A Lesson in Mission Control

By Mark Dickerson
Dryden Research Pilot
A group of volunteers from Dryden recently teamed with teachers and staff from Ed Harris Middle School in Elk Grove, Calif., to try something that none of us had ever done before. We hooked up a real-time audio and video link connecting more than 60 students to give them a chance to find out what it is like to be in a NASA control room managing a research flight.

We set up a laptop and webcam in a Cessna 172 for a flight over the Antelope Valley. We installed an Internet “hotspot” in the plane and established an Internet connection with the class before takeoff by using free Skype video-conferencing software. Before the flight, via a NASA Digital Learning Network link-up, Dryden operations engineer Callie Holland explained the purpose and techniques used in a real-world control room so the students would understand what they were about to do. Then she gave them our pilot test cards, which had blank spaces in which students could copy the climb, cruise and turn performance data in real time during the flight.

Image above: Dickerson prepares the Cessna 172 for flight.

After takeoff, we performed the test maneuvers while the students got a chance to observe the entire flight from a webcam mounted in the co-pilot’s seat. (Keep in mind that Skype and hotspot software and equipment were all created for ground-based use.) For this first-time, in-flight application, the picture was kind of grainy and the audio carried more background noise than we expected, but we got the mission done, and the students came away excited about flight research.

It was a lot of fun, and the teachers want to do it again next year!

Image left: Dryden Distance Learning Network coordinator David Alexander, right, and Shaun Smith from the Dryden education office provide support (from the back seat) for the digital link-up that made the project possible.

Fire and Ice: Memories of Challenger

Fire and Ice: Memories of Challenger

By Peter Merlin
NASA Dryden History Office
While attending college in Florida in the mid-1980s I had the opportunity to view numerous space shuttle launches, including first flights of Discovery and Atlantis. I’ll never forget the thrill of witnessing spectacular nighttime and early morning liftoffs, the building excitement of the countdown, the startlingly bright flames of the vehicle’s solid-fuel rocket boosters, and the all-penetrating sound as the shuttle breached the heavens.

Unfortunately, images of Challenger’s destruction 25 years ago are also indelibly etched in my mind. This first loss of a shuttle and crew forever shattered the illusion that manned spaceflight had become as routine as traveling on a commercial airplane.

On the morning of Jan. 28, 1986, I joined a throng of tourists and space buffs on a narrow strip of land spanning the Banana River between Kennedy Space Center and Cape Canaveral Air Force Station, roughly six miles from the launch pad. Bitterly cold temperatures – it was 36 degrees at launch time – had failed to deter me. The sky was deep blue and cloudless, and I huddled against the chill.

Excitement built in the final moments as the launch announcer called out the countdown. “Ten, nine, eight!” Billowing steam clouds signaled main engine start. “Three, two, one, zero!”

People began to cheer as the rocket rose silently into the sky atop a pillar of flame and smoke. It took nearly 10 seconds for the thunderous sound of liftoff to reach the spectators. A distant crackling quickly built to a pulsating roar that shook my bones.

As Challenger soared upward, everything seemed normal. But suddenly, the rocket’s smoke trail blossomed into a brownish-orange ball. The vehicle’s two boosters cut diverging paths across the sky, disappearing seconds later in twin flashes of fiery yellow. Various smaller objects emerged from the expanding cloud, each ascending in a ballistic arc and trailed by a plume of white vapor.

I heard a woman shout, “Look, booster separation!” I knew, however, that it was far too soon for that. At this point in the flight Challenger would have scarcely reached 50,000 feet. “No,” I said to her. “Something is very, very, wrong.”

The NASA public address system had fallen silent so I could only watch and wonder. Not yet grasping the full import of what I had witnessed, I still expected the orbiter to somehow emerge from the cloud and return for an emergency landing in what astronauts call RTLS – a return-to-launch-site abort. The truth gradually dawned as I registered the amount of debris falling toward the ocean.

Challenger’s smoke trail, brilliant white against azure, ended in a twisted mushroom cloud. Small pieces of debris, like a snowstorm of glitter, drifted on the wind for nearly an hour. As my disbelieving eyes scanned the sky for an orbiter that would not return, I saw people pointing in forlorn hope at a white parachute that I recognized as part of a booster rocket. It soon became clear that the crew of seven astronauts was lost.

Over the ensuing months, the nation mourned. Presidentially appointed investigators determined causes and made recommendations. The shuttles eventually returned to flight when Discovery blasted into orbit Sept. 29, 1988.

Since that day, there have been more than 100 successful shuttle missions and one additional fatal mishap, the loss of Columbia and its crew in 2003. As the shuttle fleet approaches retirement in 2011, I feel a sense of awe at all that has been accomplished by the men and women who created, maintained and operated the most complex space vehicle ever built, and I remember those who sacrificed their lives in pursuit of exploration on the final frontier.

