U.S. patent application number 11/593440 was filed with the patent office on 2010-12-16 for propulsion system with canted multinozzle grid.
Invention is credited to Daniel Chasman, Stephen D. Haight.
Application Number | 20100313544 11/593440 |
Document ID | / |
Family ID | 39721782 |
Filed Date | 2010-12-16 |
United States Patent
Application |
20100313544 |
Kind Code |
A1 |
Chasman; Daniel ; et
al. |
December 16, 2010 |
PROPULSION SYSTEM WITH CANTED MULTINOZZLE GRID
Abstract
A propulsion system includes a canted multinozzle plate, which
has a multitude of small nozzles angled (not perpendicular) to
major surfaces of the multinozzle grid plate. The multinozzle plate
may be a cylindrical section or plate, and the multitude of nozzles
may be substantially axisymmetric about the cylindrical plate. The
propulsion system includes a pressurized gas source which may be
placed either forward or aft of the multinozzle grid plate. The
propulsion system may have a conical insert, an internal flow
separator cone, to aid in changing directions of flow from the
pressurized gas source, to divert the flow through the multiple
nozzles.
Inventors: |
Chasman; Daniel; (Tucson,
AZ) ; Haight; Stephen D.; (Tucson, AZ) |
Correspondence
Address: |
Renner, Otto, Boisselle & Sklar, LLP (Raytheon)
1621 Euclid Avenue - 19th Floor
Cleveland
OH
44115
US
|
Family ID: |
39721782 |
Appl. No.: |
11/593440 |
Filed: |
November 6, 2006 |
Current U.S.
Class: |
60/204 ;
60/228 |
Current CPC
Class: |
F05D 2250/30 20130101;
F42B 10/665 20130101; F02K 9/97 20130101; F05D 2240/128 20130101;
F05D 2250/323 20130101; F05D 2250/324 20130101 |
Class at
Publication: |
60/204 ;
60/228 |
International
Class: |
F02K 9/84 20060101
F02K009/84 |
Claims
1. A propulsion system comprising: a pressurized gas source; and a
multinozzle grid plate operatively coupled to the pressurized gas
source, wherein the multinozzle grid plate is substantially
cylindrical, having major surfaces; wherein the multinozzle grid
plate has plural convergent-divergent nozzles therein that are
canted nozzles, angled relative to the major surfaces of the
multinozzle grid plate; wherein the nozzles are in multiple rows
longitudinally spaced along the multinozzle grid plate; and wherein
pressurized gas from the pressurized gas source is ejected from the
nozzles of the multinozzle grid plate.
2. The propulsion system of claim 1, wherein the propulsion system
is part of a rocket vehicle.
3. The propulsion system of claim 2, wherein the multinozzle grid
plate is located in the rocket vehicle aft of the pressurized gas
source.
4. The propulsion system of claim 2, wherein the multinozzle grid
plate is located in the rocket vehicle forward of the pressurized
gas source.
5. (canceled)
6. The propulsion system of claim 1, further comprising a flow
separator cone within the multinozzle grid plate.
7. The propulsion system of claim 6, wherein the flow separator
cone turns flow from the pressurized gas source toward the
nozzles.
8. The propulsion system of claim 7, wherein the flow separator
cone has a curved surface that turns the flow.
9. The propulsion system of claim 7, wherein a surface of the flow
separator cone has an outer edge that is directed in substantially
along a direction of the nozzles.
10. The propulsion system of claim 1, wherein the nozzles are
substantially axisymmetrically located about the multinozzle grid
plate.
11. (canceled)
12. The propulsion system of claim 1, wherein the nozzles of the
multiple rows are axially aligned with one another.
13. The propulsion system of claim 1, wherein the nozzles are
substantially flush with an outer major surface of the multinozzle
grid plate.
14. The propulsion system of claim 13, wherein the nozzles perform
substantially as untruncated nozzles.
15. The propulsion system of claim 2, wherein the cylindrical
multinozzle grid plate is a structural member of the rocket
vehicle.
16. The propulsion system of claim 1, wherein convergent sections
of the nozzles are substantially axisymmetric.
17. The propulsion system of claim 1, wherein the nozzle plate
includes at least 100 canted nozzles.
