SP-4220 Wingless Flight: The Lifting Body Story

 

CHAPTER ONE

THE ADVENTURE BEGINS

 

[1] My journey in February 1953 to the NACA High Speed Flight Research Station (as the Muroc Flight Test Unit had come to be called in 1949) actually began about a decade earlier in several small mountain towns in Idaho, about as far from the center of aerospace innovation as one can get. My roots are with farmers and ranchers, my grandfather having moved his family members from Kansas to the sagebrush country of southern Idaho to carve out their future in agriculture, both of my parents the children of farming families.

Around age twelve, I was smitten with what would prove to be a lifelong love of airplanes. I still remember the summer day when I saw my first sailplane. John Robinson had come to Ketchum, Idaho, with his one-of-a-kind sailplane called the Zanonia to try for some world sailplane records. A beautiful craft, the Zanonia had gull wings reminiscent of some of the German sailplanes of the time. Robinson cleared the brush from a flat area across the road from my family's home, making a small dirt strip. Here, Robinson would use a car to tow the Zanonia aloft, the sailplane rolling on a dolly with a set of dual wheels that would drop by parachute after take-off.

For two weeks that summer, I helped Robinson, untangling the tow-line from the brush after the glider had been launched and picking up the parachuted landing gear. I loved to lie on the grass, watching the Zanonia riding the air currents around the mountain peaks. Robinson set two world altitude records in the Zanonia that summer, flying the waves and thermals above the Sawtooth Mountains.

I then began building and flying model gliders and free-flight model airplanes. A hundred miles stood between me and the next modeler in those days, so I was fairly much on my own, except for some occasional help from my mother who was good with crafts and taught wood shop at the local grade school. Fairly quickly I learned I had to limit the duration of my engine runs, else chance losing my models when they glided down on the other side of the hills or mountains.

One September day, one of my models did exactly that. It caught a thermal and flew over a nearby mountain. Two weeks later, my father found that model perched unharmed on a bush at the bottom of a gully two miles from the ridge it had flown over. I flew that model for another year, during which I equipped it with floats so it could fly off of a nearby mountain lake.

Across the street from my high school in Hailey, about 12 miles south of Ketchum, was a grass field where a bush pilot-operator named Bob Silveria kept two airplanes. During the summer and fall months, the big radial engine of his old Waco cabin [2] biplane could be heard lumbering through the Sawtooth Mountains, carrying fishermen and hunters to the primitive wilderness landing strips along the Middle Fork of the Salmon River. Silveria also had a 65-horsepower Aeronca Defender L-3 airplane at the grass field, using it to give flying lessons as well as to transport hunters into the flats south of Hailey where they chased coyotes.

By the time I was sixteen, even my high-school physics and chemistry teacher, Mr. Kinney, knew that I was interested in airplanes. A private pilot who was good friends with Silveria and occasionally rented the little Aeronca airplane across the street from the school, Mr. Kinney offered to teach a class in aeronautics if I could round up eight interested students. I found six interested boys fairly easily, but I had to overcome my shyness around the opposite sex long enough to talk two girls into joining us to fill the class.

Mr. Kinney used the little Aeronca as a teaching tool. We learned to hand-prop to start the airplane and taxi it around the grass field. We did everything but fly. Seeing my enthusiasm, Mr. Kinney encouraged me to apply for a student license and take some flying lessons. I did not know that his suggestion was part of a plot hatched between him and Silveria to see how soon they could get me to solo.

On a cool September day in my sixteenth year, I had my first flying lesson. As I sat in the front seat of the Aeronca, Silveria told me that my job was to handle the throttle, rudder pedals, and brakes, that he would do everything else with the stick from the back seat. All I had to do was put my hand lightly on the stick and follow his movements.

Since Mr. Kinney had earlier done a good job in teaching me in the class on how to taxi a tail-wheel airplane, I had no problem when Silveria told me to set the trim, taxi to position, and start the takeoff run. I knew that my task was simply to steer the rudder pedals and touch but not move the control stick. As we rolled across the grass field, the tail came up eventually and we rolled along on two wheels. I remember thinking what a smooth pilot Silveria was, for I hadn't noticed any movement at all on the stick. Soon we were flying, but I still hadn't noticed any movement on the stick. We had climbed to an altitude of 500 feet when Silveria, his first words to me since the takeoff, said, "Do you know that you made that takeoff by yourself without my help?"

I couldn't believe it, for I was doing practically nothing to fly the airplane. All I had done was made very small and gentle inputs to the rudder while we were on the ground and once we were in the air. I think I made those small control inputs automatically, perhaps subconsciously, because I had learned from building and flying model airplanes that a properly designed airplane can do a pretty good job of flying, even without the pilot.

A few days later, after three and a half hours of flight instruction, I soloed. By age sixteen, then, I was totally hooked on aviation. At first, I thought I wanted to be a bush pilot in Alaska or somewhere else equally exciting, but my high-school principal talked me into going to college and studying engineering. Off I went to the University of Idaho in Moscow. Unlike other universities at the time, Idaho didn't offer a major in [3] aeronautical engineering, but all I could afford was Idaho. I majored in mechanical engineering, taking as many aeronautical courses as I could.

