US3319520A

US3319520A - High speed low shock separation system

Info

Publication number: US3319520A
Application number: US466387A
Authority: US
Inventors: Nicholas M Stefano; Stanley H Rush; Stanley L Green
Original assignee: TRW Inc
Current assignee: Northrop Grumman Space and Mission Systems Corp
Priority date: 1965-06-23
Filing date: 1965-06-23
Publication date: 1967-05-16
Anticipated expiration: 1984-05-16

Description

y 16, 1967 N. M. STEFANO ETAL 3,319,52fl

HIGH SPEED LOW SHOCK SEPARATION SYSTEM 2 Sheets-Sheet 1 Filed June 23, 1965 all mGGOGQGQOOGQPD 00909000090 ooooooooeooo@oo\ ooooooooo B Nicholas M. S'ie'fcmo, Stanley H. Rush,

Stanley L. Green,

INVENTORS AGENT.

y 16, 1967 N. M. STEFANO ETAL 3,319,520

HIGH SPEED LOW SHOCK SEPARATION SYSTEM 2 Sheets-Sheet 2 Filed June 23, 1965 Fig. 3.

Fig. 4.

Nicholas M. Stefano Stanley H Rush,

Stanley L. Gree mvsmons.

AGENT.

United States Patent Office iifii fi il Patented May I6, 1 .96?

HIGH PEED LQW SHOCK ERARATIQN @YSTEM Nicholas M. Stefano, Rolling Hills, Stanley II. Rush,

Chatsworth, and Stanley L. Green, Gardenia, Calif,

assignors to TRW Inc, Redondo Beach, Calif., a corporation of Ohio Filed .Iune 23, 1965, Ser. No. 466,387 9 (Ilaims. (Cl. 89---1) This invention relates to a pyrotechnic separation system and more particularly to a unique system for removing the fairing on a nose cone of a space vehicle prior to the ejection of a payload such as a satellite from the launch vehicle.

The existing pyrotechnic separation systems employ explosive devices usually held in close proximity to a structural member which is designed to rupture under forces and pressures developed by the explosive device. Because of the explosive devices used, a massive backup structure is needed to protect the payload from damage due to flying debris which thereby adds a weight penalty to the launch vehicle. In addition, the high level of shock transmitted to the basic structure by the backup structure can excessively damage the space vehicle and the payload, thus jeopardizing the mission.

In the present invention, disadvantages associated with the prior art devices are substantially eliminated by the novel use of well known and presently available materials. There is presently available from the Pyrofuze Corp. of Mount Vernon, New York, a sandwich construction comprising a sheet of aluminum held between two sheets of palladium and sold under the trademark Pyrofuze.

The tensile strength of the Pyrofuze sandwich is a function of the thickness of the materials used. For present day applications, a preferred thickness is 0.060 inch with each layer being 0.020 inch. Should the structural requirements of the system require a thicker sandwich, then additional alternate layers of aluminum and palladium are recommended until the aggregate desired thickness is obtained. The Pyrofuze sandwich is initiated by the application of sufficient heat to melt the aluminum which causes the palladium to alloy violently and exothermically with the aluminum. Once the reaction is started, the alloying reaction of the material will continue at a rate of approximately 9 inches per second until either all the material is consumed or the material is cooled down below the operating temperature.

Typical applications of the Pyrofuze sandwich involve the construction of a complete structure of at least two parts with the Pyrofuze as the structural bonding material. By initiating a suitable detonating device at one end capable of generating a temperature higher than the required alloying temperature will cause the Pyrofuze sandwich to alloy. Since the resulting alloy does not have structural capabilities, the structure thereby will be reduced by component parts and separate. For large spacecraft applications, it is most important that the fairing structure separate as quickly as possible and substantially simultaneously rather than at one end first. In a preferred application, the contemplated fairing is approximately 15 feet high and feet in diameter and constructed in two parts. The Pyrofuze sandwich would therefore be approximately 30 feet long. Initiating a burning at one end of the Pyrofuze sandwich would require at least 40 seconds before separation of the opposing halves of the fairing could be contemplated. In actual practice, that time delay is intolerable and further the separation along a moving point tends to create an unbalancing force which could destroy the complete mission.

The present invention solves all the problems associated with the present day techniques. Briefly stated, one preferred embodiment of the present invention consists essentially of a Pyrofuze sandwich separation device extending along a separation line on the structure to be cut substantially as described for the prior art. The Pyrofuze sandwich is preferably secured to the inside of the fairing to be cut along a substantially straight line forming the joining surface between the individual parts comprising the fairing. A fuse such as a Pyrocore fuse of the type manufactured by Dupont is positioned in close contact along the complete length of the Pyrofuze sandwich to initiate the alloying action. The Pyrocore fuse is typically a small diameter metal containing a detonating ignition core, capable of being ignited by electrical or non-electrical means. The Pyrocore fuse burns at a rate up to 21,000 feet per second.

