US3390529A - Inflatable nozzle plug for reaction engine - Google Patents

Description

July 2, 1968 c. PEL. ETAI. 3,390,529

INFLATABLE NOZZLE PLUG FOR REACTION ENGINE Filed Nov. 29, 1966 United States Patent O 3,390,529 INFLATABLE NOZZLE PLUG FOR REACTION ENGINE Cornelius Pel, Encino, and Heinrich Epple, Gardena, Calif., assignors to the United States of America as represented by the Secretary of the Air Force Filed Nov. 29, 1966, Ser. No. 597,811 4 Claims. (Cl. 60-271) ABSTRACT F THE DISCLOSURE A closure arrangement for sealing the exhaust opening of a reaction engine comprising an inflatable flexible material having a fluid drain portion and a scuttle device for rupturing said material.

This invention relates to a novel closure arrangement for plugging the exhaust opening of a reaction engine. More particularly, the invention is concerned with providing an inflatable structure for covering the nozzle opening of a reaction engine such as a rocket, the structure being jettisonable in response to an electrical signal which causes tearing to occur in a prearranged pattern followed by separation from the carrying vehicle.

In order to protect the interior of reaction engines, such as rocket or jet engines, from the effects of hot gases emitted by other auxiliary motors mounted and operating nearby, it is desirable to seal off the nozzle section of the main engine while the other motors are in operation. The gases, if allowed to enter the combustion chamber through the nozzle section` could adversely effect the initial operation of the main engine. Various covering means, such as spring ejected cover plates, have been used to plug the nozzle of the main engine, but none have been entirely satisfactory because of the possibility of damage to other portions of the vehicle upon jettisoning of a cover plate type of plug and also the relatively heavy weight of the solid plug.

The present invention provides a novel closure arrangement made from a suitable flexible material such as nylon which can be inflated to form a close tting seal to prevent the hot gases from other nearby motors from entering the main engine through the nozzle section.

Means are provided for draining away any oxidizer which may leak into the outer section of the nozzle. Also, the present invention can be jettisoned without damaging adjacent structures of the engine and a considerable weight saving is accomplished by employing a thin flexible inilated structure rather than the solid, presently used, cover plate.

Accordingly, it is an object of the invention to provide a novel closure for plugging the nozzle of a rocket engine. The closure is fabricated from a light-weight material and is inflatable so as to conform to any distortions in the nozzle section.

Another object of the invention is to provide an inflatable nozzle plug for a reaction engine which is jettisonable by tearing in a prearranged pattern in response to an electrical signal and parting from the carrying vehicle without causing damage thereto.

Still another object of the invention is to provide an inflatable nozzle plug having a slanted upper extremity to permit drainage of leaking oxidizer to a low point from where it can be carried away to the outside atmosphere.

A further object of the invention is to provide an inilatable nozzle plug which has the general geometric configuration of a truncated conical structure, the side area of which substantially conforms to the inner surface of the nozzle section.

A still further object of the present invention is to pro- 3,390,529 Patented July 2, 1968 rice vide an inflatable nozzle plug constructed of a fabric material that is coated with neoprene or polyurethane having a portion coated with Teflon or Kel-F so as to be resistant to the effect of the oxidizer (nitrogen tetroxide).

These and other objects, features and advantages will become more apparent after considering the following detailed description taken in conjunction with the annexed drawing and appended claims.

In the accompanying drawing, there is shown an elevation view partly in cross section and fragmentary of a reaction engine inflatable nozzle plug -according to the invention.

Referring now to the drawing, the novel nozzle plug illustrated therein is shown positioned in the nozzle section 13 of a reaction motor. Within the lowermost section of the nozzle 13, there is poistioned an inflatable closure structure generally designated by the character reference numeral 15. Geometrically, the structure 15 resembles a truncated cone with the inner base 17 slightly `slanted to permit drainage of leaking oxidizer toward a drain tube 19 through which it can be evacuated to the outside.

The inner base area 17 as well as the walls 21 may be made of nylon fabric coated with neoprene or polyurethane. A very thin coating of Teflon or Kel-F may be added over the previously described coating in the inner base area 17 so that any oxidizer coming in contact therewith will not cause deterioration of the structure. The outer base area comprises an end disk 23 which serves to externally seal the nozzle and the reaction motor combustion chamber. The heat resistant material such as Gengard 44 having a thickness of one-fourth inch is used to fabricate the end disk 23 which forms outer base area. This material, in addition to being flexible and impervious, is also heat resistant and will endure a heat flux of 10 B.t.u. per second per square foot for a duration of seconds. A fill valve 25 having a protruding fill hose 27 is attached on the side of the inflatable structure and extends into the interior thereof for the purpose of pressurization of the structure once it is in position in the nozzle 13.

