Angular rate sensing apparatus and methods

Navigational guidance system apparatus comprising:

• (a) a laminated body rotatable about a control axis and including:
• (1) a main rate sensor lamina having an interaction channel, a nozzle portion having an inlet channel and a discharge channel opening forwardly into said interaction channel and communicating with said inlet channel, said discharge channel having a flow axis generally perpendicular to said control axis, a pair of receiving channels spaced forwardly of said nozzle portion and having inlets communicating with said interaction channel on opposite sides of said flow axis, and a splitter member positioned between said inlets and intercepted by said flow axis, said splitter member having a rearwardly facing leading edge, and
• (2) a plurality of auxiliary laminae positioned on opposite sides of said main lamina and defining in said body an inlet passage communicating with said nozzle portion inlet channel, and a pair of outlet passages each communicating with a different one of said receiving channels, whereby a fluid may be flowed inwardly through said inlet passage to form a fluid jet exiting said discharge passage along a jet axis, forwardly traversing said interaction channel, impinging upon said splitter edge and being divided thereby into two separate streams each received by one of said receiving channels to thereby create between said outlet passages a pressure differential indicative of the rate and sense of rotation of said body about said control axis;
• and
• (b) calibration means associated with the assembled body for correcting for fabricational inaccuracies in said main rate sensor lamina therein to render said pressure differential substantially zero during operation of said apparatus in the absence of rotation of said body about said control axis, said calibration means including means for adjustably venting one of said pair of receiving channels,
• said means for adjustably venting one of said pair of receiving channels including a pair of vent passages defined in said laminated body by said auxiliary laminae, each of said vent passages communicating with a different one of said receiving channels, and means for adjustably restricting one of said vent passages to selectively elevate the operating pressure of the receiving channel with which it communicates,
• said one of said vent passages extending directly beneath an outermost one of said auxiliary laminae, and said means for adjustably restricting said one of said vent passages comprising a portion of said outermost one of said auxiliary laminae adapted to be deformed inwardly into said one of said vent passages.

Navigational guidance system apparatus comprising:

• (a) a laminated body rotatable about a control axis and including:
• (1) a main rate sensor lamina having an interaction channel, a nozzle portion having an inlet channel and a discharge channel opening forwardly into said interaction channel and communicating with said inlet channel, said discharge channel having a flow axis generally perpendicular to said control axis, a pair of receiving channels spaced forwardly of said nozzle portion and having inlets communicating with said interaction channel on opposite sides of said flow axis, and a splitter member positioned between said inlets and intercepted by said flow axis, said splitter member having a rearwardly facing leading edge, and
• (2) a plurality of auxiliary laminae positioned on opposite sides of said main lamina and defining in said body an inlet passage communicating with said nozzle portion inlet channel, and a pair of outlet passages each communicating with a different one of said receiving channels, whereby a fluid may be flowed inwardly through said inlet passage to form a fluid jet exiting said discharge passage along a jet axis, forwardly traversing said interaction channel, impinging upon said splitter edge and being divided thereby into two separate streams each received by one of said receiving channels to thereby create between said outlet passages a pressure differential indicative of the rate and sense of rotation of said body about said control axis;
• and
• (b) calibration means associated with the assembled body for correcting for fabricational inaccuracies in said main rate sensor lamina therein to render said pressure differential substantially zero during operation of said apparatus in the absence of rotation of said body about said control axis,
• said calibration means including means for selectively moving said leading splitter edge to bring it into precise alignment with said flow axis of said discharge passage,
• said means for selectively moving said leading splitter edge including means for adjustably bending said laminated body about an axis generally parallel to said control axis.

Navigational guidance system apparatus comprising:

