Hypersonic Vehicle Systems Integration Vehicle Stability and Control

1
Hypersonic Vehicle Systems IntegrationVehicle
Stability and Control

• 12 September, 2007
• Dr. Kevin G. Bowcutt
• Senior Technical Fellow
• Chief Scientist of Hypersonics
• Boeing Phantom Works

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Summary of Stability and Control Criteria
Item
Criteria

• Longitudinal Stability
• Longitudinal Control
• Directional Stability
• Directional Control
• Lateral Stability
• Lateral Control

• Minimum time-to-double for augmented stability
• Nose wheel rotation at takeoff speed
• Land with control margin
• Trim over acceleration, reentry and at cruise
  with maneuver margin
• Positive sideslip stability with inlet unstart
• Landing crosswinds of 30 kts
• Takeoff crosswind of 30 kts with partial engine
  failure
• Dutch roll frequency at high speed
• Roll acceleration rate at high speed

3
Aero Control Surface Options
All-moving Horizontal Tail or Wing Tip Pitch
and Roll
Elevon Pitch and Roll
Body Flap Pitch
Canard Pitch and Roll
All-moving Vertical Tail or Rudder Yaw
Control Surface Sizing Rules of Thumb
4
Vertical Tail Design Drivers

• Tail location issues
• Hypersonic lateral / directional stability
• Yaw control
• Outboard cant and toe-in improve effectiveness

Wing Tip Tail Best Aerodynamically, But Creates
Structural Problems
Forward Tail Excessively Destabilizing
Center Line Tail Ineffective (Shadowed) at Even
Small Angles of Attack at Hypersonic Speeds
Outboard Fuselage Best Aerodynamic/ Structural
Compromise
After Harsha 9
5
Vertical Tail Effectiveness on Yawing Moment
M 8.18
0.008
Wind Tunnel Test Data
0.004
Legend
Sym
Configuration
0
Tail Off Single Tail Twin Tail Twin Canted Tail
Yawing Moment Coefficient Cn
-0.004
-0.008
? 0
-0.012
Twin Canted Tail Provides Best Control
Effectiveness
-0.016
-12
-8
-4
0
4
8
12
Angle of Sideslip Degrees
From Harsha 9
6
Control Surface Sizing Issues and Requirements

• Sizing
• Engine-out control
• Inlet start and unstart transients
• Stability augmentation requirements
• Handling qualities
• Low Q and on orbit (RCS augmentation)
• Location
• Rudder
• Elevon
• Body flap
• Canard
• Actuation
• Frequency requirements
• Hinge moments
• Type (technology) / power source

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Hypersonic Vehicle Stability Challenging Given
Large Neutral Point Variation With Mach

• High speed stability driven by unstable short
  period oscillation
• Time-to-double amplitude must be large enough
  for state-of-the-art stability augmentation
  systems

T2 ? ?n2 / M? / Iyy , M? ? q? CM?
Required T2 ? 0.25 sec
-10
Neutral Point ( Body Length)
Nominal
Blended Body
Wing Body
10
0
4
8
12
16
20
Mach
After Page and Welge 8
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Longitudinal Stability and Control Plus Trim (1)
)
)
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Longitudinal Stability and Control Plus Trim (2)
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Longitudinal Stability and Control Plus Trim (3)
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Longitudinal Stability and Control Plus Trim (4)
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Longitudinal Stability and Control Plus Trim (5)
Plots from Raymer, Daniel P., Aircraft Design A
Conceptual Approach, Fourth Edition, AIAA
Education Series, 2006
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Longitudinal Stability and Control Plus Trim (6)
From Hoerner, Aerodynamic Lift
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Longitudinal Stability and Control Plus Trim (7)
From Hoerner, Aerodynamic Lift
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Longitudinal Stability and Control Plus Trim (8)
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Longitudinal Stability and Control Plus Trim (9)
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Longitudinal Stability and Control Plus Trim (10)
From Raymer, Daniel P., Aircraft Design A
Conceptual Approach, Fourth Edition, AIAA
Education Series, 2006
18
Lateral-Directional Stability and Control Plus
Trim (1)
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Lateral-Directional Stability and Control Plus
Trim (2)
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Lateral-Directional Stability and Control Plus
Trim (3)
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Preliminary Assessment of Longitudinal Stability
Control and Trim

• Suggested longitudinal SC/trim analysis cases
• Subsonic Supersonic

• Hypersonic

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Preliminary Assessment of Lateral-Directional
Stability Control and Trim

• Suggested lateral-directional SC/trim analysis
  cases
• Subsonic Supersonic

• Hypersonic