Power plants – Reaction motor – Interrelated reaction motors
Reexamination Certificate
1999-04-22
2001-09-25
Thorpe, Timothy S. (Department: 3746)
Power plants
Reaction motor
Interrelated reaction motors
C060S230000, C060S232000, C060S245000, C060S246000, C060S250000, C060S251000, C060S279000, C060S279000
Reexamination Certificate
active
06293091
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to airframes having a combined rocket engine and ramjet or scramjet.
2. Description of the Prior Art
Ramjets provide fuel efficient propulsion of airframes at high Mach numbers. A ramjet operates under locally subsonic combustion conditions while a scramjet or supersonic combustion ramjet, operates under locally supersonic combustion conditions. To date, ramjets are in use and scramjets are currently under design but not yet field deployed. The current state of the art of scramjet technology involves ground testing in high speed wind tunnels and certain flight articles have been flown on forebodies of missiles and research airplanes. Scramjets were proposed on the X-30 high speed propulsion system but this program was cancelled before the technology was taken to fruition.
A need exists for an inexpensive high speed cruise type airframe having a fixed geometry which does not eject objects, such as staging that could injure civilians in the flight path, having a long operation range such as between 400-700 nautical miles. In order to successfully operate a ramjet engine in this environment, it is necessary to boost its speed to takeover velocities, about Mach 2 or greater, where the liquid fueled ramjet engine can operate efficiently and propel the missile for the remainder of the flight. A scramjet, or supersonic combustion ramjet, typically operates at speeds above Mach 6. Like a ramjet it requires another means to accelerate itself to operational speeds.
Chemical rocket engines provide the simplest mechanism for accelerating a platform up to takeover velocity but suffer from the deficiency of being space inefficient as a consequence of the necessity to carry oxidizer. The oxidizer is the majority of the propellant mass in a rocket-based missile which can reduce its effective range by factors between three to six times compared to ramjet engines which burn atmospheric air.
Plug nozzles were developed in the 1970's. A plug nozzle has a plume which is shaped by the external atmospheric air.
Two missile systems have been developed which utilized a solid rocket engine mounted within the combustion chamber of a ramjet. The first missile system is the French ASMP (AirSol-Moyenne-Portee') medium range air to ground missile having a range of 250 km. and a maximum speed of about Mach 3.0. The second missile is the Russian SA-6 Gainful ground to air missile which has a range of 60 km., at an altitude of 18 km. and a maximum speed of about Mach 2.8.
The U.S. Navy's Talos surface to air system, which is no longer in service, utilizes a separate rocket booster motor in conjunction with a ramjet.
SUMMARY OF THE INVENTION
The present invention is an improved airframe which contains a rocket engine, which may use either solid or liquid propellant, that is nested in the longitudinally extending air passages of an axisymmetric ramjet or scramjet engine. The rocket engine quickly boosts the airframe up to takeover velocity of the ramjet or scramjet engine at which fuel efficient ramjet or scramjet operation is produced for long ranges such as 400 to 700 Nmi. The rocket engine is cleared from the longitudinal extending air passages of the jet engine to permit full ingress and passage of external air to the ramjet or scramjet combustion chamber. The chemical rocket engine is disposed in an annular cross section of the longitudinally extending passages symmetrical about the longitudinal axis of the airframe which provides efficient space utilization.
The plug nozzle provides automatic compensation for changes in external pressure which permits launching from underwater, ground level or from aircraft while providing high propulsion performance. Additionally, the plug nozzle is equally efficient at producing thrust for rocket and ramjet/scramjet operation across the altitude range.
The invention has application for high speed missiles or the first stage of a space launch vehicle. Furthermore, operation across multiple platforms and multiple operating conditions may be achieved.
The longitudinal passage is located between an outer cylindrical wall and inner cylindrical wall of the vehicle; and a liquid fuel tank having an outer cylindrical surface is inside an inner surface of the inner cylindrical wall so that the pressurized liquid propellant tank resists compressive force produced by combustion by the solid or liquid propellant rocket engine. An inner ablative material is positioned adjacent an outer surface of the thrust plug. An outer ablative material is positioned adjacent the end and spaced from the inner ablative material to define an annular exit opening through which combustion gas is passed from the solid or liquid propellant rocket. The thrust plug is pivotable relative to a longitudinal axis of the airframe to direct thrust relative to the longitudinal axis to provide direction control. Fuel injectors for the ramjet or scramjet are disposed in the longitudinal passage forward of the solid or liquid propellant rocket engine and flame holders are disposed in the longitudinal passage forward of the solid fuel rocket engine and to the rear of the fuel injectors. The solid fuel or liquid propellant rocket engine has a bulkhead which faces forward, is frangible and shatters upon ending of operation of the solid fuel rocket engine to clear the longitudinal passage to the flow of external air. An explosive may be disposed in the forward bulkhead for shattering the forward bulkhead upon ending of operation of the solid or liquid propellant rocket.
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Hodge Kathleen F.
Seymour Nathanael F.
Hayes Eric
Thorpe Timothy S.
Thousand Connie M.
TRW Inc.
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