FROM THE CORNER OFFICE

For AIAA, a year of change

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TRAJECTORIES

Testing the C Series jet

96

EDITOR’S NOTEBOOKAngel in the details

2017

YEAR IN REVIEWDECEMBER 2017 | A publication of the American Institute of Aeronautics and Astronautics | aerospaceamerica.aiaa.org

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READY FOR 2018

EDITOR ’S NOTEBOOKAndrew Lofthouse/CREATE-AV Quality Assurance

The angel in the detailsOn its surface, our annual Year-in-Review special issue adds up to a compendium of the nittygritty aerospace engineering and scientiﬁc work accomplished in 2017. We depict the often-unsung research that will make it possible for this community to continue achieving astounding operational breakthroughs, such as SpaceX reusing a rocket stage for the ﬁrst time, as it did in March.
Consider for example the descriptions of novel aerodynamic measurement techniques on Page 17 or
the efforts described on Page 10 to turn the uncertain wind responses of rotorcraft into a predictive tool.
These and many other projects will empower engineers of the future to achieve extraordinary breakthroughsin the years ahead.
Illuminating that kind of work is one reason this issue is valuable, but I see another reason, too. Thesepages provide a glimpse into the aerospace technology culture for students or those who work on thefringes of the community or even outside of it. Members of this community value data, knowledge,problem-solving and professionalism. The best of them share data and insights as much as possible. They
publish articles in AIAA’s technical journals. They attend AIAA forums. They participate on technicalcommittees. They volunteer to write articles for this special issue. They are passionate, but also fact-based.
This is not to make a claim that all is perfect in this community, but these pages demonstrate that thetrajectory is sound. Outliers are rare. In the years ahead, I’m conﬁdent we’ll see even more workforce
inclusiveness and diversity in the aerospace profession in the U.S. and abroad, and this will fuel evenmore advances.
It’s refreshing to pause at the close of a tumultuous political year to remember what humans can accomplish when they operate in a culture that values respect and dedication to facts. Some of those involvedin the research in these pages will no doubt shift out of engineering at some point in their careers, andthey will take these values with them. Some will become business executives, entrepreneurs or leaders ingovernment agencies. Some might even dare to enter politics. Of the 535 lawmakers in the U.S. Congress,
just eight have engineering backgrounds, according to the Congressional Research Service, which analyzed
Congressional Quarterly’s “Member Proﬁles.” It shows.
More than once as I read the articles for this special issue, I wondered, “How did they even think to try
that?” Innate human creativity and originality partly explain things, but those attributes can ﬂourish only
when a culture lets them. What you see in these pages is an aerospace culture that’s starting to ﬁre on allcylinders. That should make us optimistic about 2018. +Ben Iannotta, editor-in-chief, beni@aiaa.org

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DECEM B ER 2017|aerospaceamerica . aiaa .org

This CREATE-AV
Kestrel simulation
predicts aerodynamic
loading during difficult
maneuvers. The colors
in the wake of theaircraft are the vortical
disturbances created dueto aerodynamics andengine exhaust.

A E R O S PAC E S C I E N C E S

the Schiaparelli module and the orbiter during
Validating advanced thermophysics models entry
allowed data to be transmitted at 10 trajectory
BY AARON BRANDIS AND ROSS CHAUDHRYThe Thermophysics Technical Committee promotes the study and applicationof mechanisms involved in thermal energy transfer and storage in gases,
liquids and solids.
DLR

COMARS 1

COMARS 2

Radiometer
COMARS 3

n 2017, the thermophysics community
obtained aerothermal ﬂight data at Mars,
improved the ability to use fundamental
chemistry data in design tools, and investigated meteor entry in high-enthalpy experimental
facilities.
Researchers from the European Space Agency’s
ExoMars mission in June presented ﬂight data fromthe Schiaparelli module’s entry into the Martianatmosphere. The data obtained during Schiaparelli’s
descent will be invaluable for validating models
used to design thermal protection systems for futureMars missions. Reliable ﬂight data is essential forthe optimization of heat shield design, which ingeneral is carried out with relatively high safetymargins. High margins compensate for the large
uncertainties associated with simulation tools whenused to predict aerothermal loads on a spacecraft.
For example, consider the radiative heating that iscreated by hot carbon dioxide molecules in the ﬂow
around the back-shell. This heating mechanism has
not been accounted for in most previous Mars mission designs. Therefore, DLR, the German Aerospace
Center, developed the Combined Aerothermal
and Radiation Sensor package, called COMARS+,
to measure the aerothermal and radiative loads at
different backshell positions on Schiaparelli. COMARS+ consisted of three combined aerothermal
sensors, one broadband radiometer sensor and anelectronic box. Because Schiaparelli crashed on theMars surface, DLR could not retrieve the complete
data package. However, communications betweenI28|

DECEM B ER 2017|

The Combined
Aerothermal andRadiation Sensor
package on COMARS+
was installed on
the back cover ofEurope’s Schiaparelli
spacecraft to measure
the aerothermal andradiative loads at
different backshell
positions during theMars descent.

