www.nasa.gov

Volume 65 Number 6 June 2023

National Aeronautics and Space Administration

AFRC2022-0131-10 NASA

New paint

NASA F/A-18D gets a fresh look

NASA’s X-57 tests the motors spinning on all battery power. The X-57 has provided a path for industry through lessons learned and solutions 

to some of the complex elements of electric flight. See page 4.

X-57 contributions
 X-Press 2

X-66, page 7

The X-66A is the X-plane specifically aimed at helping the United States achieve the goal of net-zero 

greenhouse gas emissions by 2050. To build the X-66A, Boeing will work with NASA to modify an MD-90 

aircraft, shortening the fuselage and replacing its wings and engines. The resulting demonstrator aircraft 

will have long, thin wings with engines mounted underneath and a set of aerodynamic trusses for support. 

The design, which Boeing submitted for NASA’s Sustainable Flight Demonstrator project, is known as a 

Transonic Truss-Braced Wing.

 NASA illistration

AFRC2022-0153-12 NASA/Carla Thomas

X-66: 

U.S. Air Force assigns number for 

new flight demonstration project 

By Rob Margetta

NASA Public Affairs Officer

NASA and Boeing said the 

aircraft produced through the 

agency’s Sustainable Flight 

Demonstrator project has been 

designated by the U.S. Air 

Force as the X-66A.

The new X-plane seeks 

to inform a potential new 

generation of more sustainable 

single-aisle aircraft – the 

workhorse of passenger airlines 

around the world. Working with 

NASA, Boeing will build, test, 

and fly a full-scale demonstrator 

aircraft with extra-long, thin 

wings stabilized by diagonal 

struts, known as a Transonic 

Truss-Braced Wing concept.

“At NASA, our eyes are 

not just focused on stars 

but also fixated on the sky. 

The Sustainable Flight 

Demonstrator builds on 

NASA’s world-leading efforts 

in aeronautics as well climate,” 

said NASA Administrator Bill 

Nelson. “The X-66A will help 

shape the future of aviation, 

a new era where aircraft are 

greener, cleaner, and quieter, 

and create new possibilities for 

the flying public and American 

industry alike.”

The X-66A is the first X-plane 

specifically focused on helping 

the United States achieve 

the goal of net-zero aviation 

greenhouse gas emissions, 

which was articulated in the 

White House’s U.S. Aviation 

Climate Action Plan.

“To reach our goal of net zero 

aviation emissions by 2050, we 

need transformative aircraft 

concepts like the ones we’re 

flying on the X-66A,” said Bob 

Pearce, associate administrator 

for NASA’s Aeronautics 

Research Mission Directorate, 

who announced the designation 

at the American Institute of 

Aeronautics and Astronautics 

Aviation Forum in San Diego. 

“With this experimental 

aircraft, we’re aiming high 

to demonstrate the kinds of 

energy-saving, emissionsreducing technologies the 

aviation industry needs.”

NASA and Boeing sought 

the X-plane designation shortly 

after the agency announced the 

Sustainable Flight 

Demonstrator project award 

earlier this year. The Air Force 

confers X-plane status for 

development programs that 

set out to create revolutionary 

experimental aircraft 

configurations. The designation 

is for research aircraft. With few 

Aaron Rumsey and Beto Hinojos carefully add weight to a 6-foot model 

of the Transonic Truss-Braced Wing at NASA’s Armstrong Flight Research Center, in Edwards, California. The aircraft concept involves a 

wing braced on an aircraft using diagonal struts that also add lift and 

could result in significantly improved aerodynamics. Look here for more.
News

at NASA

Mars 

copter 

phones 

home

Room to roam

June 2023 3

A bobcat finds shade in the Mojave Desert at NASA’s Armstrong 

Flight Research Center in Edwards, California.

A desert tortoise, native to the Mojave Desert at NASA’s Armstrong 

Flight Research Center in Edwards, California, goes for a walk.

NASA

NASA

By Laura Mitchell

NASA Armstrong Public Affairs

Each NASA facility has its 

own unique micro-climate 

and geography. At NASA’s 

Armstrong Flight Research 

Center in Edwards, Calif., 

the high-desert climate is an 

interesting natural habitat for a 

variety of wildlife.

