Francis Clauser

Francis H. Clauser (BS '34, MS '35, PhD '37), the Clark Blanchard Millikan Professor of Engineering, Emeritus, passed away on March 3, 2013, at age 99. Born in the decade following the Wright Brothers' first powered flight, he was a founder of modern aeronautics and helped usher in the Space Age.

Francis was the younger of identical twins born to Celeste and Claude Clauser in Kansas City, Missouri, on May 25, 1913. When Francis and his brother, Milton, were 17, their father died, leaving the boys to support their mother and younger sister, Betty. Fortunately, Celeste "was talented and resourceful," says Clauser's daughter, Caroline Ryan. "She made puppets with papier-mâché heads and elaborate costumes, and she and the boys supported the family by staging marionette shows to the accompaniment of a hand-cranked Victrola." The twins enrolled in Kansas City Junior College, but upon learning of Caltech's constellation of luminaries, they decided to apply as transfer students. When they were accepted, the entire family packed up and moved to Pasadena.

As Caltech undergrads, the twins joined a local magician's society, the Mystic Thirteen. Their act consisted of one brother doing a trick before disappearing behind a screen. The other brother would then emerge in a totally different outfit and perform another trick. They did this faster and faster until the costume changes got impossibly short, at which point the screen would "accidentally" fall to reveal one brother in bright red undershorts.

Upon earning bachelor's degrees in physics, the Clausers entered the aeronautics program run by Theodore von Kármán. Unable to tell the twins apart but well aware of their hijinks, von Kármán made it clear that he expected two separate and distinct dissertations, saying, "Each of you can do one, one of you can do both, or both of you can do both." Thus Milton and Francis produced an experiment-based thesis on "The Effect of Curvature on the Transition from Laminar to the Turbulent Boundary Layer," while Francis and Milton wrote a mathematical treatise on "New Methods of Solving the Equations for the Flow of a Compressible Fluid."

On July 30, 1937, a month after receiving their doctorates, Francis married Catharine McMillan, Caltech's humanities librarian and sister of future chemistry Nobel laureate Edwin McMillan (BS '28, MS '29), in a double ceremony with Milton and his bride, Virginia Randall.

The brothers joined the Douglas Aircraft Company in Santa Monica, where Francis soon became the director of aerodynamic design research. There he assembled a team that included several future Caltech faculty members and profoundly influenced aviation design by developing mathematical methods for shaping tails, wings, engine nacelles, and air scoops.  

When Germany fell to the Allies in 1945, Clauser "was temporarily inducted into the U.S. military as an instant full colonel" as part of Operation Paperclip, says his son, John Clauser. Such high ranks were routinely given to civilian experts sent into the war zone in order to expedite the American effort to collect as many of Germany's best scientists and as much of its key hardware as possible before the Russians did.

Soon after Clauser's return, Henry "Hap" Arnold, the commander of the Army Air Forces, commissioned Clauser's design team to study the feasibility of spaceflight. The 340-page "Preliminary Design of an Experimental World-Circling Spaceship," dated May 2, 1946, concluded that a rocket based on the German V-2 could put a 500-pound payload into orbit for at least 10 days and outlined the military, scientific, and telecommunications uses to which such a satellite might be put. Unfortunately the estimated cost—$150 million over five years—was deemed too high, and the US ceded first rights to the final frontier to Sputnik, launched by the USSR a decade later. The report also noted that "there is good reason to hope that future satellite vehicles will be built to carry human beings," recommending a winged, reusable spacecraft as the best way to return them safely to Earth. This report was the first to be produced by what Arnold dubbed the RAND (for Research and Development) Project; several of the people who wrote it went on to become founding members of the RAND Corporation when it was spun off from Douglas Aircraft in 1948.

Clauser, however, left the company in 1946 to found the aeronautics department at Johns Hopkins University. He chaired the department until 1960, recruiting leaders in the field from many countries to create a world-class research center. The department's facilities included three large wind tunnels, one of which was supersonic and "all of which Clauser personally designed," John says, "so that they exhibited very low residual turbulence in their test sections."

