P1253553549ZwlQO

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Conceptual Design of a Guided Interceptor

• Jason Williams, Kelsey Brekke, Steve Patrick,
  Russell Crosswy
• Philip Hahn and Dr. Robert A. Frederick
• UAH Propulsion Research Center
• The University of Alabama in Huntsville
• Huntsville, Alabama 35899
• hahnp_at_email.uah.edu
• http//www.uah.edu/research/PRC/
• 41st AIAA Joint Propulsion Conference
• July 12, 2005.

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IPT Educational Objectives

• Integrated Product Team (Senior Design Project)
• Educational Objectives
• Develop System-level perspective
• Develop Communication Skills
• Develop Critical Thinking Skills
• Develop Character qualities
• In an international, teamwork environment.
• Collaboration
• Mechanical and Aerospace Engineering (UAH)
• Computer and Electrical Engineering (UAH)
• Industrial and Systems Engineering (UAH)
• Fluid Dynamics students (ESTACA, France)

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UAH IPT

• Four Phases
• Phase 1 Baseline Concept
• Phase 2 Alternative Concepts
• Phase 3 Concept Refinement
• Phase 4 Manufacturing
• 4 Interdisciplinary design teams.
• Teams consisted of 13-15 members.
• Results from the winning team (Team 4) presented
  today.

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The Threat
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Static and Lethality Requirements

• Static Target 1000m out, 1000m up.
• Maneuverability up to 30m in any lateral
  direction at (1000, 1000).
• Hit-To-Kill, fully intersecting 100mm volume.
• 32 kJ Kinetic Energy.
• 90 probability of kill.
• Less than 30 projectiles.
• No existing military system has the ability to
  negate these threats after they are launched.

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Additional Requirements

• Weather Conditions
• -51.3 to 39.3 C.
• Up to 85 km/h gust winds, 65 km/h sustained.
• Gun System
• Must be an existing, implemented gun system
• Must be capable of handling up to 4 threats at
  0, 180, 270 and 90 in a period of 10 seconds.
• Deployment
• Flown from Ft. Knox to Kabul via C-130J
• Sling-loaded to site via Chinook 3 flights or
  less.
• Intercept before entering 500m defense volume.

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Gun System

• Selected gun system Bofors L/70
• 40mm rounds
• Meets all weather, gun system and deployment
  requirements.
• Can be mounted on a pallet or an armored vehicle.
  

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Hammerhead Configuration
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Squib Pack

• 3 rings of 10 squibs
• Mounted at the CG to avoid moments
• Utilized to overcome radar and gun pointing
  errors, projectile random motion, cross winds and
  manufacturing defects.

30 Thrusters, 4.28mm X 10 mm Thruster Impulse
0.13 Ns Average Force 520 N Burn Time
0.00025 s Ignition Delay 50
ms Required Current 100 mA Manufactured by
Pacific Scientific
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Squib Pack (cont)
Time 3 s
Mass 1.49 kg
Impulse 3.9 Ns
Diversion 7.85 m
PRODAS Results PRODAS Results
Diversion 4.86 m
Conclusion The requirements state the projectile
must divert 30m. Therefore, we must design squibs
from a high energy solid propellant.
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Squib Pack (cont)
Spinning Projectile Squib firing is dictated by
spin rate. Losses are incurred.
Conclusion Firing the squibs as soon as possible
gives us the most diversion for the least amount
of propellant.
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Command Guidance System

• Transponder
• Sends unique ID to radar system
• Radar System
• Tracks threats and ECAPs.
• Determines vector for ECAP to follow to intercept
  threat.
• Modulates radar wave to send vector to ECAP.
• Antenna
• Detects the modulated wave.
• If command is prefixed by the ECAPs unique ID
  number, use the vector given for guidance.

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Guidance (cont)
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Modeling and Simulation

• PRODAS
• 6 Degrees of Freedom
• Create a mass model
• Assign a gun
• Assess stability
• Run trajectory analysis
• Add sequences of squibs or aero forces to the
  trajectory to evaluate diversion requirements.

Length 235 mm
Mass 1.495 kg
CG (from nose) 113.06 mm
CP (from nose) 62.07 mm
Ix 0.000311 kgm2
Iy, Iz 0.00488 kgm2
Mach 1.47
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Modeling and Simulation (cont)
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Modeling and Simulation (cont)
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Modeling and Simulation (cont)
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Modeling and Simulation (cont)

• In order to be gyroscopically stable our
  projectile must have sg gt 1.2.
• Trades between
• Spin Rate (p)
• Spin moment of inertia (Ix)
• Velocity (V)
• Final Decisions
• Increase Ix by using Tungsten for the airframe.
• Increase p the team chose to increase the number
  of riflings in a stock Bofors barrel.
• Decrease V (carefully).

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Operational Scenario
Elevation Azimuth KE Time of Flight Firing time after Threat Launch Downrange Impact Coordinates
deg mrad kJ s s m
9.59 -0.740 95.5 4.04 3.91 4612.65, -3.14
10.01 -0.464 119.0 2.59 7.36 4741.81, -2.20
8.87 -0.276 145.6 1.39 10.56 4379.69, -1.08
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Operational Scenario (cont)
Elevation Azimuth KE Time of Flight Firing time after Threat Launch Downrange Impact Coordinates
deg mrad kJ s s m
52.0 -0.927 78.7 4.84 9.16 8712.53, -200.18
59.43 -0.653 94.8 3.53 20.47 7407.94, -214.64
17.67 -0.194 151.1 1.14 32.86 6777.91, -38.05
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Manufacturing / Rapid Prototyping

• Manufacturing was done in-house on a lathe.
• CAD drawings to machine code
• Machine code to finished product
• Rapid Prototyping models were also manufactured
  offsite.

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Defining Success

• Squibs Commercial squib pack does not divert
  30m new squib pack needs to be developed.
• Guidance Command guidance is feasible
• Kinetic Energy Greater than 32kJ for powered
  flight.
• Stability Gyroscopically stable throughout
  flight.
• Probability of hit 22 shots, meets requirements.

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Future Research

• Autopilot
• Trade studies
• Adding fidelity to internal components
• Error budget analysis to input using
  response-surface methods.

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