18. A propulsion system comprising: a pressurized gas source; a
multinozzle grid plate operatively coupled to the pressurized gas
source, wherein the multinozzle grid plate is substantially
cylindrical; and a flow separator cone within the multinozzle grid
plate; wherein the multinozzle grid plate has plural
convergent-divergent nozzles therein that are canted nozzles,
angled relative to major surfaces of the multinozzle grid plate;
wherein the flow separator cone turns flow from the pressurized gas
source toward the nozzles; wherein the nozzles are substantially
axisymmetrically located about the multinozzle grid plate; wherein
the nozzles are substantially flush with an outer major surface of
the multinozzle grid plate; and wherein the nozzle plate includes
at least 100 canted nozzles.
19. A method of propelling a rocket vehicle, the method comprising:
providing a propulsion system that includes a pressurized gas
source, and a cylindrical multinozzle grid plate having at least
100 convergent-divergent nozzles, wherein the nozzles are canted
relative to major surfaces of the multinozzle grid plate, and
directing gas from the pressurized gas source through the
convergent-divergent nozzles, thereby providing thrust for the
rocket vehicle.
20. The method of claim 19, wherein the directing includes turning
flow from the pressurized gas source using a flow separator cone of
the propulsion system that is within the multinozzle grid plate.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention is in the field of propulsion systems, such
as rocket motor propulsion systems.
[0003] 2. Description of the Related Art
[0004] There are launch systems, missiles, rockets, and projectiles
that require a propulsion unit that either mounts in front of other
units, or straps to a main propulsion unit to be separated after
use. An example of the first type is an escape module for a booster
rocket, such as the launch escape assembly for the Apollo Saturn V
rocket. Another example of the first type is in wire-guided
missiles, where a missile motor is located in front of a spool of
fiber optic wire. An example of the second type of motors is used
in ejection seats of aircraft.
[0005] In such systems output from a standard rocket motor nozzle
cannot be directed straight rearward, since to do so would cause a
plume of very hot exhaust gases to contact other structures. To
remedy this problem nozzles in such prior art propulsion systems
have been canted. That is, the nozzles have been angled away from a
centerline of the vehicle.
[0006] FIG. 1 shows a prior art launch escape assembly 10 used for
separating a crew module 12 from a main rocket (not shown) in the
event of a malfunction during launch or early in the flight
procedure. The launch escape assembly shows two types of canted
nozzle arrangements used in prior systems. A main launch escape
motor 16 has a set of canted nozzles 18 at its aft end. The launch
escape motor canted nozzles 18 are located behind an aerodynamic
skirt 20, and protrude beyond the diameter of the cylindrical
launch escape motor 16. The launch escape assembly 10 also has a
tower jettison motor 24 that has canted nozzles 26 that are
substantially flush with an outer surface of the main cylindrical
part of the launch escape assembly 10. The tower jettison motor 24
is located toward a forward end of the launch escape assembly 10,
near a nosecone 30 and a canard assembly 32.
[0007] The launch escape assembly 10 also includes a launch escape
tower 36, used to maintain separation between the launch escape
motor canted nozzles 18 and the crew module 12. Although the launch
escape motor canted nozzles 18 are angled somewhat away from the
centerline of the launch escape assembly 10, some additional
separation is required to avoid undesirable heating of the crew
module 12.
[0008] The two types of canted nozzles 18 and 26 illustrate some of
the shortcomings of prior art propulsion systems that are placed
forward relative to other components. The launch escape motor
canted nozzles 18 require a diameter greater than that of the main
cylindrical portion of the launch escape assembly 10. And despite
being angled away from the centerline of the launch escape assembly
10, an additional structure (the launch escape tower 36) is still
necessary to provide separation from the crew module 12. The launch
escape tower 36 adds additional cost and weight, and increases the
overall size of the launch escape assembly 10.
[0009] Although the tower jettison motor canted nozzles 26 are
substantially flush with the outer cylindrical surface of the main
portion of the launch escape assembly 10, this feature is achieved
at a performance cost. Truncating the canted nozzles 26 reduces
overall performance when compared to converge-diverge nozzles that
do not have truncated shapes.
[0010] From the foregoing it is seen that there is room for
improvement with regard to propulsion systems of this type.
SUMMARY OF THE INVENTION
[0011] In accordance with an aspect of the invention, a multinozzle
grid plate has a multitude of canted nozzles. The multinozzle grid
plate may have a cylindrical shape.
[0012] In accordance with another aspect of the invention, a
portion of a rocket structure has a multitude of canted nozzles
substantially flush with a cylindrical rocket wall. The nozzles are
convergent-divergent nozzles with convergent and divergent portions
defined by shapes within the thickness of the rocket wall.
