Abstract
A system and methods are provided for combining systems of an upper stage space launch vehicle for enhancing the operation of the space vehicle. Hydrogen and oxygen already on board as propellant for the upper stage rockets is also used for other upper stage functions to include propellant tank pressurization, attitude control, vehicle settling, and electrical requirements. Specifically, gases from the propellant tanks, instead of being dumped overboard, are used as fuel and oxidizer to power an internal combustion engine that produces mechanical power for driving other elements including a starter/generator for generation of electrical current, mechanical power for fluid pumps, and other uses. The exhaust gas from the internal combustion engine is also used directly in one or more vehicle settling thrusters. Accumulators which store the waste ullage gases are pressurized and provide pressurization control for the propellant tanks. The system is constructed in a modular configuration in which two redundant integrated fluid modules may be mounted to the vehicle, each of the modules capable of supporting the upper stage functions.
Claims
1. An upper stage launch vehicle comprising: at least one main upper stage rocket for propelling the launch vehicle in space; a pair of main vehicle tanks for storage of liquid propellants therein including a hydrogen tank and an oxygen tank; an internal combustion engine powered by waste ullage hydrogen and oxygen vented from said tanks, said internal combustion engine having an output shaft; a power generator communicating with said output shaft of said internal combustion engine for generating electrical current; a battery in electrical communication with said generator for storing the electrical power; a gaseous oxygen accumulator for storing oxygen from the oxygen tank; a gaseous hydrogen accumulator for storing hydrogen from the hydrogen tank; and a plurality of thrusters to provide attitude and settling control of the vehicle, at least one of said plurality of thrusters being selectively powered by exhaust gas from the internal combustion engine, and at least one of said plurality of thrusters being selectively powered by oxygen and hydrogen gas from said accumulators.
2. A system, as claimed in claim 1, further including: pressurization lines from said accumulators to said tanks for pressurizing the tanks; and tank pressurization controls for selectively controlling the tank pressures.
3. A system, as claimed in claim 1, wherein: said plurality of thrusters includes at least one yaw thruster, at least one pitch thruster, and at least one axial thruster, said at least one yaw and pitch thrusters being powered by hydrogen and oxygen gas from said accumulators, and said at least one axial thruster being powered by a combination of hydrogen and oxygen gas from ullage volumes or said accumulators and the exhaust gas from the internal combustion engine.
4. A system, as claimed in claim 3, further including: at least one heat exchanger in communication with said at least one axial thruster for selectively modifying temperature of at least one of said waste ullage gases or liquid propellants prior to transfer of said gases to one of said accumulators.
5. A system, as claimed in claim 1, further including: an oxygen pump for pressurizing the oxygen accumulator, and a hydrogen pump for pressurizing the hydrogen accumulator, said pump being driven by corresponding pump motors, said pump motors being powered by at least one of electrical current from said battery and/or mechanical power from said output shaft of said internal combustion engine.
6. A system, as claimed in claim 1, wherein: said internal combustion engine includes a Wankel engine, said Wankel engine including an internal rotor rotating within an engine block, said rotor dividing internal space within said engine block into three separate compartments including an intake chamber, a combustion chamber, and an exhaust chamber.
7. A system, as claimed in claim 6, wherein: said Wankel engine further includes a cooling jacket surrounding said engine block, and wherein hydrogen gas from hydrogen ullage flows in the space between said engine block and said jacket to cool the engine.
8. A system, as claimed in claim 7, wherein: said hydrogen circulating between said cooling jacket and said engine block is further circulated within the engine block to the intake chamber for use as fuel within the engine.
9. A system, as claimed in claim 1, wherein: said internal combustion engine, said power generator, said battery, said accumulators, and said plurality of thrusters comprise an IVF module mounted to an aft portion of said launch vehicle.
10. A system, as claimed in claim 9 wherein: said IVF module includes a pair of IVF modules, each of said modules mounted to opposing sides of said launch vehicle to provide redundant capabilities.