Beginnings and Endings

By David McBride
Center Director
NASA Dryden Flight Research Center

April 12 is a significant date in space history. On that day in 1961, Soviet Yuri Gagarin became the first person in space. On that same day in 1981, NASA launched space shuttle Columbia on its maiden voyage into space, marking not only America’s return to space but also the first flight of the nation’s new shuttle transportation system. The shuttle was the first – and so far, only – reusable spacecraft, itself an extraordinary accomplishment. Dryden played a major role in the development of this system.

Image: Space shuttle Columbia comes in for the STS-1 landing at Edwards Air Force Base on April 14, 1981.

Yesterday NASA announced the four locations where the existing orbiters will be put on permanent display once the program draws to a close. It may appear to many as though the shuttle’s retirement means an end to American space-faring, but that is a shortsighted perspective. We took a six-year break between the final Apollo mission and the launch of the first shuttle, during which time no American flew in space. NASA’s current focus is on transferring the space launch business to private enterprise, and during that time we will continue to launch Americans into space in cooperation with our Russian partners.

Through all this, Dryden has remained involved in our nation’s space initiative. It was a pattern that was set in the late 1950s with the X-15 program then continued through the 60s and 70s with the Lunar Landing Research Vehicle, lifting bodies, Approach and Landing Tests for the space shuttle, right down through our direct support of the shuttle program as the missions were flown. Our role hasn’t merely been one of support, however; we have been directly involved in aerospace innovation. The first integrated scramjet was demonstrated here, opening new possibilities for access to space, and Dryden plays a central role in the Flight Opportunities Program, which is part of the president’s new plan for NASA. And of course we were the center responsible for testing the Pad Abort system for the Orion Crew Exploration Vehicle. Even now Dryden engineers are at work on new ways to gain access to space, through research on electromagnetic acceleration down a rail and airborne rocket launches into low-Earth orbit.

We are not done perfecting the science of flight. There are many new discoveries waiting to be made through flight research programs. Just as our predecessors united for a common cause, we, too, are looking ahead, developing next-generation aircraft that are more environmentally friendly and systems that will take us to destinations beyond low-Earth orbit.

As the primary backup-landing site for the shuttle program, we stand ready to support the final two missions. While some hope for a landing at Edwards so they can say goodbye to an old friend, I look for the inspiration to be found in all that we’ve accomplished, and the challenges that lie ahead as we do it all over again.

Getting The Word Out

By Sarah Merlin
NASA Dryden Public Affairs
Assistant Editor/Tybrin Corp.
NASA pilots talk to the public at an air show exhibit.
NASA is known the world over as a workplace filled with the best scientific and technical brains ever to fire up an experiment. The agency’s engineers and scientists have spawned some of the most incredible and far-reaching discoveries ever made in the fields of research and space exploration, and in this new era, they show no signs of slowing down.

Image: NASA Dryden pilot Nils Larson, left, and photographer Jim Ross sign photos at the Folklife Festival in Washington, D.C.

Fortunately for people like me, though, you don’t necessarily have to be good at math to have a great job at NASA. Sometimes I think working in my office, public affairs, is one of the best jobs a liberal arts graduate could have – the chance to use your education and experience as a writer, editor or journalist to connect the American public with the achievements of the best scientists in the country.

It’s our job to provide the media and the public with information about what NASA does. When NASA was established in 1958, the idea that the American public should know about the agency’s achievements was considered so important that it was written into the founding charter as part of the mission. So that’s what our job is: spreading that information to as many people as we possibly can beyond a strictly technical audience and, in the process, hopefully stimulating interest in what are known as the “STEM” disciplines – science, technology, engineering and mathematics – among young people who will be NASA’s next generation of scientists and engineers. At air shows, in print publications, on TV and the Web, at schools and community events large and small across the country, we’re doing everything we can to tell America about all the great things NASA scientists do. And in more than eight years of working here, I’m happy to say that few things in my professional life have been more rewarding than standing in a NASA exhibit at a hot Midwestern air show, sharing information with a public that overwhelmingly seems to love its space agency. Anytime our research pilots volunteer to help out by joining us at those air shows, the line for their autographs is out the door all day.

Our challenge is turning information that’s most often really technical in nature into terms that are friendly to a general-readership audience. My background as a print journalist and an English major helps a lot. In journalism, you’re called on every day to boil down the high points of one topic or another, and do it as briefly and accurately as possible. (Using proper grammar and spelling!) That kind of background is ideal for what we do in our office: we learn about an aircraft or a research project or a new technology, and then write about it in ways that are clear and accessible to a wide variety of readers. It might be for a reporter interested in doing a more in-depth piece about a project or aircraft. It might be for a teacher who wants to incorporate information derived through NASA research into a classroom science lesson. Or it might just be for an average guy or girl out there who’s loved airplanes ever since he or she can remember. Whoever it’s for, we want to tell them whatever they want to know about NASA’s work.