[0013] In accordance with yet another aspect of the invention, a
propulsion system includes: a pressurized gas source; and a
multinozzle grid plate operatively coupled to the pressurized gas
source. The multinozzle grid plate has plural convergent-divergent
nozzles therein that are canted nozzles, angled relative to major
surfaces of the multinozzle grid plate.
[0014] In accordance with still another aspect of the invention, a
propulsion system includes: a pressurized gas source; a multinozzle
grid plate operatively coupled to the pressurized gas source,
wherein the multinozzle grid plate is substantially cylindrical;
and a flow separator cone within the multinozzle grid plate. The
multinozzle grid plate has plural convergent-divergent nozzles
therein that are canted nozzles, angled relative to major surfaces
of the multinozzle grid plate. The flow separator cone turns flow
from the pressurized gas source toward the nozzles. The nozzles are
substantially axisymmetrically located about the multinozzle grid
plate. The nozzles are substantially flush with an outer major
surface of the multinozzle grid plate. The nozzle plate includes at
least n canted nozzles, with n=(I.sub.ESN/t.sub.plate).sup.2 or
n=(d.sub.ESN/d.sub.plate).sup.2, where I.sub.ESN is the length and
d.sub.ESN is the throat diameter of an Equivalent Single Nozzle
(ESN), while t.sub.plate is is the thickness of the MNG plate
obtained from stress analysis of MNG plate made from selected
material. The d.sub.plate is i the throat diameter of a scaled
single nozzlette in the MNG. ESN is a single nozzle having the same
convergent and divergent angles as well as throat area and exit
area as that of a MNG with n nozzlettes. For example, nozzlette
area population efficiency study showed that 85 nozzlettes MNG on a
disk has 82.2% population efficiency.
[0015] According to a further aspect of the invention, a method of
propelling a rocket vehicle includes: providing a propulsion system
that includes a pressurized gas source, and a cylindrical
multinozzle grid plate having at least n convergent-divergent
nozzles, wherein the nozzles are canted relative to major surfaces
of the multinozzle grid plate, and directing gas from the
pressurized gas source through the convergent-divergent nozzles,
thereby providing thrust for the rocket vehicle.
[0016] To the accomplishment of the foregoing and related ends, the
invention comprises the features hereinafter fully described and
particularly pointed out in the claims. The following description
and the annexed drawings set forth in detail certain illustrative
embodiments of the invention. These embodiments are indicative,
however, of but a few of the various ways in which the principles
of the invention may be employed. 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 drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] In the annexed drawings, which are not necessarily to
scale:
[0018] FIG. 1 is an isometric, partial cutaway detail of a prior
art launch escape assembly;
[0019] FIG. 2 is an isometric, partial cutaway detail of a launch
escape system that utilizes a propulsion system in accordance with
an embodiment of the present invention;
[0020] FIG. 3 is a cutaway view of a first embodiment of a
multinozzle grid for use with the propulsion system of FIG. 2;
[0021] FIG. 4 is a detailed view of a portion of the multinozzle
grid plate of FIG. 3;
[0022] FIG. 5 is a cutaway view of a second embodiment of a
multinozzle grid for use with the propulsion system of FIG. 2;
[0023] FIG. 6 is a detailed view of a portion of the multinozzle
grid plate of FIG. 5;
[0024] FIG. 7 is an illustration showing aspects of a process for
configuring a multinozzle grid in accordance with an embodiment of
the invention.
DETAILED DESCRIPTION
[0025] A propulsion system includes a canted multinozzle plate,
which has a multitude of small nozzles angled (not perpendicular)
to major surfaces of the multinozzle grid plate. The multinozzle
plate may be a cylindrical section or plate, and the multitude of
nozzles may be substantially axisymmetric about the cylindrical
plate. The multitude of nozzles may be canted at any of a wide
variety of angles relative to the longitudinal axis of the
cylindrical multinozzle grid plate, such as angles from 30 degrees
to 150 degrees. The propulsion system includes a pressurized gas
source which may be placed either forward or aft of the multinozzle
grid plate. When the pressurized gas source is placed aft of the
multinozzle grid plate, flow turning may be required to get the
pressurized gas to pass through the multiple nozzles and provide
forward thrust. The propulsion system may have a conical insert, an
internal flow separator cone, to aid in changing directions of flow
from the pressurized gas source, to divert the flow through the
multiple nozzles. The conical member may aid in performance and
reduced stagnation losses. Due to the nozzlettes scaling, the
propulsion system advantageously fits within a cylindrical vehicle
body, without any need to truncate the nozzles in a way that
adversely affects performance. The multinozzle grid plate may be
configured to obtain performance comparable to that of conventional
multiple separate nozzles. Other advantages of the propulsion
system include reduction of weight, ease of manufacture, reduction
of overall vehicle size, and flexibility in placement of nozzles
and pressurized gas sources.
