December 2005/January 2006 
Volume 04, Issue 8 
Special Feature

Blowing into the 21st century

Philadelphia's wind tunnel: one of the world's best


The goal was to make it one of the best wind tunnels in the world. Today, it's everything those planners dreamed of.

Enhancements over the past several years to the Boeing Vertical/Short Takeoff and Landing Wind Tunnel (BVWT) in Philadelphia have transformed it into one of the world's best places to obtain aerodynamic performance data.

Operated by Integrated Defense Systems, it's become an important element in Boeing's network of engineering laboratories and test facilities across the United States. One of a handful of Boeing wind tunnels, the BVWT fills a niche for testing aircraft at speeds up to Mach 0.3—the takeoff and landing segment of the flight regime.

Since the tunnel's opening in 1968, Boeing aerodynamicists have logged more than 65,000 hours of testing; they have generated vital data for different designs of helicopters, jet fighters, commercial airplanes, and other vehicles.

Bill Grauer, the tunnel's senior manager, says the BVWT was one of the most advanced wind tunnels in the world when it first began operating. However, by the late 1990s the facility could not meet the company's needs for aerodynamic testing in the 21st century.

"We developed a seven-year strategic plan that had a three-pronged approach to greatly improve our productivity, data quality and value to our customers," says Grauer. "The goal was to make this one of the best wind tunnels in the world.

Wind tunnel facts and figures

The Boeing Vertical/Short Takeoff and Landing Wind Tunnel (BVWT) near Philadelphia is the largest privately owned wind tunnel in North America. A low-speed, closed-circuit tunnel, its quarter-mile-long air path contains 42 tons of air, which can be accelerated to 225 knots when it's squeezed through the tunnel's 20-foot by 20-foot test section. At that maximum speed, the tunnel's drive system and its fan with huge wooden blades draws over 8 megawatts of power—and produces 15,000 horsepower.

The entire tunnel structure is made of concrete, with the exception of the test section bellmouth contraction and the fan section, which are made of steel. The test section, with walls that weigh a combined 24 tons, is versatile enough for testing fixed and rotary wing aircraft, as well as non-aeronautical vehicles and structures.

Engineers and technicians use wind tunnels to test many different configurations of a proposed aircraft. Fewer tests are needed today, because modern computational fluid dynamics (CFD) tools allow designers to consider and run virtual experiments on designs with a higher degree of confidence than ever before. But wind tunnel testing is necessary to fully understand and develop final designs.

Low-speed tests at the facility measure aircraft configured with a variety of high-lift surface settings to simulate takeoff and landing performance.

In typical test scenarios, sophisticated models, which often take months to build, are attached to a force and moment balance in the wind tunnel's test section. Embedded with hundreds of pressure sensors, the models are subjected to tons of fast-moving air. Wind tunnel operators "fly" the models with automated and manual controls to determine in-flight loads, as well as to provide valuable diagnostics of the aerodynamic performance of a given design.

"An important aspect of the plan was to keep BVWT online, ready to support the company's testing needs, while undergoing major facility upgrades," he says. "This made it especially challenging."

Since 1998, Grauer and his team have worked on a series of capital investments to improve the BVWT's airflow and data quality, productivity and customer satisfaction. The improvements have included installation of a fully automated test-model positioning system and air-speed controller, which allow operators to run better tests in less time; a new, more efficient data-collection system; better instrumentation; and the addition of metal honeycomb to improve flow quality.

The upgrades have helped earn the BVWT the title of Boeing's "Low Speed Center of Excellence."

"We have improved our test productivity, data quality and value to our customers," says BVWT Chief Test Engineer Bob Wozniak, noting that typical test times have been greatly reduced as a result of the improvements.

"We could not have had these gains without the tremendous technical help and advice from the wind tunnel community across the Boeing enterprise," Wozniak says. "We assembled a team from across the company—experts in automation, complex controls, test productivity, airflow quality, model design and systems integration. Their combined knowledge and experience allowed us to achieve our goals."

IDS' P-8A Multi-mission Maritime Aircraft program recently benefited from BVWT productivity improvements. This summer, the P-8A program conducted a major series of low-speed tests using a 1,000-pound, 11 percent scale model of a modified 737-800. The model, with 1,900 embedded pressure sensors and a 12.5-foot wingspan, was carefully examined to evaluate its aerodynamic performance and how closely it matched predictions.

According to Mike Smyth, lead Stability and Control engineer for the P-8A program, the overall test program went "extremely well." It finished under budget, ahead of schedule, and accomplished all of its priority objectives.

 Commercial Airplanes' 787 program is next in line to take full advantage of the improvements made at the BVWT.

"We are proud of the achievements that we have made and could not have done it alone," says Grauer. "We have developed a culture of continuously looking forward and improving. Our wind tunnel is a reflection of that. We believe that this is the culture of the 21st century, and we are ready for it."


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