Here at Dryden and all across NASA, our rock star engineers and pilots make the job great. In our office, we’re so proud of everything they do and it’s a privilege to be in a position to help get the word out about their groundbreaking accomplishments. Our goal is to tell as many taxpayers as we can about the advancements being made in their name, and to live up to our mission as it was spelled out in the NASA charter. Me, I’m better off leaving the scientific breakthroughs to the math whizzes.

Laminar Flow and the Holy Grail

By Al Bowers
Associate Director for Research
NASA Dryden Flight Research Center

For aerospace engineers, the holy grail of low drag means conquering laminar flow. NASA (and the NACA before us) has spent a LOT of effort and money to make laminar flow work in real-world applications, which would mean dramatic improvements in fuel efficiency.

Image: The black test section of the upper wing skin on this NASA Gulfstream III research aircraft has a line of miniscule bumps at the leading edge that allows the boundary layer airflow to remain stable and smooth over most of the wing’s upper surface. The tiny vertical airfoils mounted outboard of the black test section are vortex generators that keep the airflow attached over the wing surface at cruising speed.

Laminar flow is essentially the way airflow travels above and below wing surfaces. A certain amount of air turbulence occurs on the surface of most aircraft wings, regardless of their shape and size. As air moves across a wing, it’s altered by the friction between it and the wing’s surface, changing from a laminar, or smooth, flow at the forward area to more turbulent flow toward the trailing edge. The ideal would be laminar airflow across the entire surface of the wing with no sign of turbulence, which hinders flying performance by increasing aerodynamic drag and fuel consumption.

In various efforts dating back decades, NASA has attempted to achieve that ideal. Research by the NACA began in the 1930s with smoke trails photographed in a Langley wind tunnel and continued through the 1990s using such test beds as a Lockheed JetStar and an F-16XL. Today, a new program is getting under way at NASA Dryden that will use the center’s Gulfstream III aircraft and build on the work of the world’s most knowledgeable researchers in this area, Bill Saric and Helen Reed of Texas A&M University.

The idea Saric and Reed had is so good it’s simply sheer genius. It’s a known fact that if airflow is excited to a HIGHER frequency than the unstable frequency, waves are stable. Let me say that again: if waves are excited to a higher frequency, airflow is stable; that is, it remains laminar and does not immediately break down and transition to turbulent flow.

Saric and Reed’s simple but brilliant idea was to put bumps on the laminar-flow part of a test wing. By carefully adapting the size of the bumps to the depth of the boundary layer (that part of the air flowing next to the skin of the wing), a stable wave can be established in the boundary layer and this allows the flow to remain laminar for long runs (30 to 50 percent of the upper surface) over the wing. The Air Force Research Laboratory issued a grant to Saric and Reed for an experiment that flew to Mach 0.3, a lift coefficient of 0, and a Reynolds number of about 7 million, and showed laminar flow back to about 70 percent over a 30-degree swept wing.

Fay Collier, NASA’s expert in laminar flow, was so interested in their idea that he wanted to pursue it further. He was instrumental in getting the Gulfstream project funded to see whether laminar flow could be sustained at the full cruise flight conditions of a modern airliner. The goal will be to achieve significant runs of laminar flow at Mach 0.75, a lift coefficient of 0.3, Reynolds numbers of 25-30 million with laminar flow back to 60 percent over a 30-degree swept wing. These numbers correspond to those of medium-size airliners – somewhere between a 737 and 757. Dryden’s team will be focused on achieving that goal for NASA.

To do the job, NASA needed an airplane that had properties similar to aircraft in this size range and could be flown cost-effectively. The Gulfstream III fit a lot of the criteria. The G-III’s wing is big, and the aircraft cruises easily at the necessary flight conditions. Most important, should NASA achieve the proposed laminar flow runs, the promise of a 20-30 percent reduction in fuel burn might save a lot of fuel and energy.

Okay. Those of you who are truly interested in the technical aspects of all this and want to dive into the real nuts and bolts, keep reading.

So what was the big hold-up in the research all these years? Making laminar flow work in the real world isn’t easy. Minor imperfections in manufacture – things like ripples, wrinkles, rivet heads, bugs, small imperfections in shape, waves in the wing – all prevent laminar flow. Worse, many of these imperfections can be invisible in casual inspection by observers, and prevent laminar flow. And even if all these problems could be solved, it’s still possible to fail in achieving significant runs of laminar flow. It turns out that to cruise at Mach 0.7 to 0.8, the sweep of the wing is an enemy to laminar flow. And cruising at Mach 0.7 to Mach 0.8 is where we want to cruise with modern airliners.