11. A system, as claimed in claim 1, wherein: each of said tanks include a plurality of vent, purge, and bleed lines communicating therewith, each of said hydrogen and oxygen tanks including a vent line, a pressurization line, a bleed line, and a purge line.
12. A system, as claimed in claim 1, wherein: said plurality of thrusters is arranged on a thruster panel assembly including a hydrogen manifold and an oxygen manifold for delivering hydrogen and oxygen to said thrusters.
13. A system, as claimed in claim 1, wherein: said internal combustion engine includes a piston engine.
14. A method of providing mechanical energy for supporting functions of an upper stage launch vehicle, said method comprising: providing: (i) a pair of tanks for storage of propellants therein including a hydrogen tank and an oxygen tank; (ii) an internal combustion engine powered by hydrogen and oxygen removed from said tanks; (iii) a power generator communicating with an output shaft of said internal combustion engine for generating electrical current; (iv) a battery in electrical communication with said generator for storing the electrical current; (v) a gaseous oxygen accumulator for storing oxygen removed from the oxygen tank; (vi) a gaseous hydrogen accumulator for storing hydrogen removed from the hydrogen tank; (vii) a plurality of thrusters to provide attitude and settling control of the launch vehicle; powering at least one thruster of said plurality of thrusters by exhaust gas from the internal combustion engine; powering at least one thruster of said plurality of thrusters by oxygen and hydrogen gas from said accumulators; and powering at least one thruster of said plurality of thrusters by hydrogen and oxygen from the main vehicle tanks.
15. The method of claim 14, further comprising an alternator, and wherein said battery is in communication with said alternator, and said alternator is in communication with said generator, and the battery is charged by current passing through the alternator.
16. A method of pressurizing a propellant tank of an upper stage launch vehicle, said method comprising: providing: (i) a pair of tanks for storage of propellants therein including a hydrogen tank and an oxygen tank; (ii) an internal combustion engine powered by hydrogen and oxygen removed from said tanks, said internal combustion engine having an output shaft; (iii) a power generator communicating with said output shaft of said internal combustion engine for generating electrical current and for starting the internal combustion engine; (iv) a battery in electrical communication with said power generator for storing the electrical current; (v) a gaseous oxygen accumulator for storing oxygen from the oxygen tank; (vi) a gaseous hydrogen accumulator for storing me hydrogen from the hydrogen tank; (vii) a plurality of thrusters to provide attitude and settling control of the vehicle; pressurizing the accumulators by communication with at least one pump, said at least one pump being powered by at least one of electrical current from said battery or mechanical energy from said output shaft of the internal combustion engine; and pressurizing the tanks by pressurization lines from said accumulators.
17. A method of providing electrical power for an upper stage launch vehicle said method comprising: providing: (i) a pair of tanks for storage of propellants therein including a hydrogen tank and an oxygen tank; (ii) an internal combustion engine powered by hydrogen and oxygen removed from said tanks; (iii) a power generator communicating with an output shaft of said internal combustion engine; (iv) a battery in electrical communication with said generator for storing the electrical current; (v) a gaseous oxygen accumulator for storing oxygen from the oxygen tank; (vi) a gaseous hydrogen accumulator for storing hydrogen from the hydrogen tank; (vii) a plurality of thrusters to provide attitude and settling control of the vehicle; generating electrical current by said electrical power generator driven by an output shaft of the internal combustion engine; storing the electrical power in the battery; and selectively using electrical current stored in said battery for electrical systems of said launch vehicle.
