Scientists and engineers gathered for a week in Lake Tahoe this August at a conference dubbed “The Aerodynamics of Heavy Vehicles II: Trucks, Buses and Trains” ( They met to discuss how computer simulation and experimental techniques could be used to design more fuel-efficient trucks, buses and high-speed trains for the future.

The late Dr. Paul MacCready, a physicist and aerodynamics expert, would probably have applauded the program. Recognized internationally for his pioneering work in human-powered flight, MacCready was a man obsessed with aerodynamics. When cyclist/pilot Bryan Allen successfully crossed the English Channel in 1979 in MacCready's Gossamer Albatross, the feat won for MacCready's team the (then-largest) cash prize in aviation and a permanent spot in history.

I interviewed Dr. MacCready in 1995 and I still have the taped conversation. Listening to it again after his death this August at the age of 81, it is clear that he could have contributed much to that recent conference on aerodynamics. The perspectives he shared more than a decade ago are still relevant today.

“Here's how we'd begin,” he said when asked about how he would set about improving truck aerodynamics. “We would first explore all the literature and find the approaches that have already been used, but typically without any real understanding of their fundamentals or why they were made to work, at least to a limited extent. In other words, we'd try to get an understanding of the potentials and pitfalls of solutions that presently exist.

“Simultaneously, we'd do some brainstorming of all possible other approaches, beginning with a theoretical construct-the perfect fluid that has no viscosity so that there is, theoretically, no aerodynamic drag for a steadily moving object, no leftover turbulence when a truck goes by. Then we'd begin to add viscosity or resistance, such as air creates, to see how it begins lapping away at our efficiency,” he continued. “When we understand that, we can really go to work on ways to handle it.

“Next, we'd consider some of the many new tools we have at our disposal now that didn't exist before, such as sensors, which could perhaps be used to cover inexpensively every millimeter of the surface of the truck and somehow manipulate the flow of air over it. After all, we might be able to do some more active and positive things with that air,” MacCready reflected. “It might be possible to extract some energy from it while we are guiding it around the truck, perhaps it could actually be used to help with the guiding…”

MacCready was a big believer in harnessing the power of technology to improve aerodynamics, but he believed even more strongly in the power of enlightened political policy to create positive change. “Policy is the key, not technology, which we have in abundance,” he noted prophetically in 1995. “If fuel were to dramatically increase in price in North America, for example, you would see some very high priority placed by government and industry on how to use less fuel. That policy would not be a technical solution, but a mechanism for unleashing all sorts of technical solutions.”

More than a decade later, that's exactly what's taking place in engineering labs across the country. “The transportation field is in a unique situation, with huge potential for global benefits to society, individuals and business,” MacCready said. “In 15 years, we'll be able to assess how we treated this responsibility and opportunity.” Good-bye Dr. MacCready, and thank you for a lifetime spent encouraging good ideas to take flight.