Automated Aerial Refueling: Extending the Effectiveness of Unmanned Air Vehicles

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Automated Aerial Refueling Extending the
Effectiveness of Unmanned Air Vehicles

• Jacob Hinchman
• Program Manager
• Automated Aerial Refueling
• Jacob.Hinchman_at_wpafb.af.mil

Distribution A Cleared For Public Release
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Significance to Air Force

• Unmanned Aerial Vehicles
• Extends Range
• Shortens Response for Time-Critical Targets
• Maintains In-Theater Presence Using Fewer Assets
• Deployment with Manned Fighters and Attack
  Without the Need of Forward Staging Areas

We will leverage long-range and stealthy assets
to ensure we can access any target and quickly
defeat enemy defenses to allow other forces to
operate. Global Strike Vision

• Manned Aircraft
• Provides Adverse Weather Operations
• Improves Fueling Efficiency
• Reduces Pilot Workload

AAR Will Assist UAVs in Reaching Their Full
Potential and Greatly Enhance Manned Refueling
PA AFRL/WS-04-1076
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AAR Program Key Aspects

• Automating the Receiver
• Demonstrate an Operationally Feasible UAV
  Refueling Capability
• Near-Term Focus Boom/Receptacle Refueling
• Target was Air Force UAVs
• Near-Term Refueling Requirement
• Challenge Technology Base
• Future Application to Probe Drogue Refueling
• Leverage Tech Base Developed in B/R
• More Challenging End-Game

Crawl, Walk, Run Spiral Approach to Provide
Timely Technology Transition
PA AFRL/WS-04-1076
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Boom/Receptacle Refueling

• From the Receivers Perspective
• Close Formation Flight
• Follow Tankers Lead Around Refueling Track
• Can Take up to 30min for Heavys
• From the Tankers Perspective
• Tanker Flies in a Predictable Manner
• Boom Operator Flies Boom into Receptacle
• Tanker Control Fuel Offload and Rate

PA AFRL-WS 05-1166
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Probe/Drogue Refueling

• From the Receiver's Perspective
• Fly Formation with Tanker
• Capture the Drogue/Basket
• Push Basket Forward for Fuel to Flow
• From the Tankers Perspective
• Fly in a Predictable Manner

PA AFRL-WS 05-1166
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National AAR Team
AFRL/VA
ACC
ASC
AMC
AFRL/HE
AFRL/SN
Navy
PA AFRL/WS-04-1076
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Key Technology Challenges

• See Near
• Determine Relative Position with Tanker
• Using Position/Velocities to Close Control Loop
• High Confidence in Position Accuracy
• Avoid Aircraft in AAR Area
• Collision Avoidance
• AAR Brings Many Aircraft into Same Airspace
• Moving from ARIP to ARCP

• Command and Control
• Assure UAV Accurately Responds to Boomer
  Break-Away Commands
• Commands are Flight Critical
• Real World Considerations
• Fitting Solutions into a Low Probability of
  Detect/Intercept Environment
• Latency, Drop-Outs, Re-Encryption, and Limit
  Power Settings

PA AFRL/WS-04-1076
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Key ChallengesIntegration of Technologies

• Refueling Affects Most Aircraft Systems
• Fuel, Navigation, Flight Controls, Sensing, Comm,
  and Ground Station
• Pilot in Command Issues
• Ground Station has Limited Situational Awareness
• Data Latencies due to Datalink Delays
• Autonomy of Vehicle Increases
• Fault Detection and Safety need to be On-Board

• Technologies Needed
• Formation Flight
• Automated Collision Avoidance
• Precision Positioning
• Tanker to UAV Comm
• Ground Station SA

Dist A Public Released
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Mission Profile
Dist A Public Released
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The CONOPS

• Working with ACC AMC to Develop CONOPS
• Used F-16 Procedures As Baseline
• Refueling 4-Ship UCAS Packages
• Manned Refueling Procedures
• Extensive use of simulation to validate and
  demonstrate CONOPS to warfighter