18. A method of providing vehicle settling for a space launch vehicle in orbit, said method comprising: providing: (i) a pair of tanks for storage of propellants therein including a hydrogen tank and an oxygen tank; (ii) an internal combustion engine powered by hydrogen and oxygen removed from said tanks; (iii) a generator communicating with said output shaft of said internal combustion engine for generating electrical current and for starting the internal combustion engine; (iv) a battery in electrical communication with said generator for storing the electrical current; (v) a gaseous oxygen accumulator for storing medium pressure oxygen from the oxygen tank; (vi) a gaseous hydrogen accumulator for storing medium pressure hydrogen from the hydrogen tank; (vii) a plurality of thrusters to provide attitude and settling control of the vehicle; activating at least one thruster of said plurality of thrusters by exhaust gas from the internal combustion engine for long duration, low thrust requirements; and activating at least one thruster of said plurality of thrusters by waste ullage gas stored either in said accumulators, or by venting oxygen and hydrogen from said tanks directly to said at least one thruster.
19. A method of venting propellant tanks of an upper stage launch vehicle, said method comprising: providing: (i) a pair of tanks for storage of propellants therein including a hydrogen tank and an oxygen tank; (ii) an internal combustion engine powered by waste ullage hydrogen and oxygen vented from said tanks, said internal combustion engine having an output shaft; (iii) an alternator communicating with said output shaft of said internal combustion engine for generating electrical current; (iv) a battery in electrical communication with said alternator for storing the electrical current; (v) a gaseous oxygen accumulator for storing moderate pressure oxygen extracted from the main oxygen tank; (vi) a gaseous hydrogen accumulator for storing moderate pressure hydrogen extracted from the main hydrogen tank; (vii) a plurality of thrusters to provide attitude and settling control of the vehicle; (viii) providing a gaseous hydrogen vent line from the hydrogen tank and a gaseous oxygen vent line from said oxygen tank, said vent lines communicating with at least one of said plurality of thrusters; and venting the propellant tanks by the vent lines and using the gaseous hydrogen and gaseous oxygen as fuel and oxidizer for activation of said at least one of said plurality of thrusters.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) FIG. 1 is a fragmentary perspective view of part of an upper stage of a space launch vehicle illustrating an IVF module mounted to the aft deck of the upper stage;
(2) FIG. 2 is an enlarged perspective view of the IVF module;
(3) FIG. 3 is a schematic diagram illustrating one aspect of the invention, namely, the provision of an internal combustion engine in the IVF system to produce mechanical power;
(4) FIG. 4 is a cross-sectional schematic diagram of the ICE of the present invention, in the form of a Wankel engine;
(5) FIG. 5 is another schematic diagram for another aspect of the invention, namely, the provision of electrical power;
(6) FIG. 6A is another schematic diagram illustrating yet another aspect of the invention, namely, provision of a thruster assembly for sustained vehicle settling using exhaust gas from the ICE;
(7) FIG. 6B is another schematic diagram for the aspect of FIG. 6A, but using ullage gases for powering the thruster assembly;
(8) FIG. 7 is a simplified schematic diagram illustrating the port and starboard positioning of separate IVF modules for the upper stage of the vehicle;
(9) FIG. 8 is a perspective view of an example construction for a thruster assembly including a panel to which the thrusters may be mounted, along with hydrogen and oxygen manifolds for delivery fluids to the thrusters;
(10) FIG. 9 is a schematic diagram illustrating another aspect of the invention, namely, tank pressurization and vent;
(11) FIG. 10A is a schematic diagram illustrating another aspect of the invention, namely, venting the propellant tanks directly through the thrusters;
(12) FIG. 10B is a schematic diagram illustrating the aspect of FIG. 10A, but venting through the ICE;
(13) FIG. 11 is schematic diagram illustrating another aspect of the invention, namely, accumulator replenishment;
(14) FIG. 12 is a schematic diagram of one type of axial thruster, namely, exhaust gas thrusting;
(15) FIG. 13 is a schematic diagram of another type of axial thruster, namely, one that combusts GH.sub.2 and GO.sub.2;
(16) FIG. 14 is another schematic diagram illustrating basic functions of the IVF module; and
(17) FIG. 15 is a system schematic illustrating the primary elements within the integrated fluid system and fluid connections between the elements in the system.
