ASlayoutX

8/6/2019 ASlayoutX

http://slidepdf.com/reader/full/aslayoutx 1/19

AEROSPACE SCIENCES

Applied aerodynamics

This year saw significant progress in industry,research labs, and academia in the developmentof flow-control concepts, novel configurationaerodynamic concepts, and aerodynamic im-provement technologies for enhancing the fuelefficiency and performance of aircraft and sur-face vehicles. Progress in applied aerodynamicsincluded wind tunnel and flight testing com-bined with CFD optimization methods underconstraints from fluid dynamics, structures,controls, flight dynamics, and other disciplines.

Aerodynamics of commercial aircraftIn the U.S., Boeing rolled out its first 787-8 air-craft in preparation for flight testing. The 787 is

an all-new, technologically advanced and envi-ronmentally progressive airplane scheduled toenter service in 2008. Significant improvementsin 787 fuel efficiency are partly due to enhancedaerodynamic performance afforded by largewingspan (enabled by carbon-fiber compositestructure) and advanced wing-tip and fuselageshapes, together with large-scale optimizationusing CFD and testing methods. The compositestructure allows smoother aerodynamic sur-faces. The Mach-0.85 aircraft has a compacttrailing-edge high-lift flap system with smallflap-track fairings. The highly integrated na-

celles are shaped for minimizing drag and noise.In Europe, Airbus delivered the first A380

for use in passenger revenue service, whileaerodynamic design and wind tunnel studiesare progressing toward definition of the new

Airbus A350-XWB aircraft (also incorporating acomposite wing). Both cruise at Mach 0.85.

Aerodynamics of new configurationsThe innovative Blended Wing Body (BWB) X-

48B scaled research aircraft flew for the firsttime in July at NASA Dryden. The 21-ft-spanunmanned test vehicle was developed by Boe-

ing Phantom Works in cooperation with NASAand the Air Force Research Laboratory (AFRL)

to gather information on stability and flightcontrol characteristics, especially during take-offs and landings.

The Silent Aircraft Initiative, a collaborativestudy by Cambridge University, MIT, and sev-eral industry and government partners, dissem-

inated the SAX-40 conceptual design, a quietaircraft concept with novel centerbody aerody-namics and boundary-layer-ingesting distrib-uted propulsion. These highly integrated BWB

concepts have the potential to yield a stepchange in noise emission and fuel burn com-pared to existing aircraft.

Next-generation tactical transport AFRL, NASA, and industry partners are devel-oping technologies for aircraft configurations toenable efficient flight at low speed (90 kt) aswell as at transonic cruise speeds (Mach 0.8 orhigher). This would enable future transport air-craft to take off and land in short distanceswhile providing fast transportation for intrathe-ater missions.

Wind tunnel tests on high-lift configura-

tions have been conducted to validate systemarchitectures, to study flow fields of blownflaps, and to gather an aerodynamic databasefor simulations. Also being investigated aretransonic drag reduction technologies, includ-ing bumps and blowing mechanisms to reducewave drag.

Applied aerodynamic flow control Advances in lightweight materials, actuatortechnology, and aerodynamics are coming to-gether in attempts to improve flight and controlcharacteristics of swept-wing tailless UAVs.

West Virginia University and NASA Dryden co-operated on an adaptive washout morphingmechanism for control of tailless aircraft. Con-trol was achieved by using five morphing“feathers” on the outer portion of the wing toprovide adaptive washout.

Feasibility of this morphing mechanismwas demonstrated by flight testing a 7-ft-wingspan swept-wing tailless scaled aircraft.

Wind tunnel, CFD, and free-flight data were ingood agreement in the range of test conditions.

Progress was made in the application of plasma flow-control concepts to practical actu-

ators. Under an Air Force Small Business Inno-vative Research program, researchers at OrbitalResearch and the University of Notre Dame in-vestigated a plasma enhanced wing for aerody-namic control without movable surfaces. Dis-tributed wing surface-mounted dielectricbarrier discharge (DBD) plasma actuators wereinstalled on a 47-deg sweep 1303 UCAV modelin wind tunnel tests with a mean-chord Rey-nolds number of 0.4 million.

The DBD plasma actuators in the leadingedge altered the flow field over the lee side of the wing to impart longitudinal and roll controlat angles of attack between 15 and 35 deg. Ac-

4 AEROSPACE AMERICA/DECEMBER 2007

West Virginia University’s 7-ft- span swept-wing tailless demon- strator used wing-tip morphing for control.

8/6/2019 ASlayoutX

http://slidepdf.com/reader/full/aslayoutx 2/19AEROSPACE AMERICA/DECEMBER 2007 5

tuators applied on the windward side near thetrailing edge with a separation ramp producedlift control from 0 to 20 deg. Orbital Researchand Notre Dame have applied similar actuatorsto wind turbines for PACE (plasma aerody-namic control effector) flow control that allows

virtual shaping of turbine blades to increase en-ergy capture and reduce noise and vibration.

Aerodynamic flow control has potentialsynergistic benefit for active load control in thedesign of slender lifting surfaces such as wingsand blades for helicopters or wind turbines.One concept for active load control is an ac-tively controlled trailing-edge tab where the tabslides out of the surface side near the trailingedge of an airfoil to enhance (or mitigate) lift.Unsteady numerical flow simulations of thesliding-tab concept have been conducted, and

its effectiveness has been demonstrated in windtunnel tests at the University of California,Davis. The change in lift coefficient for this con-cept is approximately 0.2. The advantages of a sliding tab configuration are the small forceneeded for tab deployment and the short de-ployment times for rapid load control.

Configuration improvements AFRL researchers, in conjunction with Snow Aviation, performed flight tests on a modifiedC-130E aircraft fitted with functional tip tanksto determine their effects on the performance

and flight characteristics of an aircraft modifiedwith improved eight-bladed propellers andwith extended dorsal and rudder surfaces. Thetip tanks could replace traditional fuel tanksand may improve aileron effectiveness while re-ducing drag.

Using Snow Aviation’s instrumentation,tests of the modified aircraft showed significantimprovement in takeoff/landing distances, stallspeed, and minimum control speed in compar-ison with a “stock” C-130E, as well as in ceiling,specific range, and noise in audible range.

Surface vehicles and wind turbinesIndustry, academia, and governments contin-ued to make important contributions towardpractical geometry and/or flow-control modifi-cations to reduce drag of surface vehicles. Forexample, Georgia Tech Research Institute per-sonnel continued development of pneumaticaerodynamic concepts for drag reduction of tractor trailers and SUVs.

Wind tunnel investigations have shown upto 32% drag reduction on scaled long-haultruck models, while full-scale road tests havedemonstrated a 12% increase in fuel economywith pneumatic flow control. Active pneumatic

control could also provide increased safety fromyielding increased drag (when desired) forbraking and for increased lateral/directional sta-bility. Researchers at Delft University in theNetherlands plan road testing with fixed-geom-etry fairings added to the blunt aft-end of trac-

tor trailers to passively reduce flow separation.Thick airfoils have been pursued for vari-ous applications, including section shapes forinboard regions of blades on wind turbines. Re-cent research has demonstrated that blunt trail-ing edges may significantly improve the liftcharacteristics for such airfoils with maximumthickness/chord ratio greater than 25%. Thickairfoils typically have poor lift characteristicswhen boundary-layer transition occurs near theleading edge because of surface contamination.Incorporating a blunt trailing edge withoutmodifying the camber distribution has been

demonstrated in wind tunnel tests by the Uni-versity of California, Davis, to significantly re-duce the sensitivity of thick airfoils to leading-edge transition.

Space vehicles in atmospheric phaseNASA is developing the Orion spacecraft tocarry astronauts into orbit, to the Moon, andbeyond. Based on Apollo, the Orion commandmodule is a blunt body that achieves lift with anoffset center of gravity. An effort is under wayto characterize the dynamic stability of Orionduring reentry and launch abort scenarios. In

wind tunnel testing, NASA Langley is workingto obtain free-flight data without sting effectswhile matching flight lift-to-drag values. Thishas not been possible over long distances in in-door ballistic range.

The Army Research Laboratory performedfree-flight experiments in an outdoor range withtelemetry instrumented Orion scaled models.This technique combines the gun-launch of aprojectile using a double-length 120-mm gunwith an instrumentation package contained in-side the test article. Aerodynamic coefficientswere extracted from on-board instrumentationand position/velocity histories tracked by radar. by Paul VijgenGary Dale

The X-48B scale model flew for the first time at NASA Dryden in July.

8/6/2019 ASlayoutX

http://slidepdf.com/reader/full/aslayoutx 3/196 AEROSPACE AMERICA/DECEMBER 2007

AEROSPACE SCIENCES

Aerodynamicmeasurement technology

Researchers at Michigan State, in collaborationwith MIT and Iowa State, have introduced the

use of quantum dot (QD) nanoparticles formeasurements in fluid flows. Measurement ca-pabilities include characterization of scalar con-centration and temperature distributions usingQD tracers, in addition to imaging single QDs

for near-surface velocimetry.NASA Langley researchers are using high-

resolution, 1-kHz-rate video cameras to trackthe motion of falling crew exploration vehicle(CEV) test articles in support of the Orion Con-stellation program. A frame-by-frame object-to-image-plane scaling procedure is being applied

to help capture the dynamic impact of the vehi-cles before, during, and after ground contacts.Calculations are furnished for vehicle displace-ment, pitch and yaw angle changes, and verticaland horizontal velocities of the CEV models.Photogrammetric data obtained during testing,along with other instrumentation onboard thedrop vehicles, helps validate computations.