NASA Armstrong, housed at 

Edwards Air Force Base, sits 

on more than 300,000 acres of 

desert land. Part of that landscape 

is Rogers Dry Lake, a drainage 

basin that retains water with no 

outflow to external bodies of 

water like rivers, other lakes, or 

the ocean. This unique climate 

makes it an ideal location for the 

experimental flight testing that 

NASA Armstrong is known for.

It is also home to desert 

tortoises, bobcats, lizards, 

snakes, scorpions, and 

burrowing owls. To ensure the 

safety of the wildlife and the 

personnel, NASA biologists and 

the environmental office monitor 

the wildlife and their behavior. 

Mark Bratton, environmental 

scientist and wildlife biologist, 

monitors and tracks the wildlife 

on center and across the base in 

conjunction with the Air Force.

The desert tortoise is native to 

the Mojave Desert. The desert 

tortoise can live between 50 

and 80 years and grow to be 

10 – 14 inches. Some tortoises 

on base have been outfitted 

with radio transmitters on their 

shells, and other tortoises that 

have been relocated to different 

areas of the base. “The radio 

transmitters help us know where 

the adult female tortoises are 

so when they are ready to lay 

their eggs, we can take the 

females to holding pens were 

they lay/deposit their eggs in 

predator-proof pens. After the 

Wildlife, page 8

The 52nd flight of NASA’s 

Ingenuity Mars Helicopter 

is now in the official 

mission logbook as a success. 

The flight happened on April 

26, but mission controllers 

at NASA’s Jet Propulsion 

Laboratory in Southern 

California lost contact with 

the helicopter as it descended 

toward the surface for landing.

The Ingenuity team expected 

the communications dropout 

because a hill stood between 

the helicopter’s landing 

location and the Perseverance 

rover’s position, blocking 

communication between the 

two. The rover acts as a radio 

relay between the helicopter 

and mission controllers at 

JPL. In anticipation of this 

loss of communications, the 

Ingenuity team had already 

developed re-contact plans for 

when the rover would drive 

back within range. Contact was 

re-established June 28 when 

Perseverance crested the hill 

and could see Ingenuity again.

Flight 52, a 1,191-foot 

(363-meter) and 139-secondlong flight, repositioned the 

helicopter and took images of 

the Martian surface.

The target for Flight 53 is 

an interim airfield to the west. 

Then an additional westward 

flight will land at a new base 

of operations.
 X-Press 4

AFRC2021-0071-072 NASA/Carla Thomas

 NASA

Susanah Kowalewski prepares a cruise motor controller for testing 

at NASA’s Glenn Research Center in Cleveland.

Paving the way

X-57 project creates paths for electric aviation

By Sarah Mann

NASA Armstrong Public Affairs

NASA’s X-57 Maxwell allelectric aircraft project will 

conclude aircraft operational 

activities by the end of 

September, with documentation 

and close-out activities 

continuing for several months 

afterwards. The research from 

the X-57 provides aviation 

researchers with hundreds of 

lessons learned, as well as 

revolutionary development 

in areas ranging from battery 

technology to cruise motor 

control design.

“NASA’s goal is to 

drive innovation through 

groundbreaking research and 

technology development. The 

X-57 project team has done just 

that by providing foundational 

information to industry through 

lessons learned, and we’re 

seeing the benefits borne out by 

American commercial aviation 

companies that are aiming to 

change the way we fly,” said 

Brad Flick, director of NASA’s 

Armstrong Flight Research 

Center in Edwards, California, 

where the X-57 aircraft was 

developed. “I’m incredibly 

proud of their tenacity and 

ingenuity as they led the 

way in advancing electrified 

NASA’s X-57 all-electric aircraft in the Mod II configuration undergoes high-voltage testing in 2021 at 

NASA’s Armstrong Flight Research Center in Edwards, California.

AFRC2023-0038-125 NASA

NASA’s X-57 lithium-ion batteries are installed in the aircraft in 2022.

propulsion. The future of 

electrified propulsion is possible 

because of their contributions.”