DETAILED DESCRIPTION
(18) FIG. 1 illustrates the upper stage 10 of a space launch vehicle. The outer covering or shell 12 is broken away to view the propellant tanks 14, which comprise the liquid hydrogen tank 60 and the liquid oxygen tank 62 with a common bulkhead separating the tanks. The aft of the vehicle includes a circumferential deck 16 that provides for mounting of various system components 20 such as avionics, fluid and mechanical devices as well as the IVF module 30 of the present invention. FIG. 1 also illustrates the main propulsion rockets 18 that are used to propel the upper stage 10. In the Figure, the relatively small size of the IVF module 30 is shown. Preferably, there is an IVF module mounted on opposite sides of the aft deck 16. Twin IVF modules are able to generate more than enough power to supply all of the upper stage system requirements, yet reduce overall vehicle weight by eliminating much of the wiring harness mass associated with traditional vehicles that use battery power. The elevated DC voltages that can be provided by the battery of an IVF module is also valuable for reducing EMA actuator mass. The particular vehicle 10 illustrated is a conceptual 41 ton propellant capacity upper stage. However, the IVF module of the present invention can be used with any type of upper stage vehicle that has at least some minimal space for mounting of exterior components.
(19) Referring to FIG. 2, an example is provided for an IVF module design. In this Figure, major structural components of the IVF module are illustrated to include a GO.sub.2 accumulator 34, a GH.sub.2 accumulator 36, and mounting straps 38 that can be used to mount the accumulators to a frame of the module. Lines 40 and 42 communicate with the accumulators 34 and 36, and represent either vent, purge, or pressurization lines associated with the accumulators. A housing 44 is provided for the internal combustion engine (not shown), and a plurality of various other gas/liquid lines 50 are shown protruding from the frame for delivering gas or liquid throughout the system. A thruster group or assembly 46 is illustrated as another component of the module having a plurality of thrusters for settling and attitude control of the upper stage. As shown, the thruster assembly 46 includes a pair of axial thrusters 98, two pairs of opposing pitch thrusters 94, and a pair of yaw thrusters 96. A vehicle battery 48 is also illustrated and is secured to the IVF module, the battery 48 being charged by a generator connected to the output shaft of the ICE as discussed below.
(20) FIG. 3 illustrates one aspect or concept of the present invention, namely, the provision of a small internal combustion engine (ICE) 80 that is used to provide power for the upper stage systems. In a preferred embodiment, the size of the ICE 80 is approximately 200 cc, and runs at a preferred mixture ratio between 0.6 and 2.0. As shown in the Figure, ICE 80 receives its GH.sub.2 fuel from the liquid hydrogen tank 60 by vent line 64. The oxidizer, GO.sub.2, is provided by an oxygen accumulator 34, through line 176, and metered through valve 76. The hydrogen vent line 64 communicates with a hydrogen intake mixture valve 72 that modulates the amount of hydrogen provided to the ICE. Depending upon demand, the ICE can also receive hydrogen through a dedicated hydrogen bleed line 66 that provides liquid hydrogen to the intake mixture valve 72. The metered amount of hydrogen is then combusted with the oxygen within the ICE, thereby producing a mechanical output shown as shaft 82. The exhaust gas from the ICE 80 is captured in exhaust line 84 that can be used for powering the axial thrusters as discussed below. The hydrogen vent line 64 would typically be used to dispose of waste ullage hydrogen gas. In the present invention; however, the waste ullage hydrogen is used to fuel the ICE. Optionally, the GH.sub.2 carried by line 100 downstream of the valve 72 can be used to cool the engine exterior, maintain pressure in the crank case, and cool the internal rotor of the ICE.
