fire control naval weapons systems. we know: how the target is detected, how the target is tracked,...
TRANSCRIPT
Fire ControlFire Control
Naval Weapons SystemsNaval Weapons Systems
We Know:We Know:How the target is detected, How the target is tracked, How the weapon is launched, How the weapon is propelled, How the weapon finds the target, How the weapon knows when to detonate,How the weapon detonates.
What is missing?????
What is Fire ControlWhat is Fire Control
How must a weapon be fired at a How must a weapon be fired at a stationary or moving target from a stationary or moving target from a
launcher that is stationary or launcher that is stationary or moving in order to hit the target?moving in order to hit the target?
The Fire Control ProblemThe Fire Control Problem
Determining the target positionDetermining the target position
Target motionTarget motion
Weapon path that intercepts the targetWeapon path that intercepts the target
The Fire Control ProblemThe Fire Control Problem
Factors affecting the problem:
- Effects of relative motion during flight
- Effects of physical phenomena (exterior ballistics)
Relative MotionRelative Motion
Present target positionPresent target position
Relative velocityRelative velocity– Own ship motionOwn ship motion– Target motionTarget motion
Bearing rateBearing rate
Speed across line-of-sightSpeed across line-of-sight
Future target positionFuture target position
Relative MotionRelative MotionThe apparent motion of an object when viewed from a point.
10 mph
10 mph20 mph
A
B
C
Affects of Target Relative Motion on Range and Bearing
PresentPosition
FuturePosition
Ship’s Heading
Pres
ent R
ange
Future Range
Range ChangeBearing Change
Present
Bearing
Solving the Relative Motion Solving the Relative Motion Problem Problem
Launch Platform Sensors
Target Position
Navigation Systems (location)Gyrocompass (course)Electromagnetic Log (speed)Dead reckoning Analyzer Depth indicator
Radar (search and fire control)SonarElectronic warfare equipmentData Systems (NTDS)
INPUT
Target CourseTarget SpeedTarget RangeTarget Bearing
Output
Ballistics ProblemBallistics Problem
Target DataTarget Data– Target position from sensorsTarget position from sensors– Target motion (Target Motion Analysis)Target motion (Target Motion Analysis)
Own ship data from ship sensorsOwn ship data from ship sensors
Weapon exterior ballisticsWeapon exterior ballistics
Exterior BallisticsExterior Ballistics
GravityGravity
DragDrag
WindWind
DriftDrift
Coriolis forceCoriolis force
Weapon specificsWeapon specifics
Effects of GravityEffects of Gravity
Line of Sight
Line of Fire
Gravity tends to accelerateobjects downward. (The longerthe flight time the more the curve)
Effects of DragEffects of DragDrag is loss of energy of a projectile during flight.
Energy is lost through: a. Creation of air waves (function of projectile shape) b. Creation of suction and eddy currents (shape) c. Formation of heat (friction)
Drag will change the aim point by changing the speed of theprojectile, increasing flight time, increasing curve caused bygravity.
Effects of DriftEffects of DriftDrift is caused by the rotation of a projectile (rifling).Drift results in a lateral displacement in flight path.
Vertical Plane
Drift
Horizontal Plane
Line of Fire
Effects of WindEffects of Wind
WindWind
Line of Fire
Horizontal Effects
Wind
Wind
Line of Fire
Vertical Effects
Coriolis EffectCoriolis EffectCaused by the earth’s rotation. Results in apparent right curve in the northern hemisphere, left in southern.
20 mph
10 mph
Fire Control ProblemFire Control ProblemInputInput– Target dataTarget data– Own ship dataOwn ship data
ComputationsComputations– Relative motion equationsRelative motion equations– Ballistics equationsBallistics equations
Fire Control Problem Con’t.Fire Control Problem Con’t.SolutionsSolutions– Weapons time of flightWeapons time of flight– Bearing rateBearing rate– Line of Sight(LOS): The course the Line of Sight(LOS): The course the
weapon must follow to intercept the targetweapon must follow to intercept the target– Speed across LOSSpeed across LOS– Future target positionFuture target position– Launch anglesLaunch angles
Launch azimuthLaunch azimuth
Launch elevationLaunch elevation– Weapon positioning ordersWeapon positioning orders
The Iterative Process to the The Iterative Process to the Fire Control SolutionFire Control Solution
Step 1
Step 2
Step 3 Last Step
A 3-Dimensional ProblemA 3-Dimensional Problem
Horizontal Reference Plane
Line of Sight
Present R
ange
Target Elevation
GunElevation
Solving the Fire Control Solving the Fire Control ProblemProblem
Continuously MeasurePresent Target Position
Stabilize Measured Quantities
Compute RelativeTarget Velocity
BallisticCalculations
Relative Motion Calculations
Time of Flight
Future TargetPosition
Prediction Procedure
Unstabalized Launch Angles
Environmental Inputs
Launch Angles (Stabilized)
Weapons Positioning orders