Physics defying motorcycleSubscribe to this blog RSS Feed
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    1 of 4
    Sitwon
    10 years ago
    http://www.kickstarter.com/projects/windcycleev/electri...

    If you listen to his description of how he plans to use turbines mounted on the side of the bike to help recharge the battery while you ride... I'm pretty sure that would violate the laws of physics. Still, electric bikes are the next big thing, right? 
    2 of 4
    rshaug
    10 years ago
    Almost really interesting There isn't any defying of physics going on that I could see but they are certainly going to be bitten by some electromechanical truths and some Newtonian physics reminders. Placing small wind turbines into the airflow on the bike could absolutely generate electricity. The problem they are going to face is the amount of electricity that can be generated. The amount of power required for an application like this tends to be a lot more than people realize. The recent movie about the electric bikes in the Isle of Man TT that is in another thread provides a number of examples of the challenges involved.

    Driving relatively large motors for transportation take some rather high amperage at fairly high voltage. Using a mid-range Agni motor as an example (the model 135): max voltage is about 80V and pushing a whopping 170 Amps! giving around 13kW of power which is only about 18HP. that would take a mighty wind indeed.
    3 of 4
    Sitwon
    10 years ago
    Regardless of where on the bike they place the turbines, I find it unlikely that the electricity generated by the turbines would be equal to or greater than the additional power draw required to overcome the drag of the turbines. Small turbines don't generate a whole lot of power, and they aren't particularly efficient.



    We could simplify this down to an alternator and a motor. Let's say you have an alternator hooked up to a battery to charge it. In order to turn the alternator you attach an electric motor that draws power from the same battery. The energy required to turn the alternator is greater than the energy output of the alternator, so the battery will only decrease in charge, never increase. Prolonging the battery life by increasing the load on the engine and decreasing its efficiency sounds like broken physics to me.
    4 of 4
    rshaug
    10 years ago
    at the least it's an exercise in negative efficiency