A Great Day to Go Flying

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By Mike Holtz
NASA Project Lead, Operations/Flight Test Engineer
Weather was on the warm side as we prepared for another mission in NASA F/A-18 #852 testing the Mars Science Laboratory landing radar, but it was still a great day to go flying.  

After intensive and lengthy ground operations on the order of an hour in the aircraft, we taxied out for our flight. We climbed up to 48,000 feet altitude and lined up for the first series of dives. We flew dive angles at 20, 30, 45 and 60 degrees.

Image right: NASA research pilot Nils Larson, left, and Mike Holtz review flight test cards before a test mission in an F/A-18.

The MSL radar within the QTEP – Quick Test Experimental Pod – was set to run several different gimbal angles, some locked and some actively slewing, all with the intent of radiating off the lakebed in some combination with the dive angles from the F-18. All but one test point on the flight cards was achieved before we hit our “bingo,” or minimal fuel remaining, and we had to land. The radar was developed by NASA’s Jet Propulsion Laboratory, and the JPL engineers were very happy with the flight. The radar engineers said the data looked fantastic.  

A very good mission, plus I’m pretty sure I lost 5 pounds sweating in the cockpit!

Shaking Hands With A Hero

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By Don Johnson
Deputy Project Manager
Ikhana UAS
As part of my job supporting NASA, I recently gave a short presentation to a committee doing an assessment of Dryden Flight Research Center, where I work. I work on the Ikhana – a modified Predator B unmanned aircraft system – and that is what my presentation was about. A couple of the key people with whom I work were on business travel that week, so the duty to make the planeside presentation fell to a couple of other team members and me.

This was a tour of Dryden’s aircraft and capabilities, so the committee received numerous briefings during the afternoon as they toured from hangar to hangar. Now, this committee is part of the Aeronautics and Space Engineering Board of the National Research Council. In other words, a typical government bureaucracy – well, maybe not so typical. The committee is made up of a bunch of high-roller VIPs from places like MIT, Georgia Tech, Lockheed-Martin, Boeing…really BIG brains, about 15 of them, plus several local Dryden managers.

Now flash back to when I was but a lad, not yet 15 years old. I would sit, mesmerized, in front of our little black-and-white TV, watching Walter Cronkite talk about the major milestones and big events of the American space program – yep, NASA. Then, on July 20, 1969, the first human uttered the words, “That’s one small step for man, one giant leap for mankind.”

I was 14 years old that day, attending the Boy Scout National Jamboree at Lake Pend d’Oreille in Idaho along with about 50,000 other Boy Scouts from around the country. Somehow, the scouting organization managed to create some kind of giant big-screen projection system so that we – all 50,000 of us – could watch that first moon step in real time. Remember, this was 1969 – amazing! That event in history, that first step, will be remembered for as long as there is history and there are people to remember Apollo as one of humanity’s greatest accomplishments.

In addition to the big-screen presentation, the guest speaker on the night of this Boy Scout gathering was astronaut Frank Borman, the commander of Apollo 8. That was the mission in 1968 that first orbited the moon (no landing), the mission on which astronauts read from the book of Genesis on Christmas Eve. He arrived at the outdoor theater right next to where I was sitting on the grass. I think I still have the picture I snapped of him while he was standing there waiting to go onstage.

Well, living through these special events made quite an impression on a young lad, and set the direction of my life for the next 45-plus years. Years later, I became an aerospace engineer, and went to work for the Air Force at Edwards Air Force Base. By the time I graduated in 1977, the Apollo program was over and NASA was drawing down – kind of like the same situation as now due to the space shuttle program coming to an end. There is only one shuttle launch left to go, after which our astronauts will get to and from the space station on Russian spacecraft. After 32 years with the Air Force, I retired and went to work for Tybrin Corp., supporting…NASA. Well, that’s pretty cool!

Back to the present. If you haven’t guessed by now, it turns out that one of the members of this committee of 15 Big Brains hired to assess Dryden capabilities in 2011 was indeed that same first human to step on another heavenly body – the moon – in 1969: Neil Armstrong. He is STILL in the aeronautics business! I had the honor of telling him about our little Ikhana project, and then he and some other committee members asked us a few questions. After the briefing ended, Neil Armstrong immediately stood up and came over to the three of us who had just briefed and shook our hands, thanking us for the presentation, then quietly moved on to the next set of briefings.

There aren’t many people in this world that I consider a hero. He is one of the very few.

Some days, it really pays to get up in the morning!

Image: Ikhana deputy project manager Don Johnson (at right in tan shirt) is among listeners as Ikhana lead operations engineer Greg Buoni briefs members of the National Research Council Aeronautics and Space Engineering Board during a visit to NASA Dryden. Apollo 11 astronaut and first man on the moon Neil Armstrong (in white jacket) is seated at left.