Finalizing aircraft operations 

by September 2023 will not 

incorporate first flight of the X-57 

aircraft. The project encountered 

several challenges to safe flight, 

including mechanical issues 

late into its lifecycle and a 

lack of availability of critical 

components required to develop 

experimental hardware. Given 

the approaching planned end of 

aircraft operations, the timeline 

would not allow the team to reach 

acceptable flight conditions. 

Although most of the X-57’s 

development will complete by 

September 2023, the team will 

officially conclude its work 

several months afterward with 

additional technical publications.

The primary goal of the 

X-57 project was to provide 

knowledge about the aircraft’s 

electric-propulsion-focused 

design and airworthiness process 

with regulators. This information 

has already impacted and 

will continue to impact the 

development of advanced 

X-57, page 8
 June 2023 5

AFRC2023-0072-04 

NASA/Genaro Vavuris

NASA researchers 

Jeanette Le, Curt 

Hanson, and Erik 

Waite, look on as 

pieces of a newly 

installed motion 

simulator are tested 

at NASA Armstrong 

Flight Research 

Center in Edwards, 

California on April 

26. The simulator 

includes virtual reality goggles depicting 

an aircraft cabin and 

city environment, as 

well as noise and seat 

motion, to simulate 

an air taxi ride.

How’s the ride?

New air taxi ride simulator aims to find out

During an experiment, test subjects will be secured in the seat on 

top of a platform that can move on six axes to realistically simulate 

motion in an aircraft and tests will gauge their level of discomfort. 

They will wear a virtual reality headset and headphones to create a 

fully immersive experience.

As each subject virtually flies around a projected scene of 

downtown San Francisco, they will be asked to indicate any time they 

feel uncomfortable by pressing a handheld button. These discomfort 

cues can later be correlated with recorded visual and motion stimuli, 

as well as with physiological measurements, such as heart rate and 

breathing rate.

NASA researchers will be able to provide guidance on elements 

of air taxi design like seat placement and window size based on the 

results of these experiments. It will also help inform where the aircraft 

will take off, land and fly. This information will help industry and 

government make informed decisions to ensure a positive experience 

for future air taxi users.

This simulator testing is one element of NASA’s Revolutionary 

Vertical Lift Technology (RVLT) project. Other focus areas include 

improving noise, safety, and efficiency for vertical lift aircraft. The 

research performed by the RVLT project supports NASA’s Advanced 

Air Mobility research to integrate air taxis, drones, and cargo delivery 

aircraft into our sky.

By Teresa Whiting

NASA Armstrong Public Affairs

To create a future where air taxis are a regular form of transportation, 

passengers need to be comfortable. That’s why researchers at 

NASA’s Armstrong Flight Research Center in Edwards, California 

are exploring how passengers may experience an air taxi ride by 

building a custom virtual reality flight simulator.

NASA is currently researching the human physiological response 

to motion, vibration, noise, and visual stimuli that passengers may 

experience during an air taxi flight, and the new simulator is a major 

part of that effort. It includes virtual reality goggles depicting an 

aircraft cabin and city environment, as well as noise and seat motion, 

to simulate an air taxi ride. NASA will make data collected with the 

simulator available to industry and other stakeholders to help shape 

the design of electric air taxis, locations where the aircraft will take 

off and land, and desired flight paths through cities.

“In the 1970s, NASA was instrumental in developing passenger 

ride quality metrics for jet airliner noise, seat vibration, and motion 

sickness through human subject testing using a unique passenger ride 

quality simulator located at NASA’s Langley Research Center,” said 

Curt Hanson, senior flight controls researcher for this project. “Now, 

NASA’s Armstrong Flight Research Center is taking this technology 

into the 21st-century.”
 X-Press 6

Students, page 7

Students tap NASA tech

 Photo courtesy of the University of Idaho

The students designed and demonstrated an automated assembly process 

for turning thin-film solar cells into larger photovoltaic arrays using two 

robotic arms working in tandem. The technology, called Print-Assisted 

Photovoltaic Assembly, was developed by NASA’s Marshall Space Flight 

Center in Huntsville, Alabama, to create an automated manufacturing 

process for lightweight solar arrays.