• (a) a laminated body rotatable about a control axis and including:
• (1) a main rate sensor lamina having an interaction channel, a nozzle portion having an inlet channel and a discharge channel opening forwardly into said interaction channel and communicating with said inlet channel, said discharge channel having a flow axis generally perpendicular to said control axis, a pair of receiving channels spaced forwardly of said nozzle portion and having inlets communicating with said interaction channel on opposite sides of said flow axis, and a splitter member positioned between said inlets and intercepted by said flow axis, said splitter member having a rearwardly facing leading edge, and
• (2) a plurality of auxiliary laminae positioned on opposite sides of said main lamina and defining in said body an inlet passage communicating with said nozzle portion inlet channel, and a pair of outlet passages each communicating with a different one of said receiving channels, whereby a fluid may be flowed inwardly through said inlet passage to form a fluid jet exiting said discharge passage along a jet axis, forwardly traversing said interaction channel, impinging upon said splitter edge and being divided thereby into two separate streams each received by one of said receiving channels to thereby create between said outlet passages a pressure differential indicative of the rate and sense of rotation of said body about said control axis;
• and
• (b) calibration means associated with the assembled body for correcting for fabricational inaccuracies in said main rate sensor lamina therein to render said pressure differential substantially zero during operation of said apparatus in the absence of rotation of said body about said control axis, said calibration means including means carried by said laminated body for exerting selectively variable forces on said main rate sensor lamina to precisely align said flow axis, said jet axis, and said leading splitter edge.

An angular rate sensor comprising:

• (a) a member rotatable about a control axis;
• (b) nozzle means for receiving fluid from a source thereof and discharging a fluid jet having a jet axis,
• said nozzle means being carried by said member for rotation therewith and having a flow axis generally perpendicular to said control axis, said nozzle means further having a pair of wall surface areas along which portions of the fluid exiting said nozzle means separate therefrom;
• (c) jet-receiving means for utilizing the jet to produce a pair of outputs adapted for comparison to determine the rate and sense of rotation of said member about said control axis,
• said jet-receiving means being carried by said member for rotation therewith and including splitter means, spaced apart from said nozzle means, for dividing the jet into two streams having a relative cross-sectional area differential indicative of said rate and sense of rotation of said member;
• and
• (d) calibration means for correcting for fabricational inaccuracies in said rate sensor to render said outputs substantially identical at zero rotational rate of said member about said control axis,
• said calibration means including means for precisely aligning said jet axis and said flow axis, said axis aligning means including means for selectively adjusting the position of one of said pair of wall surface areas relative to the other of said pair of wall surface areas.

An angular rate sensor comprising:

• (a) a member rotatable about a control axis;
• (b) nozzle means for receiving fluid from a source thereof and discharging a fluid jet having a jet axis,
• said nozzle means being carried by said member for rotation therewith and having a flow axis generally perpendicular to said control axis;
• (c) jet-receiving means for utilizing the jet to indicate the rate and sense of rotation of said member about said control axis, said jet-receiving means being carried by said member for rotation therewith, being spaced apart from said nozzle means, and including:
• (1) splitter means positioned in the path of the jet for dividing it into two separate streams,
• (2) a pair of receiving passages each positioned to receive one of the streams, and
• (3) a pair of outlet passages each communicating with one of said receiving passages whereby, during operation of said rate sensor, the operational pressure differential between said outlet passages is indicative of the rate and sense of rotation of said member about said control axis;
• and
• (d) calibration means operatively associated with said nozzle means and said jet-receiving means for compensating for fabricational inaccuracies in said rate sensor causing misalignment between said splitter means and said flow axis, and said flow axis and said jet axis, to thereby render said operational pressure differential substantially zero in the absence of rotation of said member about said control axis, said calibration means including means for adjustably venting one of said receiving passages,
• said jet-receiving means further including a pair of vent passages each communicating with one of said receiving passages, and said means for adjustably venting one of said receiving passages including means for adjustably restricting one of said vent passages,
• a portion of said one of said vent passages extending inwardly adjacent and generally parallel to an exterior surface portion of said rate sensor, said exterior surface portion being adapted to be deformed a predetermined distance into said portion of said one of said vent passages, said means for adjustably restricting one of said vent passages including said exterior surface portion of said rate sensor.

An angular rate sensor comprising:

• (a) a member rotatable about a control axis,
• (b) nozzle means for receiving fluid from a source thereof and discharging a fluid jet having a jet axis,
• said nozzle means being carried by said member for rotation therewith and having a flow axis generally perpendicular to said control axis;
• (c) jet-receiving means for utilizing the jet to indicate the rate and sense of rotation of said member about said control axis, said jet-receiving means being carried by said member for rotation therewith, being spaced apart from said nozzle means, and including:
• (1) splitter means positioned in the path of the jet for dividing it into two separate streams,
• (2) a pair of receiving passages each positioned to receive one of the streams, and
• (3) a pair of outlet passages each communicating with one of said receiving passages whereby, during operation of said rate sensor, the operational pressure differential between said outlet passages is indicative of the rate and sense of rotation of said member about said control axis;
• and
• (d) calibration means operatively associated with said nozzle means and said jet-receiving means for compensating for fabricational inaccuracies in said rate sensor causing misalignment between said splitter means and said flow axis, and said flow axis and said jet axis, to thereby render said operational pressure differential substantially zero in the absence of rotation of said member about said control axis, said calibration means including means for moving said splitter means into precise alignment with said flow axis, said means for moving said splitter means including means for adjustably bending said member about an axis generally parallel to said control axis.