Stanford University is investigating twonew classes of diode-laser-based sources forwavelength-tunable light in the mid-IR. Thewavelength-tunable 3.30-µm lasers are basedon difference-frequency conversion of two

fiber-amplified diodelasers in periodicallypoled lithium nio-bate. The wavelengthtunability enables di-verse new strategiesto suppress noiseand background sig-nals in harsh com-bustion and propul-sion environments.

Advances in opticallyactive materials have

also enabled exten-sion of tunable diodelasers to wavelengthsin the range 2.3-2.7µm, enabling exten-sion of diode lasersensing strategies tothe stronger absorp-tion features of theCO2 and H2O com-bustion products.These stronger tran-sitions offer potentialfor precise measure-

ments of lower concentrations, shorter opticalpaths, and improved time resolution.

Also at Stanford, research into the ignitionchemistry of practical fuels and propellants,such as JP-8, JP-10, and DF-2, requires special-ized laboratory test facilities to overcome the

low room temperature vapor pressures of thesesubstances, where the real possibility of pretestdecomposition and oxidation of the fuel exists.To circumvent this problem, a new method forstudying low-vapor-pressure fuels has been de-veloped. A liquid fuel aerosol is introduced intoa shock tube, and the heat-rise from the inci-dent shock wave vaporizes the aerosol, rapidlyproducing a controlled mixture of fuel vapor.The high-temperature-ignition chemistry of thefully vaporized fuel can be studied behind thesubsequent reflected shock wave.

This method provides complete and rapidconversion of fuel to vapor phase without pretest fuel decomposition and oxidation, and completecontrol of the mixture and test conditions—pres-sure, temperature, and equivalence ratio. Laserabsorption is used to measure time-histories of the concentration of a wide variety of chemicallyimportant species: fuel components (alkanes,aromatics) are measured in the mid-IR usingdifference frequency generation lasers; transientradical species (OH, CH3) are measured in theUV using frequency-doubled and -quadrupledlasers; products (CO, CO2, and H2O) are mea-

sured using near-IR and mid-IR tunable diodelasers; and aerosol droplet loading is measuredwith nonresonant near-IR laser extinction. Us-ing the aerosol shock tube and its laser-baseddiagnostics, fundamental chemical processes of

jet fuels, jet fuel surrogates, and new syntheticfuels such as Fischer-Tropsch fuels can be stud-ied at elevated temperatures and pressures.

Vanderbilt University, Arnold EngineeringDevelopment Center, and the University of Tennessee Space Institute conducted the firstdemonstration of hydroxyl tagging velocimetry(HTV) in a gas turbine exhaust, operating a GE

J85 engine from idle to full throttle. HTV is alaser-based nonintrusive technique that pho-todissociates water vapor (H2O) in the exhaustinto OH and H using a grid of ultravioletpulsed laser beams.

The resulting OH grid “written” in the flowis subsequently “read” by imaging the grid’sOH fluorescence utilizing another ultravioletpulsed laser sheet. Flow displacement measure-ment through grid image comparisons andknowledge of the write-read delay time provideinstantaneous velocity field data. Exhaust ve-locities up to 500 m/sec (1,100 mph) weremeasured.

J85 engine at UTSI shows HTV laser flow tagging optics at exit.The red lines indicate grid-writ-ing laser path; blue indicatesPLIF “read” laser sheet.

8/6/2019 ASlayoutX


Atmospheric flightmechanics

There were a number of firsts to note in the fieldof atmospheric flight mechanics over the past

year. To begin with, the first flight of the F-35Lightning II took place on December 15, 2006.This marked the beginning of a 12,000-hr flighttest program that will also include Navy and V/STOL variants. The second first occurred onMarch 19 with two nearly simultaneous land-ings of the Airbus A380, one in New York andone in Los Angeles. Finally, on the carefully se-lected date of July 8, Boeing rolled out the 787

Dreamliner from its factory facility in Everett, Wash. The first flight of the 787 is scheduled forthe first quarter of 2008, as part of an ambitious

flight test program slated to conclude with FAAcertification later in the year.In an attempt to unlock some of the secrets

that allow birds to achieve agile flight, engineersworking with zoologists are attempting toquantify the flight performance of large birds.

What began as an interesting foray has now be-come an active area of research for the Air ForceResearch Laboratory(AFRL). The programinvolves mountingcameras on largebirds to observe vari-

ous aspects of animalflight. The develop-ment of microcam-eras and wirelesstechnology has al-lowed researchers toplace wireless camerapacks on birds forpurposes of carryingout these studies.

Initial observa-tions of an eagle’swing in flight showed

the deployment of the bird’s “covertfeathers” during certain maneuvers, similar toan aircraft’s deployment of leading-edge slats.

What was remarkable about this was that ithappened so quickly, and only at certain flightconditions. Other observations were also noted,such as wing morphing (or bending) for flightcontrol, and head movement in coordinationwith turns.

AFRL is now teaming with Oxford Univer-sity on a project that entails outfitting the birdswith a high-quality instrumentation package torecord accelerations, Euler angles (the bird’s

flight path angle with respect to the Earth), andangular rates. These data, coupled with cameraobservations, will allow engineers to correlatethe motion of the bird with changes of the wing.

This has been an important year for the V-22 Osprey as the aircraft moved from develop-

ment testing to full-scale operational testing. InFebruary and March, VMS-22 (Marine TiltrotorTest and Evaluation Squadron 22) logged 185flight hours with four aircraft in just 18 days,operating in the California and Arizona deserts.In June, the aircraft was pronounced fit for op-erational deployment, and a fleet of 10 Ospreyswas scheduled to deploy to Iraq in September.Developmental testing for envelope expansionand operational capabilities continues at NAS

Patuxent River, Md., and Edwards AFB, Calif.In other news, the UCAS-D program was

awarded in August and will demonstrate for thefirst time unmanned operations of a large air-craft from a Navy aircraft carrier.

This also has been an eventful year for thespace shuttle fleet. In-orbit reviews of the in-tegrity of the shuttle tiles continue to uncoverdamage associated with the ascent through theatmosphere. On the June flight of the space

shuttle Atlantis, the mission was extended bytwo days so that the astronauts could repair aninsulation blanket on the aft rocket pods. Re-pairs went without incident, and the shuttlelanded safely at Edwards AFB. On the Augustflight of Endeavour, foam shed from the exter-nal fuel tank again damaged the critical tiles. Inthis case the aluminum skin below the tile wasnot exposed or compromised. After much de-liberation, risky in-orbit repairs were deemedunnecessary, and on August 21, Endeavourlanded safely at Kennedy Space Center.

by David H. Klyde

Gregg AbateDavid Mitchell

Instruments mounted on a bird of prey will make observationsof various features during

flight. (Photo courtesy Gregg Abate.)

8/6/2019 ASlayoutX


AEROSPACE SCIENCES

Fluid dynamics

Exciting research developments have been re-ported in the past year in the various subfieldsof fluid dynamics. A snapshot of some of these

developments is provided below.

CFD methods and applicationsThe application of hybrid Reynolds-averagedNavier-Stokes (RANS) /large-eddy simulation(LES) methods to aerodynamic flows continuedto be an active area of research in the U.S. andabroad. Symposia held in London, England,and in Kerkyra, Greece, highlighted the suc-cesses and shortcomings of these techniques. In

the Boltzmann equation have been applied byresearchers at the Hong Kong University of Sci-ence and Technology, and at Old DominionUniversity to simulate nonequilibrium flows. Bymaking the relaxation time parameter from theBGK approximation a function of the flow gra-

dients, resolution of shock structures with ac-curacy comparable to DSMC was demonstratedat a significantly lower computational cost.

Flow controlFlow control continues to be an active area of research, with electromagnetic energy additionreceiving significant attention. The computa-tional plasma program at the University of Florida, in collaboration with the Computa-

addition to the canonical separated-flow appli-cations, the method is being used increasingly

for wall-modeled LES and for zonal simulations.Research continued in the development of

techniques that improve the solution behaviorat the interface between RANS and LES. Boeingand TTC Technologies independently im-proved and applied high-order-based hybridRANS/LES procedures to accurately simulatethe flow and fluctuating pressure fields requiredfor jet noise prediction in a coupled nozzle/jetplume model.

In other developments, Stanford Universityresearchers demonstrated remarkably accurateLES predictions of turbulent separation and its

control for flow over the wall-mounted hump,first used in the 2004 NASA Langley Workshopon CFD Validation. Their results, obtained us-ing nondissipative numerics and the dynamicsubgrid-scale model, demonstrated that predic-tions of separation control can be achievedwithout resorting to direct numerical simula-tion, reducing computational costs by orders of magnitude.

