Technology isn't just about wires and widgets and levers and code. It's also about the people who make it happen, who help translate electrical and mechanical possibilities into things that work--and work right--in the real world. In the world of aviation, the people who get some of the most critical hands-on experience are a hardy, daring breed known as test pilots. Into the wild blue yonder they go, strapped into aircraft that often have yet to be proven fully airworthy, and in so doing help push the boundaries of flight science.
In the United States, some of the earliest organized aeronautical research--that is, after the jump start by the Wright Brothers and other intrepid individuals--was done under the auspices of the National Advisory Committee for Aeronautics. NACA began its operations at Langley Field in Virginia, and here, in a photo from about 1920, we get a glimpse of NACA's first civilian test pilot, Thomas Carroll, tucked into the front cockpit of a biplane. Behind him, more prominent in the white shirt, is engineer John Crowley Jr.
Here's a better look at Carroll, in dramatic profile, from March 1923.
In those earliest days of powered flight, when so much had yet to be proven about aircraft technology and handling, almost any pilot was a test pilot of sorts. Those early fliers were often self-taught, or taught each other informally.
In October 1925, NACA test pilot Paul King poses with a Vought VE-7 "Bluebird" biplane, typically used as an advanced trainer, before taking flight. He's dressed in a fur-lined leather flying suit and has donned his oxygen facepiece.
It was a Vought VE-7 that three years earlier, on October 17, 1922, performed the first-ever take-off from the USS Langley, the nation's first aircraft carrier. Clearly, that flight made a test pilot, at least for the day, of Lt. Cmdr. Virgil C. "Squash" Griffin.
The event was later recalled by another naval aviator, as noted on the Vought Aircraft Web site: "We had no brakes, so the plane was held down on the deck by a wire with a bomb release at the end. This was attached to a ring in the landing gear. 'Squash' Griffin climbed in, turned up the Hispano Suiza engine to its full 180 hp, and gave the 'go' signal. The bomb release was snapped and the Vought rolled down the deck. Almost before it reached the deck-center elevator it was airborne."
NACA's second research lab was established in 1939 at Moffett Field in Sunnyvale, Calif. (It's now known as NASA's Ames Research Center.) Here, in November 1940, test pilot W.H. McAvoy steps out of a North American O-47, the first test airplane at Ames. Research flights by McAvoy and fellow pilot Lawrence Clousing included looking into the problem of ice buildup on aircraft.
Those flights often were done in a two-engined Lockheed 12 airplane. "McAvoy and Clousing...flew the little transport plane into some of the worst weather they could find on the West Coast," according to a NASA account. "Ice would sometimes form on the windows so thickly that they could not see whether the wings were ice-free or not, the radio would cut out due to icing, and ice would sometimes form on the tail surfaces, which were only partially protected by an inflatable rubber shoe."
According to the U.S. Centennial of Flight Commission, Chuck Yeager just wanted to be a mechanic when he entered the Army Air Forces right out of high school. But not long thereafter, with World War II in full swing, he earned his wings, and then after the war became a maintenance officer--a job that involved flight-testing airplanes.
By 1947, serving at Muroc Air Base in California (it later became Edwards Air Force Base), he was a bona fide test pilot, and just in time for a spectacular opportunity--the chance to be the first person to fly a plane faster than the speed of sound. On October 14 of that year, he accomplished that feat, flying the rocket-powered X-1 aircraft past Mach One. This photo shows Yeager about six years later, with the even more powerful X-1A, which he flew to a then-record Mach 2.4.
Now we see Walker in 1958 in an early partial-pressure suit, apparel designed to protect pilots if they lost cockpit pressure at high altitudes where the low air pressure poses a severe threat to health. He's standing beside an X-1E at the NACA High-Speed Flight Station (now the Dryden Flight Research Center) at Edwards Air Force Base in Southern California.
In 1960, Walker would make the first flight for what was now NASA in the X-15, one of the most significant of all the X-Planes. Within the next several years, he would fly X-15 aircraft to Mach 5.92 (just above 4,100 miles per hour) and to an altitude of 354,300 feet (67 miles).
NASA rules at the dawn of the Space Age held that only military test pilots could become astronauts--and at that time, there were no female test pilots in the military. So even though in 1961 Jerrie Cobb, a versatile and experienced pilot, became the first woman to pass all three phases of the Mercury astronaut program, she was not allowed to go any further in the astronaut corps. Here, in April 1960, she's having a go at a gimbal rig (the long name is "multiple axis space test inertia facility," abbreviated to MASTIF), which was designed to help astronauts get a feel for controlling a tumbling spacecraft.
In its early work to get ready for the moon landings, NASA tried out this odd-looking contraption, the Lunar Landing Research Vehicle, built by Bell Aerospace (it was Bell Aircraft that built the X-1). This is the LLRV during a flight in April 1965. The first man to fly an LLRV, in October 1964, was test pilot Joe Walker, who eventually made 35 flights on the LLRV.
How did it fly, you're wondering? It had a vertically mounted turbofan engine in the center, which was used to lift the LLRV to the target altitude of about 1,500 feet. At that point, according to NASA, the pilot would throttle back to help simulate the moon's lower gravitational pull, and then would use a combination of two lift rockets and 16 smaller, paired rockets (for control of pitch, roll, and yaw) to practice setting the LLRV back on the ground.
In 1977, the space shuttle prototype Enterprise made its first free flights, in Earth's atmosphere, after separating from the 747 that carried it aloft. Writes NASA, not too melodramatically, in a short essay on test pilots: "When it came to launch the never-before-flown space shuttle from the back of a 747, nerves of steel were required yet again. When the Enterprise lifted off a 747 in 1977, no one knew for sure if it would clear the carrier aircraft's tail. Two pilots aboard the fledgling spaceship and two on the 747 put their lives on the line to find out."
Being a test pilot is an inherently very risky business. Some were badly burned in crashes, and others died in the line of duty, including NACA's Howard Lilly, whose D-558-1 jet-powered research airplane crashed on take-off in 1948, and X-2 pilot Jean Ziegler, who perished in 1953 (along with mothership crew member Frank Wolko) in an explosion during a captive flight under a B-50.
The man on the right here is Fitzhugh Fulton Jr., who was the project pilot in the 747 for those shuttle launch flights in 1977. During the 1960s, he piloted the modified B-52 that NASA used as the mothership to launch research aircraft including the X-15 and the lifting bodies, and he also flew the XB-70 prototype supersonic bomber.
On the left in this photo from 1992 is NASA research pilot Ed Schneider, who also flew NASA's B-52 mothership along with other planes including the F-15B aeronautical research aircraft.
In the background is an F/A-18 Hornet, which at the time was used as a chase aircraft at the Dryden Flight Research Center. Chase aircraft at Dryden are flown by research pilots to make sure test flights are conducted safely.
The spirit of the early aviators lives on in projects like the experimental Solar Impulse, a solar-powered plane that made its initial, barely-off-the-ground test flight in December 2009. Here, pilot Marcus Scherdel converses from the cockpit of the aircraft--which has the wingspan of a 747 but the weight of a midsize car--before heading down the runway.
A more ambitious nighttime flight, drawing on batteries that have been charged during daylight hours, is expected sometime this summer.
As ambitious as the project is, Solar Impulse founder Bertrand Piccard see it as more than just about aeronautics. "If an aircraft is able to fly day and night without fuel, propelled solely by solar energy, let no one come and claim that is impossible to do the same thing for motor vehicles, heating and air conditioning systems, and computers," he said in June 2009 when the aircraft made its public debut.