Turbulence and the so-called boundary layer, the thin layer of fluid immediately adjacent to a solid surface, had been particular interests of Clauser's since graduate school. In fact, his first assignment at Douglas had been to figure out why the DC-3, which had just debuted as a transcontinental passenger plane and would remain in military production through World War II, tended to roll onto its back upon stalling. An aerodynamic "stall" occurs when the tilt of a wing's leading edge—the so-called angle of attack—increases to the point where lift is no longer generated. Clauser realized that as one wing fell, the angle of attack at its tip would increase, making it stall more. To break this runaway feedback, he invented the now-standard "washout" wing twist, in which the wing tips are more or less horizontal and the angle of attack increases closer to the fuselage. Any stall thus begins near the fuselage, where the wing's lever action is minimal, while the ailerons out near the wing tips do not stall and the pilot remains in control of the aircraft.

Clauser wrote two seminal papers on the turbulent boundary layer in 1954 and 1956. As emeritus professor of aeronautics Donald Coles (MS '48, PhD '53) explains, "Normally, as you follow the boundary layer across the wing, the velocity profile will be controlled by the pressure variation. Clauser invented what he called 'equilibrium flows' in which he controlled the pressure gradient so that the velocity field didn't change as you went along the flow. The pressure was still rising, but he had a trick for adjusting the rate at which it rose, so that the velocity obeyed a 'similarity law.' It didn't matter where you measured the velocity profile, because it always followed the same curve. And anybody could duplicate his family of flows in their own wind tunnels just by properly shaping the channel."

This gradient generates the wing's lift and begins as a zone of low pressure near the wing's leading edge, extending outward and backward until ambient atmospheric pressure is restored. If not handled properly, it can force the airflow to leave the wing prematurely—as it did in the stall that had plagued the DC-3. The gradient's behavior depends on the interplay between the wing's shape and the boundary layer itself, which in turn is governed by a set of deceptively simple differential equations whose exact solutions often still tax modern supercomputers. Clauser's work was so important because in the days when designs were primarily worked out with slide rules and pad after pad of graph paper, the fewer variables one had to manipulate experimentally, the better.

"Clauser was one of the four founders of the science of boundary layers as it stands today," Coles says. "In a 10-year period, these people put together a consistent, coherent description that is still the place where you start teaching the subject."

Clauser was a member of the 1968 Task Force on Space, chaired by Nobel laureate Charles Townes (PhD '39). Clauser again championed the notion of a winged, reusable space vehicle. This time, the idea got traction and the Space Shuttle was born.

During the Hopkins years, Clauser acquired a reputation for educational innovation, establishing cross-disciplinary courses designed to illuminate basic principles that could later be applied to whatever field a student might choose. He was invited to the newly created University of California campus in Santa Cruz in 1965 to set up the engineering school, and he served variously as the academic vice chancellor, vice chancellor for science and engineering, and professor of applied science.

In 1969, Clauser returned to Caltech to chair the Division of Engineering and Applied Science. He stepped down in 1974 but remained the Clark Millikan Professor of Engineering until his retirement in 1980.

Clauser, having arrived at the dawn of the environmental movement, launched Caltech's interdisciplinary graduate program in environmental engineering science in 1971. The following year he established the Environmental Quality Laboratory, or EQL, as an "action-oriented unit," in his words, along the lines of JPL—"associated with Caltech, carrying on Caltech's high standards but not engaged in teaching." Organized in partnership with JPL, the RAND Corporation, and the Aerospace Corporation, the EQL studied the scientific, engineering, economic, and political aspects of issues such as pollution control, water and energy policy, and sewage disposal. 

The interdisciplinary applied physics option was initiated during Clauser's term as well, providing an academic home for the solid-state physicists and electronics engineers who were powering the computer revolution. Clauser also oversaw the construction of the Earle M. Jorgensen Laboratory of Information Science. This building housed not only computer scientists but the Campus Computing Center, which ran the mainframe computers that were becoming important research tools in many disciplines.