The Direct Simulation Monte Carlo(DSMC) method is currently the most commontool used to simulate nonequilibrium flows atfinite Knudsen numbers. Recently, gas-kineticschemes based on the BGK approximation to

tional Sciences Center of Excellence at the AirForce Research Laboratory (AFRL), has success-

fully predicted plasma-based stall control forNACA airfoils and turbine blades at high anglesof attack. Also in the past year, simulations atthe AFRL center explored the use of asymmetricdielectric-barrier-discharge plasma-based actu-ators to control the flow over blades of transi-tional, highly loaded low-pressure turbines,commonly employed as the propulsion systemsfor UAVs. The blades are susceptible to separa-tion in high-altitude cruise, resulting in block-age of the flow passages, transition to turbu-lence, wake total pressure losses, and a decreaseof turbine efficiency.

Various aspects of control strategies for anisolated turbine blade were investigated usinghigh-order CFD combined with a phenomeno-logical model to represent plasma-inducedbody forces imparted by the actuator on thefluid. The AFRL researchers completely elimi-nated separation with minimal plasma powerrequirements. They observed an 85% reductionin the wake total pressure loss coefficient. Theflow physics by which this efficiency improve-ment was achieved were also identified.

Rutgers University has reported significantprogress in the use of microwave energy depo-sition, expanding the possible regimes for flow

by Foluso LadeindeTom McLaughlin

Meelan ChoudhariUgo Piomelli

Isosurfaces of vorticity magni-tude, which are colored by the

streamwise velocity component, show the effects of plasma-based techniques to control

separation on transitional,highly loaded, low-pressureturbine blades.

No control Dual actuatorsSingle actuator

8/6/2019 ASlayoutX


control in high-speed flows. A series of experi-ments and theoretical analyses was performed

jointly with Russian collaborators from the In-stitute for High Temperatures to quantitativelyevaluate the effect of a laser spark precursor onthe breakdown voltage required for microwave

energy deposition in air, at subatmospheric toatmospheric pressure. The microwave genera-tor employed has a maximum power of 700k W operating at 13 GHz. The electric fields of the laser and microwave are mutually perpen-dicular. The results imply the potential for cre-ating microwave discharges at arbitrary loca-tions in the vicinity of an aerodynamic body.

Likewise, researchers at the University of Illinois Champaign-Urbana are investigatinglaser and microwave energy deposition meth-odologies and actuators with an eye toward un-

covering opportunities for exploiting instabili-ties that can be controlled with the techniques.The experiments have resulted in the successfulforcing of large-scale structures in a supersoniccavity shear layer using energy deposition.Princeton University has demonstrated nano-second pulse, sustained high-velocity dielectricbarrier discharge surface jets, and “snowplowarc”-driven separation control.

In the emerging research area of feedbackflow control, a major problem has been theavailability of suitable (meaning simple enoughto solve) mathematical descriptions of the flow.

Traditionally, low dimensional dynamic modelsof flow fields have been fraught with mathe-matical stability problems as well as a limitedrange of validity.

However, over the past year, several prom-ising approaches have emerged. Trust-RegionPOD (CNRS, France) as well as Balanced Trun-cation (Princeton University) have been shownto improve the range of validity, or the numeri-cal stability, respectively. A method combiningDouble POD and system identification based onneural networks (DPOD-ANN-ARX) improvesstability, range of validity, and models actuation

effects for both open-loop and closed-loop flowstates (Air Force Academy). These develop-ments can be expected to lead to greatly im-proved understanding of open-loop controlled-flow physics and practical feedback controllersin the near future.

TransitionSeveral exciting developments highlighted thecontinued pace of research in laminar-turbulenttransition, especially in high-speed boundarylayers.

NASA’s computational analysis of the Pega-sus flight experiment from 1998 provided the

first flight validation of stability-based predic-tion methods for crossflow-dominated transi-tion in high-Mach-number 3D boundary layers.Specifically, the correlation of disturbancegrowth factors with in-flight transition locationsvia the eN method indicated that the same range

of N factors as found earlier for low-speed flowsalso correlates observed transition characteris-tics over both the cold wing glove and the in-board, hotter tile region of the Pegasus wing.

Extensive analysis and ground tests wereperformed by an AFRL-led team in preparationfor flight one under the HIFiRE (Hypersonic In-ternational Flight Research and Experimenta-tion) project. HIFiRE will use a series of flightswith low-cost sounding rockets to develop anddemonstrate fundamental hypersonic technolo-gies deemed critical to the realization of next-

generation aerospace weapon systems. Flightone will test high-frequency instrumentation ina flight environment, with a focus on boundary-layer transition and shock-boundary layer in-teraction. The preflight effort has shown thathypersonic smooth-body transition should beachievable with the proposed configurationconsisting of a 7-deg half-angle cone with 2.5-mm nose radius. However, one side of the vehi-cle will be tripped to ensure transition and toobtain rough-wall data.

To gain fundamental insights into the dy-namics of hypersonic shear flows, NASA Lang-

ley researchers have begun using the nitric ox-ide planar laser-induced fluorescence, or NO-

PLIF, technique. In one experiment, NO wasseeded into a Mach 10 laminar boundary layerthat passed over discrete triangular and rectan-gular trips and became turbulent downstream.The shape of trip-induced flow instabilities ap-pears to be consistent with the hairpin-shapedvortices observed in lower speed regimes.

In subsonic flow, as part of technology de-velopment for low-weight, high-efficiency air-frames to allow persistent loiter capability for AFRL’s SensorCraft program, Texas A&M Uni-

versity demonstrated the efficacy of distributedroughness elements (DRE) in extending thelength of laminar flow from 30% to 60% chordon a subsonic swept wing at chord Reynoldsnumber up to 8.1 million. The flight test of the37-deg swept wing was accomplished on aCessna O-2 with the test article mounted to ahard point of the Cessna’s port wing. Infraredthermography was used to measure the extentof laminar flow. A surprisingly strong correla-tion between transition location, DRE height,and test article surface roughness was observed,which was also confirmed via nonlinear parab-olized stability computations.

8/6/2019 ASlayoutX


AEROSPACE SCIENCES

Aeroacoustics

Tangible reduction of aircraft noise to meet thepublic’s expectations remains a challenge. Re-search this year concentrated on gaining better

insights into the noise source mechanisms andon developing metrics that better capture theimpact of aircraft operations on communitieslocated near airports.

In a joint effort, NASA and Pratt & Whit-ney demonstrated the noise reduction benefitsof an advanced ultra high bypass (UHB) cyclefan concept called the geared turbofan. Thisnew engine cycle has been designed to obtain

peak performance and reduce propulsion noiseusing a slower, lower-pressure-ratio, gearedfan. In wind tunnel tests, the 22-in.-scalemodel version of the fan demonstrated mea-sured noise levels that were consistent with thepredicted levels for a low-speed, low-pressure-

ratio UHB fan.Many airports are using alternate noise

metrics to supplement the Day-Night-Level tobetter communicate noise exposure to the pub-lic and to assess sleep disturbance and speechinterference effects. Case studies by Wyle showthat the NA (Number-of-events Above) metric,which is the frequency of aircraft operations ator above a selected threshold level, has clearlyemerged as the best metric to assess these ef-fects. It is now the most widely used supple-mental metric in aviation noise analysis.

As part of a project funded by the Office of Naval Research to reduce the noise from tactical

fighters, a team of researchers from Florida StateUniversity, the University of Mississippi, Boe-ing, and CRAFT developed a suite of noise re-duction concepts. Detailed aeroacoustic mea-surements carried out at the Boeing wind tunnelfacility revealed significant noise reduction in all

the noise metrics without performance penalty.These concepts are currently being evaluated fora twin-podded engine configuration.

Under NASA’s Supersonic Fundamental Aeronautics Project, a NASA F-18 research air-craft flew unique profiles at Edwards AFB topresent sonic booms of overpressures from 1.0to 1.4 psf to a house constructed with modernmethods and materials, and instrumented tomeasure both pressure and vibration. The pri-mary goals of the test were to collect data on thehouse’s structural response to sonic booms and

to compare these results with data collected in2006 during a test using an older house slatedfor demolition.

Advanced experimental techniques andnumerical simulations have furthered our un-derstanding of noise sources. Honeywell Aero-space, as part of NASA’s Engine Validation of Noise and Emission Reduction Technologyprogram, led and completed a static test for thecharacterization of the engine noise sources.The fan of Honeywell’s Tech977 engine was re-moved, and the engine was successfully oper-ated using a water brake dynamometer, to iso-

late engine core noise sources.The Curved Duct Test Rig has been devel-

oped for study of sound propagation and evalu-ation of noise control techniques in ducts ap-proaching the scale of the aircraft engine aftbypass. This new tool in NASA Langley’s linertechnology effort has been used in conjunctionwith a finite-element analysis to investigate theeffect of higher mode order and flow on theacoustic performance of a locally reacting linersample.

The definition and measurement of thesource of turbulence-generated jet noise at-

tracted significant effort from numerous re-searchers. Time-resolved particle image veloc-imetry flow data from heated jets acquired atNASA Glenn helped establish the effect of tem-perature on various turbulence statistics, includ-ing fourth-order space-time correlations. A teamof investigators from Florida State University,Boeing, Georgia Tech, and the Ohio AerospaceInstitute presented a comprehensive experimen-tal study using four types of measurements. Allthe results strongly indicate the presence of twodistinct noise sources: the noise from the fine-scale turbulence and the large coherent struc-tures of the jet flow.by Krishna Viswanathan

A 22-in. scale model of aNASA/Pratt & Whitney geared turbofan was tested in the NASA9x15-ft Acoustic Wind Tunnel.