Based AAR Procedures On Current Manned Aircraft
Procedure Ensuring Seamless Integration, Ease
Transition
Public Release ASC 04-1036
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Example CONOPSContact Position
Authorized UCAS Stabilizes in Pre-Contact Position
Boomer Authorizes UCAS to Contact Position
Authorized UCAS Stabilizes in Contact Position
Boomer Plugs UCAS
UCAS Acknowledges Contact to MCS Operator
Confirmation of Contact Is Provided to Tanker
UCAS Maintains Contact Position
UCAS Takes Fuel
Dist A Public Released
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AAR Conceptual Design Families

• Navigation-Based
• Advantages
• Lowest Technical Risk For Initial Capability
• All Weather Capability
• Compatible With Navy Ops
• Simple Vehicle Integration
• Disadvantages
• Requires Tanker Modifications
• Susceptible to GPS Degradation

• Sensor-Based
• Advantages
• Most Affordable Conceptual Design
• Sensor May Enable Additional UCAS Capabilities
• Disadvantages
• UCAS Vehicle Integration
• Sensor Development Risk

Public Release ASC 04-1271
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An Equivalent Model for
UAV Automated Aerial
Refueling Research

Dist A Public Released
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Planform Control Surfaces
Equivalent Model
ICE 101
Leading Edge Flaps
Spoiler Slot Deflector
Flap (Pitch)
Clamshell (Yaw Speed Brake)
Clamshell
Aileron (Roll)
All Moving Tip Deflector
Pitch Flap
Elevon
Dist A Public Released
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Equivalent Model Initial Agreement
Model will be non-proprietary
The ICE aspect ratio will be modified to a value
of 3.7
To properly model gust sensitivity in the pitch
axis, wing loading will be adjusted to 50 lb/ft2
Control power will be modeled as required to meet
acceleration requirements and provide a
predictable, linear, inner-loop response
Control surface effectiveness and interactions
will be simplified since control allocation is
not the focus of this effort
Dist A Public Released
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Flight Limits and Airframe Response
Flight Envelope
Altitude 20K to 30K Airspeed 225 KCAS to Mach
0.8 Angle of Attack -5 to 10 Side Slip Angle
/- 5
Total Fuel Weight 17,500 lbs Total Gross Weight
40,430 lbs
Short Period, Roll, and Dutch Roll Mode Response
Pitch time to double - neutral Roll - stable Yaw
time to double - neutral
Acceleration Response
Pitch 5.52 rad/sec2 (independent use of
full pitch flaps) Roll 7.84 rad/sec2
(independent use of full elevons) Yaw 1.17
rad/sed2 (independent use of one
clamshell) Deceleration 12.35 ft/sec2
(independent use of both clamshells-
assumes no
yaw input)
Dist A Public Released
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Target Closed Loop Dynamics
Longitudinal Axis Short Period Frequency 4.5
rad/sec Short Period Damping 0.8 Roll
Axis Bank Frequency 2.2 rad/sec Bank Damping
0.9 Directional Axis Dutch Roll Frequency
1.5 rad/sec Dutch Roll Damping 0.8 Speed
Control Speed control requirements will be
developed as part of the AAR contract. Use of
modulated speed brakes will only be pursued if it
is determined adequate control can not be
achieved through use of engine control alone
Note Stability margins of 6 db and 45 to be
maintained with guidance loops closed
Dist A Public Released
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Role of Flight Simulation

• Integrated Aerial Refueling RD Simulation Being
  Developed
• Boomer Station
• UAV Operator Station
• Tanker Pilot Cube
• Other Receiver Stations
• Provides Test Bed for AAR System Development
• Allows Rapid Prototyping and Early Operator
  Interactions
• Helps Develop and Visualize Correct Story Boards

PC Based Simulation
Infinity Cube Simulation
Facilitate Early Operator Interaction with the
AAR System
Dist A Public Released
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Simulation Structure

• Simulation consists of five main components
• Simulation control console
• KC-135 boom operator station
• KC-135 pilot station
• UAV operator station
• Observer-Referee station
• D-Six stations
• Windows-based, real-time simulation environment
• Includes four UAVs, KC-135 tanker, and boom model

Dist A Public Released
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Simulation Stations

