US 3457861 A
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I July 29, 1969 s. R. CROCKETT 3,457,861
MISSILE BOOSTER PRESSURE CONTROL MECHANISM Filed Jan. 25, 1968 2 INVENTOR.
O SYDNEY R. CROCKETT BY W A T TOR/V575 United States Patent O 3,457,861 MISSILE BOOSTER PRESSURE CONTROL MECHANISM Sydney R. Crockett, Oxnard, Calif., assignor to the United States of America as represented by the Secretary of the Navy Filed Jan. 25, 1968, Ser. No. 700,644 Int. Cl. F42b 15/10 U.S. Cl. 10249.4 4 Claims ABSTRACT OF THE DISCLOSURE A plug of consumable propellant serves to delay application of booster pressure to the second stage of a missile until acceleration forces are sufficiently great to prevent stage separation during launch.
The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.
BACKGROUND OF THE INVENTION Field of the invention This invention relates to control devices for preventing premature application of booster burn out pressure to a subsequent stage of a missile. It may form a part of any missile stage separation programming system.
Description of the prior art Heretofore it has been proposed to provide mechanical timing devices, latches or detents to prevent missile stage separation during the initial stages of missile flight and particularly before sufficient G forces accumulate to prevent accidental separation of the stages. Such devices are frequently bulky in size, costly in construction and are not always reliable in operation.
SUMMARY Briefly the present invention provides a coupling device for interconnecting a missile probe and its booster in which a time delay plug of a propellant is employed to block a passage and prevent booster pressure from reaching the probe base until sufficient acceleration force is achieved. Thus initial separation of the missile probe from the booster during launch is prevented.
Accordingly an object of this invention is to provide a coupling device for a missile stage and its booster motor in which the separation thereof is prevented until satisfactory conditions exist.
Another object of this invention is to provide a separation means between a missile stage and its booster motor wherein the application of booster pressure to the missile stage is delayed until substantial launch velocity is achieved.
Another object is to provide a chemical means of preventing separating a missile stage from its booster motor until a desired time after launch.
A further object is to provide a relatively small, simple and reliable device for controlling missile stage separation.
Other objects, advantages, and novel features of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a longitudinal sectional view :of the separation device with the booster motor and missile stage closely connected one to the other.
3,457,361 Patented July 29, 1969 FIGURE 2 is a change position view showing the missile stage during the act of separation.
DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring particularly to FIGURE 1, there is shown generally a booster motor section 10 with a missile stage, rocket probe or other payload 12 positioned partially therein. The booster motor section 10 includes an outer casing I14 within which a conventional hollow core propellant grain 16 is positioned, and a conically shaped booster nose fitting 18 with the base thereof lying flush with the end of said propellant grain 16. The booster nose fitting 18 extends slightly within the aforesaid casing 14 and is sealed by gasket 20 and maintained in fixed position by the retaining ring 22 of square cross section as shown.
Booster nose fitting 18 is provided with communicating axially aligned openings 19, 21 and 23. Opening 19 receives the aft portion of a probe or missile stage 12 in a free sliding relationship and central opening or passage 21 receives an axially aligned piston 24 of diameter less than the end of the probe 12. The piston 24 is sealed against presure loss by an O-ring gasket 27. Directly behind the cylinder in a blocking position within opening 23 and extending slightly within the hollow bore 30 of booster motor I10 is a plug or charge 26 or propellant material, preferably of the same type as propellant grain 16 in order to assure temperature and burn rate compatability.
The plug 26 is retained in opening 23 by a lock ring 31 located at the after end and at the forward end contacts a perforated disc 32. The rear portion of plug 26 is open to the hollow bore 30 of booster motor 10 and heat from a burning booster motor 10 will obviously ignite the said plug 26 which will block passage opening 23 until consumed. Thus, plug 26 keeps booster pressures from being applied to the aft end of piston 24 during the launch and until sufficient missile acceleration force has been obtained.
The aforementioned support disc 32 is positioned between the aft end of cylinder 24 and the forward end of the plug material 26. In addition to providing support for the plug 26 while under high pressure, it also controls the exposure of piston 24 to the booster motor pressure. This is true since, until consumed, the disc 32 and the gasket 25 prevent portions of propellant plug 26 from being blown against piston 24. The support disc 32 will remain intact until plug 26 has burned to the surface of said disc 32; after which it will be subjected to such heat and pressures from the booster motor section 10 that, due to its relatively low melting point, it will be consumed and leave passage 23 open permitting piston 24 to receive gas pressure from the booster motor section 10. Support disc 32 preferably comprises a material which melts at about 215 F. and supports the plug 26 until about 25 Gs boost acceleration is attained. The small apertures 36 in the support disc 32 create higher thermal conductivity and facilitate consumption thereof.
Upon launch of the assembled missile and booster, there is little acceleration force exerted by the booster upon the missile and hence a small pressure on piston 24 would expel the missile. However the acceleration force increases rapidly and after 2 or 3 seconds is such that full boost pressure against the relatively small diameter after end area of the piston 24 would be insufiicient to expel the missile. At booster burnout, however, there is a diminution in booster pressure and there is even greater decrease in the acceleration force. The end of the payload 12 which is at or near apogee starts to separate and withdraw from the booster motor section 10. When the after edge of piston 24 clears the forward edge of opening 21, the full force of the tail off booster pressure is applied to the much larger rear end of the payload 12 and expels the said payload from the booster motor section 10 at high velocity.
It is now clear that propellant plug 26 and support disc 32 merely delay the application of launch boost pressure so that it cannot reach the cylinder 24 until accelerator force has been achieved.
What is claimed is:
l. A missile booster interconnection coupling which separates in response to decrease in missile acceleration forces aided by booster propulsion pressure comprising:
an elongate booster body having a propellant gas generating area and provided at its forward end with a missile base receiving cavity into which a missile base is normally urged by acceleration forces;
said booster forward end having a passage communicating said cavity with the propellant gas generating area;
means limiting the missile base area to which booster gas generating force is applied,
means for initially inhibiting access of boost pressures to said reduced area until acceleration forces are suflicient to normally prevent separation of said stages and;
wherein a greater portion of said missile base area is subjected to the booster gas generating 'force in response to a decrease in acceleration forces.
2. The device of claim 1 wherein the reduced area includes a piston slidable in said passage.
3. The device of claim 1 wherein the inhibiting means includes a combustible plug normally isolating the piston end area from the boost pressure.
4. A separable coupling for interconnecting two objects one of which contains a pressure producing propellant comprising:
first means responsive to said pressure generated by propellant combustion for inducing a separation operation of said coupling, and
second means adapted to inhibit the separation operation of said first means until the propellant has been substantially consumed,
said second means including a piston of reduced area exposed to pressures generated by combustion of said propellant and a combustible plug after destruction of which combustion pressure may be applied to the particular piston surface, and
wherein initial piston movement as a result of decreased forces tending to keep the parts coupled serves to expose a larger area of said first means to the combustion pressures.
References Cited UNITED STATES PATENTS 2,779,283 1/1957 Baughman 102-49.4 2,945,442 7/1960 Adelman et a1 102-49.S 3,026,772 3/1962 Moreland 10249.5 X 3,038,407 6/1962 Robertson et a1. 102--49.5 X 3,118,638 1/1964 Rohr.
3,160,098 12/1964 Schulze et al. 10249.5 3,211,095 10/1965 Foster 10225 VERLIN R. PENDEGRASS, Primary Examiner