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Presentation to 39th AnnualGun/Ammo & Missiles/Rockets Conference

Deconstruction of Fuze Well Guidance Requirements

April 14, 2004Chris Geswender

cegeswender@raytheon.com Andy Hinsdale

Andrew_J_Hinsdale@raytheon.com

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Synthesis of Course Correcting Fuze Design

Determine best Solution Spaceto developing a fuze well based

guidance package to providefirst shot accuracy < 50 meters

Corrects major errors including• Inherent Gun laying errors• Muzzle Velocity Variation• MET errors

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Derived Requirements• Increase effectiveness and efficiency of cannon artillery

• CEP<50 meters

• Reduce logistics• Increase OPTEMPO

• Exploit large existing projectile war stocks• Fuze well implementation

• Reversionary mode (fuze only)

• Corrector must still be a fuze• Easy to install, program, and be robust to field handling

• Volume for fuze functions

• Must have a reversionary mode

• Cost << $5000

Unguided1DOF

2DOF

3DOF-7DOF

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ACCURACY Definitions

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Gun Target Line

(GTR)

Target Center

DEFLECTION Bias Error

Mean Point of Impact (MPI)

RANGE Bias Error

Mean Point of Impact

(MPI)

DEFLECTION

RANGE

Precision Error

(Range)

Precision Error

(Deflection)

Mean Point of Impact

(MPI)

(Dispersion)

(Dispersion)

Range errors dominated by• Muzzle velocity variation• MET

Deflection errors dominated by• Gun Laying errors• MET

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Alternate Concepts Number of known concepts1DOF- Downrange

1DOF- Cross range

2DOF-DecoupledRoll stabilizedRoll rate Stabilized

2DOF-Body fixedRoll Rate/Aerobrake (1+)Flow disruptionHF Fixed canardHF trailing canard / solenoid

Wide Potential Solution Space

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Some Examples

1DOFRange Correctors

2DOFRange/Deflection Correctors

NSWC GIF

STAR SPACIDODMS

MIT Concepts

ANSR

1DOFDeflection Corrector

CMATD

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Theory of Operation - 1DOF-R

Projectile initializedand fired

“over” target

Projectile acquires“truth” of its positionand estimates impact Projectile determines

best point for high dragtrajectory to impact

Projectile deploys

aerobrakes

Minor modificationto firing tables

required(range and deflection)

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Theory of Operation - 2DOF

Requires no modificationsto firing tables

Projectile initializedand fired at target

Projectile acquires“truth” of its positionand estimates impact

Projectile determines best point for start guidance

Projectile deploys

aero surfaces

Projectile continuously

corrects impact

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x 2 VmFCCF

mV

Out of plane force

Mass

Velocity

Rotation

Aerodynamic Force Vector

Spin Stabilizing Rotation

Body Rotational Moment

Aerodynamic Force Vector

No Rotation

Body Rotational Moment

Projectile (12)

Fc ( coriolis acceleration ) (15)

V ( linear motion ) (14)

( rotation ) (13)

Theory of Operation - 2DOF Control

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Potential “truth” sources for Guidance

• Ballistic

• Inertial

• Data Link Update (Command)

• GPS

• Ground Beacon Array

• Terminal Seeker • (seeker range, packaging, costs issues)

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Summary of “Truth” Sources for Guidance

Ba

llis

tic

Ine

rtia

l

Gro

un

d

Be

ac

on

s

GP

S /

IM

U

Co

mm

an

d (

PT

S)

Beacon Error Sources

Maximum range LOS altitudeBeacon siting error

Beacon NORTHing error

Beacon signal errors - range noise

Beacon signal errors - angle noisePlatform error corrections

Corrects Gun- Laying angle errorsCorrects gun NORTHing error

Corrects Muzzle exit velocity errorsOperational Considerations

All-weather

Sensitivity - Countermeasures

Compatible to moving targets

Radiating Shooter

GPS or GPS/INS Appear to be Most Appropriate Truth Sources

See

ker

Technical and Cost Considerations

Integration ChallengesUnit Cost

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Electronics

Stowed AeroSurfaces

Actuators

Representative 2DOF Fuze / Guidance Kit

Battery

FS&A Booster

Primer

Fuze

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Various Studies Have ShownConcept Feasibility

CL~.02

CL~.015

Reference –Aerodynamic Fuze Characteristics A.M. BudgeJune 1998 MIT

•Various CCF/GIF Studies have indicated sufficient Maneuverability with Low aerodynamic effect lifts. •However, these studies widely vary as to real life implementation fidelity (winds aloft / guidance law interaction, guidance start times, actuation constraints)•Without considering realistic winds aloft many control concepts will appear satisfactory•But due to physics of the spinning projectile there is a practical limit to useful CL authority

52224.0184222.05119941.0965133250.5877469690.25

67%33%10%Wind

Canard

6.0

4.0

2.0

1.0

0.5

0.25

100%67%33%10%

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Representative Winds Aloft

Surface

3,000 ft

12,000 ft

30,000 ft

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GIF/CCF Requirements Deconstruction

Can Correct Trajectory Dispersion

1D-R 1D-D 1D+ 2D 3D 4D 5D 6D 7D

1D+ 2D 3D

1D+ 2D 3D 4D 5D 6D 7D

NATO STANAG Compatible Concepts

1D-R 1D-D 1D+ 2D 3D 4D 5D 6D 7D

Can Correct CEP <50m

Can Cost < $5K

1D+ 2D 3D

Fuze Well Compatible

1D+ 2D

A/J capable with no special handling HIGH GPS AJ capable

3D

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Summary

• Depending on desired Operational Flexibility and Cost Sensitivity, there are a number of potential solutions.

• Spiral development from the 1DOF (presently easily implementable) to the final desired operational product (2DOF or 3DOF) is an option

• GPS or GPS/INS are the most appropriate “truth” sources

• Joint service kit requires 2DOF or 3DOF kit at minimum

• To avoid developing new ballistic tables, nose weight/shape should conform to NATO STANAG OML

• Implementation of actuation and power source are the technical challenges

• Packaging of a gun hardened unit is also a challenge