Propulsion Issues for Future Earth to Orbit Systems

1
Propulsion Issues for Future Earth to Orbit
Systems

• AIAA Space 2004
• Conference and Exposition
• 28 - 30 September 2004
• San Diego, California
• Randy C. Parsley
• Pratt Whitney Space Propulsion

2
Requirements for Future ETO Systems

• Safety
• Safety
• Safety
• Cost
• Maintainability
• Durability

3
Understanding the Contributing Elements of
Propulsion Safety

• Minimize Engine Shutdown Rate
• Minimize the Fraction of Shutdowns that Result in
  an Uncontained Event
• Minimize the Fraction of Uncontained Events
  that Result in Loss of Vehicle

4
Typical Current Propulsion Safety Baseline
5
Putting Current Status Into Perspective

• Consider a robust test-case for space
  utilization
• Assume (for fun),
• 10 countries participating robustly in space
• 2 flights per day, per country
• 5 engine booster (enabling engine-out
  capability)
• 5 engine orbiter (enabling engine-out
  capability)

6
Putting Current Status Into Perspective

• 2

10
10
365
FlightsDay - Country
Engine MissionsFlight
DaysYear
Countries
x
x
x
73,000
Yields
Engine MissionsYear
7
Addressing the Contributors to Safety

• Minimize Engine Shutdown Rate
• Strict observance to previous lessons learned
• Jet-Engine-Like design and development process
• Engine Health Management System (EHMS)
• Minimize the Fraction of Uncontained Shutdowns
• Engine cycle and configuration selection
• Strict observance to previous lessons learned
• EHMS
• Minimize Uncontained Event Propagation to LOV
• Engine and propellant feed system isolation
• Engine/component arrangement with respect of
  critical vehicle subsystems (perhaps with local
  shielding)

8
Typical Future Propulsion Safety Targets
3X Improvement
3X Improvement
3X Improvement
9
Putting 3X Improvement Into Perspective

• 2

10
10
365
FlightsDay - Country
Engine MissionsFlight
DaysYear
Countries
x
x
x
73,000
Yields
Engine MissionsYear
10
Approach for More Aggressive 5X Goals

• Minimize Engine Shutdown Rate
• Fewer combustion devices and valves
• Lower system pressures, temperatures and thermal
  strains
• Minimize the Fraction of Uncontained Shutdowns
• Inherently self-limiting power cycle
• Lower potential for ducting burn-through
• Minimize Uncontained Event Propagation to LOV
• Lower probability of hot gas release
• Lower system pressures (I.e., lower stored
  potential energy)

11
Next Generation Engine Safety Needs
5X Improvement
5X Improvement
5X Improvement
12
How About 5X Across-the-Board Improvement

• 2

10
10
365
FlightsDay - Country
Engine MissionsFlight
DaysYear
Countries
x
x
x
73,000
Yields
Engine MissionsYear
13
Propulsion for Future ETO Systems

• Safety is the Key Robust Architectures
• Drastic Improvements Will Be Needed
• Demonstrated Solution Paths Exist