8/6/2019 ASlayoutX


Astrodynamics

Spacecraft encounters of various forms domi-nated astrodynamics news this year. In Januarythe People’s Republic of China demonstrated its

antisatellite weapons technology by launching adirect-ascent vehicle from the Xichang LaunchCenter against one of its old polar-orbitingweather satellites, FengYun 1C.

The result of that impact produced a cloudof debris comprising over 2,000 pieces largeenough to be tracked by the U.S. Space Surveil-lance Network. NASA’s Orbital Debris ProgramOffice estimated that over 35,000 pieces of de-bris larger than 1 cm were created. Analysis of the orbital lifetimes of the larger debris frag-ments shows that they will remain a hazard to

much of the LEO satellite population for manydecades to come.Elsewhere, spacecraft flybys enabled, ex-

tended, and enhanced a variety of scientificmissions throughout the year. In January, theSTEREO (Solar Terrestrial Relations Observa-tory) mission performed its second lunarswingby, completing the setup of its two obser-vatory spacecraft in Earth-leading and Earth-trailing heliocentric orbits. The European Ro-setta spacecraft, continuing its odyssey to thecomet 67P/Churyumov-Gerasimenko, swungby Mars in February, followed by the New

Horizons flyby of Jupiter and its magnetotail afew days later.

The MESSENGER (Mercury surface, spaceenvironment, geochemistry, and ranging) space-craft performed its second of two Venus flybysin June, setting up for its first flyby of Mercury,to take place in early 2008. And throughout theyear the Cassini spacecraft performed 17 flybysof Titan, as well as flybys of Tethys, Rhea, andIapetus. Cassini also completed a 180-deg rota-tion of its orbit, known as a pi-transfer, withinthe Saturnian system, placing the subsequentapoapses in between the Sun and Saturn to en-

able atmospheric and ring observations.New spacecraft departing Earth orbit in-

cluded Phoenix, which will deliver a lander tothe Martian polar latitudes in May 2008; Dawn,which will ultimately orbit the Main Belt aster-oids Ceres and Vesta; and SELENE (JapaneseSelenological and Engineering Explorer), whichwill deploy relay and gravity subsatellites fromlunar orbit.

In June, DARPA’s two Orbital Expressspacecraft performed a rendezvous, conductedproximity operations and stationkeeping, andaccomplished the first-ever autonomous cap-ture of a satellite by another satellite using a ro-

botic arm. This enabled the first unassisted in-space exchanges of propellants and compo-nents (batteries) in history. In the future thesecapabilities will extend spacecraft performanceand lifetime and reduce the workload of hu-man-piloted missions.

Back on the ground, JPL hosted the SecondGlobal Trajectory Optimization Competition.The objective of this international astrodynam-

ics design contest was to optimize the trajectoryof a “Grand Asteroid Tour.” A hypotheticalspacecraft employing electric propulsion was tobe launched from Earth to rendezvous with oneof each of four different types of asteroids. Thedesign challenge was to find the “best” low-thrust trajectory using an objective functionthat rewarded both low propellant consump-tion and total flight time. The winning team for2007 was from the Politecnico di Torino inItaly. A workshop presenting the methods andresults from the competitors was held at the AAS/AIAA Space Flight Mechanics Meeting in

Sedona, Ariz., in January 2007.Elsewhere on Earth, the 10 antennas of the

VLBA (Very Long Baseline Array), spanningbaselines up to 10,000 km in length, were usedfor the first time to track a radar-illuminated as-teroid (in this case, the binary system 2006 VV2). These observations provide precisionmeasurements of the objects’ angular positionand permit an unambiguous three-dimensionalshape reconstruction.

The year ended with two more Earth fly-bys: Rosetta on November 13 and Deep Impact(currently targeted to fly by the comet Boethin)on December 31.

A lunar transit of the Sun was seen from the STEREO spacecraft.

by L. Alberto Cangahuala

Cassini completed its closest flyby of theodd moon Iapetus in September.

8/6/2019 ASlayoutX


AEROSPACE SCIENCES

Aerodynamic decelerators

In a particularly busy year, the aerodynamic de-celerator systems community touched a broadrange of disciplines and attained several major

milestones.

DOD airdrop programs Airdrop systems such as JPADS (Joint Precision Airdrop System) have saved lives and had anenormous impact on current operations, whilethe push for increased accuracy, higher reliabil-ity, larger and lower payload weights, and lowercost systems continues. JPADS encompasses afamily of systems being created through numer-

ous efforts, partners, and funding sources. Allefforts are managed and executed by a joint

team from the NSRDEC ( Army Natick SoldierResearch Development and Engineering Cen-ter), Product Manager Force Sustainment Sys-tems, Air Force Air Mobility Command, DeputyUnder Secretary of Defense for Advanced Sys-tems and Concepts, Joint Forces Command,Transportation Command, Marine Corps, Spe-cial Operations Command, and others.

The JPADS family consists of “self-guided”cargo parachute systems, a common missionplanning and weather system, and navigationaids for Military Free Fall parachute systems.The 700-2,400-lb variant entered Milestone B

in March; the 5,000-10,000-lb variant transi-tioned from a very successful advanced concepttechnology demonstration to a formal Programof Record (POR), with MS-B approved in Au-gust. The formal Capability Development Doc-ument for both increments was approved bythe Joint Requirements Oversight Council inMarch. The 2-klb POR is developing the Firefly

system from Airborne Systems of North Amer-

ica and will be entering developmental testingby year’s end. The 10-klb system will be chosenafter the submission of this annual report.

The USAF and USA have been using JPADS

in Afghanistan and Iraq. Primary airdrops are

using the JPADS Mission Planner developed byPlanning Systems and the Charles Stark DraperLabs. The system is providing improved com-puted aerial release point calculations for tradi-tional “dumb” parachutes for Army high-alti-tude airdrops and for updating missions to theStrong Enterprise SCREAMER system, whichhas been used in Afghanistan since 2006. JPADS

airdrops have been documented as savingwarfighters’ lives in emergency resupply mis-sions and are being used at a rate of approxi-mately 500,000 lb per month.

Continued use of JPADS for logistics resup-ply is expected as the systems have reportedlyeliminated the need for hundreds of convoysand thousands of soldiers from the roads(which pose IED exposure risks) and many heli-copter resupply missions. Large quantities of JPADS-type systems and capabilities are ex-pected to be rapidly fielded for use in theateroperations in the near future because of theirdemonstrated positive impact and rapidly im-proved technology readiness level.

The Low Cost Airdrop System is a rapidfielding program that explored and fielded nu-

merous low-cost, one-time-use, very-low-alti-tude airdrop systems weighing from 50 to 450lb. This system was fielded to theater and is alsobeing used extensively to support small-sizedunits with enormous success. Systems are beingutilized from as low as 150 ft above groundlevel, and thousands of pounds of supplies havebeen airdropped.

NSRDEC is executing a 30,000-lb ArmyTechnology Objective and has demonstrateddeployment and autonomous control of thelargest parafoil system ever deployed (9,000ft2), with Airborne Systems North America,

Wamore, and Draper Labs. This system wasscheduled to be demonstrated to an interna-tional audience in October.

NSRDEC executed a Precision AirdropTechnology Conference and Demonstration(PATCAD) in October at the Army Yuma Prov-ing Ground. PATCAD 2007 demonstrated 23different systems utilizing five aircraft with 14lifts over three days. More than 140 cargo air-drops took place, with weights ranging from 5lb to 30,000 lb, for a total of over 300,000 lbdropped. Numerous Special Operations militaryfree-fall systems were demonstrated.

NATO was a sponsor of PATCAD 2007,

by the AIAA Aerodynamic

Decelerator SystemsTechnical Committee

The JPADS Mission Planner provides computed aerial release point calculations for updating missions to the SCREAMER

system, which has been used

in Afghanistan since 2006.

8/6/2019 ASlayoutX


and the NSRDEC continues to act as the DOD

lead for the NATO Precision Air Drop (PAD)

Technology for Special Operations Forces(SOF) Defense Against Terrorism (DAT) proj-ect, for which the U.S. is lead nation. “PAD forSOF,” one of 10 NATO DATs, is being executed

through a NSRDEC-chaired Joint Precision Air-drop Capability Working Group. The group isexecuting PAD concepts of operation and dem-onstrations and working to ensure interoper-ability of PAD systems between NATO nations.

Mars Science LaboratoryThe Mars Science Laboratory (MSL) is NASA’s

next rover mission to Mars, scheduled to reachthe red planet in 2010. MSL is designed togather detailed information on past and presentenvironments that might have supported, or

currently support, microbial life. MSL will de-liver the largest, most capable rover ever devel-oped by NASA, enabling in-situ analysis of Mar-tian rocks and soil. The entry, descent, andlanding (EDL) system of MSL will enable accessto previously unattainable landing sites withgreater precision than any previous extraterres-trial landed mission.

The MSL parachute decelerator system(PDS), a key component of the EDL missionsegment, will be the largest and highest load ex-traterrestrial parachute ever flown. The PDS isto be deployed at Mach 2.2 and 750 Pa, achiev-

ing a peak inflation load of 286 kN. Its super-sonic trajectory is similar to that of BLDT

(Viking Balloon Launched Drop Test), enablingdirect comparison of BLDT flight tests for thedetermination of drag and peak inflation load.