(21) Referring to FIG. 4 a particular construction is provided for the ICE 80 in the form of a Wankel engine. As illustrated, GO.sub.2 is provided through line 176, while the GH.sub.2 is provided through line 100 downstream of the intake mixture valve 72. The hydrogen is first circulated in a gap 92 between the engine block 90 and a cooling jacket 88. As the low pressure GH.sub.2 is circulated, it warms by heat transfer from the block 90, and finally flows to the intake port 93. Valve 104 can be used to meter the GH.sub.2 flowing into the ICE. Once inside the engine, the hydrogen first enters the fuel intake chamber 108. A solenoid injector valve 76 opens at the correct moment during the intake phase to inject the GO.sub.2. This injector also prevents GO.sub.2 back flowing into the GH.sub.2 system, and also controls the engine mixture ratio. As the rotor 114 rotates about the eccentric shaft 116, the hydrogen and oxygen are then compressed with an area defined as the combustion chamber 110. Spark plugs 102 provide the source of ignition for igniting the fuel within the combustion chamber 110. The expansion of the gases in the combustion chamber provide the motive force for rotating the rotor 114, thus moving the combusted gas to the portion of the engine defined as the exhaust chamber 112. The high temperature, GH.sub.2 rich and pressurized gas exits the exhaust port 118 into the exhaust line 84. Although one will appreciate the simple, yet effective design for a Wankel engine incorporated in the IVF system of the present invention, it shall be understood that a standard piston engine (not illustrated) can also be used as the ICE 80. The GO.sub.2 and GH.sub.2 are provided to the piston engine in the same manner as illustrated for the Wankel engine. More specifically, the GO.sub.2 is provided through line 176, while the GH.sub.2 is provided through line 100 downstream of the intake mixture valve 72. The hydrogen can be circulated in a gap between the engine block and cooling jacket of the piston engine. As the low pressure GH.sub.2 is circulated, it warms by heat transfer from the block, and finally flows to a fuel intake port of the piston engine. Valve 104 can be used to meter the GH.sub.2 flowing into the piston engine. Once inside the engine, the hydrogen is transferred to the cylinders. One or more injector valves can be used to inject the GO.sub.2 into the cylinders for mixing with the GH.sub.2. Spark plugs 102 provide the source of ignition for igniting the fuel within the cylinders. The expansion of the gases upon ignition provide the motive force for rotating a crankshaft of the piston engine, and the combusted gases are evacuated from the cylinders to the portion of the engine defined as the exhaust chamber 112. The high temperature, GH.sub.2 rich and pressurized gas exits the exhaust port 118 into the exhaust line 84.
(22) Referring to FIG. 5, in another aspect of the present invention, electrical power is provided by an electrical alternator 86 that is driven by the output shaft 82 powered by the ICE 80. The alternator 86 in turn provides electrical current for charging a battery 48. For IVF system pumping requirements to charge the accumulators as discussed below, power can be supplied either from the battery 48, or power can be provided by the output shaft 82 to a clutch (not shown) connected to the accumulator pumps. The clutch can be engaged and disengaged to operate the pumps. As the vehicle operates, the battery 48 will discharge during peak loading requirements, but will recharge during vehicle coasts, i.e., those times during which power demands are low. The use of a charged battery 48 removes previous restrictions on peak power and total available energy that was a problem with prior launch vehicle systems in which power was limited to only battery power.
(23) FIG. 6A is another schematic diagram illustrating another aspect of the invention, namely, sustained settling modes provided by the thruster assembly 46. The thruster assembly as mentioned includes a pair of axial thrusters 98 that provide settling thrust. For long duration, low thrust settling, the high temperature, high pressure exhaust 84 can be used directly from the ICE to generate thrust 120. However, the thrust 120 provided in this mode is limited by the peak mass flow through the engine and the allowable engine combustion temperature. Using the exhaust gas of the ICE is a very efficient method for sustained settling, since the ICE is normally operating to provide vehicle power and will rarely cease to operate for any extended period of time. Therefore, there is a constant flow of exhaust gas 84 that can be used for providing thrust. In another vehicle settling mode shown in FIG. 6B, settling thrust can be provided directly through the GH.sub.2 ullage vent line 64 to the thruster assembly, with oxygen provided directly through the GO.sub.2 ullage vent line 68. These ullage gases are then combined and combusted in combustion chamber of the thrusters. The ullage gases provide more than sufficient fuel and oxidation material for running the axial thrusters.