Little better than an average student in high school, I found myself getting almost straight A's in college. I had found my nitch in aeronautical engineering, thanks to a love of flight and airplanes that had begun when I was only twelve, a young boy in small mountain towns in Idaho, far away from the center of aviation's innovative future.

As I took college courses, I found myself more and more intrigued by what I was reading in magazines about what was happening at Edwards AFB in Southern California, where a small contingent of NACA people were flight-testing the world's first supersonic airplane, the rocket-powered X-1. Little did I know, as I read these articles, that soon I would be a part of that small contingent of NACA people, conducting my own aeronautical experiments on the X-1 and becoming personally acquainted with the famous test pilot Chuck Yeager.

Before leaving Idaho in early 1953 to report to work at the High Speed Flight Research Center in the Mojave Desert, I did some reading on the history of the NACA and the Mojave Desert site. And then I got into my car, drove south from Idaho and west across the Nevada desert to the town of Mojave, California, where I made a sharp southeastern turn into the middle of nowhere.

At that time, Edwards Air Force Base was very small and compact, located on the edge of Muroc Dry Lake, now known as Rogers Dry Lake. The name of the base had changed only a few years earlier from Muroc Army Airfield to Edwards Air Force Base in honor of Captain Glen W. Edwards, killed in June 1948 in the crash of a Northrop YB-49, an experimental flying wing bomber.

In late 1946, the NACA had sent thirteen engineers and technicians from the NACA Langley Memorial Aeronautical Laboratory to Muroc Army Airfield to assist in flight-testing the Army's XS-1 rocket-powered airplane. These thirteen individuals fairly much made up what was then called the NACA Muroc Flight Test Unit. Over the next fifty years, the NACA Muroc Flight Test Unit grew into what is today the NASA Dryden Flight Research Center with about 900 NASA employees and contractors supporting NASA's premiere flight-test activities.

 

 

Ground Zero: The Place Where Tomorrow Begins

 

The flight-testing of all experimental and first-model military aircraft occurred here along an ancient dry lake now called Rogers Dry Lake, located on the western edge of California's Mojave Desert just south of Highway 58 between the towns of Boron and Mojave. Only a few miles northeast is the world's largest open-pit borax mine. Within sight from Rogers Dry Lake is one of the first immigrant trails through California.

The original name of the site, the NACA Muroc Flight Test Unit, comes partly from local history. "Muroc" is "Corum" spelled back-wards. The first permanent settlers in the area, the Corum family located near the large dry lake in 1910. Later, they tried to get the local post office named Corum. However, there was already one with a [4] nearly identical name (Coram) elsewhere in California, so they reversed the letters to spell Muroc. 1

What was there about this dry lake that made it ideal as the later site of major aviation flight-test history? About 2,300 feet above sea level, Rogers Dry Lake fills an area of about 64 square miles-nearly three times larger than New York's Manhattan Island-and its entire surface is flat and hard, making it one of the best natural landing sites on the planet. The arid desert weather also provides excellent flying conditions on almost every day of the year.

Rogers Dry Lake is the sediment-filled remnant of an ancient lake formed eons ago. Several inches of water can accumulate on the lakebed when it rains, and the water in combination with the desert winds creates a natural smoothing and leveling action across the surface. When the water evaporates in the desert sun, a smooth and level surface appears across the lakebed, one far superior to that made by humans.

Water on the surface of Rogers Dry Lake also brings to life an abundance of small shrimp-several unique species of the prehistoric crustacean-but they disappear once the desert sun evaporates the water. Annual rainfall here is only about four to five inches, considerably less in some years. In extremely wet years, the annual rainfall can rise to six or even nine inches.

Winds are quite predictable, usually from the southwest during spring and summer, with a mean velocity of six to nine knots. Sunrises and sunsets can be breathtakingly beautiful, as can the spring wildflowers with enough rain.

The surrounding area is typical of the California high desert with rolling sand hills and rocky rises, ridges, and outcroppings punctuated in the low spots with dry lakebeds. Mountains lie on three sides-at the south, west, and north-with the mighty Sierra Nevada range to the north rising to over 14,000 feet. Joshua trees cluster among the chaparral and sagebrush. A type of Yucca (a member of the Lily family), the Joshua tree has clusters of very sharp and dark green bayonet-shaped or quill-like spines that grow six to ten inches long and that only a botanist would call "leaves." Like everything else in the surrounding desert, the Joshua tree is well suited for survival in a harsh environment. In summer, temperatures can reach or exceed 120 degrees Fahrenheit, with 10 to 15 percent humidity. In winter, temperatures can fall to nearly 0 degrees Fahrenheit.

In a curious coincidence, two entirely different and likely unrelated men named Joe Walker figure prominently in local pioneering history, separated by about 115 years. In the spring of 1843, Joseph B. Chiles organized and led one of the first wagon trains out from Independence, Missouri, to California. At Fort Laramie in Wyoming, he met an old friend, Joe Walker, who joined the California-bound wagon train as a guide. Once in California, the wagon train ran low on provisions and split into two groups, one on horseback led by Chiles that went north to circumvent the Sierra [5] Nevadas, the other in the wagons led by Joe Walker heading south. The Walker party had to abandon their wagons just north of Owens Lake, arriving on foot at what is now called Walker Pass at eleven in the morning on 3 December 1843. Walker Pass, named after the first Joe Walker, is only 56 miles across the southern Sierra Nevadas from Edwards AFB where, 115 years later, another man named Joe Walker, the prominent NACA/NASA X-15 research pilot, was engaged in a very different kind of pioneering.