To support this effort, the MSL parachuteteam is leveraging and expanding on the designand construction techniques developed for theMER and Phoenix parachute programs and thesupersonic qualification of the Viking-era para-chute development efforts. A supersonic deltaqualification program is also under way, to ad-dress the large size of the MSL parachute rela-

tive to the Viking BLDT heritage supersonicqualification dataset. The delta qualificationprogram, led by JPL, NASA, University of Min-nesota, and University of Illinois, is developingand validating fluid structure interaction (FSI)

tools to provide insight into the fundamentalphysics of supersonic parachute operation andquantify parachute performance and healthduring its supersonic transit.

The preliminary design of the parachuteand mortar system is complete. The parachute isan 80-gore continuous-line construction diskgap band (DGB) with nylon broadloom fabricand a kevlar structural grid. The mortar system

uses a precision-machined canis-ter with an integral blow-down,MER-scaled gas generator at thebase. Several prototype para-chutes have been built andtested in an aerial drop test pro-

gram demonstrating the inflatedshape, construction techniques,and structural design. Development mortartubes and gas generators have been fabricatedand tested with static function and close volumetests. A 2%-scale rigid parachute supersonicwind tunnel test program was conducted atNASA Ames to validate the CFD solvers beingused in the FSI tool development.

Activities to come before year’s end includea structural qualification program in the Na-tional Full Scale Aerodynamics Complex, where

the parachute will be deployed in 80x120-ftsubsonic wind tunnel and 5%-scale supersonicwind tunnel test program in the NASA GlennResearch Center 10x10 unitary tunnel to ex-plore supersonic performance at MSL deploy-ment conditions.

Crew exploration vehicleThe Orion program has chosen to baseline theuse of parachutes for landing the next genera-tion of NASA human-rated spacecraft. The crewexploration vehicle (CEV) will implement aparachute recovery system architecture very

similar to that used during the Apollo program.Once the command module has achieved sub-sonic flight, a pair of mortar-deployed drogueparachutes will decelerate and stabilize the cap-sule. After the drogues are released, a cluster of three mains will be individually deployed bymortar-deployed pilot parachutes. The CEV

parachute assembly system has been chosen as aGovernment Furnished Equipment project toCEV prime contractor Lockheed Martin.

Development testing of the component-level parts, including air drop tests of the pilots,drogues, and mains, began in January. The de-

velopment parachutes, called Generation 1, aredesigned to recover a 14,400-lb suspendedmass and nominally deliver a rate of descent of 26 ft/sec and 33 ft/sec for a single main failureat a landing zone elevation of 4,000 ft MSL. De-velopment testing will culminate in spring2008 with a demonstration of the entire systemassembled onto a boilerplate test article ex-tracted out of a C-17. All development para-chute testing is being conducted at the Army

Yuma Proving Grounds and the Naval Weap-ons Center. The development parachute systemwill be integrated into the first pad abort test,scheduled for September 2008.

The Orion program has chosena parachute recovery system toland the CEV.

8/6/2019 ASlayoutX


AEROSPACE SCIENCES

Thermophysics

Major activities in the field of thermophysicsthis year focused on the MEDLI (Mars ScienceLaboratory Entry, Descent, and Landing Instru-

mentation) project and on materials for thermalprotection systems.

MEDLIThe MEDLI project’s main objective is to mea-sure aerothermal environments, subsurfaceheat shield material response, vehicle orienta-tion, and atmospheric density for atmosphericentry during the entry and descent phases of the Mars Science Laboratory (MSL) entry vehi-cle. The flight science objectives directly ad-dress the largest uncertainties in our ability to

design and validate a robust Mars entry system,including aerothermal, aerodynamic, and atmo-sphere models and thermal protection system(TPS) design. Therefore, although MSL will notdirectly benefit from this data set, all futureMars entry and aerocapture missions will bene-fit from the model validation and improve-ments enabled by the MEDLI data.

By design, this development effort is inde-pendent of MSL, will not significantly impact itsmission schedule, and will engage MSL at well-defined entry points.

MSL’s rover compute elements over the MSL

EDL-1553 bus for storage until the data are sentto Earth after the landing.

The project instrumentation consists of three main subsystems: the MEDLI integratedsensor plugs (MISP), a series of plugs in the TPS

that contain embedded thermocouples and re-cession sensors; the Mars entry atmosphericdata system, a series of through-holes, or ports,in the TPS that connect via tubing to pressuretransducers mounted on the heatshield interior;and the SSE, an electronics box that conditionssensor signals, provides power to the sensorsand transducers, and connects to MSL’s data ac-quisition system.

Each integrated sensor plug includes fourthermocouples and a recession sensor. Thestacked thermocouples will record heating data

at varying depths in the heat shield. The reces-sion sensors will measure the thickness of theTPS as it ablates during atmospheric entry. Thepressure ports are arranged to provide a flushatmospheric data system from which aerody-namic data can be computed.

After signal conditioning, the analog signalsfrom the sensors will be digitized and trans-ferred via a 1553 bus to the DPAM system lo-cated in the MSL descent stage. The additionalmass, volume, and channels required by MEDLIare subject to constraints from MSL.

Mission descriptionand project organization

MEDLI will fly on the MSL mission scheduled tolaunch in September 2009. The data from theinstrumentation will be recorded during the en-try, descent, and landing (EDL) portion of themission and stored on the MSL rover. Afterlanding, the data will be transmitted back toEarth. Collected data will be analyzed andprocessed by the project science team, and thedata products will be made available to the en-gineering community.

Development of EDL instrumentation is of

significant interest to NASA’s Exploration Sys-tems Mission Directorate, which funds the proj-ect. NASA’s Science Mission Directorate (SMD) isresponsible for the MSL project and spacecraft.Because MEDLI modifies the heatshield of theMSL entry vehicle, SMD has significant interestin and oversight of MEDLI via the MSL ProjectOffice. The MEDLI Project Office, located atNASA Langley, is responsible for project imple-mentation and management under the center’sExploration and Flight Projects Directorate. Theproject has direct commitments with otherNASA centers, including Ames and JPL, and acontract with Lockheed Martin Space Systems.

A PICA coupon undergoes testing at the Arnold Engineering Development Center.

MEDLI consists of seven pressure ports andseven integrated sensor plugs (containing fourthermocouples and a recession sensor) that areinstalled in the forebody heatshield of the MSL

entry vehicle. The sensors are wired to a sensorsupport electronics (SSE) box that providespower and conditions and digitizes the sensorsignals. The digital data stream is sent to MSL’s

descent stage power and analog module(DPAM), which then relays the data to one of

8/6/2019 ASlayoutX


Coated and self-coating carbon-carbonResearchers at Sandia National Laboratories aredeveloping coated and self-coating carbon-car-bon thermal protection materials for an emerg-ing new generation of flight. These materials,which are protected by a combination of silox-

ane-based infiltrates and ceramic and inorganiccoatings, must remain intact under intenseheating rates for short durations followed bylong durations at moderate heating rates.

Sandia screens candidate materials in theradiative heating environments of its NationalSolar Thermal Test Facility (NSTTF) and solarfurnace, which provide heat fluxes up to 700 W/cm2. Materials have also been tested in theLHMEL laser heating facility at Wright Patterson AFB and the arc jet facilities at NASA Ames.Current efforts include computer simulations of

these novel materials in both flight and arc jetenvironments.

Orion TPSFor the past two years researchers and engi-neers at several NASA centers (Ames, Langley,

Johnson, Kennedy, Glenn, and JPL) have beendeveloping the next generation of mannedspacecraft thermal protection systems. The goalof the TPS Advanced Development Project(ADP) is to reduce the performance risks associ-ated with a lunar direct return-capable heatshield and help the Orion prime contractor de-

velop, design, and build the heat shield. TheOrion lunar-direct return entry velocity is onthe order of 11 km/sec, and the heat shieldmust be capable of withstanding a peak heatrate of over 750 W/cm2.

Compared to returning from LEO, wherethe velocity is on the order of 7.5 km/sec andthe peak heat rates are less than 150 W/cm2, thenew lunar-return-capable heat shield representsa significant jump in performance requirementsrelative to the space shuttle. The TPS ADP is re-sponsible for developing the entire heat shieldsystem, including the heat shield acreage TPS

material, carrier structure, compression pads,and separation system, and the main seal be-tween the forebody aeroshell and the backshell.The TPS ADP is also responsible for developingthe overall TPS margin management plan forthe heat shield and for providing the primecontractor with a recommended heat shieldqualification and certification plan.

The ADP has down-selected from five can-didate TPS materials to PICA (phenolic impreg-nated carbon ablator) as the primary heat shieldmaterial. Produced by Boeing and Fiber Mate-rials, PICA is a low-density carbon-fiber-basedmaterial impregnated with phenolic resin and

made in blocks measuring up to 42x24 in.These are then machined into panels and at-tached to the carrier structure. The design de-tails of boundaries between the PICA panels areunder development and will require either agap or seam.

The TPS ADP, in partnership with Boeingand Textron, is also developing alternate lunarreturn-capable heat shield materials. Currentlyunder evaluation are the Apollo heat shield ma-terial Avcoat 5026, 3DQP, and BPA.

