Concept Model 02 Back-to-Back
Modeled by Jeff Bartels
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The back to back design has an advantage of frontal area. The front profile is minimal. Also, a single roll bar can protect both riders, saving weight. The rear person has to look to the rear, which may be a downside. A transmission has been designed (not pictured) which will allow the rear person to pedal forward, like a regular bike, in unison with the front rider to propel the HPV. A fairing has been designed by Simon, but it was not in the assembly when these images were created.  Isometric view. Notice the truss type frame. It is incredibly light and rigid.  Frontal view. The fairing will not be much wider than the handlebars, and the front wheels will have individual moving fairings to reduce frontal area.  Side view. The truss frame is not a final design. A few areas will be optimized.  A COSMOS simulation was run for about 1.5 hours to produce these results. The loads include two 600 lb riders (to account for basic predicted dynamic forces), a very high force exerted on the pedals (higher than the average person can put out), and a side force on the pedals. The result is a very strong frame. The maximum displacement of any point on the frame is less than 2 mm.  Side view of frame. It looks bad, but the magnitude of deformation is amplified to better interpret results. ©2006 Jeff Bartels 10/08/2006 (Back) |