An angular rate sensor comprising:

• (a) a member rotatable about a control axis;
• (b) nozzle means for receiving fluid from a source thereof and discharging a fluid jet having a jet axis,
• said nozzle means being carried by said member for rotation therewith and having a flow axis generally perpendicular to said control axis;
• (c) jet-receiving means for utilizing the jet to indicate the rate and sense of rotation of said member about said control axis, said jet-receiving means being carried by said member for rotation therewith, being spaced apart from said nozzle means, and including:
• (1) splitter means positioned in the path of the jet for dividing it into two separate streams,
• (2) a pair of receiving passages each positioned to receive one of the streams, and
• (3) a pair of outlet passages each communicating with one of said receiving passages whereby, during operation of said rate sensor, the operational pressure differential between said outlet passages is indicative of the rate and sense of rotation of said member about said control axis;
• and
• (d) calibration means operatively associated with said nozzle means and said jet-receiving means for compensating for fabricational inaccuracies in said rate sensor causing misalignment between said splitter means and said flow axis, and said flow axis and said jet axis, to thereby render said operational pressure differential substantially zero in the absence of rotation of said member about said control axis, said calibration means including means for precisely aligning said jet axis and said flow axis, said axis aligning means including means for exerting a selectively variable force upon said nozzle means in a direction generally perpendicular to said flow axis.

An angular rate sensor comprising:

• (a) a member rotatable about a control axis,
• (b) nozzle means for receiving fluid from a source thereof and discharging a fluid jet having a jet axis,
• said nozzle means being carried by said member for rotation therewith and having a flow axis generally perpendicular to said control axis;
• (c) jet-receiving means for utilizing the jet to indicate the rate and sense of rotation of said member about said control axis, said jet-receiving means being carried by said member for rotation therewith, being spaced apart from said nozzle means, and including:
• (1) splitter means positioned in the path of the jet for dividing it into two separate streams,
• (2) a pair of receiving passages each positioned to receive one of the streams, and
• (3) a pair of outlet passages each communicating with one of said receiving passages whereby, during operation of said rate sensor, the operational pressure differential between said outlet passages is indicative of the rate and sense of rotation of said member about said control axis;
• and
• (d) calibration means operatively associated with said nozzle means and said jet-receiving means for compensating for fabricational inaccuracies in said rate sensor causing misalignment between said splitter means and said flow axis, and said flow axis and said jet axis, to thereby render said operational pressure differential substantially zero in the absence of rotation of said member about said control axis, said splitter means including a leading splitter edge, and said calibration means including means for precisely mutually aligning said splitter edge, said flow axis and said jet axis, and
• said means for mutually aligning said splitter edge, said flow axis and said jet axis including means for adjustably bending said nozzle means and said member about axes generally parallel to said control axis.

Angular rate sensing apparatus comprising:

• (a) a fluidic angular rate sensor having jet-forming means for receiving fluid from a source thereof and discharging a fluid jet, and jet-receiving means spaced from said jet-forming means for utilizing said jet to create a pair of fluidic output signals having a relative pressure differential indicative of the rate and sense of rotation of said rate sensor about a control axis;
• (b) means for supplying fluid to said jet-forming means;
• and
• (c) jet-control means operatively associated with said fluid-supplying means for maintaining the Reynolds number of said jet within a predetermined range to thereby environmentally stabilize the operation of said rate sensor,
• said jet-control means including means for sensing the temperature of said jet, means for sensing the pressure of said jet, and means for varying the velocity of said jet in response to the sensed temperature and pressure thereof.