Avcoat is a mid-density syntactic (silica-phenolic) foam packed into honeycomb matrixthat is attached to the carrier structure. The ma-terial is cured as a single monolithic article andthus has no gaps and seams. The 3DQP dual-layer material consists of a thin outer layer madeof a high-density quartz phenolic and an inner

low-density syntactic foam insulation layer.

3DQP is produced in panels and attached to thecarrier structure with fitted joints. Both Avcoatand 3DQP are manufactured by Textron. BPA,or Boeing phenolic ablator, is a mid-density ma-terial manufactured by Boeing and made of aphenolic resin with organic and inorganicfibers, as well as organic and inorganic micro-

spheres. Like Avcoat, it is packed into a honey-comb matrix that gets attached to the carrierstructure, making it a monolithic heat shield.

By year’s end, the TPS ADP will select oneof these three alternate lunar-capable materialsas the “primary alternate.” Both the PICA base-line and the primary alternate material will bepresented as the two final candidate systems atthe TPS subsystem PDR (preliminary design re-view) next year. Much of the current TPS ADP

efforts are focused on achieving a deep under-standing of the TPS material capabilities and ondeveloping comprehensive integrated heatshield designs involving these materials.

A PICA coupon is arc jet test inNASA Ames’ Interaction Heating Facility.

8/6/2019 ASlayoutX


AEROSPACE SCIENCES

Atmospheric and spaceenvironments

Numerous advances occurred this year in theareas of atmospheric and space environments(ASE). Progress in space involved new flight in-strumentation to verify plasma environments,and ground testing to predict long-duration

charge buildup. In addition, NASA released thefirst in a series of new charging standards.

On the atmospheric side, internationalpartnerships continued in the area of icing re-search. These studies accomplished multiple

goals, including improved understanding of both airfoil and aircraft performance with dif-ferent ice shapes. Also, NASA completed a com-prehensive update of its handbook on the ter-restrial environment.

New standardsNASA released the long-awaited Low Earth Or-bit Spacecraft Charging Design Standard as twovolumes, NASA-STD-4005 and NASA-STD-

4006. These first-of-their-kind standards, devel-oped by NASA Glenn and NASA Marshall, en-able spacecraft designers to prevent and

mitigate spacecraft charging by high-voltage so-lar arrays and other power systems in equatorialLEO. Development has started at JPL on a newNASA standard to treat GEO, polar, and deepdielectric charging. It will take the place of theprevious NASA-HDBK-4002 and the old andoutdated (1984) NASA TP-2361.

Work has begun in Asia, Europe, and theU.S. on a new ISO standard for electrostatic dis-charge testing of space solar arrays. These stan-dards reflect the growing maturity of spacecraftcharging as a design discipline and the growinginterest in high-voltage and high-power space-craft for all orbits.

New instrumentation Astronauts installed the floating potential mea-surement unit (FPMU) on the InternationalSpace Station. The floating potential is the elec-trical potential at which the ISS structure“floats” in the surrounding plasma. It is deter-

mined by the electron collection on the high-voltage solar arrays, the ion collection on theISS structure, and the so-called vxB potential

caused by ISS cutting the Earth’smagnetic field lines. FPMU mea-sures the plasma parametersthrough which ISS flies, deter-mines the charging of ISS due toits new solar arrays, and is in-tended to confirm the measure-ments and the model for floatingpotential that resulted from the

FPP (floating potential probe)that was previously on ISS.The FPMU has four separate

instruments for measuring the ISS

plasma parameters and ISS float-ing potential. There is goodagreement between the measure-ments of the four instruments. As

the ISS changes configuration with added PV ar-

rays, the FPMU will provide data for the charging

model development and validation.

Charging effects at low temperatures

NASA Marshall has begun buried-charge testingof spacecraft cable materials at low tempera-tures, such as will be encountered on the James

Webb Space Telescope. At cryogenic tempera-tures, the conductivity of dielectrics becomesso low that natural space radiation charges maybe trapped for months, years, or decades, lead-ing to eventual discharges when the internalelectric fields reach breakdown strengths.

Preliminary results have shown that theburied charge concerns are real, and suggestthat so-called “leaky” dielectrics (with artifi-cially enhanced conductivity) may be needed

for long-term missions in permanent shade,such as the lunar poles or the dark side of thetelescope sunshade.

Icing testsNASA Glenn, in collaboration with the Frenchaerospace research organization ONERA andthe University of Illinois, recently completedaerodynamic testing of high-fidelity ice simula-tions on a full-scale model. This testing tookplace under a multiyear research effort designedto investigate aerodynamic simulation of ice ac-cretion. The goal of this program is to deter-mine methods and accuracies for which ice ac-

by John Prebola,Dale Ferguson, HaroldAddy, Andy Broeren,

William W. Vaughan, Jenching Tsao

A 6.5%-scale S-3B Viking modelwas tested in the Bihrle Applied Research’s Large Amplitude Mul-tipurpose facility.

8/6/2019 ASlayoutX


cretion can be simulated at small scale andlower Reynolds number to achieve aerody-namic effects equivalent to the full-scale caseand to provide full-scale benchmark data forthis effort and CFD development.

The aerodynamic testing was carried out in

two phases at the ONERA F1 full-scale, pressur-ized wind tunnel in southern France. The goalof the first phase was to document the aerody-namic performance of the airfoil model with sixdifferent ice shape simulations. The goal of thesecond phase was to acquire detailed flow fielddata for a single ice simulation configuration.Particle-image velocimetry was used to investi-gate the separated and reattaching flow fieldabout a large, simulated ice ridge for a subset of angle of attack, Reynolds number, and Machnumber. The full-scale data acquired in this

program will allow for the continued develop-ment of methods for simulating the iced airfoilaerodynamics on subscale geometries andReynolds numbers. In addition, an excellentdatabase exists for the continued developmentof computational tools in ice accretion model-ing and aerodynamics.

A 6.5%-scale Lock-heed S-3B Viking com-plete airplane model wastested with various simu-lated ice shapes in theBihrle Applied Research’s

Large Amplitude Multi-purpose facility in Neu-burg, Germany, June 26to July 10. The objectivewas to develop a databaseof complete airplane mo-ments and forces for thenon-iced airplane and twoiced configurations.

This database will beused to expand the under-standing of icing effects onairplane performance, sta-

bility, and controllability,and to develop flight sim-ulation models for preflight test analyses of theS-3 iced flight characteristics.

The icing configurations that were testedrepresented an ice protection system (IPS) fail-ure case and a runback shape that can occur onthermally deiced wings and tails. The IPS failureice shapes were predicted with the NASA icingprediction code, LEWICE 3D. Runback iceshapes are typically spanwise ridges that formaft of the heated leading edges. In this test,these were simulated with square balsa strips of various sizes. Initial results indicated significant

degradations of lift and stall angle of attack, aswell as pitch and roll control effectiveness.

Terrestrial environment handbook updateNASA has completed an in-depth revision of the Terrestrial Environment (Climatic) Criteria

Handbook for Use in Aerospace Vehicle Develop-ment. First published in the early 1960s, thishandbook has been a major source for the de-velopment of terrestrial environment inputs forthe design and operational requirements usedin the development of space vehicles and asso-ciated facilities by NASA and other organiza-tions. The handbook provides information rel-ative to the natural environment for altitudesbetween 90 km and the surface of the Earth forthe principal space vehicle development, oper-ational, and launch locations used by NASA

and for the associated local and worldwide geo-graphical areas.The handbook is based on the interactions

over the years with design and operational per-sonnel relative to studies, analyses, and engi-neering questions associated with natural envi-ronment information inputs. Given the signifi-

cance of winds to the design of a vehicle’s con-trol and structural system, significant coveragein the document is devoted to wind topics. Thisnew revised handbook is undergoing final re-view and is scheduled for publication in early2008. Requests for the handbook can be ad-dressed to the Natural Environments Branch(Code EV44), NASA Marshall Space Flight Cen-ter, Huntsville, Ala., 35812. A copy of thehandbook can also be downloaded from theNASA Technical Standards Program Website:http://standards.nasa.gov.

The FPMU was installed on the International Space Station.

8/6/2019 ASlayoutX


AEROSPACE SCIENCES

Plasmadynamics and lasers

This year saw several noteworthy milestonesmarking progress toward innovative plasmady-namics and lasers system applications, although

investment in long-term aerospace sciences andtechnology continued trending downward andprospects for an upturn remained bleak.

PlasmadynamicsThe Hypersonic Vehicle Electric Power System(HVEPS) program, sponsored by the Air ForceResearch Laboratory, achieved a major mile-stone with the successful demonstration of magnetohydrodynamic (MHD) power extrac-tion from the exhaust stream of an NaK-seeded

technical feasibility of the rocket-driven config-uration had been established in previous R&D

efforts, and the experiment was mainly in-tended to provide detailed measurements oncombustion/plasma conditions and generatorperformance to validate a state-of-the-art 3D

MHD generator code under development byPurdue University.

Observed power generation performancewas in very good agreement with preliminaryanalysis projections, and detailed evaluationand validation efforts continue.

