On Sat, Jul 5, 2014 at 6:35 PM, Peri Hartman via EV <[email protected]> wrote:
> Really, as creative as it is, can it be more effective than a bicycle > mechanism? You'd be surprised. Any crank mechanism is rather limited in efficiency. At the top and bottom of the stroke it doesn't matter how hard you push - all the force goes into compressing/stretching the crank components (minimally) and none goes into moving the vehicle. You only get full efficiency at 90°. (What's the area under a sine curve, 60-some percent of a constant function? That's about the best you can hope for with linear input force.) Yes, a cyclist can apply rotary forces to the crank, and experienced cyclists do, but the human body just isn't kinesthesiologically configured to do this well. The leverage is all wrong. A rower gets much better efficiency in terms of the mechanism that puts power into motion, but that has its limitations too. (For example, it's one-way only.) Years ago I did preliminary development on an HPV to compete for the duPont prize (http://www.ihpva.org/land.htm) that ditched the traditional crank mechanism, and should be better than a rower. But then I detoured and went to college instead. That concept might make a killer recumbent bike. I've always wanted to follow through on that. Maybe in retirement.... Chris -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20140706/4c8b2613/attachment.htm> _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
