Aeronautics and astronautics – Missile stabilization or trajectory control – Automatic guidance
Reexamination Certificate
1997-09-23
2001-11-13
Tudor, Harold J. (Department: 3641)
Aeronautics and astronautics
Missile stabilization or trajectory control
Automatic guidance
C060S228000, C239S265290, C239S265310, C244S169000
Reexamination Certificate
active
06315239
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to rocket propelled vehicles such as missiles, and more particularly, to arrangements for steering such vehicles by a combination of steering fin control and jet reaction control.
2. Description of the Related Art
Missile control can be effected using a variety of steering schemes. One such scheme involves pivoting the thrust vectoring nozzle of the missile about a pivot point and controlling the direction of its thrust in order to provide steering in a desired direction.
Another method utilizes movable aerofins projecting into the airstream around the missile. This imparts to the missile the necessary forces to change its direction during flight within the earth's atmosphere and thereby effect steering control.
Jet reaction control (JRC) provides yet another method for steering a missile during flight, and is shown in U.S. Pat. No. 5,016,835 of Kranz. This method involves selective firing of jet nozzles disposed radially around the periphery of the missile in order to orient the missile in a desired direction. The fired jets impart an opposing reactive force on the missile and, depending on their arrangement, can serve to produce a change in direction along the yaw, pitch and/or roll axes.
It is also known in the art to effect missile control during flight using a combination of steering methods. One such combination, disclosed in U.S. Pat. No. 5,505,408 of Speicher et al., assigned to the same assignee as the present invention and incorporated herein by reference, relies on both jet reaction control (JRC) and control actuator fins. The two steering schemes operate in conjunction with one another to effect missile control, and yield a particularly advantageous arrangement because in some situations, when the dynamic pressure is low, such as during high attack angles or in a reduced atmosphere, the jet reaction control mechanism can compensate for the diminished effectiveness of the steerable aerofins, avoiding a compromise of missile maneuverability.
SUMMARY OF THE INVENTION
Arrangements in accordance with the present invention use an integrated missile steering system in which both jet reaction control and steerable aerofins are employed. An improved mechanical linkage between the jet reaction control and the steerable aerofins is provided, enhancing overall system performance. Use is made of a variable coupling arrangement which operates to completely decouple the two steering mechanisms or to change their relative responsiveness to steering command signals.
Different embodiments of the invention utilize various mechanical linkages between the steerable aerofins and the pintles which control the efflux of exhaust gases from the nozzles of the jet reaction control mechanism. These mechanical linkages can be arranged such that the ratio between the fin motion and the pintle motion can be adjusted so that small fin motions give large pintle motions. Moreover, the invention allows large pintle motions with small fin motions to be used initially in the missile flight and then, upon-burn out of the thrust vectoring gas generator, allows large fin motions without over stroking the pintle actuator. Use with a multiple burn gas generator is also contemplated, where the pintles would decouple between gas generator burns and couple during burns.
According to the invention, the decoupling is performed in a cost effective and highly reliable manner, allowing full motion of the aerofins without damage to the pintles or pintle drive mechanisms. Two implementations are employed, one in which a yoke plate is used, and the other in which differential area pistons in the pintles themselves are used.
According to the first, yoke plate arrangement, use is made of a simple mechanism which effectively unlocks the pivot bearing of the joystick lever which manipulates the individual pintles, allowing the joystick to move sideways, rather than to pivot about a point, when forces are applied thereto by the yoke plates, effectively disengaging it from the pintles. This mechanism is reliable and Low cost and is simply activated by the process of pressurizing the gas generator. Upon pressurization of the gas generator, a piston is pushed axially to capture the pivot bearing of the joystick, preventing ineffectual sideways movement of the pivot bearing and joystick and coupling the joystick to the pintles. When pressure is released at burn-out of the gas generator, forces on the joystick push the piston axially to unlatch the pivot bearing. The result is a system which is normally unlocked until the gas generator is pressurized and which stays locked during gas generator pressurization and then subsequently unlocks at depressurization. This allows full aerofin control during periods of the flight when jet reaction control is not desired or is unavailable. It also allows different ratios to be selected to optimize the response of the pintle actuators while the aerofin in motion could be restrained due to this ratio selection. An alternative embodiment uses radially, rather than axially, mounted pistons.
The second arrangement provides the mechanical coupling using a differential area piston in the pintle itself. This differential area piston extends the pintle to an internal hard stop when the gas generator chamber is pressurized. This allows normal functioning of the gas generator and pintle system at pressurization. Upon depressurization or burn out, the differential area piston allows the pintle to move axially when the aerofin actuator causes the pintle to contact the nozzle throat. This system is inherently simple and relies on chamber pressure to control the pintle state and allows inherent decoupling from the aerofin actuator upon depressurization. If the pintle repressurizes, the pintles are recoupled to the stick.
In one configuration the joystick is dispensed with and the pintle is driven by a pinion coupled directly to the actuator which operates the aerofins. A dual pintle arrangement is used, with dual differential area pistons which cause the pintles to be extended internally until they reach a hard stop. When the chamber pressure drops, the pintles are allowed to retract into the housing which supports them, thereby allowing the aerofin actuator to have larger strokes than a hard mounted pintle would.
REFERENCES:
patent: 4826104 (1989-05-01), Bennett et al.
patent: 4955558 (1990-09-01), Machell et al.
patent: 5016835 (1991-05-01), Kranz
patent: 5405103 (1995-04-01), Girardeau et al.
patent: 5456425 (1995-10-01), Morris et al.
patent: 5505408 (1996-04-01), Speicher et al.
patent: 5630564 (1997-05-01), Speicher et al.
Bissell Henry M.
Tudor Harold J.
Versatron, Inc.
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