In a straight wing, airflow is “pulled” along from the leading edge of the wing to near the wing’s point of maximum thickness, and this helps promote laminar flow. At the maximum thickness, airflow is at its lowest pressure (the low pressure on the upper surface is lower than that of the lower surface, and this pressure difference is the lift; discovery of this phenomena is attributed to eighteenth-century Dutch-Swiss mathematician Daniel Bernoulli). From the max thickness point back to the trailing edge, the air is increasing in pressure. This can be thought of as the air “coasting” uphill against the pressure. As the air does this, the subtle variations in the smoothness of the air are amplified. These small perturbations cause waves in the boundary layer and the flow abruptly breaks down and becomes turbulent. This turbulent flow “scrubs” against the surface of the wing and causes the skin-friction drag of the wing to rise dramatically. Turbulent flow isn’t all bad, as the additional energy in the boundary layer helps prevent flow separation from the surface of the wing (which would cause even more drag than the increased skin friction of turbulent flow). To maximize the amount of laminar flow on a straight wing, designers use very carefully tailored shapes to move the maximum thickness very far aft on the wing. Laminar flow runs of 70 percent on the upper surface and nearly 100 percent on the lower surface are possible if caution is used. The resulting drag is very low compared to conventional turbulent airfoils producing the same lift, as much as 70 percent less. So all this is on the straight wing.

A swept wing, which is necessary for flight at high Mach numbers (like Mach 0.7 to 0.8), has a different problem. In this case, the swept leading edge causes an immediate transition from laminar to turbulent flow. The culprit is called crossflow transition. As the flow meets the leading edge, it’s easier for the air to move along the leading edge with the sweep than for it to move over the wing, as it would have on an unswept (or straight) wing. So the flow starts out moving towards the wing tip, and then it curves over the upper or lower surface and finally moves aft toward the trailing edge. But once the flow starts out toward the tip in crossflow the boundary layer transitions from laminar to turbulent and, once transitioned, it is nearly impossible to make the airflow laminar or smooth again.

Remember those unstable “waves” in the airflow on the straight wing? The unstable waves in crossflow can be calculated, and are dependent on flight condition. One oddity is that these waves are inherent in the air, and not related specifically to the size of the aircraft; waves don’t scale up or down with the size of the aircraft – wavelength is an inherent property of air. So a T-38 and a 747 (if they had the same wing sweep and wing shape) would experience the same wavelength and pattern.

Saric and Reed’s idea resolved the question of what to do about these unstable crossflow waves. With the latest Gulfstream research effort, Dryden hopes to build on their accomplishments as well as on NASA/NACA laminar-flow research spanning nearly 80 years. Here’s hoping that we’re getting closer and closer to that holy grail of ideal conditions and greatly improved fuel efficiency, which will pay off in the form of reduced cost for all kinds of air travel.

Art Meets Aerospace

(Editor’s Note – NASA’s Jet Propulsion Laboratory and Dryden Flight Research Center are among aerospace facilities featured in an artistic photography exhibit on display through Feb. 12 at the Blythe Projects gallery, 5797 Washington Blvd., Culver City, Calif. In the following blog, the photographer shares some of his thoughts on creating the imagery.)  

By Michael Salvatore Tierney

When I grew up in Los Angeles during the 1970s and 1980s, both of my parents were employed by Hughes Ai
rcraft. The elusive and mysterious aerospace industry was at the core of my young life. My persistent desire to revisit and explore the industry that informed me personally and shaped so much of the Southern California landscape led me to create my Aerospace series.

Image above right: the Mars rover Curiosity captured during assembly in a JPL clean room.

Developments that have come out of this industry have had a profound effect on us as a region, a nation and a culture. Aerospace has been a crucible for some of man’s greatest scientific and technological achievements. It struck me that many Californians go about their daily lives mere miles from where these marvels are being carefully orchestrated, without even knowing of their existence.

The rich history and current developments in the aerospace industry lent themselves perfectly to this project. My quest led me to NASA’s Dryden Flight Research Center, JPL, Caltech and Edwards Air Force Base, all of which
Shuttleare in Southern California. I was able to explore and photograph groundbreaking achievements of the past and the most phenomenal dreams for the future.

Image right: Space shuttle Discovery encased in the Mate-Demate Device at Dryden in September 2009.

I explored these institutions from strictly a fine-art point of view rather than through the eyes of a documentarian. By deconstructing the images and rebuilding them digitally, I was able to instill the photos with both a sense of memory and obscurity. It was an honor to create images that present an innovative approach to viewing aerospace. Exhibiting the works in a contemporary fine art arena has allowed me to introduce aerospace to an audience not fully aware of this evolving phenomenon