(24) Referring to FIG. 7, a schematic diagram is provided showing that a pair of IVF modules 30 is used, each having the same construction, and mounted to opposite sides of the vehicle 10 when looking at the vehicle outer diameter in schematic cross section. The IVF modules 30 are generally illustrated showing the thruster assemblies 46 having the pitch thrusters 94, yaw thrusters 96, and axial thrusters 98. The pair of IVF modules 30 provides redundancy without adding significant weight.
(25) Referring to FIG. 8, an example is provided for a specific thruster assembly construction. Specifically, a panel 140 can be used to mount the yaw thrusters 96 on one side of the panel, while the two pairs of pitch thrusters 94 can be mounted on the other side of the panel 140. A hydrogen manifold 142 comprises a plurality of lines and fittings for carrying hydrogen to the thrusters, while an oxygen manifold 142 also comprises a plurality of lines and fittings for carrying oxygen to the thrusters. The axial thrusters 98 can also be mounted to the panel 140, or may be mounted to a separate panel. It is noted that the particular thruster panel assembly shown in the FIG. 8 can be modified to allow the thrusters to conveniently fit within the space available on the mounting structure of the space vehicle. As compared to in the FIG. 2, the FIG. 8 shows a different, yet functional arrangement for the thrusters.
(26) Referring to FIG. 9, yet another concept is illustrated with respect to the invention, namely, tank pressurization. As shown, both the LH.sub.2 60 and LO.sub.2 tanks 62 have respective pressurization lines. Specifically, an oxygen pressurization line 78 pressurizes the oxygen tank 62, while the hydrogen pressurization line 79 pressurizes the hydrogen tank 60. The accumulators 34 and 36 are maintained at an adequate pressure, and the tank pressurization controls 122 monitor and adjust pressurization. In this model, the accumulators supply all of the pressurization required for the propellant tanks to operate.
(27) FIGS. 10A and 10AB illustrate yet another aspect of the invention, namely, tank venting. Referring to FIG. 10A in one tank venting mode, the propellant tanks can be directly vented through the axial thrusters 98. The ullage gases are combined and combusted in the axial thrusters. As shown, the GH.sub.2 vent line 64 and GO.sub.2 vent line 68 both connect to the axial thrusters. The high thrust forces that can be generated with use of the ullage gases in this manner are very valuable to prevent vehicle shutdown caused by slosh of the LO.sub.2 and GH.sub.2. This high thrust producing venting mode can be activated at any time to relieve pressure in the propellant tanks, as well as to provide on demand, additional thrust for settling and attitude control. Referring to FIG. 10B in a low flow venting mode, the GH.sub.2 and the GO.sub.2 demands from the ICE engine 80 are normally sufficient for relieving pressure in the propellant tanks to maintain them in optimal pressure conditions. The vent lines 64 and 68 provide the flow of GH.sub.2 and GO2, respectively to the ICE 80. The operation of the ICE 80 in this low venting mode provides continuous settling of the vehicle, and suppresses heating within the tanks to prevent boil off of the propellants.