[0026] FIG. 2 shows a launch escape system 110, one example of an
application of a propulsion system 112 that utilizes a multinozzle
grid plate. The propulsion system 112 includes a launch escape
motor 114 for separating a crew module 116 from a main booster
rocket (not shown). The launch escape motor 114 includes a launch
escape motor propellant or pressurized gas source 120 that is aft
of a launch escape motor multinozzle grid plate 124 having multiple
nozzles (also referred to herein as nozzlettes). The term "nozzle"
as used herein refers to convergent-divergent nozzles, with
convergent portions, throats, and divergent portions. As described
in greater detail below, the launch escape motor propellant or
pressurized gas source 120 creates pressurized gas which moves
forward within the launch escape system 110, and then is turned and
ejected through the launch escape motor multinozzle grid plate 124.
The launch escape motor propellant or pressurized gas source 120
may be any of a variety of suitable sources or pressurized gas. A
solid rocket fuel is an example of a suitable propellant for use in
the launch escape motor propellant or pressurized gas source
120.
[0027] It will be appreciated that a significant amount of turning
of the flow from the launch escape motor propellant or pressurized
gas source 120 is necessary to expel the flow through the nozzles
of the launch escape motor multinozzle grid plate 124. In order to
provide propulsion to the launch escape system 110 the pressurized
gas exiting the launch escape multinozzle grid plate 124 must be
expelled in a generally rearward direction. Since the launch escape
motor propellant or pressurized gas source 120 is aft of the launch
escape motor multinozzle grid plate 124, pressurized gas from the
source 120 moves in a generally longitudinally-forward direction
toward the multinozzle grid plate 124. This movement may be
substantially parallel to a central axis 130 of the launch escape
system 110. The gas flow must be turned greater than 180 degrees in
order to exit in a generally rearward direction through the nozzles
of the multinozzle grid plate 124, but angled away from a
cylindrical housing 134 of the launch escape system 110. The
nozzles of the multinozzle grid plate 124 may be angled about 30
degrees away from a straight rearward direction. This means that
the flow turning from the generally longitudinal forward direction
to the exit through the multinozzle grid plate 124 requires a
turning of about 150 degrees.
[0028] The propulsion system 112 also includes a tower jettison
motor 138 for separating the cylindrical housing 134 from the crew
module 116. The tower jettison motor 138 includes a tower jettison
motor propellant or pressurized gas source 140 and a tower jettison
motor multinozzle grid plate 144. The tower jettison motor
propellant or pressurized gas 140 is forward of the tower jettison
motor multinozzle grid plate 144. In other words the propellant 140
is closer to a nosecone 146 than is the multinozzle grid plate 144.
Thus pressurized gas from the tower jettison motor propellant or
pressurized gas source 140 flows backward through the housing 134
to the multinozzle grid plate 144. Therefore less turning is
required to divert the flow out through the nozzles of the
multinozzle grid plate 144. Nozzles of the multinozzle grid plate
144 may be angled outward at about 30 degrees relative to the
direction of the axis 130.
[0029] FIGS. 3 and 4 show further details of the tower jettison
motor multinozzle grid plate 144. The multinozzle grid plate 144
includes a multitude of nozzles 150. Nozzles 150 are arranged in a
series of rows 152 that are axially separated from each other at
different axial (longitudinal) distances along the axis 130. The
nozzles 150 in each of the rows 152 may be located substantially
axisymmetrically about the circumference of the multinozzle grid
plate 144. That is, the nozzles 150 in each of the rows 152 may be
evenly circumferentially spaced about the axis 130. The rows 152
may be configured such that the nozzles 150 are arrayed in a series
of axially-aligned columns 154. That is, the nozzles 150 in one of
the rows 152 may be located at circumferential locations
immediately above and below the nozzles of adjacent rows.
