Stage separation using remote control release of joint with explosive inser

Mayo, J. W.

English

NASA Technical Reports Server

Feb. 11,19639 J.W. MAYO 3,42 7,047 
TL‘BULAR COUPLING HAVING FRANGIBLE CONNECTING MEANS 
Filed Nov. 30, 1966 
- -  
FIG. 2 
I 
FIG. 5 
FIG. 6 
W E h T O R  FIG. 4 JAMES W. MAYO 
54 120 BY 
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ATTORNEYS 
https://ntrs.nasa.gov/search.jsp?R=19690018112 2020-03-16T18:45:19+00:00Z
3,427,6347 
Patented Feb. 11, 1969 
H 
3,427,047 
TUBULAR COUPLING HAVING FRANGIBLE 
CONNECTING MEANS 
James W. Mayo, Newport News, Va., assignor to the 
United States of America as represented by the Ad- 
ministrator of the National Aeronautics and Space 
Administration 
Filled Nov. 310, 1966, Ser. No. 598,118 
U.S. CB. 285-3 4 Claims 
Int. CI. P16115/00,25/00 
A B S W G T  OF THE DISCLOSURE 
The invention contemplates the use of a metal sheathed 
explosive, such as a mild detonating fuse, wire of bi- 
metallic compositions which exothermically deflagrate, or 
wire of a material having a selected melting point, which 
is used as a threaded insert or shear ring to provide a 
sound mechanical joint that will surrender its mechanical 
properties upon command or upon reaching a tempera- 
ture in excess of those required for joint integrity. 
Specification 
The invention described herein was made by an em- 
ployee of the United States Government and may be 
manufactured and used by or for the Government for gov- 
ernmental purposes without the payment of any royalties 
thereon or therefor. 
Previously, various systems have been utilized to  ac- 
complish the separation of rocket stages. Such devices do 
not themselves provide separation of the stages but merely 
retain the stages in juxtaposition until a predetermined 
event or condition exists a t  which point the devices per- 
mit disconnection of the stages and thus separation of 
adjacent portions of an aerospace vehicle. Prior art de- 
vices include such items as the clamping band, commonly 
referred to as a Marman band, explosive bolts, linear 
shaped charges, and a diaphragm that fragmentates or de- 
flects to disengage threaded imembers searing the adja- 
cent stages. Each of these previously known devices has 
worked satisfactorily and some are presently in use for 
stage separation. 
However, these priorly known devices for permitting 
stage separation have various disadvantages. For example, 
the clamping band, explosive bolts and linear shaped 
charges have the shock of explosion, fragmentation and 
debris from the components that cause various undesir- 
able affects on the stages of the vehicle. The diaphragm 
generally has a limited area of location, in the structure 
and its dependency on subsequent rocket motor firing to 
accomplish separation limits its application as well as 
introducing disturbances to the separating stages. 
In view of the above discussion it is an object of this 
invention to provide a sound mechanical joint or con- 
nection which can be instantaneously released. 
Another object of the instant invention is to provide a 
joint which permits ease of assembly and which can be 
released iupon command or upon the existence of certain 
Still another object of this invention is to  provide mat- 
ing connector elements on adjacent stages of an aerospace 
vehicle with a frangible insert threaded in helical grooves 
tion of the stages upon detonation of the insert. 
A still further object of this invention is to provide a 
stage connection wherein adjacent stages of an aerospace 
vehicle are provided respectively with male and female 
flanges that interfit with helical grooves in the abutting 
faces of the flange and into which an explosive wire is 
threaded with vent holes connecting the grooves and at- 
I environmental conditions. 
I 
I 
I 
on abutting flange faces of the elements to permit separa- 
~ 
2 
nosphere to release pressures caused by detonation of 
the threaded insert. 
A more complete appreciation of the invention and 
many of the attendant advantages thereof will be readily 
apparent as the same becomes better understood by refer- 
ence to  the following description ,when considered in 
connection with the accompanying drawings wherein : 
FIG. 1 is an overall sectional view of the general in- 
stallation of the connection of the instant invention; 
FIG. 2 is an enlarged view of the assembled joint of 
FIG. 3 is another enlarged sectional viaw of the con- 
FIG. 4 is an even further enlarged sectional view of 
15 the joint of FIGS. 2 and 3 showing the instant inven- 
FIG. 5 is a sectional view similar to FIG. 2 showing an 
FIG. 6 is a view of the connection of FIG. 5 taken on 
Referring now to FIG. 1 wherein the instant inventive 
