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Mine Drop Experiment II for Operational
Mineshapes (MIDEX II) LT Charles Allen Bomb
Strike Experiment LT Greg Ray Theses Advisor
Dr. Peter Chu Second Reader Dr. Peter
Fleischer Sponsors CNMOC MIW, NAVO, and ONR
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Presentation Overview
PART II
PART I
PART III
PART IV
PART V
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Research Objectives
MIDEX II Increase the operational effectiveness
of IMPACT35 through the study and
characterization of real-world naval mines. Bomb
Strike Experiment Improve warhead lethality for
use in quick, precise and accurate strikes on
known enemy naval minefields in the littoral
combat environment.
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Introduction

• Brief History
• Mine Warfare
• Mine Impact Burial Prediction Models
• Mine Countermeasure Systems

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Introduction

• The Experiment
• Shapes
• The Test Tank
• Cameras Data Collection Equipment
• Methodology

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Introduction

• Data Retrieval and Analysis
• Results for Each Project
• Conclusions and Future Work

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Naval Mine Threat

• 80 of American commerce is conducting via
  ocean-borne trade.
• Naval mines are a grave threat to this vital
  resource.
• Sea mines are inexpensive, easy to deploy, and
  highly effective.
• 45 countries possess mining capability.
• 20 countries produce mines (13 are mine
  exporters).
• Any country or properly funded terrorist
  organization can engage in mine warfare.
• Even obsolete mines can be upgraded at a
  fraction of the cost of new mines.

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Big Bang for the Buck
The Poor Mans Navy
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Mine Countermeasures

• Mine Countermeasure operations are difficult.
• Time is the target not equipment or people
• Most mines possess complex magnetic, acoustic,
  and pressure triggering.
• Significant challenges still remain in the
  surveillance, reconnaissance, detection, and
  neutralization of mines.
• The primary challenge is to determine exactly
  where the waiting mines are located
• Attempting to obtain accurate data of potential
  enemy shores may not be easy

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Part I Mine Drop Experiment II for Operational
Mineshapes
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The Impact Burial Prediction Model
What is it? The IBPM is designed, when knowing
the release position of the mine above the
surface, predict the mines vertical position in
the air and water to ultimately determine the
burial depth in the sea sediment. 1-Dimensional
IBPM developed in 1980 by Arnone and Bowen
(improved later by Satkowiak in 1988) Primary
Weakness Assumes a cylindrical shape with a
constant mine orientation as it falls.
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IBPM Overview

• 2-Dimensional Model (IMPACT 28) developed by
  Hurst in 1992.
• Contained two momentum equations (in x- and
  z-directions) and a moment of momentum equation
  (in the y-direction).
• Able to predict the mines COM position in the
  x-z plane and the rotation about the y-axis.

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IBPM Overview

• 2-Dimensional Model Weakness Very difficult to
  include fluid motion, as any fluid motion in the
  y-axis broke the two-dimensional plane.
• Latest iteration of IBPM, IMPACT 35, is 3-D.
• With full physics, the model contains three
  momentum equations and three moment of momentum
  equations, predicting the mines COM position in
  x,y, and z space and the rotation around all
  three axes.
• Significant improvement of three-dimensional
  modeling over two-dimensional.

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Full Physics Equations
Momentum Equation

g is the gravitational
acceleration is the shape volume is the
rigid body density m, is the shape
mass Fh is the hydrodynamic force Fb -
is the buoyancy force is the water density.

Moment of Momentum Equation Mb and Mh are
the buoyancy and hydrodynamic force torques.
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2-D vs. 3-D Model Accuracy
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2-D vs. 3-D Model Accuracy
2-D and 3-D model verification carried out right
here by NPS students V. Table, T. Smith, A.
Gilles, and A. Evans.
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IMPACT35 Weakness

• There is but one significant weakness of this 3-D
  model Assumes the shape is CYLINDRICAL.
• If the model is to be used operationally, this is
  a big problem as the most widely-used bottom
  mines such as the Manta and the Rockan are not
  cylindrical.
• Determination of the hydrodynamic force and
  torque for non-cylindrical mines is crucial, but
  there is no existing formulae for these.

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Enter MIDEXII

• Direct continuation of IBPM testing process
• Use of scaled models representing real-world,
  non-cylindrical shapes to gather water-phase
  trajectory data.
• Ultimate goal is to make data available for
  follow-on IBPM modeling work.
• Four shapes tested Sphere, Gumdrop, Manta,
  and Rockan.

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The Italian MANTA

• Anti-invasion bottom mine.
• Glass-Reinforced Plastic (GRP) casing
• Triggered acoustically or magnetically
• Shelf life30 years
• Active life 17 months

Diameter 0.980 m Height 0.440
m Weight 220 kg Charge 130 kg
(HBX-3) Operating Depth 3-100 m
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The Swedish ROCKAN

• Anti-invasion bottom mine
• Acoustic and magnetic triggering.
• GRP gliding case.
• Anechoic coating

Length 1.015 m Width 0.800
m Height 0.385 m Weight 190
kg Charge 105 kg (Cemtex) Operating Depth
5-100 m
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Part II Bomb Strike Experiment
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Bomb Strike Experiment

• This is a multi-year, comprehensive effort aimed
  at enhancing the Navys fleet naval mine
  clearance capability and success.
• Use of scale models to representing real-world
  munitions, to study and characterize the
  water-phase trajectory data.
• The long-term goal of this project is to improve
  warhead lethality for use in quick, precise and
  accurate strikes on known enemy naval minefields
  in the littoral combat environment.
• Four shapes tested
• 1/12 Scale Model of MK-84 GP Bomb
• Shell (Bomb w/ No Fins)
• Cylinder
• Cylinder with Hemispheric Nosecone (Capsule)