In the 1930s, early aviators-including the military and private airplane designers such as John Northrop-used Rogers Dry Lake as a place to rendezvous and test new designs. During World War II, the U.S. Army Air Corps conducted extensive training and flight-testing at the site. This is also the general area where a colorful social club and riding stable was located, established by the aviatrix Florence "Pancho" Barnes and frequented by many of the early and famous test pilots and notables of aviation history.

In more recent times, the Air Force, NASA, and various contractors have used Rogers Dry Lake in conducting flight tests on many exotic and unusual aerospace vehicles. In the words of Dr. Hugh L. Dryden- the early NACA/NASA leader, scientist, and engineer-the purpose of full-scale flight research "is to separate the real from the imagined. . .to make known the overlooked and the unexpected," words that help clarify why a remote location in the western Mojave Desert would become the site where innovative NASA engineers and technicians would gather to help create the future of aviation.2

The official name of the site has changed over the years. It changed its name from the NACA High Speed Flight Research Station to the NACA High Speed Flight Station in 1954 and then to the NASA Flight Research Center in 1959. It became the NASA Hugh L. Dryden Flight Research Center in the spring of 1976, a name it regained in 1994 after a hiatus from 1981 to that year as the Ames-Dryden Flight Research Facility. However, when I arrived at the site in 1953, it was still called the NACA High Speed Flight Research Station, and the people at the facility were conducting all of the NACA's high-speed flight research. They were used to conducting high-performance flight research on rocket-powered vehicles that had to land unpowered. Unpowered landings with high-performance aircraft became relatively routine, but not necessarily risk-free, on the vast expanse of Rogers Dry Lake.

 

[6] Flight Research, 1953-1962

 

When I arrived at the Station in February 1953, the purely rocket-powered Bell X-1 and X-2 as well as the Douglas D-558-II experimental aircraft were being flight-tested, air-launched from B-29s and B-50s (essentially the same as the B-29, but with slightly different engines). Before I arrived on the scene, the Air Force had operated the B-29s, but the NACA had taken over operating the B-29s by the time I got there, including the B-29 used for the D-558-II, which had the distinction of being the only Navy-owned B-29 (Navy designation, P2B). Also being flown then was a second D-558-II with a hybrid turbojet-rocket propulsion system. Other experimental turbojet aircraft being flown included the Bell "flying wing" X-4 (technically, a swept wing combined with an absence of horizontal tail surfaces), the Bell variable-sweep-wing X-5, and the first high-performance delta-wing aircraft, the Convair XF-92.

At the NACA facility at that time, all new junior engineers were expected to learn the flight-research business from the bottom up. Given the limited data systems of that era, plus the lack of high-speed computing capability, a research engineer's job was about ninety percent measuring and processing data and only about ten percent analyzing and reporting the flight results. With all the weird and wonderful airplanes at that time, stability and control problems were prominent. Most of the senior engineers at the NACA facility were busy analyzing and trying to solve these problems. This meant there was a lot of pick-and-shovel work for the junior engineers to do.

My first job assignment involved measuring aerodynamic loads on the wings and tail surfaces of various research aircraft. Hundreds of strain gauges had been installed inside the structures of these aircraft as they were built in the factory. My task was to calibrate these gauges and other data acquisition devices on the aircraft, including control position indicators, air data sensors, gyros, and accelerometers.

Today, these tasks are the responsibility of instrumentation engineers. Earlier, due to the small staffing at the NACA facility, these tasks fell on the shoulders of the aero or research engineers. One advantage back then of doing things this way was that by the time research engineers finally had enough flight data to analyze, they had good knowledge of the accuracies of the instrumentation- so good that if weird glitches turned up in the data during flight tests, they were better able to determine whether the data was real or indicated a problem in the instrumentation.

My first task involved measuring the aerodynamic loads on the X-5 research aircraft, a little airplane that had evolved from a design smuggled out of Germany at the end of World War II. Bell Aircraft completed the design, building what was to become the world's first variable-wing-sweep aircraft.

My task involved measuring the bending, shear and torque loads of the wing and tail surfaces on three configurations of the X-5, one each with 20-, 40-, and 60-degree wing-sweep angles. This meant that I had to have separate wing strain gauge calibrations for each wing sweep. In those days, calibrations involved manual labor at about thirty load points on each wing and tail surface. I spent long hours over days and even [7] weeks on a jack handle, putting incremental loads on the airplane at all of these points.

Each strain gauge output was read off a meter and written down by hand, resulting in stacks of paper with handwritten data, then processed by hand on the old mechanical Frieden calculating machines. Processing involved selecting groups of multiple strain gauges and developing equations for bending moments, shear and torque.

