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AF T&E DaysHigh Speed Weapons

What is Different Today2 February 2010

Maj Gen Curt Bedke

Commander

Air Force Research Laboratory1

Approved for Public Release; 88ABW-2010-0007



Starts…and Stops

2



Persistent and Responsive Precision Engagement

On-Demand Force Projection, Anywhere

Hypersonic Capabilities

Regional Reach

Globally Deliver Full Spectrum of KineticEffects

Global Delivery of Selected Effects AgainstTime-Sensitive and High-Value Targets

Clandestinely, Globally Deliver

Autonomous, Unattended Payloads

Responsively Deliver Payloads Into, orThrough, Space

Global Reach



“Man’s got to know his limitations”. – Harry Callahan, Magnum Force

National Aerospace Plane cancelled FY95 for primarytechnical shortfalls:

1. Boundary Layer Transition flow field uncertainty

2. Scramjet Engine immaturity

4



Hypersonics: High-speed flow regime where thermodynamic and chemical

processes dominate energy transfer between the vehicle and flow

Ground simulation cannot match enthalpy, noise, Reynolds number, scale, andnonequilibrium chemistry contributing to friction and catalytic heating in flight

Scientific Challenges inHypersonics

Combustion

Boundary Layer Physics

High-Temperature Materials

Internal Thermal Management

Gas-Surface Interactions

Courtsey: R. Baurle, NASA

Shock Interactions

Propulsion Issues

Thermal Protection



When Boundary LayerTransition Occurs…

•Skin Friction Increases Vehicle Drag

•Surface Heat Transfer Rate IncreasesStructural Thermal Load

•Boundary Layer Thickness is Fuller Control Surface Effectiveness

Flow Instability

Laminar FloLORN Tran

Turbulent Fl

Pull-Out Maneuver

Hypersonic Cruise

~6x difference between peakturbulent and laminar heating rates.

C o l d W a l l H e a t i n g R a t e

Turbulent

Laminar

Pull-Out

Cruise

Time

ALT

Time

Boost-Glide Trajectory

image courtesy Hornung, Cal TechLaminar Transitional Turbulent



Scramjet Propulsion

• Light a Match and keep it burning in a “Hurricane” • Burn fuel quickly (1 millisecond)• Control shock generation

• Optimize fuel/air utilization



Cracking anddebonding of

coating

High Temperature Materials

Oxidation andburn-through

Spalling

Reinforced Carbon/CarbonLeading Edge Oxidation Failure



What is Different Today?

1. Predictive computationaltools that simulate the

flight environment withhigh fidelity

2. Material systems thatperform across the highspeed flight regime

3. Better understanding ofwind tunnel environmentand correlation to flight

9

Advances in Science & Technology are resolving crucialchallenges to hypersonic flight:



Foundation for HypersonicSystem Development

ORS

Must do an effective, efficient job of tying together all three elements

Flight Test

ComputationsGround Test



Scramjet Flow Diagnostics

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Pressure Vorticity

Axial Velocity Radial Velocity

Objectives

• Characterize internal flow field

• Measure mass flux

• Monitor combustion

• Validate computational data

Variable GeometryInlet

Combustion Monitoring

Rationale

• Inlet Control / Variable Geometry• Fuel Control / Equivalence Ratio

• Monitor Performance

• Thrust and ISP Impact



•X-51A Scramjet Engine Demonstrator

•

Falcon Hypersonic Test Vehicle 2(HTV-2)

•Hypersonic International Flight

Research Experimentation (HIFiRE)

12

Broad Program Portfolio



X-51A Scramjet Engine Demo (SED)

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Free-flying technology demonstrator for hydrocarbon-fueled scramjet propulsion. Air-launched from B-52aircraft with modified ATACMS rocket booster.

