I n t e g r i t y - S e r v i c e - E x c e l l e n c e Air Force Research Laboratories Automated Aerial Refueling: Extending the Effectiveness of Unmanned.

I n t e g r i t y - S e r v i c e - E x c e l l e n c e

I n t e g r i t y - S e r v i c e - E x c e l l e n c e

Air Force Research Laboratories

Automated Aerial Refueling: Extending the Effectiveness

of Unmanned Air Vehicles

Jacob HinchmanProgram Manager

Automated Aerial Refueling

[email protected]

Distribution A: Cleared For Public Release

I n t e g r i t y - S e r v i c e - E x c e l l e n c e 2

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

Significance to Air Force

Manned Aircraft

– Provides Adverse Weather Operations

– Improves Fueling Efficiency

– Reduces Pilot Workload

AAR Will Assist UAVs in Reaching Their Full Potentialand Greatly Enhance Manned Refueling

“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

PA #: AFRL/WS-04-1076


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


Boom/Receptacle Refueling

• From the Receiver’s Perspective- Close Formation Flight

- Follow Tanker’s Lead Around Refueling Track

- Can Take up to 30min for Heavy’s

• From the Tanker’s Perspective- Tanker Flies in a Predictable Manner

- Boom Operator Flies Boom into Receptacle

- Tanker Control Fuel Offload and Rate

PA #: AFRL-WS 05-1166


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 Tanker’s Perspective- Fly in a Predictable Manner

PA #: AFRL-WS 05-1166


National AAR Team

ACCAMCASC

CorporationSynGenics

©

Navy

PA #: AFRL/WS-04-1076


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


Key Challenges:Integration 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


Mission Profile



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 ProcedureBased AAR Procedures On Current Manned Aircraft Procedure Ensuring Seamless Integration, Ease TransitionEnsuring Seamless Integration, Ease Transition

Public Release #: ASC 04-1036


Example CONOPS:Contact 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



AAR Conceptual Design Families

Sensor-BasedAdvantages:• Most Affordable Conceptual Design• Sensor May Enable Additional UCAS

Capabilities

Disadvantages:• UCAS Vehicle Integration • Sensor Development Risk

Navigation-BasedAdvantages:• Lowest Technical Risk For Initial Capability• All Weather Capability• Compatible With Navy Ops• Simple Vehicle Integration

Disadvantages:• Requires Tanker Modifications• Susceptible to GPS Degradation

Public Release # : ASC 04-1271


An Equivalent Model for UAV Automated Aerial

Refueling Research



Equivalent Model

Clamshell (Yaw & Speed Brake)

Aileron (Roll)

Flap (Pitch)

Planform & Control Surfaces

ICE 101

Spoiler Slot Deflector

Leading Edge Flaps

All Moving Tip DeflectorPitch Flap

Elevon

Clamshell

Leading Edge Sweep 65 deg

Wing Span 37.5 ftBody Length 43.12 ft

AR 1.74

Wing Area 808.6 sq ft

Leading Edge Sweep 42.8 deg

Wing Span 54.7 ftBody Length 29.6 ft

AR 3.7

Wing Area 808.6 sq ft



Equivalent Model Initial Agreement

The ICE aspect ratio will be modified to a value of 3.7

Model will be non-proprietary

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



Altitude: 20K to 30KAirspeed: 225 KCAS to Mach 0.8Angle of Attack: -5° to +10°Side Slip Angle: +/- 5°

Flight Envelope

Pitch time to double - neutralRoll - stableYaw time to double - neutral

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)

Flight Limits and Airframe Response

Acceleration Response

Short Period, Roll, and Dutch Roll Mode Response

Total Fuel Weight = 17,500 lbsTotal Gross Weight = 40,430 lbs



Longitudinal AxisShort Period Frequency 4.5 rad/secShort Period Damping 0.8

Roll AxisBank Frequency 2.2 rad/sec Bank Damping 0.9

Directional AxisDutch Roll Frequency 1.5 rad/secDutch 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

Target Closed Loop Dynamics



• Integrated Aerial Refueling R&D 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

Facilitate Early Operator Interaction with the AAR System

Role of Flight Simulation

Infinity Cube Simulation



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



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



Precontact Command


Right Monitor During Rendezvous


GP44153002.pptAAR-Modified Conventional

Uncertainties

Tanker’s Semi-Wingspan

• AAR Auto ACAS Simulation (Summer 2004)

• UAV Position and Pathway Validation Study (Fall 2004)

• Turbulence Evaluations (Winter 2004)

Recent Simulation Events

GP44153001.ppt

Contact Position

Post-Refueling Position

Observation Position

Pre-Contact Position(50 ft behind and 10 ft below the

refueling boom pivoting point)

WingtipVortex

Inboard andOutboard Engine

Exhaust

InboardIntermediate

InboardObservation



• Rendezvous Algorithm Development (Spring 2006)

• Storyboard Evaluation (Through 2007 and Beyond)

• Flight Test Support (Summer 2005 – Fall 2007)

Future Simulation Events

ARIP

ARCPEn RouteRendezvous

Air-to-AirRefueling

Tanker Orbit275 KIAS

J-UCASs Exit Refueling Track

EAR



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


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



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



-30

-25

-20

-15

30 35 40 45

X Distance - ft

Z D

ista

nce

- ft

Refueling EnvelopeCenterGoal Envelope

Threshold Envelope

Approximation

EnvelopeApproximationApproximation

Approximation

Note: Distances are for zero azimuth angle

Precision Positioning System Accuracy Requirements at Contact

Boom Air-to-Air Refueling Envelope

One of Several Positioning System

Requirements


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



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



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->Pre-Contact -> Contact -> 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



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


I n t e g r i t y - S e r v i c e - E x c e l l e n c e Air Force Research Laboratories Automated Aerial Refueling: Extending the Effectiveness of Unmanned.

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