A staff of ten women did all the calculations on the Frieden machines. To me, they seemed the hardest working people at the facility, each of them spending long hours clanking away on a calculating machine. In those days, we worked in old barracks-type buildings with swamp coolers on the windows. The Frieden machines had to be carefully covered up during desert dust storms, for the dust coming through the coolers could ruin those mechanical wonders.

Over the years, I became a specialist in this sort of measurement work, doing flight research with the X-1E, F-100A, D-558-II, and X-15. During the X-15 program, my area of expertise expanded into aerodynamic heating, and my responsibilities grew to include each planned X-15 flight as speeds and altitudes increased far beyond those for any existing aircraft.

As the X-15 pushed closer and closer to its maximum speed of Mach 6.7 (or 6.7 times the speed of sound) and maximum altitude of 354,200 feet (or 70 miles above the earth), the Inconel-X steel and titanium structure of the X-15 could reach temperatures as high as 3,000 degrees Fahrenheit in areas of concentrated aerodynamic heating. The X-15 had been instrumented with hundreds of strain gauges and thermocouples for measuring the stresses and heat in its structure.

North American Aviation's structural designer of the X-15, Al Dowdy, and I worked as a team examining each planned flight to determine if there was any cause for concern about structural failure. For each flight, the flight- planning team and the pilot would develop a flight plan on the facility's X-15 flight simulator. With this planned flight profile of speed, altitude, angle of attack, and load factor, we could calculate aerodynamic heating inputs to the external skin on various parts of the aircraft.

Al and I selected seven critical areas of structure on the X-15 to monitor in detail during each flight program. For example, one wing area included the Inconel-X steel skin and the titanium spar caps and webs. From the information gained from monitoring these areas, I could then generate time histories of the temperature rise and decline in each element of the aircraft's structure. With this data, Al, in turn, could determine the stresses within the structure by combining calculated aero loads with my calculated temperatures. At flight-planning tech briefings, I would then report whether I thought the planned flight would be safe from the structural standpoint.

Throughout the X-15 program, we continued to test our prediction techniques by comparing our preflight calculations with measured temperature data from the actual flight. For some skin areas, we revamped our calculations to include laminar heating when we thought that it would be turbulent heating, and vice versa. Turbulent heating results in temperatures almost twice as high as those due to laminar heating, but at [8] first we weren't always smart enough to know whether the flow would be laminar or turbulent. Later, we became more skilled at predicting external aerodynamic heating. We still had to refine our calculations for internal heat flow because the structural joints did not transfer the heat as anticipated. We determined the correction factors for the heat-transfer equations while the X-15 was still flying at low supersonic speeds of up to Mach 3. By the time that structural heating became more critical near Mach 5 and Mach 6 later in the X-15 program, we could do a much more accurate job in predicting structural temperatures.

 

The Early 1960s: Concepts of the Lifting Body

 

Although I gained a great deal of satisfaction as a researcher in structures on the world's first hypersonic airplane, my interests in aeronautics always had been much broader than aircraft structures. Still very much interested in stability and control, aerodynamics, and unusual aircraft configurations, I continued to design and build model airplanes and to fly light planes and sailplanes on my own time.

I was also fascinated with the space program, following closely the activities of Walt Williams, my first boss at the facility, and the people he took with him from the NASA Flight Research Center to Johnson Space Center to conduct the Mercury and Gemini programs. While reading NASA and Air Force reports on design concepts for future spacecraft, I noticed a pattern developing. Although many of these studies included concepts of lifting reentry vehicles, when actual space vehicles were designed, they were always non-lifting or ballistic capsule-type vehicles.

At the time, it was obvious that NASA and Air Force decision-makers had little confidence in the concept of lifting reentry and even less for lifting-body types of reentry vehicles. Although it funded many studies of lifting reentry configurations of all types, including lifting bodies, the Air Force soon concluded that lifting bodies were too risky.

In September 1961, a blue-chip panel of the Scientific Advisory Board chaired by Professor C.D. Perkins had recommended to Air Force General Bernard A. Schriever that all expenditures on flight hardware be made solely for winged vehicles, not lifting bodies. The panel had questioned the control characteristics of a lifting-body design, believing they could make conventional landings hazardous. The Air Force accepted the panel's recommendation, deciding to finance only winged reentry vehicle programs: the Boeing Aircraft Company's manned Dyna-Soar X-20 and McDonald Aircraft Company's upiloted ASSET (Aerothermodynamic/elastic Structural Systems Environmental Test). Only a mock-up of the X-20 was ever built, Secretary of Defense Robert McNamara canceling the $458-million X-20 program in December 1963. In 1964, the $21-million unpiloted ASSET hypersonic glider was [9] flown successfully four times in hypersonic reentry maneuvers. Never flown subsonically, the four ASSET research vehicles were parachuted into the ocean for recovery. 3

Meanwhile, as NASA decision-makers continued to stay with ballistic shapes for the Mercury, Gemini, and Apollo programs, some NASA researchers at the field centers continued to study lifting-body reentry configurations. Actually, interest in the lifting-body concept among individuals at NASA dates back to the early 1950s when researchers-under the direction of two imaginative engineers, H. Julian "Harvey" Allen and Alfred Eggers-first developed the concept of lifting reentry from sub-orbital or orbital space flight at NACA's Ames Aeronautical Laboratory at Moffett Field in California. In March 1958, the researchers presented this work at a NACA Conference on High-Speed Aerodynamics.4