Milestones

2004 Program Initiated

2009 B-52 Captive Carry Flight

2010 Flight Tests 1-4



Hypersonic X-51AScramjet Engine Demonstrator

X-51A - Hydrocarbon fuel (JP-7), M=4.5 to Mach 6+ flight



X-51A Scramjet Engine Demo

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Flight demonstration of scramjet engine•

Thrust > Drag• Engine On Mach 4.5 – 6.0+• Fixed geometry flowpath• 12 minute durability• Affordable, high lift Waverider airframe• Logistic-friendly hydrocarbon JP-7 fuel• ATACMS booster (modified)

Before 2020: Affordable fast reaction standoff weapon

•Time sensitive targets: rapid response, long range standoff

•

Deeply buried targets•Modular payload (penetrator, explosive, or submunition)

•Reduced vulnerability to air defenses2030: Affordable on-demand access to space with aircraft-likeoperations



X-51A SED First Flight Preparation

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4 Flight Tests Feb-May 2010

Engine start

Cruiser acceleration

Scramjet engine transients

Power-on & power-offparameter identification

maneuvers



Falcon Hypersonic Test Vehicle 2(HTV-2)

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Free-flying technology demonstrator foraerodynamic performance andadvanced structures

Q i t Fl Wi dt l H l



Quiet Flow Windtunnel HelpsExtrapolate HTV-2 Flight Prediction

NASA LangleyMach 6Noisy flow

Transition

Purdue Mach 6Quiet Flow

Purdue Mach 6Quiet Tunnel

Developed 95-05 AFOSR

Demonstrated Boundary Layer Transition Reynolds #’s

at least twice those of conventional tunnels

PSE A l i P id B t HTV 2



PSE Analysis Provides Best HTV-2Flight Transition Estimates

PSE method provides order-of-magnitude improvement in

predicting transition

PSE Correlation ofWind TunnelTransition

Parabolized Stability Equations (PSE)

Most advanced correlation methodAFOSR – developed mid 90’s

ContractorTransitionCriterion

Correlated Ground TestTransition Estimate

A l t i t u d e

Velocity

Straight-In

Crossrange

Design



Critical assessment of transition and heating issues allows

certification of HTV-2 design and trajectories

Applying Basic Science Technologiesto System Demonstrators

Quiet Tunnel measurements counter indications of early transition obtained in conventional facilities Temp

measurementsS. Schneider, Purdue

Advanced Numerical Simulations Provide Revolutionary Insight: Identify Source of Near-Centerline Hot Streaks

G. Candler, U. of Minnesota

Langley Mach 10Empirical

Computational

Increased surface pressuredue to nose/leading edge shock interactions

StreamlineConvergence

StreamlineDivergence

Thickening ofboundary layerresults in lesssurface heat flux



1 Flight in FY09

9 Flights Scheduled FY10-11

Hypersonic International Flight ResearchExperimentation

Captive-booster and free-flyingresearch experiments infundamental sciences. Low-cost

sounding rocket approachprovides a flying wind tunnel tobuild “hypersonic tool kit”.



Ground Test and CFD Provide the Foundation

HIFiRE Program

Fundamental Knowledgeto Enable Future Capabilities

HIFiRE Flight Research Provides Focus

PGS

ORS

LRS M=8, h=50kft, a=0, b=0



Integrated NG&C

Propulsion &Aeropropulsion Integration

Aerosciences:

Boundary layer transition Shock/shock interactions/separations Aerodynamic heating

Propulsion: Combustion limit of HC fuels Engine mode transition

Radical farming

Guidance and Control: Vehicle dynamics and aerodynamics Integrative, Adaptive Guidance & Control w/

gain adaptation

Sensors and Instrumentation: GPS translation Aero-optical wave front aberrations Tunable Diode Laser Absorption Spectroscopy

flow field measurements Scramjet engine and boundary layers High data rate, high sensor density

measurements

Aerodynamics &Aerothermodynamics

HIFiRE Experiments

HIFiRE Fli ht 0



HIFiRE Flight 0

Launched from Woomera Test Range, South Australia: 07 May 09

We found it!



A Reminder…

•Hypersonics is not a problem to be solved, it is a lot ofproblems to be solved!

– Accelerate through jet – ramjet – scramjet – andback

– Aerodynamics

– Thermodynamics

– Sensors

– Configuration changes

– …

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L ki F d



Looking ForwardT&E Challenges for Large Scale Applications

Scale: Missile & Ground Test (1x)14’ long, 9” wide

Scale: Space Access (100x)100’ long, 10’ wide

Inlet

Combustor

Nozzle

Inlet

Combustor Nozzle



Summary

1. Air Force on threshold of truly operating scramjet-powered hypersonic test vehicles for 10s and 100s ofseconds

2. Hypersonic flight test is inherently expensive and

high risk3. The risk comes down dramatically with:

– High fidelity modeling and simulation tools

– Realistic ground test

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We need a sustained, steady effort… Focused on solving real science problems…

Driven by practical mission requirements

mg bedke high speed weapons

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