By Jim Skeen

NASA Armstrong Public Affairs

University of Idaho students 

learned real-world engineering 

skills during the 2022-2023 

school year while advancing 

two NASA technologies – a 

tailless aircraft design using 

wing twists to maneuver, and 

a process to assemble thin-film 

solar panels using robotics and 

3D printing.

One group of students 

designed, built, and flighttested a drone using the 

Prandtl-D, Preliminary 

Research Aerodynamic Design 

to Lower Drag, developed 

at NASA’s Armstrong Flight 

Research Center in Edwards, 

California. Looking like a 

boomerang, the Prandtl design 

mimics bird flight, using twists 

in its wingtips for maneuvering.

The students said their work 

is a first step in proving the 

commercial viability of the 

Prandtl-D, which could have 

such uses as watching over 

farmland and spotting wildfires.

The students set goals for their 

airplane of a minimum speed of 

30 mph, a maximum speed of 50 

mph, a carrying capacity of at 

least one pound, and the ability 

to fly for at least an hour.

Their battery-powered, 

11-foot airplane made from 

Balsa wood, carbon fibers, and 

organic materials surpassed 

their goals, having a stall speed, 

the minimum speed needed 

for controllable flight, of 28 

mph, hitting a top speed during 

testing of 55 mph. The airplane 

stayed aloft for 118 minutes, 

nearly doubling their goal, and 

carried a 1.5-pound payload 

that included a flight controller 

and a camera.

The aircraft, ground launched 

by a bungee cord, made nine 

flights, during which the team 

noticed vibration at the higher 

cruise speeds. A future team 

Engineering 

students at the 

University of 

Idaho prepare 

an airplane they 

designed and 

built based on the 

Prandtl-D design 

developed by 

NASA’s Armstrong 

Flight Research 

Center in Edwards, California. 

In the future, 

such an airplane 

could be used for 

monitoring farmland and spotting 

wildfires.

will work to address that issue.

The students shared that, 

“the Prandtl-D wing design is 

commercially viable,” in a report 

at a recent engineering expo held 

at the university. “The airfoil 

produces an excellent platform 

for a wide variety of UAV 

applications through increased 

efficiency, stability, and control 

simplicity.”

A second group of students 

worked with technology 

called PAPA, Print-Assisted 

Photovoltaic Assembly, or 

developed at NASA’s Marshall 

Space Flight Center in Huntsville, 

Alabama. The students designed 

and demonstrated an automated 

assembly process for turning 

thin-film solar cells into larger 

photovoltaic arrays using two 

robotic arms working in tandem. 

NASA is eyeing the use of 

such thin-film cells to power 

spacecraft and could even use 

 Photo courtesy of the University of Idaho
 June 2023 7

Students ... from page 6

the technology for creating solar 

arrays in space, enabling long-term 

spaceflight. The cost to build such 

arrays is about $450 per kilowatt 

while an automated process can 

cut the cost to $25 per kilowatt and 

eliminate human errors.

The students used PAPA to 

accomplish four tasks robotically 

including applying adhesive, 

placing the cells, printing the 

electronic connections between 

the cells, and adding a protective 

cover.

The students used substitute 

materials that mimicked the real 

materials but cheaper, allowing 

for more testing. The students 

had to tackle challenges such a 

cell breaking during placement 

and getting the adhesive applied 

consistently.

The students wanted the 

robotic arms to complete the 

assembly process without human 

intervention and to do it under 

35 minutes. They achieved both 

goals, with the assembly process 

taking about nine minutes without 

any operator intervention.

The university was able to 

provide the hands-on engineering 

experiences to the students 

thanks to NASA’s Technology 

Transfer University, or T2U, 

which connects universities 

with NASA-developed 

technologies.

“This one of the best 

examples of what T2U can 

be,” said Brian Boogaard, 

NASA Armstrong’s T2U 

representative. “You’ve got a 

highly motivated faculty and 

you have really sharp students.

The students built a lot of 

technology, they did a lot of 

great documentation, great 

design work, and a lot of good 

testing. It went really well.”

