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The Silver Streak

MIT had a hand in developing the country’s first diesel-powered high-speed train.
February 22, 2011

The Burlington Zephyr, America’s first diesel-powered high-speed train, was born of Ralph Budd’s vision of rail travel luxury. And with help from an MIT wind tunnel, that dream came to life, allowing passengers to eat ice cream from gold-banded bowls or to smoke while reclining in a leather seat—and watch the world go by at 100 miles per hour.

Budd, president of the Chicago, Burlington, and Quincy Railroad in the 1930s and ’40s, hoped that a radically new kind of train would get rail travel out of the slump that had accompanied the Great Depression; by 1933 local railway traffic was just 20 percent of what it had been in 1920. His solution measured 196 feet long, weighed 97.5 tons, and owed its name to Geoffrey Chaucer. Upon reading The Canterbury Tales, Budd had been taken with Chaucer’s mention of the god of the west wind, Zephyrus, who blows sweet breezes that inspire pilgrims to begin their journeys.

Wanting the Burlington Zephyr to be the country’s most aerodynamically efficient train, Budd sought the assistance of Shatswell Ober, an associate professor of aeronautics at MIT. In 1933 Ober set up a five-foot-long stationary model of the Zephyr in a wind tunnel. With a four-blade propeller fan blowing air past the model at 60 miles per hour, Ober and his team could evaluate the train’s aerodynamics as if it were slicing through the breeze.

Engineered for sleekness, the Zephyr had windows and doors that lay flush with the train’s surface, a rounded front nose, and a tapered rear. All mechanical equipment was packed tightly into a bottom compartment, leaving the train’s underbelly smooth.

The Zephyr model outshone a model of a conventional train in aerodynamic testing, but Ober had his doubts. In a report written on October 7, 1933, he expressed his worry that the five-foot-long prototype, about a 40th the size that the real Zephyr would be, was too small to give meaningful results. The idea that the model would approximate the behavior of the full-sized train, he wrote, was “questionable.”

Ober’s anxieties play out on several sheets of indigo-colored draft paper. Notations are scribbled on top of the original train plans, and broad scratches in red pencil suggest an attempt to tighten its lines.

But Ober’s model, although small and stationary, was well engineered to predict the behavior of the full-scale Zephyr. Designed to run at about 110 miles per hour, the train trumped the fastest safe speed of 60 miles per hour for earlier diesel passenger trains. And at less than a third of an ordinary train’s weight, it could run with less than half the resistance of a conventional American train. Its secret: stainless steel.

Promising lightweight engineering without loss of safety, stainless steel was seen as the material of the future—or, as a Railway Age ad for U.S. Steel called it, “the fabric of the modern world.” A 1934 advertisement for Enduro steel proclaimed that “years from now, the Enduro on the ‘Zephyr’ will gleam as brightly as the Enduro on the Chrysler spire and the Enduro on the world-famous tower of the Empire State Building.”

Even as the Depression dragged on, stepping aboard the Zephyr was like entering another era. The train featured pastel-painted compartments, rich window drapes, radio service, and a buffet offering drinks and ice cream. With space for 72 passengers and 50,000 pounds of baggage and freight, the “Silver Streak” hit a speed of 112 miles per hour during a record-setting nonstop dawn-to-dusk dash from Denver to Chicago.

In May 1934, the Zephyr pulled into Boston’s South Station on its exhibition tour. “One of the finest examples of the cold-fabricators art was seen in our fair city last week,” reported the Tech. And MIT had had a hand in putting it together: Albert G. Dean ‘31, an alumnus working for the metal fabrication company that invented shotwelding (applying short pulses of strong electrical current instead of heat, which weakens stainless steel), used that technique to bind the 46 arched side posts that formed the Zephyr’s skeleton.

In the end, the Zephyr did spark a rail revival, just as Budd had hoped. Among the first of many diesel-powered trains to hit American soil, it ushered in a new era of engineering. By 1939, 90 diesel trains were in service across the country, and rail travel had rebounded 38 percent above the 1933 level.

Today, the Zephyr sits in the Chicago Museum of Science and Industry after 26 years of service. It was, as Ober conceded in November 1934, “a strikingly handsome train.”

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