NearTerm RLV Options

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Near-Term RLV Options
AIAA Space 2004 Conference
Aeronautical Systems Center Design, Simulation
Analysis Aerospace Systems Design Analysis
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Outline

• Introduction
• Near-Term Options
• Existing Technologies
• Design Descriptions
• System Weights
• Summary
• Ops-Driven Designs
• Introduction
• Impact of Design on Maintenance
• Impact of Technology on Maintenance
• Design Parameters
• System Weights
• Maintenance Modeling
• Maintenance Estimates
• Summary

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Introduction

• National Need for Assured Access to Space
• Commercial/Scientific Needs
• Satellite Maintenance
• Space Exploration -gt Presidential Commission 2004
• Military Needs
• Responsive Space
• Intelligence, surveillance and reconnaissance
• Deployment and recovery of microsatellites
• Rapid constellation replenishment

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Near-Term Options

• PROBLEM
• Given state-of-the-art ST, how much payload,
  performance and maintenance burden would a new
  reusable launch system provide if development
  started immediately?
• APPROACH
• Surveyed existing rocket engines for performance,
  availability, and maintenance implications.
• Talked to TPS technologists about TUFI usability
  on a new system.
• Modeled TSTO systems using 4 and 5 engine
  boosters for payload variability.
• Investigated payload carriage options.
• Downselected to 4 cases of interest.

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Near-Term Options Existing Technologies

• Rockets
• Existing RD-180 RD-120s
• 92 Thrust Setting
• Single Engine-out Capability
• Tanks
• Aluminum / Aluminum-Lithium
• Integral Structure
• Shuttle Based Wt. Est. Relations
• Tanks TPS Structure
• OMS RCS APUs
• Design Margin
• 15 of empty weight except on main engines

RD-180s
RD-120s
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Near-Term Options Design Description

• Case 1
• Payload (internal carriage) delivered to 270nm
  circular orbit _at_ 28.5o east
• Case 2
• Payload (internal carriage) delivered to 100nm
  circular orbit _at_ 28.5o east
• Case 3
• Payload (external module) delivered to 100nm
  circular orbit _at_ 28.5o east
• Case 4
• Payload (external module) delivered to 100nm
  circular orbit _at_ 28.5o east
• 2nd Stage NOT sized to return payload

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Near-Term Options System Weights
1 block 20 ft
Smaller Wing Payload NOT returned
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Near-Term Options Summary

• Realizable Near-Term System can be achieved
  through
• Utilization of current technologies
• Existing engines provide required performance
  (limited re-use)
• TPS mature enough and continuously being improved
• Spiral technology can improve maintenance
  timeline
• Advanced high temperature windward TPS
• Methane/LOX autogenous pressurization (remove
  helium system)
• Electric system for actuation (remove hydraulics)

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Introduction toOps-Driven Design

• Shuttle Orbiter only existing U.S. RLV
• Provides lessons-learned
• Root Cause Analysis identifies maintenance
  problem areas
• Suggests design for ops to reduce turn-around
  time
• Ease of access
• Maintenance reduced by
• Limited of system elements
• Unmanned systems
• Long-life, reliable components
• Advanced technologies
• System development

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Ops-Driven Designs

• PROBLEM
• Given lessons learned from Shuttle maintenance,
  can design changes with advanced technologies
  significantly improve system maintenance?
• APPROACH
• Identified high payoff technologies in
  propulsion, thermal protection systems, and
  subsystems with AFRL experts.
• Designed three systems
• Baseline (not Shuttle) Aluminum structure
  (250oF), RD-180-like
• Advanced Technology Suite (ATS) New Methane
  Propulsion
• ATS metallic variant In-718 structure (1200oF)
• Utilized maintenance modeling to measure
  technologies effects.

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Ops-Driven DesignsImpact of Design on
Maintenance
Design changes alone (No Adv. Tech) can reduce
maintenance efforts
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Ops-Driven Designs Impact of Technology on
Maintenance
Advanced technologies can significantly reduce
maintenance efforts!
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Ops-Driven Designs Design Parameters
Newly designed ventilated rocket engine nacelles
Consistent Design and Modeling Highlights
Technology Benefits
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Ops-Driven Designs System Weights
1 block 20 ft
15,000 lb payloads
Aluminum structure
In-718 structure
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Ops-Driven Designs Maintenance Modeling

• Approach
• Identified major maintenance components
• Identified failure modes their probabilities
• Estimated maintenance manhours
• Model sensitive to technology, design,
  development choices
• Data Sources
• NASA subject matter experts
• Shuttle technical reports
• Major Maintenance Items
• Thermal Protection Systems (coverage area)
• Windward TPS
• Gap Filler/ Thermal Barriers
• Leeward TPS
• Main Engines (type, number, thrust, quality)
• Engine and Heat Shield Remove/Replace
• Turbopumps
• Engine Function Checks
• Fluid Related Subsystems (type, toxicity, number)
• Main Propulsion Subsystems Feed,
  pressurization, control

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Ops-Driven Designs TPS Maintenance

• ATS system has more durable, easy-to-install TPS
  and little to no waterproofing.
• ATS-metallic (In-718) minimizes TPS needs.

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Ops-Driven Designs Main Engine Maintenance

• Baseline uses parametric RD-180s (10 reuses)
• ATS uses parametric methane/lox engine designed
  for long-life (20 reuses)
• ATS uses ventilated engine nacelle concept
• ATS uses long-life turbopumps

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Ops-Driven Designs Fluid Related Maintenance

• Baseline uses high pressure helium pressurization
  and actuation which requires significant
  maintenance function checkouts.
• Baseline uses a hydraulic APU
• Baseline RCS/OMS uses toxic hypergols

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Ops-Driven Designs System Maintenance
Ops-focused Technology, Design and Development
can greatly reduce maintenance!
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Ops-Driven Designs Summary

• Maintenance improvements seen by
• Simplified system design -gt reduce of large
  system elements
• Unmanned systems
• Elimination of toxic fluids
• Advanced high temperature blankets
• Common use of Methane/LOX promotes integrated
  RCS/OMS/APU subsystems
• Elimination of high pressure hydraulics
  pneumatics reduces inspections/verifications
• Advanced technologies useful in
• reducing the maintenance burden!