Angular rate sensing apparatus comprising:

• (a) a fluidic angular rate sensor having jet-forming means for receiving fluid from a source thereof and discharging a fluid jet, and jet-receiving means spaced from said jet-forming means for utilizing said jet to create a pair of fluidic output signals having a relative pressure differential indicative of the rate and sense of rotation of said rate sensor about a control axis;
• (b) means for supplying fluid to said jet-forming means, and
• (c) means for compensating for pressure and temperature changes in said jet to assure that variations in the position of said jet relative to said jet-receiving means occur substantially solely due to variations in said rate and sense of rotation of said rate sensor about said control axis, said compensating means including means for maintaining the Reynolds number of said jet within a predetermined range,
• said means for maintaining the Reynolds number of said jet within a predetermined range including means for sensing variations in the Reynolds number of said jet, and means responsive to the sensed Reynolds number variations for varying the velocity of said jet.

A navigational guidance system comprising:

• (a) fluidic angular rate sensor means for receiving fluid from a source thereof, forming a jet from the received fluid, and utilizing the jet to create a duality of fluidic output signals adapted for comparison to determine the rate and sense of rotation of said rate sensor means about a control axis;
• (b) a pump;
• (c) supply passage means for supplying fluid discharged from said pump to said rate sensor means;
• (d) a variable speed motor drivingly connected to said pump;
• and
• (e) a Reynolds number control system adapted to maintain the Reynolds number of said jet within a predetermined range and comprising:
• (1) pressure sensing means for sensing the pressure of said jet and transmitting an output signal indicative of the sensed pressure,
• (2) temperature sensing means for sensing the temperature of said jet and transmitting an output signal indicative of the sensed temperature,
• (3) speed controller means operable to vary the speed of said variable speed motor, and
• (4) operational amplifier means for receiving said output signals from said pressure sensor means and said temperature sensor means and, in response to the received output signals, for operating said speed controller means to maintain a predetermined relationship between the temperature, pressure and velocity of said jet.

For use in controlling the rotational attitude of a body relative to a predetermined control axis thereof, the body having associated therewith control means for returning it to a predetermined rotational attitude in response to a control signal indicating a rotational deviation of the body from the predetermined attitude thereof, an angular rate sensing system adapted to be mounted on the body and comprising:

• (a) a fluidic angular rate sensor having jet-forming means for receiving fluid and discharging a fluid jet, and jet-receiving means for utilizing the jet to create a pair of fluidic output signals having a relative pressure differential indicative of the rate and sense of rotation of the body about the control axis;
• (b) means for supplying fluid to said jet-forming means;
• (c) means for sensing the pressure and temperature of said jet and transmitting a pair of output signals indicative of the sensed pressure and temperature;
• (d) means for receiving said sensed pressure and temperature output signals and, in response thereto, for controlling the volumetric flow rate of fluid supplied by said means (b) to said jet-forming means to thereby maintain the Reynolds number of said jet within a predetermined range;
• (e) means for converting said fluidic output signals from said rate sensor to a pair of oscillating signals having a relative frequency differential indicative of said rate and sense of rotation of the body about the control axis, said oscillating signals together defining a control signal;
• and
• (f) means for transmitting said control signal to the control means of the body.

A navigational guidance system for controlling the rotational attitude of a body relative to at least on control axis, said guidance system comprising:

• (a) control means operable to exert a corrective force on the body to return it to a predetermined attitude relative to a control axis in response to receiving a corrective input signal indicating a deviation of the body from said predetermined attitude thereof;
• (b) a fluidic angular rate sensor carried by the body for motion therewith and having:
• (1) passage means for receiving a fluid and discharging a fluid jet, and
• (2) means for utilizing said jet to create a pair of pressure output signals having a relative pressure differential indicative of the rate and sense of rotation of the body about said control axis, and
• (3) calibration means for rendering said relative pressure differential substantially zero, at zero rotational rate of the body about said control axis, despite fabricational inaccuracies in said rate sensor;
• (c) means for converting said pressure output signals to a pair of oscillating signals having a relative frequency differential indicative of said rate and sense of rotation, whereby said oscillating signals together define an output signal from said converting means representing the actual rate of rotation of the body about said control axis;
• (d) means for supplying fluid to said passage means of said rate sensor;
• (e) means associated with said fluid supplying means for maintaining the Reynolds number of said jet within a predetermined range;
• and
• (f) comparator means for receiving said output signal from said converting means, comparing the same to a desired rate of rotation of the body about said control axis, and responsively transmitting a corrective input control signal to said control means to operate the same.

