What Goes Up Must Come Down
Parachute engineer Robert Rodier ’51 and the art and science of soft landings
Robert Rodier ’51 has never used a parachute. And that’s OK with him. Jumping out of an airplane holds no appeal. On the contrary, Rodier has spent his life finding ways for people and things to come down easy.
From WWI to the 1930s, parachute technology remained basically unchanged—a round silk parachute was used almost exclusively for emergency jumps. In World War II, aircraft flew faster and farther, making it possible to deliver troops and the materiel of war straight to the battlefield, even behind enemy lines. The parachute’s role as a strategic combat tool paved the way for its accelerated research and development.
“Early on, parachute design was ‘cut and try,’” says Rodier, who began his career at the Army labs in Natick, Mass., in 1956. “We built what we called seam and joint samples that we’d put in the tensile tester to enhance our confidence that our designs were sound. We worked in the wind tunnel, too, but most testing was rudimentary. Cut and try.”
Jumping out of an airplane carries obvious risks. Air drop—delivering troops and heavy equipment by parachute—is also dangerous. One’s “office” is the cold, noisy fuselage of a cargo plane where one crawls among closely packed heavy equipment—with a large door wide open at high altitude.
“With air drops,” explains Rodier, “there were a million factors to account for—drift, altitude, speed—and we typically dropped from as low an altitude as possible to narrow our margin of error.” Rodier and his fellow engineers were breaking new ground, but despite their best efforts, they sometimes lost cargo. “But it was only equipment. When you talk about pilot or crew escape systems, well, there were some unhappy events. They used to call us ‘rag men.’ The people who understand what we did were glad to have us around. They knew, in certain circumstances, they were totally dependent on the quality of our work.”
In 1962 the original Mercury astronauts were household names and heroes. The first Gemini flight was still several years away, but scientists had already begun working on the Apollo systems that would carry Armstrong, Aldrin, Collins and others to the moon, and, hopefully, back.
Rodier was destined to become part of history. After five years at the Army labs, his work had been noticed. North American Aviation invited him to join the Apollo team. “So I saddled up with my wife and three kids and headed west to California.” Although the Apollo earth landing system drew heavily on the Mercury and Gemini designs, Rodier says Apollo was the greatest challenge of his career.
“We had severe design limitation with regard to weight and volume. We had little room to work with. And we didn’t—we couldn’t—concern ourselves with the capsule being dynamically out of control, since this was a variable that was impossible to predict or govern. We had to assume that we were dealing with a nominal reentry. Still, falling to earth from outer space made for deployment conditions that were fairly severe, as was the attention and scrutiny we were under.”
Millions of Americans gathered around their television sets to watch the Apollo astronauts end their daring missions to the moon. The command module swung gently under billowing parachutes as Walter Cronkite waxed eloquent about the spirit and meaning of manned space flight. Bob Rodier watched, too, with a supercritical eye, and on one occasion was surprised by what he saw.
“I remember watching one return on television and sitting up straight when I saw that the module was coming down on two parachutes. It was supposed to be coming down on three!” Rodier later learned that a purge of gases from an unrelated system had destroyed suspension lines on one of the parachutes. “We had built sufficient margin into the system so that two out of three chutes would work safely. Fortunately it worked like a charm. But I had never seen anything like that before—or since.”
Rodier also helped design the abort system for the Apollo flights. “I can tell you it was quite tricky trying to set up a test that would simulate the violence and chaos of an aborted flight. Those were nail-biting drop tests.”
“I can tell you it was quite tricky trying to set up a test that would simulate the violence and chaos of an aborted flight. Those were nail-biting drop tests.”
The tests that Rodier’s team conducted dictated a need for an advanced method of deployment. The Apollo abort system regulated the chute’s opening forces by reefing—opening in carefully timed stages. This allowed the command module to reduce its velocity and come under control in increments. Fortunately, the Apollo abort system was never needed.
Remembering Bob Rodier’s career is to follow the advancement of air and space technology in the second half of the 20th century. By the 1970s, parachute systems were designed to safely stabilize pilots who might be forced to eject at extremely high Mach speeds. The parawing gave way to the parafoil—both hybrids of maximum drag decelerators and rigid wing technology. When designed with reefing systems and equipped with precision guidance technology, these parachutes have almost unlimited use.
On July 4, 1997, such a guided parachute helped the Mars Pathfinder slow its descent through the thin Martian atmosphere. And in January 2004 a similar system of parachute and airbag will guide NASA’s Mars Exploration Rover Mission to a gentle landing on the Red Planet. For his part, Rodier was directly involved in the parachute system that would guide NASA’s Jupiter Galileo Space probe through the hot gas and clouds of the Jovian atmosphere.
When he retired in 1996, Rodier was working on the X-38, the International Space Station Crew Recovery Vehicle, which was designed to use a 7,500-square-foot ram-air inflated parafoil, the largest parafoil in the world.
“It’s important to plan a career, but it’s also important to leave yourself open to opportunities that you may never have imagined.”
Despite advanced technology, Bob Rodier will tell you that some jobs call for old-fashioned bulk and muscle. The recovery system for the space shuttle solid rocket boosters is a case in point. The booster weighs 178,000 pounds. At 81 metric tons, it is the heaviest operational payload in the world. It needs a lot of parachute to ease it out of the sky.
“The system calls for three enormous parachutes to control the descent of the boosters. The chutes weigh 2,100 pounds each,” he says. “The sheer amount of nylon that goes into building a two-thousand-pound parachute is mind-boggling. But it has proven to be very reliable.”
In 1994 Rodier was recognized for his lifelong achievements. He received the American Institute of Aeronautics and Astronautics Theodor W. Knacke Aerodynamic Decelerator Systems Award, “for contributions in the development of sophisticated parachute recovery systems used in the United States Space Program, military aircraft, and United States Army Airdrop Systems.”
“It’s important to plan a career,” says Rodier, who credits WPI for his excellent foundation in engineering. “But it’s also important to leave yourself open to opportunities that you may never have imagined. Some of the most interesting, most challenging and most satisfying things I’ve done in my career—the things I’ve really enjoyed—I never conceived of while I was at WPI. I didn’t have a clue.”
Robert Rodier may never have used a parachute. But he is the man and the mind behind a generation of soft landings.
- The American Institute of Aeronautics and Astronautics
- The X-38, the International Space Station Crew Recovery Vehicle
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Last modified: Aug 31, 2004, 17:07 EDT