The initial work of NACA researchers in the early 1950s had been done in connection with studies regarding the reentry survival of ballistic-missile nose cones, the results of which were first reported in 1953. Researchers found that, by blunting the nose of a missile, reentry energy would more rapidly dissipate through the large shock wave, while a sharp-nosed missile would absorb more energy from skin friction in the form of heat. They concluded that the blunt-nosed vehicles were much more likely to survive reentry than the pointed-nose vehicles. Maxime A. Faget and the other authors of a paper at the 1958 NACA Conference on High-Speed Aerodynamics concluded that "the state of the art is sufficiently advanced so that it is possible to proceed confidently with a manned satellite project based upon the ballistic reentry type of vehicle." Faget's paper also indicated that the maximum deceleration loads would be on the order of 8.5g, or 8.5 times the normal pull of gravity on the vehicle. 5

Other authors at the same conference presented the results of a study on a blunt 30-degree half-cone wingless reentry configuration, showing that the high-lift/high-drag configuration would have maximum deceleration loads on the order of only 2g and would accommodate aerodynamic controls. This configuration also would allow a lateral reentry path deviation of about plus or minus 230 miles and a longitudinal variation of about 700 miles. 6

[10] Following this conference-the last held by the NACA before Congress created the NASA later in 1958-the logical choice for a piloted reentry configuration seemed to be the proposed blunt half-cone 2g vehicle with controls and path deviation capability rather than the 8.5g ballistic vehicle with no controls and almost no path deviation capability. However, this was not to be, due to some practical considerations of the time.

As things turned out, the thrust capability of the available boosters versus the needed payload weights made it easier to design a small blunt shape to fit on top of the Redstone and Atlas rocket boosters. This blunt-nosed ballistic configuration became the United States' first manned spacecraft, the Atlas rocket-boosted Mercury capsule, which then evolved into the Apollo program using the Saturn rocket.

Nevertheless, the concept of wingless lifting reentry did not die. The only problem was that we had no experience with this type of vehicle, especially with the anticipated heat loads. But the advantages of a blunt half-cone or wingless reentry vehicle over the space capsules are easy to understand.

"Lifting" reentry is achieved by flying from space to a conventional horizontal landing, using a blunt half-cone body, a wingless body, or a vehicle with a delta planform (like the shape of the current Space Shuttle), taking advantage of any of these configurations' ability to generate body lift and, thus, fly. We couldn't put conventional straight or even swept wings on these vehicles because they would burn off during reentry -although a delta planform with a large leading-edge radius might work. These vehicles, or lifting bodies as we called them, would have significant glide capability down-range (the direction of their orbital tracks) and/or cross-range (the direction across their orbital tracks) due to the aerodynamic lift they could produce during reentry.

Space capsules, on the other hand, reenter the earth's atmosphere on a ballistic trajectory and decelerate rapidly due to their high aerodynamic drag. In short, although capsules can produce small amounts of lift, they also generate large amounts of drag, or resistance. Space capsules are subject to high reentry forces due to rapid deceleration, and they have little or no maneuvering capability. Consequently, capsules must rely on parachute landings primarily along the orbital flight path.

In contrast, a lifting body's ability to produce lift and turn right or left from the orbit would allow any one of many possible landing sites within a large landing zone on both sides of the orbit on the return to earth. Furthermore, deceleration forces are significantly reduced with a lifting-body vehicle, from about 8g to 2g. The lifting-body landing "footprint" for a hypersonic vehicle-that is, one with a speed of Mach 5 or greater and a lift-to-drag ratio of 1.5-includes the entire western United States as well as a major portion of Mexico, a significant improvement over that of a capsule. The prospect of achieving these advantages of lifting reentry was rather exciting, given the limited capability of ballistic reentry capsules.

 

[11] Free-Flight Model of the M2-F1 Lifting Body

 

Fascinated by the possibility of an airplane that flies without wings, I began talking in 1962 to other engineers and engineering leaders at the NASA Flight Research Center and at the NASA Ames and Langley research centers. I found skepticism to be abundant, many believing, as various design studies at the time had suggested, that some sort of deployable wings would be needed to make a lifting body practical for landing. Some of the most conservative design studies, not content to stop with deployable wings, even suggested that deployable turbojet engines should be used. Obviously, the space and weight allotment in these designs left little, if any, allowance for payloads. Even more design reports on lifting bodies gathered dust on library shelves as even more decisions were made to use symmetrical reentry capsules for spacecraft programs.

About this time, it occurred to me that for lifting bodies to be considered seriously for future spacecraft designs, some sort of flight demonstration would be needed to boost confidence among spacecraft designers regarding lifting bodies. At first, I limited myself to launching countless paper lifting-body gliders down the halls, while behind my back passersby sometimes rolled their eyes and made circling-finger-at-temple motions. Then, as much to satisfy my own growing curiosity as to demonstrate lifting-body flight potentials to my peers, I constructed a free-flight model in a half-cone design that was very similar to what would later become the M2-F1 configuration.