Atthe inner base area 17, an overpressure valve 29 is positioned to maintain a continuous overpressure of 5 p.s.i. against ambient pressure. Adjoining the Valve 29 is a scuttle device 31 which, upon receipt of an electrical signal from the signal control 33, will puncture the inflatable structure and will cause the inner base area 17 to tear along several frangible radial seams. Based on a continuous overpressure of 5 p.s.i. inside the inflabtable structure, and assuming a coefficient of friction of .69 between the rubberized nylon and the inner nozzle material, sufficient friction is created to retain the bag in place when a 3 g acceleration and a negative base pressure of 3 p.s.i.g. should occur simultaneously.

Once an electrical signal from the signal control 33 has been received by the scuttle device 31 causing the inflatable structure 15 to rupture, the pressurized gas previously contained within this structure will now occupy the entire volume forward of the end disk 23 causing the pressure to drop to approximately 2.25 p.s.i. which, because of leakage through the drain tube 19, will decrease even further. With pressure equalization, the friction between the inflatable structure 15 and the nozzle 13 will cease to function as the retaining means and the lack of external pressure against the outer base area will cause the end disk 23 to be jettisoned outward. The time interval between receiving the electrical signal from the signal control 33 and -accomplishing pressure equalization behind the end disk 23 has been estimated to be in the order of 80 milliseconds.

As seen from the preceding description of a specific embodiment of the invention, the inflatable nozzle plug prevents contaminants from entering through the exhaust section of the engine. The flexibility and ease of installation of the iniiatable structure makes possible the attachment of the plug to the nozzle section of a reaction engine irrespective of -any minor irregularities in the shape of the discharge opening. Also, the closure according to the invention, is unusually light in weight, can be installed and removed without damage to the engine, and can be manufactured relatively inexpensively from readily available materials.

Although the invention has been illustrated in the accompanying drawing and described in the foregoing speciiication in terms of a preferred embodiment thereof, it should be understood that the invention is not limited to this embodiment or to the particular uses mentioned. It will be apparent to those skilled in the art that the invention may also be employed as a closure to protect the inlet and/or the exhaust openings of jet and rocket engines from the adverse effects of dust, moisture, and foreign particles which may enter therein during the storage or servicing of the engine. Various changes, alterations, modications, and substitutions, particularly with respect to the construction details can be made in the arrangement of the several elements without departing from the spirit and scope of the appended claims.

Having thus set forth and disclosed the nature of our invention, what we claim and desire to secure by Letters Patent of the United States is:

1. An inflatable closure plug for covering the nozzle opening of a reaction engine, said closure plug comprising a iiexible hollow structure generally shaped in the form of a truncated cone, said structure being dimensioned to iit closely within and to conform substantially to the geometric configuration of the inner wall lower portion of the nozzle section of the reaction engine, lan end disc of partially heat and pressure resistant material positioned across the base of said nozzle section forming the outer base of said hollow section, means for iniiating said hollow structure to a slight overpressure, means for controlling the overpressure in said structure, scuttle means on the inner base of said infiatable structure for initiating the deflation and subsequent destruction and release of the structure from the carrying vehicle after the reaction engine starts to operate, the further operation of said engine causing the destruction of said end disc because of the lack of support by the inflatable structure and the carrying away of the `destroyed end disc along with the inatable structure.

2. The inflatable closure plug defined in claim 1 wherein the exible hollow inflatable structure being truncated conical in geometric configuration includes a downwardly slanted inner base surface, and a drain tube in communication with the outer atmosphere, said drain tube being positioned between the outer wall of the inatable structure and the inner nozzle wall, the open upper end of said drain tube being disposed to receive any liquid material which runs down the slanted inner base area.

3. The inatable closure plug delined in clairn 1 wherein the flexible hollow inflatable structure includes a plurality of prearranged radially seamed weakened areas to facilitate and control the rupture pattern during the destruction of said inflatable structure.

4. The inatable closure plug defined in claim 1 wherein the flexible hollow inflatable structure is fabricated of a fabric material, said fabric being coated with a rubberlike substance to produce a substantially air-tight arrangement, the outer surface of the inner base being further coated with a substance to protect the inflatable structure from corrosive effects of liquids which may come in contact therewith.

References Cited UNITED STATES PATENTS CARLTON R. CROYLE, Primaly Examiner.

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