• KC-135 pilot station
• Uses the Infinity Cube
• Allows pilot to observe and participate
• Provides use of autopilot or hands-on flying
• KC-135 boom operator station
• Designed specifically for AAR
• Allows boomer to evaluate technologies and
  concepts of employment
• Need boomers to support the AAR process

Dist A Public Released
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Precontact Command
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Right Monitor During Rendezvous
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Recent Simulation Events

• AAR Auto ACAS Simulation (Summer 2004)
• UAV Position and Pathway Validation Study (Fall
  2004)
• Turbulence Evaluations (Winter 2004)

Dist A Public Released
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Future Simulation Events

• Rendezvous Algorithm Development (Spring 2006)
• Storyboard Evaluation (Through 2007 and Beyond)
• Flight Test Support (Summer 2005 Fall 2007)

Dist A Public Released
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Capstone Simulation

• Objective
• Demonstrate complete set of AAR system designs
  with high fidelity models
• Full concept of operations (CONOPS) development
  for multiple UAVs
• Purpose
• Transition AAR four ship CONOPS to production
• Test Details
• Man in-the loop simulation
• Boom, manned control station, tanker pilot
• Equivalency model
• PGPS effected model
• Data link model
• Turbulence model

Improve Simulation Capability for four ship
CONOPS Development
Dist A Public Released
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Flight Test Objectives

• Mature Precision GPS (PGPS) technology throughout
  flight test
• Reduce technology development risk
• Refine simulation models
• Gain confidence in system architectures and
  designs
• Enable technology transition to future UAV systems

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Phase I Open-Loop Data Collection

• Flight Test Objectives
• Qualify Lear Jet for flying around KC-135
• Validate PGPS models and assumptions
• Body masking
• Gather real-time GPS and INS data
• Gather Electro-Optical sensor data
• Validate tanker downwash predictions

• Flight Test Purpose
• Improve PGPS simulation models for AAR system
  development
• Augment hybrid system development
• Test Details
• 107th ANG Tanker
• Calspan Lear Jet

Critical to Determine Design Feasibility
Dist A Public Released
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Precision Positioning System Accuracy
Requirements at Contact
Boom Air-to-Air Refueling Envelope
One of Several Positioning System Requirements
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TTNT Data Collection

• Flight Test Objectives
• Evaluate real-time performance of PGPS algorithm
  with data link
• Evaluate TTNT data link performance under
  real-world conditions
• Validate analytical models
• TTNT data link
• GPS Receiver
• Embedded GPS and INS
• Flight Test Purpose
• Characterize PGPS sensors and data link in
  real-time
• Critical step for ensuring system integrity
• Test Details
• NAVAIR E-2 or T-39
• Calspan Lear Jet

Real World Constraints are Critical to AAR
Design
Dist A Public Released
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PGPS Closed-Loop Station Keeping

• Flight Test Objectives
• Evaluate
• The performance of updated PGPS models
• The interface between guidance navigation system
  and flight control system
• The PGPS integrity system
• The station keeping flight control laws
• Update TTNT data link performance
• Flight Test Purpose
• Demonstrate PGPS accuracy and integrity
• Validate Lear Jet analytical model
• Verify performance of inner and outer loop
  control laws
• Test Details
• 107th ANG KC-135
• Calspan Lear Jet 25

Critical integration of PGPS and Flight Control
Laws
Dist A Public Released
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AAR Graduation Flight Demo

• Flight Test Objectives
• Demonstrate full AAR closed-loop precision
  navigation system on a Lear Jet moving around a
  KC-135 from Observation-gtPre-Contact -gt Contact
  -gt Pre-Contact Including Breakaway
• Validate PGPS performance
• Collect data from candidate EO/IR sensor for
  Hybrid system development
• Flight Test Purpose
• Prove AAR system design on Lear Jet
• Provide key metrics for simulation demonstration
• Ensure AAR technology transition to UAVs

Demonstration Ensures AAR Technology Transition
to UAVs
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Summary

• Air Force Research Laboratory is the World Leader
  in AAR
• Operationally Relevant
• Meet future refueling requirements
• Synergy between flight test and flight simulation

The AAR Team is Poised to Meet the Automated
Refueling Challenge
Dist A Public Released