I made the frame with balsa stringers and the skin out of thin-sheeted balsa. Adjustable outboard elevons and adjustable vertical rudders made up the control system. I began with the center of gravity recommended in Eggers' design studies, then changed it with nose ballast. For landing gear, I used spring-wired tricycle wheels.

I hand-glided the model into tall grass as I worked out the needed control trim adjustments. The model showed characteristics of extremely high spiral stability. The effective dihedral (roll due to a side gust) was very high, and launching the model into a bank would cause it to roll immediately to a wings-level position.

Expanding the flight envelope, I then started hand-launching the model from the rooftops of buildings for longer flight times. The outer elevons were effective but not overly sensitive to adjustments for longitudinal trim and turning control. Experimenting with the vertical rudders, I found the roll response very sensitive to very small settings of the rudders. In these first flights of the model, I did not experiment with body flaps. The model had a steep gliding angle, but it would remain upright as it landed on its landing gear.

Next, I towed the model aloft by attaching a thread to the upper part of the nose gear, then running as one does in lifting a kite into flight. The model was exceptionally stable on tow by hand. Naturally, I then thought of towing the model aloft with a gas-powered model plane since I just happened to have a stable free-flight model that I had used successfully in the past to tow free-flight gliders.

[12] Attaching the tow-line on top of the model's fuselage, just at the trailing edge of the wing, created minimum effect on the tow plane from the motions of the glider behind it. After sufficient altitude was reached for extended flight, a free-flight vacuum timer released the lifting-body glider from the tow-plane. All flights of the model were done at Pete Sterks' ranch east of Lancaster, an area where most of the NASA Flight Research Center employees lived at the time. From Sterks' ranch, I had also flown other model airplanes as well as my 65-horsepower Luscombe light plane.

I found the inherent stability of the M2-F1 lifting-body model, both in free flight and on tow, very exciting-so much so that I knew it was time to make a film to show my peers and bosses just how stable it was in flight. To film the flight of the M2-F1 lifting-body model, I enlisted the help of my wife, Donna, and our 8 mm camera. We made the film on a nice, calm weekend morning at Sterks' ranch. While I prepared the tow-plane and the M2-F1 model for launch, Donna stretched out on the ground on her stomach to film the flight from a low angle, making the M2-F1 model look much larger than it actually was.

Both the flight and Donna's film-making were successful, the film showing the M2-F1 stable in high tow, then gliding down in a large circle after the timer released it from the tow-plane. The lifting-body model reached the ground much sooner than did the tow-plane because the lifting body's much lower lift-to-drag ratio gave it a much steeper gliding angle. The M2-F1 made a good landing on Sterks' dirt strip, while the tow-plane landed unharmed in the alfalfa field next to the landing strip. Since I was just getting started in radio control at the time, I used the free-flight approach in these early flights to keep things lightweight and simple. Later, I towed the M2-F1 lifting-body model with a radio-controlled tow-plane.

 

Starting a Lifting-Body Team

 

My mounting enthusiasm began to rub off on my peers at the NASA Flight Research Center. The first to join my lifting-body cause was the young research engineer named Dick Eldredge. (In fact, we were all young at the time.) A graduate of Mississippi State's aeronautical engineering department, Dick had been a student of an aerodynamicist named August Raspet, who had established a flight-test facility at a landing strip near the university where he involved many of his students, including Dick, in flight research. As a result, Dick had brought with him to the NASA Flight Research Center a great deal of skill and enthusiasm regarding the aerodynamics and structures of aircraft design.

Having built three gliders on his own, Dick had excellent skills in design and fabrication of structures in welded steel, wood, and aluminum sheet-metal. At the time, the NASA Flight Research Center also had a small "Skunk Works" second to none in its skilled machinists, aircraft welders, sheet-metal workers, and instrument builders. Dick knew each of these craftsmen personally, not just at work but much more through contact with them on the weekends, many of these NASA craftsmen also being involved with their own airplane-building home projects.

Dick Eldredge and I made a strange but good team. Since I was tall and he was very short, some people thought of us as a "Mutt & Jeff" duo. Together, we would critique and challenge each other's ideas about how to solve design problems until we mutually came up with the best solutions. We never wasted time belaboring the problem but, after agreeing on a solution, went on to the next design challenge. I always thought of Dick as my "little buddy."

 


[
13]

Dick Eldredge and Dale Reed resting their arms on the M2-F1. In the background is a Space Shuttle, which benefitted lifting-body  research.

Dick Eldredge and Dale Reed resting their arms on the M2-F1. In the background is a Space Shuttle, which benefited lifting-body research. (NASA photo EC81 16283)


 

Dick and I enjoyed bouncing ideas off one another for new aircraft designs. At the time, the British Kramer Prize had not yet been awarded for the world's first man-powered airplane. Each year, the prize became more enticing to us as it grew in size to $100,000 and opened to persons beyond Britain throughout the world. At lunchtime, Dick and I plotted and schemed on how we could win the Kramer Prize. Dick had done a lot of research on the various British designs that, while they could fly in a straight line, could not make the required figure eight. Most of these designs included hundreds of parts and took hundreds of man-hours to build. Dick and I agreed that the winning design would have to have very low wing loading and be simple to build and repair. Unfortunately, we both were young enough to have growing families that required a great deal of our time at home, so Dick and I never had the time or means for an after-hours project of the sort that might win the Kramer Prize.

