July 15, 2006 Last week we reported on Fast Freddy Markham’s world one hour human powered vehicle record of 53.43 miles, set on a recumbent bicycle with carbon fibre fairing that resembles a torpedo – now think how hard it is to average 53.43 miles an hour in your car and wonder just what the limits might be for human powered vehicles given our ever-growing understanding of science. Next week there’s a serious attempt on the world record human powered vehicle distance record for 24 hours. A similar eight-foot long torpedo-shaped recumbent christened Critical Power has been designed and built using SolidWorks and COSMOS software for the attempt on the 1,021.36 km (634.6 miles) record. Forty-something year old triathlete Greg Kolodziejzyk will attempt the record at Redwood Acres Motor Speedway in Eureka, California, sometime between July 19 and 24, depending on weather. To take the record, Greg only needs to average just over 42 km/h, which can be achieved with a continuous output of 110 watts – not much more power than that required for a light bulb. But he’ll need to do it for 24 hours.
Greg has previously attempted the record last November when he cycled 828.4 km (515 miles) at the NCAT test track in Opelika, Alabama in 20 hours, 22 minutes before mechanical problems forced his retirement. There's a full account of the attempt here, and it's well worth a read as it gives some insight into the issues associated with a 24 hour attempt.
The retired computer imaging entrepreneur chose the Redwood Acres Motor Speedway in Eureka, Calif., as his venue after evaluating 19 other tracks in North America for climate, surface, and layout.
The 24 hour human powered distance record of 1021.36 kilometers was set in 1995 by Axel Fehlau in Cologne, Germany with a streamliner on an indoor 200 meter velodrome track.
“I believe that setting a new record for the 24 is within my capabilities, but by no means do I think it is going to be easy,” says Greg on his excellent and very thorough web site AdventuresofGreg.com
“When we do the math, we discover that an averagely decent streamliner with a drag coefficient of .3 (sq ft) can go farther than 1021 km in 24 hours on only 110 watts of human power (enough effort to go 15 kph or 9 mph on a mountain bike). But what most people don't realize is that it is difficult to end with an overall finishing average of 110 watts after an ENTIRE 24 hour period. When the cyclist stops peddling, his watt average declines dramatically! Taking short breaks and occasionally coasting would mean that one really needs to average 140 to 150 watts, just in order to end up with an average of 110 !!”
"SolidWorks and COSMOS software helped us develop what we are convinced is a superior design from aerodynamic, mechanical, and ergonomic standpoints," said Designer Ben Eadie, owner of MountainWave Design Services in Calgary, Alberta, Canada, "but the proof will be laid down on the track."
Eadie optimized the vehicle's aerodynamics by creating a "virtual wind tunnel" with COSMOSFloWorks computational fluid dynamics analysis software. He accomplished this by calibrating COSMOSFloWorks settings for turbulence, relative density, percentage error, and interactive elements with the solid body. After testing a series of established human-powered vehicle designs, he settled on an entirely new design that tapers to a thin vertical wedge in the stern. This shape serves to part the air and gently reassemble it with minimal turbulence.
The vehicle's shape resembles that of a fish. "We didn't start out thinking fish, but when my designs follow nature, I always feel like I'm headed in the right direction," said Eadie. "Natural selection is probably the best design optimization process you can hope for." The virtual wind tunnel's findings correlated by more than 98 percent with calculations experienced on the track.
COSMOSWorks analysis software helped Eadie determine the amount of carbon fiber required for the shell design. It graphically highlighted hot spots that needed reinforcement and cold spots where a layer or two of fiber could safely be removed.
Eadie started the design process two and a half years ago with a photograph of Kolodziejzyk in a position that leveraged the powerful pedal stroke the triathlete had refined over thousands of miles of training. Eadie superimposed the photo onto a SolidWorks drawing, resulting in an ultra-efficient design allowing only single millimeters of clearance in all directions. The bike literally fits like a glove.
Eadie has used SolidWorks software since 1999 to develop Critical Power as well as more traditional recumbent bicycles and special projects ranging from hydrogen fuel cells to diaper-changing tables. "With every release SolidWorks continues to prove why it is the most robust 3D CAD tool for designing better products, whether in carbon fiber, structural steel, plastics, or sheet metal," Eadie said.
Added Kolodziejzyk, "I don't know where SolidWorks and COSMOS leave off and where Ben's expertise begins, but the machine is fast. Now it's all up to me."
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