(28) Now referring to FIG. 11, in accordance with another aspect or concept of the present invention, accumulator replenishment is illustrated. One fundamental concept of accumulator replenishment is that the accumulators 34 and 36 must be pressurized. Accordingly, pumps 134 and 135 are provided to pressurize the lines 153 and 152 that charge the accumulators 34 and 36, respectively. Drive motors 132 and 133 drive the pumps 134 and 135. The drive motors 132 and 133 may be powered by either the ICE 80, or may be electrically powered by the battery 48. A LO.sub.2 bleed along with a GO.sub.2 vent from tank 62 are controlled respectively by a liquid inlet valve 148 and ullage gas inlet valve 150. In the FIG. 11, these valves 148/150 are shown as a single block. These valves then meter the ullage gas or liquid oxygen through the pump 134 for ultimate delivery to the GO2 accumulator 34. The outlet line 153 from the pump 134 carries the ullage gas/liquid oxygen in a heat exchange relationship through the thruster group 46, functioning to extract heat as necessary from one or more of the thrusters in the assembly 46. The line 153 then carries the gaseous oxygen to the accumulator 34. The same arrangement is provided for hydrogen in which liquid hydrogen or GH.sub.2 ullage are provided through the inlet control valves 149/151, the pump 135 delivers the liquid/gaseous oxygen through outlet line 152 and in a heat exchanger relationship with the thruster group 46. Line 152 then carries the gaseous hydrogen to the GH2 accumulator 36. In summary, the motor driven pumps pressurize the ullage or liquid up to the necessary accumulator pressures. Liquid compression enables high pressure requiring only low shaft power from the drive motors 132 and 133. Heat is selectively added as needed through the thruster group 46 to thereby deliver primarily GH2 and GO2 through the lines 152 and 153, as most LH.sub.2 and LO.sub.2 will boil when coming in contact with the thruster group 46.
(29) Referring to FIGS. 12 and 13, in another aspect of the invention, different types of axial thrusters are illustrated. Referring first to FIG. 12, exhaust gas thrusting is illustrated. The exhaust 84 from the ICE 80 communicates with one or more inlet ports 160 of a thruster 98. The GH.sub.2 rich exhaust gas at high temperature is then routed through internal passageways 162 of the thruster to the aft or rear end 164 of the thruster. At that point, the high temperature and pressurized gas is vented through one or more openings 168 into a first smaller chamber 168, through a nozzle or restriction 170, and then is allowed to expand within the cowl 172. The thrust is provided by the expanding gas as it passes through the nozzle 170 into the cowl 172. Therefore, efficient means are provided for axial thrusting by simply utilizing the exhaust gas from the ICE 80. Although the axial thruster 98 is illustrated, it is also contemplated that the exhaust gas 84 can be used to power any of the other thrusters.
(30) Referring to FIG. 13, another type of thruster is illustrated in which ullage GH.sub.2 is combined with ullage GO.sub.2 and then combusted to create gas expansion and production of thrust. More specifically, one or more ullage gas inlets 180 are provided for receiving ullage GH.sub.2, such as through vent line 64. Similarly, oxygen can be provided through GO.sub.2 vent line 68. The GH.sub.2 flows through passageways 182 to cool the thruster, and through openings 184 to join the GO.sub.2 in the combustion chamber 188. An ignition source (not shown) ignites the GO.sub.2 and GH.sub.2, resulting in an expansion of gas through nozzle 190 into the cowl 192. FIG. 13 also shows the heat exchange that can occur with the liquid or gaseous propellants carried in the lines 152/153. As shown, a simple heat exchanger 198 is illustrated as a jacket that allows flow of the propellants over the exterior of the thruster to absorb heat from the thruster. The propellants are then carried downstream to the respective accumulators.
(31) Referring to FIG. 14, a system overview is provided showing the basic functions of the IVF system. In general, the IVF system provides functions to include attitude control, sustained settling, tank pressurization, and a power supply. The ICE 80 provides power for an alternator 86 to generate current to be stored by the battery 48. The ICE 80 can also provide power to the drive motors 132 and 133 for powering the oxygen and hydrogen pumps 134 and 135 in order to pressurize the accumulators 34 and 36. The accumulators store GO.sub.2 and GH.sub.2 at high pressures, and provide the source of high pressure to pressurize the propellant tanks. Tank pressurization controls 122 monitor and maintain the LH.sub.2 tank 60 and LO.sub.2 tank 62 at the proper pressures. The exhaust gas 84 from the ICE 80 can be used to drive the axial settling thrusters 98. Alternatively, ullage gas, supplemented with liquid hydrogen under peak demands, provides sustained settling thrust that greatly reduces losses in the tanks. The ICE 80 as well as the settling thrusters 98 can be cooled from the waste ullage gases by first passing the gases in a heat exchange relationship prior to combustion. The ICE 80 and the battery 48 work together to share power demands. Specifically, power boosts can be easily provided by changing the fuel mixture ratio for the ICE in order to either more quickly charge the battery 48 or to provide the necessary mechanical power for other vehicle systems.