[14] However, Dick and I had a mutual friend in Paul McCready of Pasadena, who, about the time we were forced to abandon our man-powered project, got his family involved in a similar project, helped along by a number of volunteers with skills in model-building and bicycle-racing. McCready put into action the low wing loading and simple structural approach that Dick and I had only been able to talk about.

At Taft, not too far from Edwards Air Force Base, McCready demonstrated the world's first man-powered flight with the Gossamer Condor. His first flight tests of the Gossamer Condor, in fact, had been at Mojave, just down the road from Edwards AFB. McCready went on to build a second craft called the Gossamer Albatross, which the bicyclist Bryan Allan piloted across the English Channel. 7

Afterwards, I worked with McCready and a backup Gossamer Albatross on a flight research program at the NASA Flight Research Center, having gotten approval to...

 


Proposed Ames M2-F1, M1-L half-cone, and Langley lenticular bodies. Dale Reed and Dick Eldredge proposed testing the three shapes using  a common internal structure for all of them.

Proposed Ames M2-F1, M1-L half-cone, and Langley lenticular bodies. Dale Reed and Dick Eldredge proposed testing the three shapes using a common internal structure for all of them. (NASA photo E62 8933)


 

[15] ....make this official NASA project to measure the aerodynamic characteristics of the aircraft with lightweight research instrumentation installed at the Flight Research Center. This successful program resulted in a published report on the aerodynamic characteristics of the Gossamer Albatross. 8

As a team, once we both were bitten by the lifting-body bug, Dick and I developed a research plan for testing three lifting-body shapes with a common structural frame housing the pilot, landing gear, control system, and roll-over structure. The three lifting-body shapes were the Ames M2-F1, the M1-L half-cone, and the Langley lenticular.

The lenticular lifting-body shape was particularly intriguing because, to many of us, it immediately calls to mind the popular flying-saucer portrayed by the media as the spacecraft of extraterrestrials. My wife, Donna, however, had her own special appreciation of the lenticular shape, dubbing it the "Powder Puff."

All three of the lifting-body shapes were based on some sort of variable geometry. The M2-F1 was a 13-degree half-cone that achieved transonic stability by spreading its body flaps much like what's done by a shuttle cock in the game of badminton. The M1-L was a 40-degree half-cone that achieved a better landing lift-to-drag ratio by blowing up a rubber boat tail after it slowed down. The lenticular lifting-body would transition to horizontal flight by extending control surfaces after making reentry much like a symmetrical capsule.

Our concept was to construct the shapes separately, building three wooden or fiberglass shells that could attach to an inner structure common to all three shapes. If we could build the vehicles to be light enough, they could be towed by ground vehicles across the lakebed before being towed aloft by a propeller-driven tow-plane.

Dick suggested a control system that I liked instantly: a mechanical way of mixing controls that was similar to what is done now in modern high-tech aircraft by digital electronic control systems. The scheme was to connect a swashplate on the aft end of the steel-tube structure to the pilot's control stick and rudder pedals. The swashplate, pivoting on one universal joint, took up various positions, depending on the combination of roll, pitch, and yaw commands the pilot sent to the front side of the swashplate. With push rods hooked up to different locations on the backside of the swashplate, and to the horizontal and vertical control surfaces on the aft end of the lifting-body shapes, any combination in control-mixing could be achieved. These controls could be altered easily during the flight-test program or changed to fit another lifting-body shape.

 

[16] Milt Thompson Joins the Lifting-Body Team

 

Fired by enthusiasm, Dick and I kept charging down the design road with the lifting-body research vehicles so that we could make a pitch to our boss, Paul Bikle, to gain his support for a lifting-body program. One day I told Dick, "You know, if we had a pilot on our team, we would have a much better chance of selling the program concept." Then, we talked to Milt Thompson, whom we saw as the NASA test pilot most likely to be interested in our project.

Milt was a skilled pilot with a distinguished background as a Naval aviator, Boeing flight-test pilot, and NASA research pilot. As one of the twelve NASA, Air Force, and Navy pilots who flew the X-15 between 1959 and 1968, Milt had fourteen flights in the rocket-powered aircraft to his credit, reaching on separate occasions a maximum speed of 3,723 mph and a peak altitude of 214,000 feet.

Earlier in 1962, before Dick and I talked to Milt about the lifting-body project, the Air Force had selected Milt to be the only civilian pilot for the X-20 Dyna-Soar program scheduled to launch a man into earth orbit and recover with a horizontal ground landing, a program later canceled shortly after construction had begun on the X-20 vehicle. Not having an ego problem, Milt loved flying unusual or unorthodox aircraft configurations as varied as the rocket-powered X-15 and the ungainly Paresev, a vehicle designed and built at the NASA Flight Research Center's "Skunk Works" to test the Rogallo Wing concept for spacecraft recovery.

