a preferred form and constructed in accordance with the present invention.

In FIG. 1 of the drawings the inflatable decelerator 10 is shown in an exploded view while FIG. 2 and FIG. 3 show the item in operation. The decelerator 10 includes a rigid air scoop 12 made of plastic or metal cemented to the underside 14 of the bottom panel 16 of the ballute 18. The top side 20 of the bottom panel 16 is in turn cemented to a stiffener 22. The holes 24 of the air scoop 12, 25 of the bottom panel 16 and 27 of the stiffener 22 are in alignment to allow air to pass through and inflate the ballute 18. A valve 26 is placed directly on the stiffener 22 covering the holes 24 and held in place with a flare nut 28. The flare nut 28 passes through a central hole 31 in the stiffener 22, central hole 33 in the bottom panel 16, central hole 35 in the air scoop 12, central hole 29 in the valve 26 and is threadedly attached to a load stem 30, which is in turn secured to the load 32. The entire unit is packaged in the normal way. In FIG. 2 the top panel 34 is attached to the bottom panel 16 at their folded peripheral edges 38 by the stitches 36 to form a ballute 18. The type of stitch 36 and the materials used can be varied to accommodate the strength required at the seam 38. The top panel 34 and the bottom panel 16 should be made from flexible material such as high strength cloth, like Kevlar, impregnated with a rubberized material to make it air tight.

In operation the parts are in the position as shown in FIG. 2 after the device is dropped into the air stream. Initially, there is an enormous impact on the apparatus as it falls generally in a vertical fashion acquiring great speed. Air flow enters the air scoop 12 forcing the valve 26 open, inflating the ballute 18. The rate at which the ballute becomes inflated may be controlled by varying the size of the holes 24, 25 and 27. When the device has fallen a short distance deceleration takes effect and its descent is gradually reduced until it has slowed to a given speed. When the deceleration has reached a preselected velocity, air flow entering the air scoop 12 is reduced considerably, thus allowing the valve 26 to close. Without sustained air flow, the ballute collapses forming a streamer, (see FIG. 3) providing proper orientation with respect to the desired terminal velocity.

It will be understood that the total assembly comprising mass or load 32 is adapted for dispersal above a target and to fall toward the ground. Ballute 18 is formed by substantially air-impervious wall surfaces or panels 16 and 34 which define the shape of a deformable hollow chamber comprising the ballute. Holes 24, 25 and 27 comprise passage means communicating between the air scoop and the chamber, while valve 26 comprises four resiliently deformable valve closure members adapted to cover passages 27 until they open at a predetermined air pressure and reclose at another such pressure.

While only one basic illustrative example of devices according to the present invention has been specifically described herein, it is obvious that many variations and modifications thereof are possible within the scope of the teachings of this disclosure. It is therefore to be understood that the scope of the invention is not intended to be limited by the specific illustrative example described but rather by the scope and language of the appended claims.