[0030] The nozzles 150 are converge-diverge nozzles, each having a
converge portion 160, a throat 162, and a diverge portion 164. A
thickness 168 of the multinozzle grid plate 144, between major
surfaces 170 and 171 of the grid plate 144, is large relative to a
throat diameter 172 of the nozzles 150. Since the scaling of the
equivalent single nozzle (ESN) allows the multinozzle grid (MNG)
nozzles 150 to be scaled to a thickness smaller than 168, extension
of the nozzle shapes to make them flush with the outer surface 171
results in an increase in nozzle performance. Thus the nozzles 150
may be made flush with an outer surface 171 of the multinozzle grid
plate 144 while still maintaining a high expansion ratio. This is
in contrast to larger prior art flush nozzles, which must be
substantially truncated in order to make them flush. In addition,
the convergent portions 160 for the nozzles 150 are substantially
axisymmetric. This is desirable for obtaining maximal flow
entrainment, and for flexibility in orienting the multinozzle grid
plate 144.
[0031] The multinozzle grid plate 144 has an open end 178 for
receiving pressurized gases from a suitable propellant or
pressurized gas source 140 (FIG. 2). At an opposite end the
multinozzle grid plate includes a flow separator cone 180. The flow
separator cone 180 has an axisymmetric shape that is configured to
aid in desirably redirecting the flow of gases toward the
convergent portions 160 of the nozzles 150. The flow separator cone
180 has a curved axisymmetric surface 182 that culminates in a
central point 184. The curved surface 182 is configured to turn
incoming flow to the direction of entry into the convergent
portions 160 of the nozzles 150. The flow separator cone 180 aids
in reducing stagnation in the pressurized gas flow, and also in
reducing heat losses. The flow separator cone 180 is made of a
thermally insulating material, such as a short-strand
glass-reinforced phenolic or the like.
[0032] The multinozzle grid plate 144 may be made of any of a
variety of suitable materials. The grid plate material must be
compatible with the propellant used. Aluminized propellants are
compatible with refractory materials of a metallic nature. Such
materials have high densities, however, and therefore are sometimes
utilized as a thin surface layer, on the order of microns thick.
The bulk of the structural material may be a suitable composite
material or a suitable ceramic matrix material.
[0033] Turning now to FIGS. 5 and 6, the launch escape motor
multinozzle grid plate 124 may be similar in configuration to that
of the multinozzle grid plate 144. The nozzles of the two
multinozzle grid plates 124 and 144 may be the same as regards
configuration and orientation. A difference is that an open end 188
for the multinozzle grid plate 124 is at the bottom of the
multinozzle grid plate 124. This is opposite in direction, relative
to the cant of the nozzles, from the configuration of the
multinozzle grid plate 144. Thus more flow turning is required to
get flow flowing through the open end 188 into the nozzles 190 of
the multinozzle grid plate 124. A flow separator cone 194 therefore
has a different shape than the flow separator cone 180 (FIG. 3).
The flow separator cone 194 is made of a thermally insulating
material, and has a curved surface 196 configured to move the flow
seamlessly into convergent portions of the nozzles 190. The curved
surface 196 may have a downward-directed outer surface 198
directing the flow downward in a direction the same as the
direction of a central point 200 of the flow separator cone
194.
[0034] The multinozzle grid plate may have a great number of
nozzles, such as at least 100 nozzles, or dozens or hundreds of
nozzles. It will be appreciated that a wide variation in the number
of nozzles is possible. The nozzles of the multinozzle grid plate
may all be canted to substantially the same angle, and may have
substantially identical shapes. However, it will be appreciated
that variations in nozzle shape and/or angular orientation are
possible.
[0035] Although the propulsion description has been described above
with regard to a launch escape system, it will be appreciated that
the propulsion system described above may be utilized in a wide
variety of rockets, missiles, and other projectiles. Some other
uses of multinozzle grids are described in U.S. patent application
Ser. No. 10/288,943, filed Nov. 6, 2002, in U.S. patent application
Ser. No. 10/289,651, filed Nov. 7, 2002, and in U.S. patent
application Ser. No. 11/113,511, filed Apr. 25, 2005, the
descriptions and figures of all of which are incorporated herein by
reference.