In Japan, various institutions contributedadditional technology advancements of signifi-cance to aerospace system applications. Mostnotably, the Tokyo Institute of Technology con-tinued construction and development of itscontinuous-duty high-temperature closed-loop

disk generator facility. This facility uses a 300-kW thermal input electrical heater and a recu-peration heat exchanger to heat cesium-seededargon gas to 2,000 K. This is passed through asmall-scale disk generator encased within a 4.2-T superconducting magnet.

The facility, soon to attain full operationalcapability, has attracted considerable interestsince it is prototypical of system architecturesfor low specific mass closed-cycle nuclear spacepower plants.

The University of Tsukuba and NagaokaUniversity of Technology also contributed sig-

nificant developments in computational simu-lation of high-interaction MHD generator andaccelerator systems. JAXA and Shizuoka Uni-versity obtained important experimental andcomputational results that clarified underlyingmechanistic principles of MHD flow control.

The development of high-pressure arc-heater technology attained a major R&D mile-stone that developers hope will lead to the real-ization of a ground test facility capable of accurately simulating an extended range of hy-personic flight conditions applicable to missile-critical thermal protection systems. Specifically,

the Aerospace Testing Alliance’s aerothermaltesting group at the Air Force’s Arnold Engi-neering Development Center recently succeededin operating the center’s large H3 arc-heater at167 atm, setting a new world record.

Previously, reliable arc-heater operationwas constrained to chamber pressures less than120 atm by the occurrence of destructive wallarcing and unsustainable heat flux loads. Butthrough committed long-term technology de-velopment efforts, the group was able to over-come these problems and to develop a promis-ing strategy for expanding the operational rangeto 200-250 atm.

hydrocarbon-fueled scramjet combustor simu-

lating Mach 8 flight conditions. The subscaledemonstration experiment, a historic first, em-ployed a diagonal conducting wall generatorwithin a split-coil superconducting magnet toproduce 15 kW of electrical power with no ad-verse impacts on scramjet operation. This col-laborative effort by prime contractor General

Atomics, LyTec, Pratt & Whitney Rocketdyne,United Technologies Research Center, andNASA Marshall is a remarkable technical ad-vancement and has provided reliable data thatfirmly establish the technical feasibility of en-gine-integrated MHD power systems for hyper-

sonic aircraft. By building on this solid founda-tion, continued progress and advancementtoward practical realization may be expectedwith sustained R&D investment.

A parallel effort under HVEPS focused ondevelopment of a rocket combustion-drivenMHD APU concept, and a successful demon-stration experiment was recently completed bythe University of Tennessee Space Institute.This concept used the energetic plasma pro-duced from combustion of JP /aluminum-slurryfuel and K2CO3 ionization seed with oxygen todrive a Hall MHD generator within the commonHVEPS split-coil superconducting magnet. Theby Ron J. LitchfordTimothy J. Madden

The chemical oxygen-iodinelaser is operated at the German

Aerospace Center (DLR) Insti-tute of Technical Physics. Photocourtesy DLR Institute of Tech-nical Physics.

8/6/2019 ASlayoutX


LasersEfforts directed toward development of high-power gas laser systems saw considerableprogress, both in the U.S. and abroad. This wasillustrated in presentations by personnel fromthe German Aerospace Center (DLR) Institute of

Technical Physics at the 38th Plasmadynamicsand Lasers Conference. One talk discussed theGerman Ministry of Defense’s tactical chemicaloxygen-iodine laser (COIL). This tactical-scaleCOIL laser program, similar to the U.S. Air-borne Laser and Advanced Tactical Laser pro-grams, provides a critical push for high-powergas laser technology development and deploy-ment by demonstrating the capability and effec-tiveness of lasers as weapon systems in a fieldenvironment.

This medium-power laser addresses issues

such as deployment of fuels, system transporta-bility, and operation in a nonpristine laboratoryenvironment, as well as test range firing andbeam propagation. Unique innovations en-abling the use of COIL technology were alsodemonstrated in the DLR presentations, includ-ing development of a negative branch hybridresonator to address the requirements of low-gain operation in rectangular geometries underrugged operational conditions, and a cryogenicstorage system for basic hydrogen peroxide thatenables long-term storage of this fuel in the field.

Development of electrically powered alter-

natives to high-power gas lasers continues to in-tensify, as interest in reducing or eliminating thelogistical constraints of chemical lasers remainsunabated. Efforts to develop a hybrid electrical-chemical laser in the form of the discharge dri-ven electric oxygen-iodine laser (EOIL) reacheda milestone recently with a demonstration of 30% singlet-delta oxygen yield under thermallycontrolled conditions by Plasmatronics and the AFRL Directed Energy Directorate. A significantattribute of the system in which this wasdemonstrated is the scale of the device, with apotential lasing power based on the singlet-delta

oxygen yield and flow rates in the device of 2.3kW. A lasing demonstration approaching thispower would address questions regarding thescalability of EOIL to high powers.

Another hybrid gas-electric approach uti-lizes diode sources to optically pump gas-phasealkali metals such as cesium and rubidium. Thistechnology was first demonstrated by LawrenceLivermore National Laboratory in 2004 at 0.23

W, and many technical issues remain to beovercome to demonstrate relevant powers at thekilowatt level. However, DPALs may offer a hy-brid solution combining solid-state and gaslaser elements bridging the two technologies.

Solid-state laser technology continues toadvance into a power regime formerly the soledomain of gas lasers, replacing them in key ap-plications such as cutting and welding. The

Joint High-Power Solid-State Laser (JHPSSL)

program, funded by the Joint Technology Of-fice for High Energy Lasers, the Army Spaceand Missile Defense Command, the AFRL Di-

rected Energy Directorate, and the Office of Naval Research, seeks to demonstrate a 100-kWsolid-state laser for military application. Build-ing on a 350-sec, 27-kW lasing demonstrationby Northrop Grumman in Phase 2 of the pro-gram, Phase 3 looks to achieve 100 kW powers.High-power fiber lasers have also shown con-siderable promise, with single-mode power perfiber having reached 3 kW as demonstrated byIPG Photonics. As power per fiber increases, ad-vantages such as high heat rejection, single-mode operation, and efficiency may lead to100-kW high-power fiber lasers in the not too

distant future.The field of aerooptics is focused on devel-

opment of methods to control aerooptic aberra-tions and development of coupled optical fieldto CFD models to provide detailed physical in-formation and aid in the engineering process.Recent work has elucidated the difficulties asso-ciated with using conventional controllers withadaptive optics mirrors to correct the opticalfield for aerooptic aberrations given the 1-kHzand greater frequencies within the shear layer,resulting in system latencies and sensing andresponse limitations. Lines of investigation to

circumvent the difficulties associated withadapting to high-frequency aberrations includethe use of plasma or acoustic active flow controlto reduce the high-frequency content, and theuse of alternate control strategies such as adap-tive control.

CFD model development is proceedingaway from singular reliance on steady-state sim-ulation with statistical-turbulence models totime-dependent, large-eddy, and direct-eddysimulation, where the spatial and temporalscales of the dominant aberrative structures aredirectly resolved to more accurately capture theoptical field to fluid field interaction.

A frozen basic hydrogen peroxidebatch is used to demonstratelong-term fuel storage for chemi-cal oxygen-iodine laser operationat the German Aerospace Center (DLR) Institute of TechnicalPhysics. Photo courtesy DLR

Institute of Technical Physics.

8/6/2019 ASlayoutX


AEROSPACE SCIENCES

Guidance,navigation,and control

Several milestones in guidance, navigation, andcontrol technologies were achieved this year in

the areas of weapons and missiles, aircraft, andspacecraft.

Weapons systems Advances in modern nonkinetic weapons arecombining high-power microwave devices withlasers. These new directed energy weapons relyheavily on sensor fusion and target networkingrather than new breakthroughs in electronicwarfare. Modern electronic attack focuses onidentifying, compromising, and exploiting en-emy networks ranging from cell phone commu-

nication systems to air defense systems.BAE Systems is using lasers to multiply thespeed and power at which high-power mi-

crowave (HPM) weapon pulses can be pro-duced, thereby removing the need for explo-sives or high-power electrical generators.Example HPM missions include defeating cruisemissiles at operational ranges, detecting anddetonating visible or hidden improvised explo-sive devices, attacking mobile antiaircraft mis-

sile launchers, and eliminating collateral dam-age to people and structures by disablingenemy communications and electrical power.

In addition, photonically driven technol-ogy from BAE Systems could enable productionof stealth-detecting sensors for use on aircraftthat generate tens of gigawatts of power, there-by enabling the detection of a stealthy object at160 km with 30-cm resolution. Fly-by-wire air-craft flight control systems limit the use of HPM

systems because they can be interrupted or dis-abled by HPM energy spikes. BAE Systems isdesigning a fly-by-light flight control system forUAVs. Its actuators are triggered by laser light

and therefore are immune to the HPM spikes.In March the Navy accepted delivery of the

first Sentinel, an 11.6-m unmanned surface ve-hicle produced by Accurate Automation. De-signed for riverine operations, the Sentinel has amultiple configuration sensor suite and ad-

vanced sensor fusion capability that supportsboth remote and autonomous operation. Thesoftware meets full Joint Architecture for Un-manned Systems requirements with encryptedtelemetry, network-centric communication,and data acquisition systems based on UAVs.