In the preferred embodiment, a continuous length of the Pyrocore fuse is placed in close proximity to the Pyrofuze sandwich. An electrical or other suitable impulse is caused to ignite the fuse which then bums at a rate up to 21,000 feet per second. At this speed, the complete length of Pyrocore fuse for the example given above is ignited almost instantaneously over the complete length of 30 feet. Burning of the Pyrofuze sandwich causes the material to alloy simultaneously along the complete length of the Pyrocore material thereby destroying the structural integrity of the fairing substantially simultaneously.

Other objectives and advantages of the invention will be made more apparent by referring now to the accompanying drawings wherein:

FIGURE 1 is an external view of a typical fairing adapted to be separated;

FIGURE 2 is a cross-section of FIGURE 1;

FIGURE 3 is a cross-section similar to that shown in FIGURE 2 but in greater detail;

FIGURE 4 is a cross-section and enlarged detail of the Pyrofuze sandwich and Pyrocore fuse;

FIGURE 5 is a cross-section of the Pyrofuze sandwich; and,

FIGURE 6 is a cross-section similar to that of FIGURE 3 but illustrating another embodiment of this invention.

Referring now to FIGURES 1 and 2, there is shown a perspective view of a nose cone fairing It composed of two separate parts 11 and 12. The

rivets

13 and 14 located in parts 11 and 12 respectively are joined to the Pyrocore and Pyrofuze assembly 15 which serves to hold the parts 11 and 12 together into a single unified structure.

Referring now to FIGURE 3, there is shown in greater detail that portion of the cross-section illustrated in FIG- URE 2. In the preferred embodiment, the assembly 15 is composed of Pyrofuze sandwich 16 and a centrally located Pyrocore detonator 17 held in close proximity to the Pyrofuze sandwich 16 by means of a U-shaped clamp 18 as more fully illustrated in FIGURE 4. The Pyrofuze sandwich 16 is constructed of a sheet of aluminum 19 and two sheets of palladium 2t and 21, one on each side of aluminum sheet. A cross-section of the Pyrofuze sandwich 16 is more fully illustrated in FIGURE 5. As shown in FIGURE 3, the Pyrofuze sandwich 16 has the necessary thickness to maintain the structural integrity of parts 11 and 12 by means of connecting

bolts

13 and 14. The use of recessed bolt heads or flush-mounted screws is dictated solely by the requirements of the system and do not form a part of this invention. Considering the requirements of the preferred system, which is a fairing for a nose cone of a space vehicle, the individual parts 11 and 12 are formed into a fairing that is light, strong, and which offers a minimum of resistance when passing through the atmosphere. As the cross-section shows, parts 11 and 12 are constructed of a honeycombed structure which supplies the necessary rigidity, strength, and lightness. The end portions of parts 11 and 12 are preferably formed of a more solid material such as an

aluminum extrusion

22 and 23 respectively. Extrusion 22 contains the necessary cutout to accept the bolt 13 and the Pyrofuze sandwich 16. In addition, one end of extrusion 22 contacting extrusion 23 defines a chamber 24. Chamber 24 serves a dual purpose which is to accept the Pyrocore 17 and holder 18 and also to provide a chamber for initially holding the expanding gases generated by the initial detonation of the Pyrocore 17. These expanding gases provide a means of placing an initial tension on the Pyrofuze sandwich 16 which holds parts 11 and 12 together.

Since the Pyrocore fuse 13 burns at a rate of approximately 21,000 feet per second, it can be assumed that for all practical purposes, all portions of the Pyrofuze sandwich 16 are initiated and begin alloying at substantially the same time. The alloying action takes place in the centermost position of the Pyrofuze sandwich 16 and burns outwards towards parts 11 and 12. While the burning of the Pyrofuze proceeds at a rate approximating 9 inches per second, it can be appreciated that once a single portion of the Pyrofuze sandwich 16 alloys, the structural bond between parts 11 and 12 is broken. The bond will break at substantially the same time at all portions of the Pyrofuze sandwich 16. The pressures initially built up within the chamber 24 will serve to push the parts 11 and 12 away from each other, thereby insuring the complete removal of the individual parts 11 and 12 comprising the fairing 10.