Students in the 2023-2024 

school year will be able to 

pick up both projects and 

continue to develop the 

technologies, pushing them 

even closer to being ready for 

the marketplace.

“This is helping advance 

the art of the technology,” 

Boogaard said. “It’s also 

giving a bunch of students who 

are about to hit the workforce 

the ability to get their hands on 

this technology.”

To learn more about NASA’s 

T2U program, visit here. 

X-66 ... from page 2

exceptions, X-planes are intended 

to test designs and technologies 

that can be adopted into other 

aircraft designs, not serve as 

prototypes for full production.

“We’re incredibly proud of this 

designation, because it means that 

the X-66A will be the next in a 

long line of experimental aircraft 

used to validate breakthrough 

designs that have transformed 

aviation,” said Todd Citron, 

Boeing chief technology officer. 

“With the learnings gained from 

design, construction, and flighttesting, we’ll have an opportunity 

to shape the future of flight and 

contribute to the decarbonization 

of aerospace.”

For the X-66A, the Air Force 

provided the designation for 

an aircraft that validates 

technologies for a 

Transonic Truss-Braced 

Wing configuration that, 

when combined with other 

advancements in propulsion 

systems, materials, and 

systems architecture, could 

result in up to 30% less fuel 

consumption and reduced 

emissions when compared 

with today’s best-in-class 

aircraft.

Due to their heavy usage, 

single-aisle aircraft today 

account for nearly half 

of worldwide aviation 

emissions. Creating designs 

and technologies for a more 

sustainable version of this 

type of aircraft has the 

potential for profound impact on 

emissions.

NASA’s history with the X-plane 

designation dates to the 1940s, 

when its predecessor agency, the 

National Advisory Committee 

for Aeronautics (NACA) jointly 

created an experimental aircraft 

program with the Air Force and 

the U.S. Navy. The X-66A is the 

latest in a long line of NASA 

X-planes. Additionally, NASA’s 

Armstrong Flight Research 

Center in Edwards, California, 

has provided technical expertise 

and support for several additional 

X-planes.

For the Sustainable Flight 

Demonstrator, NASA has a 

Funded Space Act Agreement 

with Boeing through which the 

agency will invest $425 million 

over seven years, while the 

company and its partners will 

contribute the remainder of 

the funding, estimated at about 

$725 million. NASA also will 

contribute technical expertise 

and facilities.

The Sustainable Flight 

Demonstrator project is 

an activity under NASA’s 

Integrated Aviation Systems 

Program and a key element 

of the agency’s Sustainable 

Flight National Partnership, 

which focuses on developing 

new sustainable aviation 

technologies.

Learn more about the 

Sustainable Flight Demonstrator 

here.

 Photo courtesy of the University of Idaho

Students at the University of Idaho are working with an aircraft design 

developed by NASA’s Armstrong Flight Research Center in Edwards, 

California. See more here.
X-Press 8

Editor: Jay Levine, 

Logical Innovations, ext. 3459

Managing Editor: Megan Person, NASA

Chief, NASA Armstrong Office of Communications:

 Kevin Rohrer, NASA

Address: P.O. Box 273, 

Building 4800, MS 1422

Edwards, California, 93523-0273

Phone: 661-276-3449

The X-Press is published each month for civil 

servants, contractors and retirees of the NASA 

Armstrong Flight Research Center.

certification approaches for 

electric propulsion in emerging 

electric aircraft markets. The 

objective was not to develop 

a prototype, but to develop a 

test platform for technologies 

and design methods. And the 

team did just that, documenting 

and publishing the technology 

gaps and their solutions as 

they were discovered so that 

industry stakeholders could 

take advantage of those lessons 

as soon as possible.

“They did things that had 

never been done before, and 

that’s never easy,” Flick said. 

“While we prepare to finish 

this project later this year, I see 

a long list of achievements to 

celebrate and an industry that’s 

better today because of their 

work.”

The X-57 is part of NASA’s 

commitment to supporting 

the U.S. climate goal of 

achieving net-zero greenhouse 

gas emissions from the 

aviation sector by 2050. Since 

2016, the project has shared 

lessons learned about battery 

technology, electromagnetic 

interference, motor controller 

design, and so much more. 