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Part III The Experiment Play Movie
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Part IV MIDEX II Results
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Trajectory Patterns

• The Sphere and Gumdrop Shapes

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Trajectory Patterns
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Trajectory Patterns

• The Manta Shape

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Trajectory Patterns
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Trajectory Patterns

• The Rockan Shape

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Trajectory Patterns
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Trajectory Summary
Shape Average Time to 250cm Z Pattern Probability
Sphere 1.796s Straight-Arc 0.62
(13 total drops) Curve-Arc 0.38
Slant 0.00
Gumdrop 1.462s Straight-Arc 0.22
(9 total drops) Curve-Arc 0.56
Slant 0.22
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Trajectory Summary
Shape Average Time to 250cm Z Pattern Probability
Manta 3.703s Flat Spiral 0.40
(15 total drops) Side Twist 0.40
Erratic 0.20
Rockan 4.688s Flip-Dive-Flat 0.36
(14 total drops) Flat Spin 0.14
Swoop-Flat Spin 0.50
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Impact Position Plots
Hall Camera
-Sphere Drop Points are indicated by Red
Stars. -Gumdrop Drop Points are indicated by
Blue Circles. -Manta Drop Points are indicated
by Green Hexagons. -Rockan Drop Points are
indicated by Black Squares.
Shop Camera
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The Big Payoff

• 12 Mb of data for 51 drops.
• - Sample Data Section Below

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MIDEX II - Conclusions

• Next step of ongoing process to understand and
  predict the various parameters that affect a
  mines water-phase trajectory.
• Observed trajectories were highly variable.
• The Manta and Rockan shapes trajectories were
  generally more complex than the Sphere and
  Gumdrop trajectories.
• The denser Gumdrop shape had the fastest and
  straightest drops overall to 250cm Z.
• Because of important factors, the dispersion of
  all four shapes impact points was wide and
  variable.

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Future Work

• More realistic Manta and Rockan mine shapes (with
  detailed inner modeling)
• Larger scale versions of the Rockan to more
  closely mimic gliding.
• Changing the water column (e.g. adding currents
  or turbulence)

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IMPACT35 Future Work

• The trajectory information gathered in MIDEX II
  needs to be compared with the results of IMPACT
  35 using the same initial conditions.
• Chaotic features of MIDEX II trajectories should
  be investigated with instability and
  predictability analyses.
• Differences and similarities with IMPACT 35 can
  then be used to generate the next iteration of
  the IBPM.

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Part V Bomb Strike Results
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Bomb Strike Results

• Data Collected for Model Verification
• Clear patterns based on projectile shape
• Look at Trajectory pattern
• Look at Bottom Dispersion Patterns

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Trajectory Patterns

• 4 Trajectory Pattern Classifications

Pattern Description
Straight-Arc Straight direct flight path on one vertical axis, with slow smooth arc until terminus on remaining vertical axis
Straight Spiral Direct path to terminus of flight with tail spiraling in the wake.
Short-Arc-Flip Abrupt immediate arc within 75 cm of water entry followed by a flip of the projectile and tail first decent to terminus
Long-Arc-Flip Shallow arc for majority of flight path developing into an abrupt turn upwards near the terminus and then descending tail first.
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Trajectory Patterns
Straight-Arc
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Trajectory Patterns
Straight Spiral
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Trajectory Patterns
Short-Arc-Flip
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Trajectory Patterns
Long-Arc-Flip
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Experimental Summary
Shape of Runs Avg. Vinitial Trajectory
Bomb 8 83.0 m/s Straight-Arc
Shell 13 82.3 m/s Short-Arc-Flip
Capsule 11 68.2 m/s Long-Arc-Flip
Cylinder 12 56.6 m/s Straight-Spiral
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Trajectory Patterns

• MK-84 1/12 Scale Model Bomb
• 8 Runs Total
• Vmax 87.1 m/s Vmin 42.6 m/s
• 6/8 displayed straight arc

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Trajectory Patterns

• Shell Shape (MK-84 w/ No Fins)
• 11 Runs Total
• Vmax 109.5 m/s Vmin 29.1 m/s
• 8/11 displayed short-arc-flip

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Trajectory Patterns

• Cylinder Shape
• 12 Runs Total
• Vmax 67.9 m/s Vmin 28.2 m/s
• 9/12 displayed straight spiral

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Trajectory Patterns

• Capsule Shape
• 11 Runs Total
• Vmax 83.2 m/s Vmin 56.2 m/s
• 9/11 displayed long-arc-flip

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Trajectory Discussion

• Trajectories of shapes were consistent within a
  single shape type, but greatly varied between
  shape types.
• The most erratic shape was the Shell, probably
  due to shape of rigid body, off center CoG, and
  lack of stabilizing fins.
• Most consistent shape is Cylinder Bomb
  (Cylinder a little less due to lack of
  stabilization)

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BSE - Conclusions

• Based on these results unitary weapon could
  successfully be targeted in the littoral war
  zone.
• The major factor in determining shape trajectory
  was overall design of test shape and its
  interaction in the bubble plume
• Shapes that were stable went straight.
• Finless shapes had complex trajectories
• Dispersion Pattern was consistent for all shapes
  within their type. Both accurate and precise
  therefore predictable in a modeling scenario.

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Future Work on BSE

• Larger test with more funding, better models,
  more time.
• Test shapes at multiple angles and higher
  velocity
• Development of bomb-strike prediction model
  (STRIKE35)
• Verification of STRIKE35 with full-size bomb
  striking exercises conducted by ATR and SRT
• Ensemble model development
• Incorporation into overall organic MIW plan

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Any Questions?
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Mission Package for LCS
AMNS/ALMDS/RAMICSCombined Mission Module