connector is generally shown by numeral 10 as connect- 
ing lower stage 12 and upper stage 14 of an aerospace ve- 
hicle. Stages 12 and 14 are  powered by conventional 
As best seen in FIGS. 2 and 3 lower stage 12 has male 
connector element 18 which includes inwardly offset 
flange 20 having end face 22 thereon and offsetting end 
face 24. The outwardly directed surface 26 of flange 20 
30 has helically arranged semiciroular grooves 28 formed 
therein for a purpose to be more fully described herein- 
after. Upper stage 14 has female connector element 32 on 
the lower edge thereof for mating engagement with con- 
nector element 18. Outer flange 34 on connector element 
35 32 includes end face 36 and inner surface 38 having heli- 
cally arranged grooves 40 forming threads. Grooves 28 
and 40 are so positioned that they substantially mate 
with one mother to  receive deflagratable insert 30. Pro- 
jection 42 includes end face 44 for a purpose to be de- 
Referring to FIGS. 2 and 3 the process of assembly is 
readily apparent. Frangible insert 30 may be inserted into 
grooves 28 and connector element 32 rotated to thread- 
ingly engage grooves 40 with insert 30 and thereby pro- 
45 vide a sound mechanical joint. As is apparent from an 
inspection of FIG. 3, considerable clearance is provided 
in the grooves 40 so that during assembly the respective 
elements may be rotated and advanced without using the 
insert 30 as a driving surface and without sliding contact 
50 between the element 30 and either of the elements 18 
or 32. Thus, assembly may be easily acconiplished with- 
out overcoming high frictional loads, or deleterious scrap- 
ing of the insert element 30. As seen in FIG. 2, once the 
elements 18 and 32 have been advanced to the point that 
55 the abutment of faces 24 and 36 occurs, further relative 
rotation occurs without relative linear movement, and the 
resulting changing relative position of grooves 28 and 40 
forces the leading contours of the groove 40 into engage- 
ment with the insert 30, and hence a sound mechanical 
connection has been rendered between the elements 18 
and 32. This situation is seen in FIG. 4 which also shows 
the clearance cavity formed on the trailing side of the 
grooves 40. It is also contemplated that insert 30 could 
be forced into grooves 28 and 40 after male connector 18 
05 and female connector 32 have been matingly assembled. 
As best seen in FIG. 2, after assembly of connector 10 
faces 24 and 36 of elements 18 and 32, respectively, are 
in a force transmitting abutment with faces 26 and 38 
in juxtaposition to one another. Although FIG. 2 shows 
70 a minimal spacing between faces 22 and 44 on connector 
elements 18 and 32 respectively, it is to be understood 
that in some instances it may be desirabe to eliminate 
lo FZG. 1; 
nection of FIG. 2 during assembly; 
tion in greater detail; 
alternative embodiment of the instant invention; and 
20 line 6-6 thereof. 
25 rocket devices 16. 
40 scribed more fully hereinafter. 
3,427,047 
3 4 
such spacillg and provide for the transmittal of forces released. It is evident that the structure is extremely sim- 
from stage 12 to upper stage 14 by abutment of faces ple in design with no moving parts to thereby provide 
22 and 44 as well as 24 and 36. high reliability while avoiding the disadvantages of the 
Referring now to FIG. 4, wherein an enlarged view of known devices by eliminating undesirable shock and 
a portion of the connector of FIGS. 2 and 3 is shown to debris. It is also apparent that the instant invention can 
have vent holes 50 connecting grooves 40 with the atmos- be applied to a wide range of sizes and have cross-sec- 
phere surrounding upper stage 14. Arrows 52 and 54 de- tional shapes other than circular to enhance the load 
signate the direction that the loads go to reaction during carrying capabilities of the joint. 
launch and propulsion. Obviously, many modifications and variations of the 
When stages 12 and 14 have been assembled with con- subject invention are possible in the light of the above 
nector 10 effecting a positive connection through flanges teachings. It is, therefore, to be understood that within 
20 and 34 and their respective threaded engagement of the scope of the appended claims the invention may be 
desolidifiable insert 3Q, it is merely necessary to activate practised otherwise than as specifically described. 
a conventional device, not shown, that will effect detona- What is claimed as new and desired to be secured by 
tion or melting of insert 30 to permit disengagement or 15 Letters Patent of the United States: 
separation of connector elements 18 and 32. The gaseous 1. An insert connector assembly for coupling a pair of 