NASA will continue its research 

into electric aircraft through other 

projects, including its Electrified 

Powertrain Flight Demonstration.

The aircraft was built by 

modifying an Italian Tecnam 

P2006T to be powered by an 

electric propulsion system. 

Using an existing aircraft design 

allowed the team to compare 

their data to that of a baseline 

model powered by traditional 

combustion engines.

X-57 successes

Early in the project, the X-57 

team members found they would 

need significant developments 

in battery technology. The 

lithium-ion batteries installed 

on the aircraft warm up as 

they discharge energy and too 

much warming could result 

in overheating. The project 

worked with Electric Power 

Systems in North Logan, Utah 

to address this issue. Engineers 

demonstrated that the new battery 

system design would stay within 

acceptable, safe limits while 

powering the aircraft.

The design of the cruise 

motor controllers is another 

success of the X-57 project. 

These controllers convert 

energy stored in the aircraft’s 

lithium-ion batteries to power 

its motors, which drive its 

propellers. The controllers use 

silicon carbide transistors to 

deliver 98% efficiency intended 

for high power take-off and 

cruise, meaning they do not 

generate excessive heat and 

can be cooled off by the air 

flowing through the motor. The 

team designed inverters to meet 

demanding mass and thermal 

requirements and are sharing 

these designs in technical 

publications so that industry can 

use them as a launchpad for new 

aircraft products. Most recently, 

the cruise motor controllers 

went through successful thermal 

testing.

The aircraft reached another 

milestone with the installation 

of two 400-pound lithiumion battery packs in its cabin, 

followed by successful tests 

of its motors spinning off 

battery power. The motors 

had previously spun, but were 

drawing energy from either 

the test facility, or from the 

batteries when they were sitting 

outside of the aircraft. To reach 

this point, the X-57 project 

team repeatedly tested the 

batteries to ensure they could 

safely power the aircraft, and 

designed custom, lightweight 

cases to keep those batteries 

secure.

During the integration 

phase the team encountered 

electromagnetic interference 

that affected the operation of 

onboard systems and required 

a solution. After extensive 

research the team designed, 

developed, and installed filters 

that resolved the issue. The 

approach will be added to the 

technical papers and shared 

with industry and the electric 

propulsion community.

The value of the pathfinding 

work done on the X-57 project is 

well established and recognized 

by industry and additional 

research findings will continue 

to be published and shared with 

the technical community. A list 

of the contributions X- 57 has 

made to-date can be found on 

the technical papers site.

Wildlife ... from page 3

female lays her eggs, the adult 

female is returned to the wild 

and the eggs incubate in the 

pens until they hatch. Once the 

young hatch they are raised in 

predator-proof pens until they 

are larger and more predator 

resistant,” said Bratton.

Bobcats have been known to 

venture out at Armstrong. “We 

know of a male and female 

bobcat, and three kittens. We’re 

privileged to have the bobcats 

and even get to see them, since 

they’re pretty secretive animals,” 

said Bratton. Currently the large 

mammal study has been tracking 

some of the resident bobcats and 

coyotes on base. “Bobcats have 

different resources in different 

locations. Their water source 

might be a mile or so away from 

their den and another location 

to stalk prey,” said Bratton.

NASA employees have had the 

opportunity to witness bobcats 

lounging around some of the 

buildings and with caution, they 

have been able to take photos 

from a distance.

Snakes and lizards are also 

abundant around Armstrong. 

Bratton notes that many of 

the snakes are non-venomous 

although some like the gopher 

snake try to mimic the venomous 

snakes like the “Mojave green” 

rattlesnake by flattening out their 

head and shaking their tail in 

dried leaves to mimic a rattle.

The Environmental Office 

takes great care in managing 

the animals in residence at 

Armstrong, monitoring their 

behavior and locations for the 

safety of NASA personnel and 

the animals. In every case, if you 

see wildlife a little too up close 

and personal, Bratton suggests 

avoiding them, give them a 

wide berth and go on about your 

business.

X-57 ... from page 4