Speed is an age-old quest. LBL's James Osborn got the speed bug six years ago as a UC Berkeley mechanical engineering student. That's when he and several fellow undergraduates began designing high-speed human-powered vehicles (HPVs).
Since then, Osborn's mission and his team have evolved. On Sept. 22, 1992, the effort culminated when Osborn and company set a new world speed record for HPVs.
The Dexter HYSOL Cheetah, a semi-recumbent bicycle made of composite materials and enclosed in a shell, made a run through a 200-meter speed trap at 68.73 miles per hour (110.68 kilometers per hour). This smashed the six-year-old record of 65.48 m.p.h
Osborn, who came to the Lab in 1988, works in engineering/computer support in the Engineering Division, where he provides computer-aided design and engineering analysis for the Advanced Light Source and the Heavy Ion Fusion Accelerator Research program. He says that from the beginning, he and the three other engineers who designed the Cheetah were confident it would become the world's fastest human powered vehicle.
"The bike holding the old record was sort of pieced together by a recumbent-bicycle manufacturer without the use of scientific engineering principles," Osborn says. "We knew that if we used the engineering skills we had learned at Cal, we could set a world record."
The collaborative effort actually began in Spring 1986, when Osborn first teamed up with fellow engineering students Jon Garbarino and Kevin Frantz. Along with several other students, they built a vehicle which became Cal's first entry in the American Society of Mechanical Engineers' annual human-powered vehicle collegiate competition.
"Our bike was a metal three-wheeler that we named the Batcycle. It went about 38 m.p.h. Then in the fall," Osborn says, "we built another three- wheeler -- this one from carbon fiber -- and pushed it to 42 m.p.h."
Through these competitions, Osborn says they learned that two-wheeled HPVs are faster than three-wheelers. They also realized that a semi- recumbent rider position was a good compromise design between a normal upright bicycle position, which has the best stability and control, and a fully recumbent position (with the rider flat on his back), which is the most aerodynamic.
In 1987 the team built an adjustable prototype and developed computer software that helped them engineer and fabricate an aerodynamic shell (fairing) made of kevlar and carbon.
The result was a new bike called Concept Z. The engineering team recruited Johnny Franck, a Danish bike sprint champion, to pilot Concept Z in the Spring 1988 International Human-Powered Vehicle Speed Championships. Franck pushed the bike to 55 m.p.h., one m.p.h. slower than the winning speed.
Osborn graduated from UCB in 1989. Despite a dramatic improvement in their efforts, the design team was about to break up without ever having won a competition. Osborn, Garbarino, and Frantz, three of the core team members from the beginning, decided to remain together but elected to raise the stakes by going for the world record. To help defray expenses, they sought and received corporate sponsorship from the Adhesives and Structural Materials Division of the Dexter Corp. Franck was retained as the rider.
The world record run was attempted on an 8,000-foot-high road course in Colorado. The thin air adds about 10 m.p.h. in speed over a run at sea level. Side winds, however, hindered the effort, holding the Cheetah to a speed of 61.5 m.p.h., four m.p.h. short of the record.
After this disappointment, the corporate sponsors who had invested $50,000 in the bike bailed out. Osborn and friends refused to give up. They sought other sponsors but a year later came up empty-handed. They resolved that in 1992 they would use their own funds and vacation time for another run at the record.
The team--Osborn, Garbarino, Frantz, and new member Gorman Gong--then suffered another setback. Franck, the cyclist, quit the effort. The bike's ergonometric design--its leg extension, handlebar position, shape of the fairing, and the seat--had been custom-tailored to fit Franck. The team searched for another rider of similar dimensions, finally enlisting Chris Huber, a professional cyclist from the San Jose area. Huber proved to be a close if not perfect fit for the bike.
The world record run took place near the Great Sand Dunes National Monument in Colorado at an elevation of 8,000 feet on an essentially flat course with virtually no tailwind. Two officials from the world sanctioning organization monitored the event.
Recalls Osborn: "The Cheetah has seven gears. Huber needed about 2.5 miles to build up to top speed before the run through the 200-meter speed trap. At 7:30 a.m. on Sept. 21, he made a run and was clocked at 65.57 m.p.h., barely breaking the old record. We knew the bike had more speed in it. Late the next day, Huber made a run at 68.73 m.p.h. With this, we beat the old record by almost 5 percent."
Osborn says he has been too preoccupied with the triumph to say for certain whether this will be the end of the quest. Most likely, however, another run will be made in the future. The goal would be to break the 70 m.p.h. barrier.
"The bike is engineered to go 70 m.p.h., which would be a real milestone," Osborn says. "Chris Huber says he would ride it for us provided we make one change for him. The seat on the Cheetah was custom-designed for Johnny Franck's butt. Huber says the last run was so painful, he won't ride again without a seat shaped for his rear."
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