or other pressure caused by the detonation or melting primary members of an aerospace vehicle comprising: 
of insert 30 is vented to the atmosphere through vent male and female connector elements each connected to  
holes 50 to thereby prevent undesirable deformation of a respective primary member, said male element 
the respective connector elements 18 and 32. 20 slidingly fitted into said female element, and both of 
Referring now to FIGS. 5 and 6 wherein an alternative said elements having complementary helical grooves 
embodiment of the instant invention is shown as provid- formed therein on the interior and exterior portions 
ing a retaining ring. First member 60 has inwardly offset respectively of said female and male elements; 
male flange 62 extending therefrom with semicircular abutment means limiting sliding movement of said male 
groove 64 in the outer face of flange 62. Second member 25 element into said female element; 
66 includes outward female flange 68 having groove 70 an insert element composed of a desolidifiable material 
on the inner face thereof in a position to match the disposed in said grooves, and the cross sections of 
groove 04 of inner flange 62. Vent hole 72 connects the said insert and said grooves being formed so as to 
atmosphere with groove 70 to permit release of undesir- tightly interfit said insert wich the grooves of one 
able pressures during effectuation of the release of insert 30 of said members and loosely interfit with the other, 
74. As seen in FIG. 6, arrow 76 indicates the direction whereby said members may be assembled with little 
of force utilized to insert retaining ring 74 into mating frictional contact but form a tight mechanical con- 
grooves 64 and 70 after members 60 and 66 have been nection when said members have been advanced to 
assembled. Obviously it is necessary to provide access the limit of movement allowed lby said abutment 
opening 78 for insertion of retaining ring 74. means, and whereby the insert means may be selec- 
It is readily apparent that the insert will maintain the tively desolidified to permit separation of the male 
mechanical or structural integrity of the joint until it and female connector elements. 
changes its state from a solid to a liquid or gas. It can, 2. The assembly of claim 1 wherein the said groove 
35 
in the case of the mild detonating fuse or the exothermic formed in said other member has an asymmetrical cross 
wire, be initiated by the use of present state-of-the-art 40 section fonmed to engage the leading side of said insert 
pyrotechnic devices or be changed in state from a solid element and having a clearance cavity on the trailing side. 
to a liquid or gas by heating of the material. The liquid 3. The assembly of claim 1 wherein said desolidifiable 
and/or gasses would be expelled through the vent holes insert element is composed of a deflagratable material. 
whereupon the insert material would be in a state to per- 4. The assembly of claim 2 wherein vent holes are 
mit free disengagement of the joint. The type of insert 45 formed through said other element from the clearance 
material or the shape of the material or groove need not 
be restricted lo that specified herein. As can be seen, 
any material which changes its matter from a solid, load 
carrying member into a liquid or gas could be utilized. 
Special insert materials and shapes, as well as the dimen- 50 
sions of the groove, can be utilized to provide a more ef- 
fective joint and relatively smaller inserts can also be 
produced for use with bolts and screws. A simple ex- 
ample of such a connector would be an insert made of 
an exothermic wire shaped in the form of the commer- 55 
cially available helical coiled inserts which would release 
the bolt when the temperature reaches the melting point, 
where exothermic action takes place, or on command of 
a conventional pyrotechnic ignition system. 
this invention has a particular advantage over the prior 
art because it provides a very lightweight means of ef- 
fecting a mechanical joint which can be instantaneously 
cavity. 
References Cited 
The above description makes it readily apparent that 60 
UNITED STATES PATENTS 
2,751,238 6/1956 Vegren _ _ _ _ _ _ _ _ _ _ _ _ _  151-14 
2,805,089 9/1957 Hansen _ _ _ _ _ _ _ _ _ _  285-321 X 
3,017,836 1/1962 Guay _ _ _ _ _ _ _ _ _ _ _ _ _ _  102-49.5 
3,026,772 3/1962 Moreland _ _ _ _ _ _ _ _  102-49.5 X 
3,062,568 11/1962 Anderseil et al. _ _ _ _ _ _  85-46 X 
3,107,421 10/1963 Turnbull _ _ _ _ _ _ _ _ _  285-287 X 
2,992,017 7/1961 Dritz _ _ _ _ _ _ _ _ _ _ _ _ _ _  2 8 5 4 1  X 
THOMAS F. CALLAGHAN, Primary Examiner. 
U.S. C1. X.R. 
102-49.5; 151-14; 285-305, 390 


Tubular coupling having frangible connecting means

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