(32) Referring to FIG. 15, a schematic system diagram is provided with a more detailed view of a plumbing schematic showing the system components and manner in which they are interconnected. More specifically, an IVF module 30 is shown with components, and the general piping connections between the components. The additional IVF module 30 shown on the right side of the diagram within the dotted lines has the same piping configuration as the fully illustrated IV module on the left side of the figure, but for clarity, the piping configuration is not shown for the right side IVF module.
(33) Referring to the schematic diagram of FIG. 15, the various vent, purge, and bleed lines/elements are illustrated as they communicate with the propellant tanks. As also discussed in part with reference to the prior Figures, these vent, purge and bleed lines include hydrogen vent 64, hydrogen pressurization 79, GH.sub.2 bleed 131, H.sub.2 purge 137, LH.sub.2 bleed 66, GO.sub.2 vent 68, GO.sub.2 pressurization 78, and LO.sub.2 bleed 70.
(34) For the axial thrusters 98, the schematic diagram shows the heat exchangers 198 that receive the pressurized gas/liquid through the lines 152/153 that are pressurized by the pumps 134 and 135. Bypass valves 196 allow the fluid/gas to be delivered directly to the accumulators without passing through the heat exchangers 198. As shown, only one of the axial thrusters 98 communicates with the exhaust line 84 for receiving the GH.sub.2 rich heated gas, while both of the axial thrusters are shown as being capable of operating as combustion type thrusters in which lines carry the ullage GO.sub.2 and GH.sub.2 to the axial thrusters for combustion.
(35) For the pitch and yaw thrusters, these are preferably combustion type thrusters, each receiving GH.sub.2 and GO.sub.2 from the accumulators as shown. Specifically, pitch thrusters 94 and yaw thrusters 96 receive GO.sub.2 from line 176 that connects directly to the GO.sub.2 accumulator 34, and thrusters 94 and 96 receive GH.sub.2 fuel from lines 174 that connect directly to the GH.sub.2 accumulator 36.
(36) As also discussed previously, the combination of vent and bleed lines from the LH.sub.2 and LO.sub.2 tanks provide fuel and an oxidizer to the ICE 80 that produces power for the vehicle. FIG. 15 also shows a supplemental method of providing oxidizer to the ICE 80 by inducting oxygen directly into the ICE 80 from the LO.sub.2 tank ullage instead of from the accumulator 34 and through the injector 76. Specifically, FIG. 15 shows the supplemental method by an extension of the LO.sub.2 bleed line 70 that connects directly to another intake port of the ICE 80. A throttle valve 71 connected inline can be used to meter the LO.sub.2 into the ICE 80 at a desired rate. One advantage of this supplemental method is that the ICE 80 can be operated without having to operate any system pumps.
(37) The attitude and settling thrusters operate with combustion of the propellants, or at least one of the thrusters can produce thrust by using the exhaust gas from the ICE. The accumulators are pressurized, and control pressures in the propellant tanks. The IVF module is small, but can produce power and thrust to service all of the vehicles needs in these requirements.
(38) While the present invention has been explained and illustrated with respect to various functional features or aspects in one or more preferred embodiments, it shall be understood that the invention can be modified, commensurate with the scope of the claims appended hereto. Further, it should be understood that each of the different concepts or aspects of the invention can be considered as having separate utility. Accordingly, the invention comprises a number of separate sub-combinations and combinations that have utility with respect to supporting the functions of an upper stage space vehicle.