A three-axis navigational guidance system comprising:

• (a) three fluidic angular rate sensors each having:
• (1) a control axis,
• (2) passage means for receiving fluid from a source thereof and discharging the received fluid in the form of a jet,
• (3) a pair of outlets, and
• (4) means responsive to rotation of the rate sensor about its control axis for utilizing the jet to create in the rate sensor outlets a pair of pressure output signals having a relative pressure differential indicative of the rate and sense of said rotation;
• (b) means linking said rate sensors for conjoint movement and relatively positioning them so that their control axes are mutually perpendicular;
• (c) means for flowing fluid into said passage means of each of said rate sensors;
• (d) means for converting each said pair of pressure output signals to a pair of oscillating electrical signals having a relative frequency differential indicative of said relative pressure differential between such pressure output signals;
• and
• (e) means operatively associated with said fluid flowing means (c) for maintaining the Reynolds number of each of said jets within a predetermined range despite changes in the temperature or pressure of said jets.

A method of calibrating a fluidic angular rate sensor having:

• jet-forming passage means for receiving fluid, flowing the fluid along a flow axis, and discharging the fluid in the form of a jet having a jet axis;
• splitter means spaced from the passage means and positioned in the path of the jet for dividing it into two separate streams;
• and a pair of receiving passages each adapted to receive one of the streams and be pressurized thereby, said method comprising the steps of:
• (a) flowing fluid through the jet-forming passage means to thereby create a pressure differential between the receiving passages due to fabricational inaccuracies in the rate sensor, said pressure differential monotonically increasing with increases in the Reynolds number of the jet;
• (b) compensating for fabricational misalignment between the splitter means and the flow axis to thereby alter the relationship between said pressure differential and said Reynolds number so that said pressure differential nonmonotonically increases upon increases in said Reynolds number;
• and
• (c) precisely aligning the jet axis with the flow axis to thereby substantially eliminate said pressure differential within a range of Reynolds numbers of the jet.

The method of constructing a fluidic angular rate sensor comprising the steps of:

• (a) providing a main rate sensor lamina;
• (b) forming in said main rate sensor lamina openings defining an interaction channel, a nozzle portion having a passage extending therethrough and opening forwardly into said interaction channel, said passage having a flow axis, means connecting said nozzle portion to an adjacent portion of said main rate sensor lamina in a manner permitting movement of said nozzle portion relative to said adjacent rate sensor lamina portion, a splitter portion spaced forwardly of said passage and having a rearwardly facing leading section generally aligned with said flow axis, and a pair of receiving channels opening rearwardly into said interaction channel and positioned on opposite sides of said splitter portion;
• (c) providing a plurality of auxiliary laminae;
• (d) stacking said main rate sensor lamina and said auxiliary laminae so that said main rate sensor lamina is positioned between a pair of said auxiliary laminae;
• (e) intersecuring the stacked laminae to form a laminated body, said intersecuring being performed in a manner permitting movement of said nozzle portion within said body;
• and
• (f) providing means associated with said body for adjustably moving said nozzle portion within said body to thereby compensate for fabricational inaccuracies in said nozzle portion.

The method of constructing a fluidic angular rate sensor comprising the steps of:

• (a) providing a main rate sensor lamina;
• (b) forming openings through said main rate sensor lamina to define therein:
• (1) an interaction channel,
• (2) a nozzle portion having a rear section and a pair of opposite wall members positioned forwardly of said rear section on opposite sides of a nozzle passage opening forwardly into said interaction channel and having a flow axis, and
• (3) support sections connecting said nozzle portion to the remainder of said main rate sensor lamina in a manner permitting movement of said rear nozzle portion relative to said remainder and causing, in response to said movement, a relative movement between said opposite wall members in a direction generally parallel to said flow axis;
• (c) providing first and second pluralities of auxiliary laminae;
• (d) stacking said main and auxiliary laminae so that said main lamina is positioned between said first and second pluralities of auxiliary laminae;
• (e) intersecuring the stacked laminae to form a laminated rate sensor body, said intersecuring being performed in a manner permitting said movements of said rear nozzle portion section and said opposite wall members relative to said rate sensor body;
• and
• (f) providing means associated with said rate sensor body for exerting a selectively variable force upon said rear nozzle portion section to thereby cause a selectively variable degree of relative movement between said oppostie wall members of said nozzle portion.