Referring now to FIGURE 6, there is shown a second embodiment of the invention in which the Pyrocore fuse is not attached to the central portion of the Pyrofuze sandwich 16 but rather at one end as at 25. For certain applications, it may be more desirable to initiate the alloying of the Pyrofuze sandwich 16 at one end since it is possible to more accurately determine the time necessary for the alloying action to reach bolt 13. A review of FIGURE 6 shows that once the alloying action of the Pyrofuze sandwich 16 reaches the bolt 13, the structural integrity of the Pyrofuze is violated thereby allowing separation of parts 11 and 12. In this embodiment, the expanding gases are contained within block 26 and hence do not contribute to the separation of parts 11 and 12. This separation technique is more applicable for those systems using other means to separate the individual members and in which the timing of the separation is more precisely determinable. Block 26 is preferably constructed of a material having a low thermal conductivity such as micarta. Experience has shown that the Pyrocore fuse will not satisfactorily and consistently cause the alloying action of the Pyrofuze sandwich 16 from the end portion if block 26 is constructed of a material having a low thermal conductivity. It appears that block 26 conducts heat at such a rate that the exothermic alloying action necessary to maintain the alloying of the palladium and aluminum of the Pyrofuze sandwich 16 is quenched. By constructing block 26 of micarta or other similar material having a low thermal conductivity, the heat is maintained in the area of the Pyrocore fuse thereby maintaining the alloying reaction.

This completes the description of the embodiment of the invention illustrated herein. However, many modifications and advantages thereof will be apparent to persons skilled in the art without departing from the spirit and scope of this invention. Accordingly, it is desired that this invention not be limited to the particular details of the embodiment disclosed herein, except as defined by the appended claims.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A separating mechanism capable of reducing a complex structure into a predetermined number of parts comprising a first member and a second member joined together by a load bearing burnable material,

and a pyrotechnic contiguous fuse held in intimate contact with said load bearing burning material,

said pyrotechnic contiguous fuse adapted to generate a temperature greater than the combustion temperature of said burnable material.

2. In combination a first member and a second member structurally joined together by a sandwich of palladium and aluminum,

and a pyrotechnic fuse contacting said sandwich,

said fuse adapted to generate a temperature greater than the alloying temperature of said aluminum and palladium.

3. In combination a plurality of separable parts joined together by a load bearing bimetallic structural member having a given alloying temperature,

and a pyrotechnic fuse continuously and contiguously contacting each part of said member, said fuse adapted to generate a temperature greater than the alloying temperature of said member.

4-. A combination according to claim 3 in which said bi-metallic structural member is composed of palladium and aluminum.

5. In combination, a housing comprised of at least two separable parts, each of said parts being joined to opposing ends of bi-metallic load bearing structural member whereby said member maintains said housing as an identifiable structure,

and a continuous pyrotechnic fuse contacting each part of said bi-metallic structural member, said fuse adapted to generate a temperature greater than the alloying temperature of said bi-metallic member.

6. A combination and according to claim 5 in which said fuze contacts said structural member intermediately each of said separable parts.

7. A combination according to claim 5, in which said bi-metallic structural member is composed of palladium and aluminum.

8. In combination a housing comprised of at least two separable parts contacting each other at ends thereof,

said contacting ends determining a cavity,

a bi-metallic load bearing structural member attached to each of said separable parts passing through said cavity, and

a continuous fuse, located in said cavity and contacting said bi-metallic load bearing structural member on one side,

said fuse capable of generating a temperature at least equal to the alloying temperature of said bi-metallic load bearing structural member.

9. In combination a housing comprised of at least two separable parts contacting each other at ends thereof,

said contacting ends determining a cavity,

a bi-metallic load bearing structural member attached to each of said separable part passing through said cavity,

a continuous fuse located in any of said ends and contacting one end of said bi-metallic load bearing structural member,

said fuse capable of generating a temperature at least 5 6 equal to the alloying temperature of said bi-metallic 2,996,985 8/1961 Kratzer 102.-7.1 load bearing structural member. 3,026,772 3/ 1962 Moreland 89-4.!

3,106,162 10/1963 Hagerty 102-92.:' References Cited by the Examiner 2,114,214 4/1938 Dambla e 102 49 ROBERT F-STAHLExaminer. 2,809,583 10/1957 Ortynsky et a1. 102-7.2

Claims

1. A SEPARATING MECHANISM CAPABLE OF REDUCING A COMPLEX STRUCTURE INTO A PREDETERMINED NUMBER OF PARTS COMPRISING A FIRST MEMBER AND A SECOND MEMBER JOINED TOGETHER BY A LOAD BEARING BURNABLE MATERIAL, AND A PYROTECHNIC CONTIGUOUS FUSE HELD IN INTIMATE CONTACT WITH SAID LOAD BEARING BURNING MATERIAL, SAID PYROTECHNIC CONTIGUOUS FUSE ADAPTED TO GENERATE A TEMPERATURE GREATER THAN THE COMBUSION TEMPERATURE OF SAID BURNABLE MATERIAL.