aerospaceamerica . aiaa .org

points. Ongoing post-ﬂight analysis, including tests
in the arc jet facility L2K at DLR Cologne, are providing unique data for future Martian missions.
Computational chemists at the University ofMinnesota in July and October published potential
energy surfaces, or PESs, for O2 + O2 and O2 + O
interactions relevant to conditions representativeof hypersonic speeds. PESs are high-quality ﬁts
of the atomic forces that exist during molecularcollisions and are used to investigate the dynamics
of a dissociating gas, which are often in thermal
non-equilibrium. These investigations lead to an
improved understanding of reaction rates implemented in computational ﬂuid dynamic simulations. Researchers in aerospace departments at theUniversity of Illinois at Urbana-Champaign and theUniversity of Minnesota use PESs with two different
methods to predict non-equilibrium internal energy
distributions. In a collaboration presented at AIAA’s
2017 Aviation/Thermophysics Conference, these
two methods were demonstrated to be consistentfor the case of nitrogen dissociation. PESs are now
available for many important reactions relevant toEarth entry, and by correctly modeling non-equilibrium and its effect on chemical kinetics, this work is
expected to lower uncertainty margins and enablenovel vehicle design.
Thermophysics research groups this year leveraged high-enthalpy experimental facilities traditionally used for testing spacecraft thermal protection
system materials to study the complex phenomenaof a meteor entering Earth’s atmosphere. Researchers in Japan studied synthetic meteorites in an arc
heated wind tunnel in preparation for a planned
artiﬁcial meteor shower at the 2020 Olympic Games.
Groups in Europe, at the von Karman Institute andthe University of Stuttgart, used plasma wind tunnel
facilities, including the Plasmatron and PWK1
respectively, to study emission spectra from meteorite samples. At NASA’s Ames Research Center inCalifornia, meteoroid ablation was studied in detailin the Interaction Heating Facility in July to aid in developing models for asteroid threat assessment. The
data from all of these experiments are being used
to advance state-of-the-art numerical modeling ofmeteor entries.
By obtaining aerothermal heating ﬂight data
at Mars, understanding how to efﬁciently use
elaborate quantum chemistry data in production
design tools, and investigating the physics of meteor
entry in high-enthalpy ground tests, the ability tovalidate complex thermophysics models is greatly
improved. +Contributors: Ali Guelhan and Eric SternP R O P U L S I O N A N D E N E R GY

NASAVoyagers hit 40 years operating,Cassini mission ends
BY BARBARA MCKISSOCK AND GREGORY CARR

The Aerospace Power Systems Technical Committee focuses on the analysis,design, test or application of electric power systems or elements of electric
power systems for aerospace use.
Cassini, in an artist’srendering, ended
its mission with anintentional dive into
Saturn’s atmosphere.

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his year marked the 40th anniversary ofthe Voyager spacecraft launches. Voyager
1 launched Sept. 5, 1977, and Voyager 2
launched Aug. 20, 1977. Voyager 2 was theﬁrst (and only) spacecraft to visit all four gas giant
planets (Jupiter, Saturn, Uranus and Neptune).
Voyager 1 visited Jupiter and Saturn prior tothe Voyager 2 ﬂybys. The Voyager mission wasenabled by nuclear power, speciﬁcally radioisotope thermoelectric generators. The original
requirement for each of the three Voyager multihundred-watt RTGs was to provide 128 watts ofelectricity four years after launch for the originally planned Jupiter and Saturn ﬂybys. They havemore than exceeded that four-year requirement,
enabling Voyager 2 to be the ﬁrst spacecraft to ﬂyby Uranus and Neptune and Voyager 1 to be theﬁrst spacecraft to fully enter interstellar space.
On Sept. 15, NASA’s Cassini spacecraft entered
the atmosphere of Saturn after having spentalmost 20 years in space and 13 years orbiting theringed planet. The electrical power provided bythree general-purpose heat source RTGs madeCassini’s mission possible.
The U.S. Department of Energy, on NASA’s
behalf, continued to progress on the production ofT

DECEM B ER 2017|aerospaceamerica . aiaa .org

new plutonium-238 for use in radioisotope power systems. Sufﬁcient
targets were irradiated this year toconduct the next chemical separation demonstration. This separation
campaign will emulate a full-production batch size, predicted to lead
to about 300 grams of heat-source
plutonium oxide. In addition, theDOE has transitioned to a constantrate production strategy to produce
10-15 fueled clads each year. Thiswill reduce plutonium-238 production and NASA mission risks with asteady production and ready supplyof heat sources for RPS-enabledmissions. This constant rate production approach has the added beneﬁtof reducing the cost to missions
using an RPS by approximately 25
percent over the prior mission-fueling surge campaign model.
In July, NASA completed an RPS system study
that provided guidance toward future technology
investments in modular deep-space thermoelectric generators scaled to notionally produce 50-470
W of power. Based on continued mission need,NASA also initiated four technology development
contracts for dynamic energy conversion research.
Preliminary testing of the Kilopower (a smallﬁssion reactor power system for space missions
needing 1-10 kilowatts electric) nuclear technology demonstration assembly using an electricallyheated depleted reactor core simulator was conducted at NASA’s Glenn Research Center in Ohioin January. The full Kilopower demonstration features a 4 kilowatt thermal uranium-molybdenum
reactor core, sodium heat pipes for heat transfer
and Stirling power convertors developed during
the Advanced Stirling Radioisotope Generator
program. A highly enriched uranium core wasfabricated in July in three sections at the DOE’s
Y-12 National Security Complex in Oak Ridge,Tennessee, for shipping to the DOE Nevada National Security Site’s National Criticality Experiment Research Center, where it will be integrated
into the heat pipe. Power conversion assembly
will be tested at Glenn. The demonstration is apartnership between NASA and the DOE National
Nuclear Security Administration.
On Jan. 13, astronauts completed installationof lithium-ion batteries on two of the eight powerchannels on the International Space Station, replacing the old nickel-hydrogen battery technology on the S4 truss. The old batteries were sent tothe ISS in early 2007 and were approaching theend of their design life. +P R O P U L S I O N A N D E N E R GY