[0036] FIG. 7 illustrates an example of multinozzle grid plate
configuring. The prior art launch escape assembly 10 in FIG. 7 has
four canted nozzles 18 protected by an aerodynamic skirt 20. A
canted conventional single nozzle 201 having the same throat area
203 and exit area 204 is shown separately as one out of the four
canted nozzles 18. A dash-line box 211 bounds the canted
conventional single nozzle 201 geometry. The canted equivalent
single nozzle 202 shows the same box 212 to define the range of the
canted conventional single nozzle 201 within its geometry
demonstrating the higher extent of its exit area 205 compared with
the prior art exit area 204. Note that in all cases (i.e., 10, 201,
202 and 150) the nozzle area 203 is preserved. Recalling the
formula given above, n=(I.sub.ESN/t.sub.plate).sup.2 or
n=(d.sub.ESN/d.sub.plate).sup.2, where n is the number of nozzles
(nozzlettes), I.sub.ESN is the length, d.sub.ESN is the throat
diameter of an Equivalent Single Nozzle (ESN), t.sub.plate is the
thickness of the MNG plate obtained from stress analysis of MNG
plate made from selected material, and d.sub.plate is the throat
diameter of a scaled single nozzlette in the MNG Based on this
formula, the canted equivalent single nozzle 202 is scaled down at
a ratio of 12.247:1 to a single nozzlette 150. Accordingly, for a
canted conventional single nozzle 201 throat area of 0.575
in.sup.2, and n=150 nozzlettes in the canted MNG, each nozzlette
150 throat area is 0.0038374 in.sup.2. So the canted equivalent
single nozzle 202 throat area is maintained at 0.575 in.sup.2 based
on the ratio: nA.sub.Nozzlette=A.sub.ESN or (150)(0.0038374
in.sup.2)=0.575 in.sup.2. The canted multinozzle grid achieves a
much higher expansion ratio than conventional canted nozzles, and
consequently also achieves a higher thrust than conventional
systems.
[0037] It will be appreciated that the propulsion system 112, and
variants of such a propulsion system, offer a wide variety of
advantages relative to systems utilized previously. One advantage
is that the multinozzle grid plates are able to accommodate
scaled-down versions of full size conventional canted nozzles that
without truncation would occupy diameters larger than that of the
missile, rocket, or other vehicle. The scaled-down versions have a
smaller length and diameter, for instance allowing them to be flush
with a missile or vehicle body, without the need to truncate the
nozzles to the extent that performance would be substantially
reduced.
[0038] The multinozzle grid plate also advantageously utilizes the
housing of the rocket, missile, or other vehicle for the nozzles
themselves. In other words, the cylindrical walls function both as
structural units for the missile and as the nozzles. This results
in smaller structural mass fraction and facilitates manufacturing,
in contrast with the traditional separate structures for the
missile body and for the nozzles.
[0039] The substantially axisymmetric shape of the convergent
portion of the nozzles reduces stagnation losses in the nozzles of
the multinozzle grid. Also, the same multinozzle grid may be
utilized for both forward propellant (propellant forward of the
multinozzle grid plate), and aft propellant (propellant aft of the
multinozzle grid plate) configuration. This results in a further
reduction in manufacturing costs, and increases versatility in
configuring rockets or other vehicles.
[0040] The multinozzle grid plate provides the further advantage of
allowing the outlet from a main motor to be moved well away from
the aft end of the motor. This allows the main motor output gases
to be moved well away from any following structure, such as a crew
module or other portion of a rocket vehicle. This may reduce
overall size of the vehicle, and may also advantageously reduce the
amount of protection that would otherwise be needed to shield the
following structure from hot gases.
[0041] In configuring the nozzles 150 and 190 of the multinozzle
grid 124 and 144, one may be begin with a potential single nozzle
that embodies the best internal ballistic potential that can be
provided, without regard to added mass. A scaling down of the
potential single nozzle may be performed, scaling down the nozzle
shape to fit in with the present or desired wall thickness of the
rocket. A desired thrust output may dictate the number of nozzles
that will be required for the multinozzle grid plate. Material
strength considerations and other material properties may be used
to determine a desired spacing of the nozzles.
[0042] Although the invention has been shown and described with
respect to a certain preferred embodiment or embodiments, it is
obvious that equivalent alterations and modifications will occur to
others skilled in the art upon the reading and understanding of
this specification and the annexed drawings. In particular regard
to the various functions performed by the above described elements
(components, assemblies, devices, compositions, etc.), the terms
(including a reference to a "means") used to describe such elements
are intended to correspond, unless otherwise indicated, to any
element which performs the specified function of the described
element (i.e., that is functionally equivalent), even though not
structurally equivalent to the disclosed structure which performs
the function in the herein illustrated exemplary embodiment or
embodiments of the invention. In addition, while a particular
feature of the invention may have been described above with respect
to only one or more of several illustrated embodiments, such
feature may be combined with one or more other features of the
other embodiments, as may be desired and advantageous for any given
or particular application.
* * * * *