All In A Night's Work

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By Beth Hagenauer
Dryden Public Affairs
I settled into my assigned seat for the 10-hour journey. The red-eye flight would cross 11 states, eventually reaching an altitude of 44,000 feet and traveling 4,700 miles. The ticket price was very good – it came as part of my job as a public affairs media escort for a prestigious documentary crew.

As the aircraft lifted off at dusk from the Air Force Plant 42 runway in Palmdale, Calif., I realized this would be no ordinary 747 flight; I was aboard the SOFIA, or the Stratospheric Observatory for Infrared Astronomy, a flying astronomy observatory.

SOFIA is the airborne platform for a joint program between NASA and the German Aerospace Center DLR. The program is based at NASA’s Dryden Aircraft Operations Facility in Palmdale. To modify the 747 for its new role, a 16-foot-high hole has been cut in the aircraft’s port side and a one-of-a-kind infrared telescope installed in the opening. Most of the former airliner’s trappings – seats, food-preparation galley and movie screens – have been removed and replaced with workstations equipped with computers and sturdy passenger seats with five-point seat-belt harnesses.

Image right: Terry Herter, principal investigator with the FORCAST instrument, takes a minute during a SOFIA flight to explain a concept to a visiting television crew.

The television film crew was aboard to record the science mission; their viewers who have a working knowledge of astronomy are familiar with ground-based telescopes and satellites, but an aircraft carrying a telescope brings a different dimension to studying the solar system. The usual flight crew was on tap for the mission, but so was a gaggle of German and American scientists and telescope operators who had planned a flight route that would take us to observation points for targets with names like Alpha Boo and Frosty Leo – the latter, I learned, a dying star. The 17-ton German-built telescope sports a Cornell University instrument called FORCAST, which is an acronym for Faint Object Infrared Camera for the SOFIA Telescope.

As soon as the “Fasten Seat Belt” sign was turned off, the science crew took their stations at consoles outfitted with computer screens to begin their night’s work. About an hour into the flight, the exterior door covering the telescope cavity was opened. White dots of varying sizes surrounded by colored boxes and text that seemed to be astronomers’ code began to appear on the computer screens. The aircraft is very noisy, so all communication was via headset. One of the mission director’s tasks is to monitor scientists’ conversations and transmit information to and from the pilots if necessary – say, for changes to the flight plan that might mean getting a better look at a target.

About three hours into the flight, I went upstairs to the cockpit. More than 500 tiny lights illuminated a variety of circuit breakers and gages; the SOFIA cockpit is original technology and has not yet been upgraded with a “glass” cockpit, the current standard in modern aircraft. Looking out of the windows, I saw a sea of clouds lit by the full moon. It was easy to see stars with the naked eye – or visible light, as the astronomers refer to it – in the dark sky.

Unlike the environment in the main cabin, the cockpit was quiet except for occasional radio transmission between the NASA 747 and Federal Aviation Administration air traffic controllers in Seattle.

The most auspicious passenger was a small stuffed koala mascot that had flown more than four million miles on SOFIA’s predecessor, NASA’s fabled Kuiper Airborne Observatory. Earlier this year, the bear had been passed, along with the astronomical-research torch, from one generation of NASA scientists to the next.

Image below: Beth Hagenauer takes her seat in NASA’s newest airborne observatory, the SOFIA.


As the flight progressed the scientists continued their work, the adrenalin rush that comes from collecting real-time science data keeping them awake. (It had to have been that, because there was no hot coffee anywhere on board.) A flight on SOFIA is literally the only opportunity astronomers get to conduct their work in a shirtsleeve environment.

And my impression? Not being an astronomer by training, I still found myself in awe of the telescope. I never tired of watching its slow and precise movements, knowing that this activity replicates a tilting of the telescope mirror that was “peering” at the stars from within its specially designed cavity.

I brought my own dinner, since not even the dreaded “airline food” was available. I put my coat on when the aircraft reached 44,000 feet. Above all, I was tired when the aircraft landed at dawn back in Palmdale. As I watched SOFIA being towed back into the hangar and sent a very happy film crew on their way, I was reminded of a phrase that I’ve heard NASA colleagues say many times: “…and they pay me to do this?!”

The UAV Wild Blue Yonder

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By Hernan Posada
NASA Dryden UAV pilot
I have a pretty interesting job here at Dryden. I get the opportunity to fly some great unmanned aircraft and work with some very talented people.

I may be the only pilot signed off in the DROID – Dryden Remotely Operated Integrated Drone – as well as the Ikhana (NASA MQ-9) and Global Hawk (NASA RQ-4). These aircraft all play a vital role in NASA’s research mission but their performance and the way they are flown are very different. The DROID is a very sophisticated platform capable of autonomous flight. Though to the untrained eye it looks like a remote-controlled toy, it really isn’t; it has an autopilot, cameras, a pitot static system and brakes. It is flown through a ground system comprising a series of computers and monitors housed in a “bread van.” This aircraft is flown using “stick and rudder” skills, which basically means the pilot operates a stick to fly it.

Image right: Dryden pilot Hernan Posada flies the DROID from a ground control station.