Milt was easy to talk to and could relate readily to flight research engineers. Very methodical in planning flights, he did not take risks beyond the unavoidable ones normal for first-time aircraft configurations, a characteristic that earned him high regard from both pilots and project managers. A handsome, wild, and wonderful guy, Milt had a winning personality and persuasive charm. All the women seemed to be in love with him. Popular, he was a friend to everyone. Dick and I knew that Milt was the guy who could help us sell the lifting-body program.

We presented to Milt our idea for testing lifting bodies, asking him if he would join us and fly a lifting body-if and when we got one built. Without hesitation, he gave us a solid "yes." Now we were a team of three.

The three of us put our heads together to decide on the next step to take in promoting our program. Milt suggested that if we had one of the originators of the lifting-body reentry concept on our side, we could move our cause along more rapidly.

I phoned Al Eggers at the NASA Ames Research Center, located at Moffett Field in northern California, and described our idea to him. Very enthusiastic, Eggers asked how he could help. At the time, Eggers was a division head at Ames in charge of most of the wind tunnels. We were going to need a lot of support in wind-tunnel tests if we were to figure out how to fly these crazy aerodynamic shapes.

Telling Eggers that we were preparing a pitch to sell the idea to Paul Bikle, I asked him if he would like to hear the pitch. "Definitely," he replied. We arranged a meeting at the Flight Research Center so we could present our idea to both Paul Bikle and Al Eggers.

[17] I presented a simple program plan for building the vehicles in the "Skunk Works" shops at the Flight Research Center, instrumenting the vehicles, and then flight-testing them to measure stability, control, and other aerodynamic characteristics in flight. After I presented the preliminary design drawings that Dick and I had made, I showed the film that my wife had made of my model M2-F1 flights.

Milt Thompson's endorsement of the plan pushed it over the crest. We received a hearty "yes" from both Bikle and Eggers. Eggers offered full use of the wind tunnels for getting any data needed to support the program if Bikle would be responsible for developing and flight-testing the lifting-body vehicles. It was agreed as well, however, that we would take it one step at a time, starting with the M2-F1 configuration and building it as a wind-tunnel model to be tested in the 40-by-80-foot wind tunnel at Ames.

Armed with a cause and fired with enthusiasm, we found ourselves gaining more and more support from our peers. We even came up with an unofficial motto for our lifting-body reentry vehicle project: "Don't be rescued from outer space-fly back in style." With the space program then dependent on the ballistic capsules, the astronauts were being fished out of the ocean, sometimes nearly drowning in the process and usually after some degree of sea sickness. Wen Painter-later a prominent engineer in the rocket-powered lifting-body program-drew a cartoon depicting the difference the lifting-body reentry vehicle would make in how astronauts would return to earth, his cartoon showing the astronaut landing at an airport in style, greeted by a reception hostess.

If the great enthusiasm of the builders at the NASA Flight Research Center resulted in a wind-tunnel model capable of actual flight, well, as Bikle noted, that would be something simply beyond the control of management. Later, we would go through the official process of getting approval from NASA Headquarters for flying the vehicle. In the meantime, we decided to get to work while everyone was enthusiastic and ready to start. With this decision, the lifting-body program was launched.

 


Notes

 

1 Hallion, On the Frontier, pp. xiv-xv.

2 Hugh L. Dryden, "Introductory Remarks," National Advisory Committee for Aeronautics, Research-Airplane-Committee Report on Conference on the Progress of the X-15 Project, (Papers Presented at Langley Aeronautical Laboratory, Oct. 25-26, 1956), p. xix. I am indebted to Ed Saltzman for locating this quotation, the words for which are common knowledge at the Center named in honor of Hugh Dryden but the source for which is not well known.

3 See Richard P. Hallion, "ASSET: Pioneer of Lifting Reentry," in Hallion, Hypersonic Revolution, pp. 449-527.

4 National Advisory Committee for Aeronautics, NACA Conference on High-Speed Aerodynamics, A Compilation of the Papers Presented (Moffett Field, Calif.: Ames Aeronautical Laboratory, 1958). Notable in this connection was the paper by four Ames researchers--Thomas J. Wong, Charles A Hermach, John O. Reller, Jr., and Bruce E. Tinling--at a session chaired by Allen. The paper's title was "Preliminary Studies of Manned Satellites--Wingless Configurations: Lifting Body" and appeared on pp. 35-44 of the volume just cited.

5 Maxime A. Faget, Benjamine J. Garland, and James J. Buglia, "Preliminary Studies of Manned Satellite Wingless Configuration: Nonlifting" in NACA Conference on High-Speed Aerodynamics, pp. 19-33 with the quotation on p. 25.

6 Wong et al., "Preliminary Studies: Lifting Body," pp. 35-44.

7 See M. Grosser, "Building the Gossamer Albatross," Technology Review 83 (Apr. 1981): 52-63; Paul McCready, "Crossing the Channel in the Gossamer Albatross," Society of Experimental Test Pilots, Technical Review 14, No. 4 (1979): 232-43.

8 Henry R. Jex and David G. Mitchell, "Stability and Control of the Gossamer Human-Powered Aircraft by Analysis and Flight Test" (Washington, D.C.: NASA Contract Report 3627, 1982).


previousindexnext