> Slower acceleration leads to lower average speed. > Which leads to lower wind losses.
Not at tall. You can take all the time y ou want to get to 70 PMH, but it is not acceleration that is causing the wind loss, it is *speed*. The wind losses are proportional to the cube of *speed* period. You can accelerate to a high speed or you can coast down a hill, in either case, it is *speed* that is the only variable we are talking about there. The fact that acceleration causes speed is a second-order effect. And just confuses the layman.... Bob -----Original Message----- From: Willie2 [mailto:wmckem...@gmail.com] Sent: Thursday, November 06, 2014 9:51 AM To: Robert Bruninga; Electric Vehicle Discussion List Subject: Re: [EVDL] Range vs Speed Generally, correct. On 11/06/2014 07:49 AM, Robert Bruninga via EV wrote: > Energy used in driving is simple physics: > > Everything you put into acceleration you get back in Momentum. > Everything you put into a hill, you get back as potential energy. > Everything you put into braking is LOST (regen gains some back). > Wind resistance goes up as the cube of speed. True, but.... I believe, per unit distance traveled, energy lost to wind friction goes up with the square of the speed. That is, in a given amount of time, you cover more distance at high speed than at lower. You experience the higher wind resistance for a shorter period of time. > > So the only real control you have over energy is keeping the speed > (wind > resistance) down. > > Gas cars are actually MORE efficient at high acceleration when the > throttle plate is wide open and the pumping losses are minimized. So > creeping away from a traffic light does not really gain anything. > BUT, if it is a typical gas car and the engine then keeps running > during the coast phase, that too is 100% waste (engine running but doing nothing). > > When people say go "light on the accelerator" they are not talking > about the rate of acceleration at all. They are talking about DON'T > OVER ACCELERATE beyond what it takes to coast to the next stop without > having to use the brakes. Slower acceleration leads leads to lower average speed. Which leads to lower wind losses. _______________________________________________ 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)
