This month marked the end of a very long era for aeronautics and aerospace researchers. After nearly 80 years of service, the Langley Full Scale Tunnel has ceased operations, and the expectation is that NASA will tear down the venerable structure, which is located at the aerospace agency's Langley Research Center in Hampton, Va.
The final mission for the immense wind tunnel, built when biplanes were still the norm for aviators, was to test the aerodynamics of the futuristic X-48C and its blended-wing body. (A separate version of the prototype, the X-48B, is being tested on the other side of the country at NASA's Dryden Flight Research Center in California.)
Updated:Caption:Jon SkillingsPhoto:U.S. Air Force photo/Staff Sgt. Barry Loo
X-48C and wind tunnel propellers
When it was built in 1930, the Langley Full Scale Tunnel was the largest wind tunnel in the world, and at 30 feet by 60 feet it's still among the behemoths of the field. It was built big to test full-size aircraft, where many wind tunnels are much smaller and test only small-scale models.
The X-48C prototype seen here is itself a model. It has a wingspan of 21 feet and weighs about 500 pounds, the same as its X-48B counterpart. Both have turbojet engines, can fly as fast as 138 miles per hour, and can reach an altitude of 10,000 feet.
A crane hoists the X-48C prototype into place for testing in the wind tunnel during July and August. The tests were to assess the aerodynamic effect of recent changes, including a reduction from three engines to two and the installation of vertical fins to buffer the engine noise.
From 1995 to September of this year, the LFST had been leased to Old Dominion University, which used it to train engineering students and for other projects. It was even used to test Nascar vehicles.
In this photo from August 31, an engineer from Old Dominion monitors testing of the X-48C.
Editors' note: This photo was added October 7 because, well, we just came across it and found it too good to pass up.
Updated:Caption:Jon SkillingsPhoto:U.S. Air Force photo by Staff Sgt. Barry Loo
Earlier in this decade, the Langley Full Scale Tunnel harked back to the earliest days of airplane flight with tests on a replica of the Wright Brothers' 1903 Flyer. See the Wright Experience Web site for video of the aerodynamics tests.
Ken Hyde, the founder of the Wright Experience project, has been an outspoken supporter of preserving the Langley facility, writing on his blog: "The LFST building does need some repairs but it is not dilapidated; it still works....Keeping the LFST operational would only be a fraction of the cost to demolish it. The LFST's demolition is bad for education, bad for Virginia, and most importantly, bad for this nation!"
The LFST has been recognized as a National Historic Landmark.
The arguments of LFST fans notwithstanding, NASA says the big facility's best days are behind it: "The tunnel is scheduled for demolition because of its lack of national strategic importance, limited testing capability, deteriorating condition and the environmental liability associated with the materials used in its construction."
Back in the day, you could sometimes catch the biggest names in aviation at the LFST. This photo from Langley's May 1934 Aircraft Engineering Conference includes Orville Wright, Charles Lindbergh, and Howard Hughes, according to NASA. The aircraft overhead is a Boeing P-26A Peashooter.
The LFST isn't much to look at from the outside--but it's what happened inside that counted. The exterior dimensions: 434 feet long by 222 feet wide and 90 feet high. This photo is from October 1930, when the facility was brand new. NASA decommissioned the tunnel in 1995.
This photo from August 1930 gives a good sense of the scale of the wind tunnel, including the housings for the 35-foot propellers. As was the case with many early wind tunnels, NASA says, its structural supports are on the outside. The framework is solid steel.
The wind tunnel's propellers and fan motors were situated in the exit cone, seen here during construction. Heading up the design team was Smith J. de France, an engineer for NASA's predecessor, the National Advisory Committee for Aeronautics (NACA).
Congress approved the project in 1929 and funded it with a two-year appropriation of $900,000.
With a diameter of 35 feet, 5 inches, the two propellers--built of cast aluminum alloy--could generate air speeds from 25 to 118 miles per hour. They were powered by two 4,000-horsepower slip-ring induction motors with 24 steps of speed between 75 and 300 rpm, according to NACA records. Almost every structure in the wind tunnel was a one-of-a-kind installation.
Smith de France, the design chief, describes the functioning of this assembly, the LFST balance system, in a NACA document: "Ball and socket fittings at the top of each of the struts [hold] the axles of the airplane to be tested; the tail is attached to the triangular frame. These struts are secured to the turntable, which is attached to the floating frame. This frame rests on the struts (next to the concrete piers on all four corners), which transmit the lift forces to the scales (partially visible on the left)...
"[T]he forces in three directions are measured and by combining the forces and the proper lever arms, the pitching, rolling, and yawing moments can be computed. The scales are of the dial type and are provided with solenoid-operated printing devices. When the proper test condition is obtained, a push-button switch is momentarily closed and the readings on all seven scales are recorded simultaneously, eliminating the possibility of personal errors."
This photo from 1930 shows the circuit breaker panel prior to its installation. De France: "The two motors are connected through an automatic switchboard to one drum-type controller located in the test chamber. All the control equipment is interlocked and connected through time-limit relays, so that regardless of how fast the controller handle is moved the motors will increase in speed at regular intervals."
In 1931, the NACA evaluates a Pratt and Whitney Wasp engine mounted in a P3M-1 nacelle and attached to a 15-foot section of wing. The tests were intended to suggest ways to improve the cooling of the engine and to reduce the drag of the nacelle combination.
The 1930s and 1940s were the heyday for the LFST. "It proved especially valuable during World War II as a majority of the nation's bombers and fighters (as well as several foreign aircraft) were tested in this tunnel," NASA says.
Pictured here in 1941 or 1942 is the Lockheed YP-38 Lightning during drag cleanup testing.
NASA says that this aircraft represents America's first jet airplane, the Bell P-59, a version of which had its maiden flight in October 1942. The model pictured here some months later in 1943 is the Bell YP-59A, a service test modification.
A Sikorsky YR-4B/HNS-1 helicopter stands ready in October 1944 as a technician sets up camera equipment for a stop-action image sequence of the rotors in action. Sikorsky's R-4 helicopters are said to have been the first mass-produced helicopters.
Why limit testing to airplanes? In the 1950s, the folks at Langley brought in the Albacore--at the time, the world's fastest submarine, NASA says--to check out its drag characteristics. "Water and air are both essentially fluids of different densities," the agency says. "Air traveling at high speed can simulate water traveling at lower speed for many purposes."
A paraglider gets checked out in August 1964. In the early 1960s, people including Neil Armstrong, then a research pilot but soon enough an Apollo astronaut, proposed using paragliders as part of flight training. (Armstrong, however, apparently couldn't be spared from his other commitments.)
In early 1962, says NASA, "after expending $4280 on construction and materials, the team rolled out the Paresev I. It resembled a grown-up tricycle, with a rudimentary seat, an angled tripod mast, and perched on top of the mast, a 14-square-meter Rogallo-type parawing. The vehicle weighed 272 kilograms, had a height of over 3.4 meters, and a length of 4.5 meters."
The agency says that the Paresev was the first NASA research airplane to be constructed completely in-house.
NASA 952, a lunar landing training vehicle, undergoes testing in January 1969 after a similar Bell LLTV crashed during training at Ellington Field in Houston. Six months later, Neil Armstrong would serve as commander of the Apollo 11 mission that made the first-ever manned moon landing.