The Ikhana (a modified Predator) is also flown this way. Pilots fly the Global Hawk, on the other hand, using a keyboard and mouse. The size of these aircraft range from 10-foot wingspan and 57 lbs. (DROID) to a 66-foot wingspan and 10,500 lbs. (Ikhana) to a 116-foot wingspan and 25,600 lbs. (Global Hawk). There are all kinds of missions; local DROID flights are flown at altitudes of just 1,000 feet and less than one hour over the small UAS airspace here at Edwards. Ikhana missions vary, but may have the aircraft flying fire missions over the western United States at altitudes over 20,000 feet and for up to 20 hours at a time. The Global Hawk has seen missions over the Arctic, the Pacific and the Atlantic, altitudes of over 60,000 feet and missions lasting more than 20 hours.

Amazing platforms are being flown here at Dryden, and the technology is constantly being improved. Keep an eye on the fascinating world of unmanned aircraft!

Image left: The red-and-white DROID is parked on Dryden’s ramp along with one of NASA Dryden’s airborne science UAVs, the Ikhana.

A Lesson in Mission Control

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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

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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

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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

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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

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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.

On My Way Home

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There’s a new face in Dryden’s Employee Assistance Program office – a furry one. EAP manager Kathleen Christian has begun introducing a standard poodle named Ella into her work counseling employees and their families, and decided to share the experience in a blog. Through Ella’s perspective and her own, in coming weeks Dr. Christian will share the story of Ella the Therapy Dog’s arrival, training and impact at the center.

The use of animals in therapy is a growing practice. Wide-ranging clinical studies of its effectiveness have verified significant and positive results. Trained therapy animals like Ella are turning up in hospitals, nursing homes, counseling centers and elsewhere – anyplace they can offer human colleagues the comfort of a friendly nuzzle and some warm companionship. Follow Ella’s story here and help welcome her to Dryden!

 

 

Ella, NASA Dryden therapy dog on the right, plays with her canine friend Jack.

Ella, NASA Dryden therapy dog on the right, plays with her canine friend Jack

 

On My Way Home

10/8/10 – I could feel that this day would be different. No breakfast. Then a bath. I don’t like them.  I don’t like the grooming table, the brush, the scissors. Everything moves too fast. Two women came in a car. I liked them because I got to get down off the table and play. The women talked for a long time. I think they were talking about me. After awhile She put a rope on me. She took me outside and put me in the car. She sat with me in the back seat, and I liked that. She knew how to hug me the way standard poodles like me like to be hugged. It made me feel better. She said that someday soon we would go to work and that we would help people. I have no idea what that means. I don’t think dogs help people, and I think She may be confused about that.

 

After a long time we get out of the car. She says this place is home. I play with another dog, named Jack. He is kind to me and doesn’t growl or bite. Jack is showing me how to run really fast and jump down to the grass below, run some more and jump up to the path above. There are many new things to see and do and eat at home. Lots of trees, grass, stairs, flowers and sticks. She says not to eat the flowers. She doesn’t want me to eat the rocks, either. The horses scare me, but the cats don’t. I can hear chickens, but I can’t see them. All the other animals are on the other side of the fence. Sometimes I bark at them. She says not to. I do it anyway.

 

She takes me in the car almost every day. One day we walk down a street where there are a lot of cars and sounds. There are some ladies with red hats on coming out of a place that smells good. We walk toward them. The first lady talks very, very loud in a high voice that makes me nervous. The lady walks fast over to me, stares at me and her hands come fast toward my face. There is another lady behind her making barking noises like a small dog. I sit next to Her; I want to run, but She doesn’t run, so I try hard to be still. She looks down and I can tell She is uncomfortable, too. She tells the lady I’m a puppy and maybe the lady needs to leave me alone today. We walk away. I’m glad we are leaving. She tells me she is sorry, that was the wrong place to go.

 

I never knew there was this kind of world. I feel tired. She lets me sleep as much as I want to and lets me sleep at night on her bed. I really like that. She says when I go to work I am going to meet a lot more people and that I might help some of them. I’m not sure how that will happen. I don’t think she does, either.

 

Kathy’s note: Ella seems to be making a great transition. Although I have raised many dogs, I am a little bit surprised at her demeanor with people. She is definitely not a wiggly, jumping-on-everyone puppy. I think the best word to use for her is “contemplative.” Unfortunately, there is a fine line between contemplative and afraid. At such a young age, this training will ask a lot from her. Her ability to trust me implicitly will be a critical element, and I realize that the energy I project when greeting people will make a big difference. I am looking forward to her first day at work on Oct. 18. I expect surprises and challenges for both of us. As a therapy dog at NASA, there will be many situations she will have to handle. She will need to learn to deal effectively with employees under a tremendous amount of stress, not to mention all varieties of aircraft, associated equipment and facilities and all the smells, sights and sounds that accompany them. The adventure begins!

 

Next: Ella’s first day at work.

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