In 1973, Clauser established the Sherman Fairchild Distinguished Scholars Program, which he intended to be "as desirable and prestigious as a Guggenheim Fellowship" and which brought up to 30 eminent scientists per year to Caltech. The inaugural group included Apollo 17 astronaut Harrison Schmitt (BS '57), the only geologist to walk on the moon, and a then-obscure cosmologist named Stephen Hawking.

Upon his brother Milton's death in 1980, Clauser, his wife, and his sister-in-law established the annual Milton and Francis Clauser Doctoral Prize, awarded for the thesis judged to have the greatest potential for opening up entirely new lines of research.

A noted raconteur with a prodigious memory, Clauser was a regular at the legendary Round Table at the Caltech faculty club, the Athenaeum. Says Marshall Cohen, professor of astronomy, emeritus, "He was known as 'The Dean of the Round Table' for a couple of reasons: He was the oldest, and he would dominate the discussion. He'd say, 'Let's change the subject—I want to talk about the new style of sailboat.'" Politics, biblical archaeology, and ancient Egypt were other favorite topics, Cohen recalls. "He knew dates. And names. He knew dynasties. A decade ago I mentioned that I was interested in hieroglyphs. He said, 'I can recommend a book for you.' It turns out he and Catharine had taken a course in hieroglyphics back in the 1960s, and he still remembered the name of the textbook."

Clauser's favorite subject was travel. He and Catharine had driven through 117 countries and across every major desert on Earth—usually in a rented Volkswagen Beetle. One such trip went from Alaska to Tierra del Fuego, where he eased into the Straits of Magellan until the Bug's front bumper was submerged. Another trip followed the Silk Road through Central Asia.

The Clausers' most-storied trip took them from Tunis to Timbuktu. As recounted in Caltech's Engineering & Science magazine in 1972, the preferred method for crossing the Sahara was in Land Rovers traveling in pairs. The Clausers drove alone in a Renault R4, a vehicle light enough for them to push when it got stuck in the sand. Things went well for the first 1,600 miles or so, until the clutch gave out in central Niger. They hitched a ride to Tahoua, the nearest town, where, as Francis told E&S, they found "a 52nd-hand car dealer who let us have an ancient clutch for $24. Then we rented a set of tools for $10 from a German mechanic and went out and sat by the road for two hours before we caught a 70-mile ride back to our car." The next day, they dismantled the engine in front of an audience of Fulani herdsmen and Tuaregs on camels, only to discover that the new old clutch didn't fit. An examination of the old old clutch revealed that it had packed itself full of sand as they tobogganed through the dunes. They extracted the sand with a paring knife and a safety pin, and drove back to Tahoua, where they resold the new old clutch back to the 52nd-hand dealer for $20.

Catharine died in 1999, but Francis remained in the family home in La Cañada until he lost his right leg to the flesh-eating bacterium Clostridium septicum in 2008. He moved into Villa Gardens to recuperate—on the condition that he not miss lunch at the Round Table. A shuttle would drop him off daily, says Cohen, "but occasionally he'd drive himself home in his electric wheelchair by way of his dentist."

Clauser's publications included papers on nonlinear mechanics, guided missile technology, magnetohydrodynamics, and partial differential equations as well as a book, Plasma Dynamics, compiled in 1960 following a symposium he chaired on what was then a very young field. He was a Fellow of the American Institute of Aeronautics and Astronautics, the American Physical Society, and the American Association for the Advancement of Science. He was also a member of the National Academy of Engineering, the scientific research society Sigma Xi, the engineering honor society Tau Beta Pi, and Caltech's Gnome Club.  He was named a Distinguished Alumnus in 1966, one of the initial class of 23 to be so honored.

Clauser is survived by his sister, Betty Celeste Valois of Denver; his son, Wolf laureate in physics John Francis Clauser (BS '64) of Walnut Creek, California; and his daughter, Caroline Helen Ryan, of New York City. A memorial service will be held at 11:00 a.m. at the Caltech Athenaeum on May 25, the day that would have been his hundredth birthday.