Nagoya University

Advances made toward rotating
detonation engines
BY STEPHEN HEISTER AND V. TANGIRAL A

The Pressure Gain Combustion Technical Committee advances theinvestigation, development and application of pressure-gain technologies
for improving propulsion and power generation systems and achieving new
mission capabilities.
ith the promise of performance gains of
10-15 percent, researchers are advancing the technologies required to makeunsteady detonation-based engines areality for aerospace propulsion and stationary
power-generation applications. The rotating detonation engine, or RDE — a device that exploits
continuous detonative combustion in a thinannular channel — is the main focus of research,and several critical advances were made in 2017.
Russia’s NPO Energomash and Lavrent’ev
Institute of Hydrodynamics conducted along-duration ﬁring of a large-diameter oxygen/kerosene liquid rocket engine with RDE combustion. The U.S. Air Force Research Laboratory in
April demonstrated thermally steady operationof an air-breathing RDE with a ceramic matrix
composite outer body. In February, AFRL also
tested an RDE integrated into a T63 gas turbine as
the combustor; results show low nitrogen oxide
production and good combustion efﬁciency,indicating promise for the technology.
The U.S. Department of Energy’s National
Energy Technology Laboratory continued leading
the implementation of RDE technology into stationary power-generation systems. Aerojet Rocketdyne planned to conduct hot-ﬁre testing of an
air-breathing, natural gas-fueled RDE in November under a $6 million contract awarded in 2016.
And efforts at Purdue University, the universitiesof Michigan, Alabama and Central Florida, andthe Southwest Research Institute complemented
the NETL program with advanced measurements
and fundamental studies.

WJapanese researchersdeveloped and tested
a 900 N-class oxygen/ethelene rotating
detonation engine.

Detonation-based engine research expanded internationally. Japan has a large number ofefforts in both RDE and pulse detonation engine
technology. In August, a team from Nagoya andKeio universities, the Japan Aerospace Exploration Agency and Muroran Institute of Technology conducted a 330-second speciﬁc-impulse,
near-vacuum and 895-newton high-thrustexperiment with an ethylene/oxygen RDE withcombustion efﬁciency exceeding 95 percent.
In China, several university groups are working to advance RDE technology. Peking University studied ignition delay time and re-initiation
phenomenon. National University of Defense
Technology conducted air-breathing RDE experiments and established operability limits. Nanjing
Institute of Technology achieved detonative
performance in a gasoline-oxygen RDE. Tsinghua
University conducted experimental research onRDE combustion instability.
Russia’s Semenov Institute of Chemical Physics and Institute of Theoretical and Applied Mechanics focused on a hydrogen-fueled scramjetof signiﬁcant scale (1.05-meter long and 0.31 m indiameter) demonstrating speciﬁc impulse as highas 3,600 seconds in wind tunnel tests over a Mach
4-8 range. Both rotating detonation and longitudinal pulsation modes were observed.
In France, national research center CNRS andthe University of Poitiers tested different innercylinder sizes, while MBDA developed a full-scale
RDE for ground tests. ONERA’s numerical simulations focused on optimization of injector performance. Warsaw University of Technology studied
gaseous methane-oxygen RDE combustors of 150
millimeters and 200 mm outer diameters. The
ﬁrst International Constant Volume and Detonation Combustion Workshop was held in June atENSMA near Poitiers.
In the U.S., military researchers advanced
both rocket and air-breathing RDE technology.
The Naval Research Lab studied inlet/combustor
interactions in a ramjet RDE operating at 42,000
feet and Mach 2.5. NRL also developed detonation models for fuel blends, quantifying the effectof blending hydrogen with methane through propane on induction times and detonation stability.
The Naval Postgraduate School explored theimpact of engine inlet characteristics on theperformance of an air-breathing RDE. The investigation involved hot-ﬁre testing with detonation
zone imaging, optical diagnostics and collaborative computational efforts with NRL. Purdue
tested a high-pressure rocket RDE fed by gas froma liquid oxygen preburner using both natural gasand methane fuels. Operation was demonstrated
at pressures exceeding 400 psi. +aerospaceamerica . aiaa .org|

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