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Tyler Folsom

Apr 17, 2012


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"Bicycling Science" supports part of your idea. 10^3 mpg is possible; 10^4 is highly dubious. Steel on steel produces the lowest rolling resistance (if noise is acceptable). Above 20 kph, aerodynamic resistance is bigger than rolling resistance for a bike or HPV. The lighter the vehicle, the lower the speed at which aerodynamics dominates. The most aerodynamically efficient vehicle is tear-dropped shaped with minimal frontal area. For ultra-efficiency, the rider would have about as much space as in a coffin.

Brian Chow

Apr 18, 2012


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Tylerfolsom you have excellent points. The supine vehicle position shouldn't be a problem as long as the seat (more like a recliner) is comfortable. Wilson (3rd ed, p. 166) shows that a road bike at 4 mph has about 2,400 mpg equivalent. If the drag coefficient is cut by 80%, and the rolling resistance cut by a similar amount, this would mean that somewhere between 80-90% of power is saved in the locomotion, since at 4 mph the rolling resistance accounts for the majority of apparent friction. If we can assume for convenience the power is saved by a factor of 8 then the speed is doubled to around 8 mph, or 2,500 mpg at 8 mph. The value at 4 mph would certainly be greater than this, but alas it is not a practical speed. I have calculated my own bicycling trips to be somewhere in the range of 800-1300 mpg based on food consumption. Thus, if a vehicle can be made that can reach far beyond this efficiency, then 10^3 is easily achieved already as a starting point. Keep in mind that this solely relies on the efficiency of the human body, which thermally (correct me if I'm wrong) is app. in the 10-20% range (I can only recall Campbell-Reese-Mitchell and Bicycling Magazine). Thus if electric assists, regenerative braking, or wholly-electric systems (it is possible to combine the three as one) are used, the efficiency may be reaching the upper 10^3 mpg equivalent ranges, close to 10^4 mpg. Suppose a fossil fuel plant generates electricity with a thermal efficiency of roughly 40%. The electric transmission losses amount to 10%, and the battery storage another 20%, and the motor yet another 10%. The product of complements gives about 24%, which represents a figure better than typical human efficiency. Analogously the implementation of electric technologies has enabled road-based gas vehicle efficiency to jump from the 10^1 to 10^2 mpg orders. The electric technologies for ultra-light vehicles range from relatively developed, for e-bikes, to virtually infeasible, such as in regenerative braking. However with the efficiency of this system's vehicles the latter may be re-examined. Basically to sum it up, the technology starts with 10^3 just with raw human efficiency. With electrical technology integrated and developed, the vehicles should get closer to 10^4 mpg. That is where my rationale stems from. However, I am always open to comments and independent analyses which can show otherwise. If the case is compelling the description should be changed to reflect the better estimate.

2013transportationjudges 2013transportationjudges

Jul 24, 2013


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Thank you for your Climate CoLab contest entry. We appreciate your willingness to share your ideas and also the time and effort you put into developing a proposal and submitting it to the CoLab site. The Judges strongly considered your proposal and found that it was very novel and futuristic. Unfortunately, it has not advanced to the finalist round. We’ve posted feedback that we hope will be useful: - Sounds very novel and futuristic! - Monorail requires a completely new infrastructure; why is it necessary? - Proposal is very detailed and suggests significant impacts, but difficult to assess whether these impacts are realistic - Feasibility needs to be assessed more thoroughly - Essentially this is a proposal that involves significant infrastructural investment therefore needs to be analysed in much more detail We encourage you to stay involved in the Climate CoLab community. You can support and comment on proposals that have been named finalists and even volunteer to join one those teams if you have relevant expertise. We also encourage you to submit another proposal in the next round of contests, which will start in November 2013. If you have questions or concerns, please contact the CoLab staff at