The vehicle has optional UAV launchingand landing facilities, and work is ongoing todevelop a UAV recovery capability. The Sentinelfeatures a patented sensor fusion network thatperforms target identification and employs atowed, offboard sonar system, onboard real-

time optical sensors, a radar system, and acous-tic sensors. A GPS with an inertial measurementunit is used by the autonomous navigation sys-

tem. The Sentinel uses an adap-tive control, guidance, and navi-gation system that featuresintelligent wave navigation, an-tiporpoising detection and com-pensation, obstacle avoidance,and multiship operation. It isalso able to support intelligence,surveillance, and threat recon-naissance, mine warfare, anti-

submarine, and, eventually, sur-face warfare.

In June the Missile Defense Agency successfully demon-strated that an Aegis destroyerequipped with a ballistic missile

defense system is capable of intercepting athreat missile during the midcourse phase. TheUSS Decatur, an Aegis destroyer, detected thethreat missile, which originated from the PacificMissile Range Facility in Kauai, and launched aStandard Missile 3 Block 1A interceptor that de-stroyed the threat missile after booster separa-

tion occurred.

AircraftIn August, the Navy awarded a NorthropGrumman-led team a contract under the Un-manned Combat Air System Carrier Demon-stration (UCAS-D) program to conduct the firstever at-sea carrier launches and recoveries witha fixed-wing unmanned air system, the X-47B.The company demonstrated a similar capabilityin 2006 with its MQ-8 Fire Scout rotary-wingUAV—the first completely autonomous VTOL

aircraft to land aboard a Navy vessel under way.The first of two UCAS-D air vehicles is sched-

by Daniel J. Clancy

Nijel GrandaLeena Singh

The Sentinel unmanned surfacevehicle has optional launching and landing facilities for UAVs

such as this GLOV.

8/6/2019 ASlayoutX


uled to fly in late 2009 and will begin a series of detailed flight envelope and land-based carrierintegration and qualification events beginningin 2010. The first autonomous at-sea carrierlandings are planned for late 2011, with follow-on analysis and program completion expected

by 2013.On July 8, Boeing rolled out the 787

Dreamliner, whose gust suppression systemsenses pressure differences before inertial mo-tion begins. Sensors around the aircraft mea-sure changes in angular velocity and pressuredistribution. Gyros and accelerometers detectthe motion caused by external disturbancessuch as wind gusts. At the same time, pressuresensors detect pressure distribution changesaround the skin of the airplane through a se-lected number of static air intake ports.

During flight, the flight control systemtakes in the data, applies proprietary softwarealgorithms, and sends the appropriate com-mands to the rudder, elevators, spoilers, ail-erons, and flaperons. As a result, the aircraft au-tonomously actuates the control surfaces itneeds to prevent its own inertial reaction to thewind gusts.

High-flying RQ-4 Global Hawk unmannedaerial systems built by Northrop Grummancompleted their 1,000th flight. The fourth pro-duction Global Hawk, designated AF-4, flewthe milestone mission June 14-15 in support of

the global war on terrorism. AF-4 cruised at ex-tremely high altitudes for over 18 hr withoutrefueling. This was the 517th combat missionflight for the Global Hawks, which have loggedmore than 10,700 combat hours, accountingfor 71% of the program’s total flight time of 15,135 hr. The aircraft are operated overseas by

Air Force pilots from a mission control elementstationed at its main operating base at Beale AFB near Sacramento, Calif. The pilots’ maininteraction with the vehicles and their flightcontrol systems is with a keyboard and mouse.

In December 2006, the Lockheed Martin

F-35A Lightning II conducted its maiden flight.The fifth-generation stealth fighter will provideits pilot with unsurpassed situational aware-ness, allowing full spherical surveillance andtracking, positive target identification, and pre-cision strike under any weather conditions.

SpacecraftIn June, EADS Astrium announced that it hadbegun preliminary development of a spacetourism vehicle that would carry four passen-gers and fly at suborbital altitudes up to 100km. The space bus is designed to lift off andland from commercial airports with conven-

tional jet engines, with a second, rocket enginestage that ignites at 12 km altitude to providesufficient thrust to reach 100 km. Small rocketthrusters to control the space vehicle’s trajec-tory will permit 3 min of flight in orbit beforedescent into the atmosphere. The company

plans to start full-scale development in 2008,with first commercial flight by 2012.

Also in June, Bigelow Aerospace launchedthe Genesis 2 inflatable space module on a con-verted Russian ICBM. The spacecraft is con-trolled from the Bigelow space control center inLas Vegas, Nev. Along with Genesis 1, Bigelownow has two commercial space modules in ap-proximately 480-km orbits.

China conducted its first successful anti-satellite missile experiment in January this year,colliding a missile with its Fengyun 1C polar-

orbiting weather satellite and producing thelargest single-event sourced debris field thatranges from below 200 km in altitude up to al-most 4,000 km. A NASA Earth observing satel-lite, Terra, had to maneuver at least once on

June 22 to avoid debris from this collision.The Far Ultraviolet Spectroscopic Explorer

(FUSE) satellite mission was extended in Aprilwhen the NASA Goddard/Johns Hopkins Uni-versity team performed a “brain transplant” byuploading new flight control software for theattitude control, instrument data, and fine-er-ror sensor processor systems. In December2006, FUSE was nearly lost when two of its re-action control wheels failed. Another part of the attitude control problem fix implementedby the FUSE team was to establish a local elec-tric field by running electricity through themagnetic torque bars, which enables con-trollers to use the Earth’s magnetic field to helppoint the satellite.

Artist’s concept shows the X-47Blanding on an aircraft carrier.

8/6/2019 ASlayoutX

http://slidepdf.com/reader/full/aslayoutx 19/19

AEROSPACE SCIENCES

Meshing,visualization,and computationalenvironments

Computational analysis for product design andresearch is enjoying growth both in the numberof projects that are successful and in the sizeand complexity of the simulations. Automatedmesh generation, driven directly from CAD andefficient, economical cluster computing, permitsmore analyses to be run and can generate hugeamounts of data to be postprocessed to providegreater understanding for users.

With simulation requirements growingever more complex, a case management envi-

ronment is needed to provide a solution forusers to prepare, submit, monitor, and managethese CFD runs more efficiently to improve thesimulation throughputs. To address this need,DOD’s Major Shared Resource Center (MSRC)

sponsored the development of a computationalenvironment tool called CaseMan, under theUser Productivity Enhancement and Technol-ogy Transfer (PET) program (Project CFD-KY7-001). CaseMan is a tool designed to make set-ting up, submitting, and monitoring CFD jobseasier and less complex.

To provide a flexible computational envi-

ronment for most commonly used CFD solversand computing facilities, and to give end usersan easy way to incorporate more flow solversand HPC systems into CaseMan, the tool’s de-sign allows abstraction on solvers and comput-ing environments. This makes CaseMan solver-neutral and system-independent. The tooleliminates the need for users to edit complexinput files, write submission scripts, or learnthe intricacies of each solver. CaseMan hasbeen tested on several DOD MSRC and com-modity HPC systems under various job-queu-ing environments.

CAD-centric enterprise product life-cycle

management tools came of age this year. Thetimely rollout of the Boeing 787 was signifi-cantly enabled by Boeing’s Global CollaborativeEnvironment. A key supplier to this environ-ment was long-time French partner DassaultSystèmes, maker of the CATIA-V CAD software.

At the same time, Boeing selected competitorSiemens/ UGS’s Teamcenter as its enterprise datamanagement system for all its new programs. Itseems that multiple sourcing is not just for air-lines, but also for aircraft manufacturers.

We also saw the introduction of simula-tion-centric collaborative engineering softwarebased on enterprise Web application serverssuch as IBM’s WebSphere and BEA’s Weblogic.

These new tools allow engineers to cre-ate and reuse standardized simulationmodels and share them with partners

through Internet, intranet, and VPNclients. Alenia of Italy is deploying MSC

Software’s SimManager for its ALENET

program to improve engineering effi-ciency. This software’s strength is itsability to control and access simulationdata and trace project history. Mean-while, Engineous’ iSIGHT-FD/FIPER sys-tem is being used by Pratt & Whitney toexecute large automated design studies.Distinctive features of Engineous are its

open, vendor-neutral approach with respect todata management, grid computing, CAD and

CAE integration, and its ability to allow engi-neers to set up their own projects without pro-gramming or IT services.

In the area of large-scale postprocessing,parallel computation on HPC resources is be-coming a more common workflow practice. Re-cently, Intelligent Light was subcontracted tocreate data extracts and movies for the CH-47

helicopter program. The company’s AppliedResearch Group, contracted by the Army AFDD

(through Monterey Technologies), is usingNASA’s Columbia supercomputer, where theunsteady CH-47 Overflow computation was

run. With a model size of 71.1 million gridpoints, each time step requires 3.1 Gb of diskstorage—five revolutions of the rotors produces2.35 Tb of data.

Intelligent Light’s FieldView software, runin parallel batch jobs, is being used to processthe results of the computation, creating bothmovies and highly compressed 3D extract filesthat are used with the company’s ATViewer

product. As data sizes for unsteady calculationsand solution spaces for parametric studiesgrow, data management and the use of auto-mated knowledge extraction are becoming in-creasingly important.

Unsteady CFD computationshave been made of the CH-47 Chinook tandem helicopter in

hover. Image courtesy Boeing and the Army AFDD.

b St M L k

ASlayoutX

Documents