Power plants – Reaction motor – Solid propellant
Reexamination Certificate
2002-04-26
2004-03-30
Gartenberg, Ehud (Department: 3746)
Power plants
Reaction motor
Solid propellant
Reexamination Certificate
active
06711890
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention is directed to sealing joints for mated bodies. In a particularly preferred embodiment the invention is directed to a pressure-actuated joint, especially a pressure-actuated joint of a solid rocket motor, such as a reusable solid rocket motor.
2. State of the Art
Reusuable solid rocket motor (RSRM) designs can be found in many rocketry applications, with perhaps the best known application involving the two solid rocket boosters of the Space Shuttle. The solid rocket boosters of the Space Shuttle are attached to opposite sides of a main external tank of the Space Shuttle. On the launch pad, the two solid rocket boosters, and in particular the cases of the boosters, structurally support the entire weight of the external tank and orbiter and transmit the weight load through their structure to the mobile launch platform. Together, the solid rocket boosters furnish the majority of the thrust required to launch the Space Shuttle from its mobile launch platform and contribute to accelerate the vehicle to more than about 4800 km per hour (3,000 miles per hour) before detaching and separating from the external tank.
FIG. 1
illustrates an example of an RSRM of the Space Shuttle vehicle. The RSRM is generally designated by reference numeral
10
in FIG.
1
. The RSRM
10
comprises a plurality of detachable segments connected to each other by field joints
12
and factory joints
14
, as identified in FIG.
1
. The term “field joint” is commonly used in the field of rocketry to denote joints capable of being assembled in either a factory or the field. The field joints
12
and segmented design provides maximum flexibility in transportation, handling, recovery, refurbishment, assembly, and fabrication of the RSRM
10
. For example, the segmenting of the solid rocket motor facilitates propellant casting procedures and permits transportation of the large segments on heavy-duty railcars incapable of carrying the assembled RSRM
10
.
FIG. 2
illustrates the major segments of each RSRM
10
of the Space Shuttle vehicle by depicting the RSRM
10
in an exploded view. Proceeding from the forward end to the aft end of the RSRM
10
, the RSRM
10
comprises a nose cap
30
, a frustum forward cap
32
containing forward separation motors, a forward skirt
34
, a forward segment
20
, a forward-center segment
22
, an aft-center segment
24
, an aft segment
26
, an exit cone
36
, and an aft skirt
38
. The forward segment
20
, forward-center segment
22
, aft-center segment
24
, and aft segment
26
each contain a solid propellant grain structure, which is illustrated as a center-perforated propellant grain structure
40
. The forward segment
20
also contains an igniter assembly (not shown in
FIGS. 1 and 2
) installed at the forward end of the center-perforated propellant grain structure
40
.
The RSRM
10
includes an outer case (unnumbered in
FIGS. 1 and 2
) that surrounds the center-perforated propellant grain structure
40
. Like the propellant grain structure
40
, the outer case is also of a segmented design. In particular, each of the segments
20
,
22
,
24
, and
26
has a corresponding annular outer case segment containing a segmented portion of the propellant grain structure
40
. Although not apparent from
FIGS. 1 and 2
, interposed radially between the propellant grain structure
40
and each of the outer case segments are insulation and liner layers. The insulation layer protects the outer case from the heat and particle streams generated during combustion of the propellant grain structure
40
. The liner bonds the propellant grain structure
40
to the insulation and/or any non-insulated portions of the outer case. In addition to its adhesive function, the liner may also serve the additional functions of inhibiting an approaching flame front of the burning propellant grain
40
and contributing to the prevention of leakage of combustion gases or liquid to the outer case.
Special precautions must be taken at the field joints
12
between connected segments—i.e., segments
20
and
22
, segments
22
and
24
, and segments
24
and
26
—to prevent hot combustion gases from escaping past the insulation and reaching the outer case. Penetration of the combustion gases through the insulation can create an extremely hazardous condition.
Thus, there is a strong interest in the art, as well as public interest, to continue improving upon the field joints of a rocket motor, especially rocket motor components of manned vehicles, such as the RSRM's of the Space Shuttle.
OBJECTS OF THE INVENTION
It is therefore one of the objects of this invention to provide a pressure-actuated joint system suitable for establishing a sealed joint at the interface of two mated bodies. In regards to this object, it would be especially advantageous to provide a pressure-actuated joint system suitable for use in pressure vessels generating high internal pressures, such as rocket engines.
It is a further object of this invention to provide a pressure vessel comprising a plurality of segments, in which at least one of the interfaces between segments comprises a joint, such as a field joint, sealed with the pressure-actuated joint system of this invention.
It is still a further object of this invention to provide a rocket motor, such as a reusable solid rocket motor, comprising a plurality of segments, in which at least one of the mating interfaces between the segments of the rocket motor comprises a joint, such as a field joint, sealed with the pressure-actuated joint system of this invention.
Additional objects and advantages of the invention will be set forth in the description that follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations pointed out in the appended claims.
SUMMARY OF THE INVENTION
To achieve foregoing objects, and in accordance with the purposes of the invention as embodied and broadly described in this document, a pressure vessel according to a first aspect of this invention comprises an outer case structure, a first annular rubber layer, and a second annular rubber layer. The outer case structure comprises a plurality of annular case segments, the annular segments including a first case segment and a second case segment, the first case segment mating with the second case segment. The first annular rubber layer is associated with and disposed radially inboard of the first case segment. The first annular rubber layer has an interfacing surface portion. The second annular rubber layer is associated with and disposed radially inboard of the second case segment, and has a thickness defined between a radial inner surface and a radial outer surface of the second annular rubber layer. The second annular rubber layer also has a slot extending from the radial inner surface across a portion of the thickness of the second annular rubber layer to define a main body portion and a flexible portion of the second annular rubber layer. The flexible portion has an interfacing surface portion abutting against the interfacing surface portion of the first annular rubber layer and is sufficiently flexible to follow movement of the first annular rubber layer during operation of the pressure vessel. The slot is positioned for receiving pressurized gas from the pressure vessel and for establishing a pressure-actuated joint between the interfacing surface portions. At least one of the interfacing surface portions has a plurality of recesses formed therein, the recesses being enclosed and sealed by the first annular rubber layer and the flexible portion of the second annular rubber layer.
To achieve other objects, and in accordance with the purposes of the invention as embodied and broadly described in this document, a rocket motor according to a second aspect of this invention is provided. The rocket motor comprises a rocket motor outer case structure including a plura
Alliant Techsystems Inc.
Gartenberg Ehud
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