A method of maintaining a moving body in a desired rotational attitude relative to a control axis of the body, said method comprising the steps of:

• (a) providing a fluidic angular rate sensor having:
• (1) a splitter member having a leading edge,
• (2) a discharge passage spaced from said leading edge and having a flow axis generally aligned therewith, and
• (3) a pair of receiving passages positioned on opposite sides of said splitter member;
• (b) flowing fluid through said discharge passage to create a fluid jet which exits therefrom, flows along a jet axis, impinges upon said leading edge and is divided thereby into a duality of streams each of which flows into and pressurizes a different one of said receiving passages;
• (c) associating said rate sensor with the body for motion therewith so that rotation of the body about the control axis causes a deflection of said jet relative to said leading edge toward one of said receiving passage to thereby increase the pressure therein and decrease the pressure in the other of said receiving passages;
• (d) substantially equalizing the pressures in said receiving passages at zero rotational rate of the body about the control axis despite fabricational inaccuracies in said rate sensor causing undesired misalignments among said leading edge, said jet axis and said flow axis;
• (e) limiting appreciable deflection of said jet relative to said leading edge to that caused by rotation of the body;
• and
• (f) providing means for utilizing rotationally induced pressure differentials between said receiving passages to return the body to said desired rotational attitude thereof,
• said pressure equalizing step including the step of adjustably bending said rate sensor.

A method of navigationally guiding a moving body comprising the steps of:

• (a) providing jet-forming means for receiving fluid from a source thereof and discharging a fluid jet;
• (b) associating said jet-forming means with the body for motion therewith;
• (c) supplying fluid to said jet-forming means;
• (d) utilizing said jet to create a duality of output signals collectively indicative of the rate and sense of rotation of the body about a control axis;
• (e) utilizing said output signals to return the body to a predetermined attitude relative to said control axis;
• and
• (f) maintaining the Reynolds number of said jet within a predetermined range despite variation in the temperature or pressure of said jet.

A fluidic angular rate sensor constructed by a method comprising the steps of:

• (a) providing a main rate sensor lamina;
• (b) forming in said main rate sensor lamina openings defining an interaction channel, a nozzle portion having a passage extending therethrough and opening forwardly into said interaction channel, said passage having a flow axis, means connecting said nozzle portion to an adjacent portion of said main rate sensor lamina in a manner permitting movement of said nozzle portion relative to said adjacent rate sensor lamina portion, a splitter portion spaced forwardly of said passage and having a rearwardly facing leading section generally aligned with said flow axis, and a pair of receiving channels opening rearwardly into said interaction channel and positioned on opposite sides of said splitter portion;
• (c) providing a plurality of auxiliary laminae;
• (d) stacking said main rate sensor lamina and said auxiliary laminae so that said main rate sensor lamina is positioned between a pair of said auxiliary laminae;
• (e) intersecuring the stacked laminae to form a laminated body, said intersecuring being performed in a manner permitting movement of said nozzle portion within said body;
• and
• (f) providing means associated with said body for adjustably moving said nozzle portion within said body to thereby compensate for fabricational inaccuracies in said nozzle portion.

A fluidic angular rate sensor constructed by a method comprising the steps of:

• (a) providing a main rate sensor lamina;
• (b) forming openings through said main rate sensor lamina to define therein:
• (1) an interaction channel,
• (2) a nozzle portion having a rear section and a pair of opposite wall members positioned forwardly of said rear section on opposite sides of a nozzle passage opening forwardly into said interaction channel and having a flow axis, and
• (3) support sections connecting said nozzle portion to the remainder of said main rate sensor lamina in a manner permitting movement of said rear nozzle portion relative to said remainder and causing, in response to said movement, a relative movement between said opposite wall members in a direction generally parallel to said flow axis;
• (c) providing first and second pluralities of auxiliary laminae;
• (d) stacking said main and auxiliary laminae so that said main lamina is positioned between first and second pluralities of auxiliary laminae;
• (e) intersecuring the stacked laminae to form a laminated rate sensor body, said intersecuring being performed in a manner permitting said movements of said rear nozzle portion section and said opposite wall members relative to said rate sensor body;
• and
• (f) providing means associated with said rate sensor body for exerting a selectively variable force upon said rear nozzle portion section to thereby cause a selectively variable degree of relative movement between said opposite wall members of said nozzle portion.