Power plants – Reaction motor – With thrust direction modifying means
Reexamination Certificate
1999-12-01
2001-10-09
Freay, Charles G. (Department: 3746)
Power plants
Reaction motor
With thrust direction modifying means
C239S265110, C239S265170, C239S265190, C239S265230, C239S265390
Reexamination Certificate
active
06298658
ABSTRACT:
TECHNICAL ART
The instant invention generally relates to fluidic thrust vectoring nozzles by which the direction of flow of a stream of primary gas is controlled by one or more control ports that operatively couple a source of pressure differential to one or more nozzle surfaces along which the stream of primary gas flows.
BACKGROUND OF THE INVENTION
Rockets, missiles, aircraft and other jet or rocket powered objects frequently use a thrust vectoring system for steering the object being thrusted. For example, a rocket or missile may be steered by controlling the orientation of a gimbaled nozzle., which can provide continuous control of the direction of the thrust vector over the range of travel of the nozzle assembly, but at the penalty of increased cost and complexity, and reduced reliability.
Alternately, the direction of thrust of a stream of exhaust gas exiting from a nozzle may be controlled fluidically by using either lateral control jets, attachment surfaces or a combination thereof. In accordance with the Coanda effect, a fluid stream traveling parallel and proximate to a surface can becomes attached thereto by the vacuum created between the fluid stream and the surface. A fluid stream may also be deflected by control jets by transfer of momentum from the control jets to the fluid stream. Furthermore, a fluid stream may be drawn towards a proximate surface by applying a vacuum to ports disposed along the surface.
U.S. Pat. No. 3,204,405 teaches a three-dimensional jet vectoring system wherein a thrust nozzle is provided with two orthogonal pairs of control jets along the surfaces thereof, and associated fluidic control valves that control the discharge of a portion of the exhaust stream from a reaction propulsion motor, to control the deflection of the thrust jet exiting from the nozzle. In the longitudinal thrust state, the thrust jet is centered within and not attached to the surfaces of the thrust nozzle, whereas in the oblique lateral thrust modes, the thrust jet becomes attached to the portion of the nozzle surface towards which the thrust jet is deflected by the associated control jet. In the longitudinal thrust state, the thrust jet is not attached to a surface and accordingly is subject to directional variation. Furthermore, the direction of the attached thrust jet in the oblique lateral thrust modes is subject to variation depending upon the relative strengths of the orthogonal control jets, and is accordingly sensitive to variations in the control jet signals.
U.S. Pat. No. 3,740,003 teaches a missile control system wherein bi-stable fluid amplifies control the discharge of a portion of an exhaust stream through a plurality of control jets at the discharge of a nozzle, wherein each of the plurality of control jets discharges in one of two opposed lateral directions. The thrust direction of the control jets is symmetric about the longitudinal thrust direction , and a separate thrust nozzle is required for longitudinal thrust.
U.S. Pat. No. 3,806,063 teaches a monostable thrust control system for a missile wherein the power stream is discharged as a free stream away from the surface of the missile to provide lateral control, or is discharged as an attached stream along the surface of the missile so that the power stream augments the thrust to the missile. In the lateral thrust mode, the free stream is not attached to any surface and is accordingly subject to directional variations. Moreover, a separate thrusting system is needed to provide the principal longitudinal thrust to the missile.
U.S. Pat. No. 4,018,384 teaches an attachment device for modifying the direction of flow of an exhaust nozzle by causing a portion of the exhaust gases exiting therefrom to become attached to the attachment surface that is oblique to the direction of exhaust flow, thereby providing an oblique lateral control flow, wherein different attachment surfaces are provided for different oblique lateral thrust directions. Ambient air is directed through a plurality of ports on the attachment surface to detach the attached flow therefrom. This invention provides for free stream flow in the longitudinal thrust mode, and provides for the redirection of only a portion of the exhaust flow in the oblique lateral thrust mode, accordingly providing limited lateral control authority.
U.S. Pat. 4,537,371 teaches a system for controlling small caliber guided projectiles wherein ambient air is discharged through diametrically opposed exhaust nozzles along the side of the projectile, wherein the distribution of flow between the exhaust nozzles is fluidcially controlled in accordance with the Coanda effect. The thrust direction of the control jets is symmetric about the direction of forward travel, and there is no provision for providing a pure longitudinal thrust state.
SUMMARY OF THE INVENTION
The instant invention overcomes the above-noted problems by providing a bi-stable thrust vectoring nozzle for discharging a stream of primary gas across first and second surfaces downstream of a nozzle throat, wherein the stream of primary gas attaches to either the first or second surface, responsive to a differential pressure or flow signal across respective control ports on the respective first and second surfaces, corresponding to respective first and second control states. The first and second surfaces are each opposed to one another and at a different angle with respect to the nozzle axis, i.e. the axis of the stream flow within the nozzle throat, so that the stream of primary gas discharged from the bi-stable thrust vectoring nozzle in the respective control states provides respective thrust vectors that are asymmetric with respect to the nozzle axis. Accordingly, with the nozzle axis substantially aligned with the longitudinal axis of an object to be thrusted, i.e. aligned with the corresponding direction of forward travel, in a first control state with the stream of primary gas attached to the first surface, the resulting thrust vector provides forward thrust to the object, whereas in a second control state with the stream of primary gas attached to the second surface aligned obliquely to the longitudinal axis of the object, the resulting thrust vector provides oblique lateral thrust to the object so as to provide combined directional control and forward thrust.
In the first control state, a pressure or outflow is applied to the one or more control ports on the second surface, and a vacuum is applied to the one or more control ports on the first surface, thereby causing the stream of primary gas exiting from the nozzle throat, if attached to the second surface, to deflect away from the second surface and become attached to the first surface, in accordance with the Coanda effect. A vacuum applied to the one or more control ports on the first surface further improves the attachment thereto.
In the second control state, a pressure or outflow is applied to the one or more control ports on the first surface, and a vacuum is applied to the one or more control ports on the second surface, thereby causing the stream of primary gas exiting from the nozzle throat, if attached to the first surface, to deflect away from the first surface and become attached to the second surface. A vacuum applied to the one or more control ports on the second surface further improves the attachment thereto.
Whereas preferably both a pressure or outflow is provided to the one or more control ports on the surface from which the stream of primary gas is to be deflected, i.e. the non-attached surface, and a vacuum is simultaneously provided to the one or more control ports on the surface to which the stream of primary gas is to become attached, i.e. the attached surface, it will be understood by one of ordinary skill in the art that the instant invention can be practiced with a single control signal, i.e. either a pressure applied to the control port on the non-attached surface or a vacuum applied to the control port on the attached surface.
A pair of bi-stable thrust vectoring nozzle elements may be combined to form a multi-stable
Freay Charles G.
Hayes Ed
Williams International Co. L.L.C.
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