The Impact Of Weight On Automobile Economy
Thursday, February 4, 2010 at 12:00PMAt Edison2 we pursue low weight as the first of two virtues to maximize efficiency in the automobile; the second is low aerodynamic drag.
One economy that accompanies a move to low weight is in the cost of materials. Low weight means not only less materials used, and hence lower production costs, but also lower maintenance costs, such as for brakes and tires (and roads).
The greatest savings with low weight is in energy consumption while driving. These savings are a function of the aerodynamic and resistance drag and the actual weight of the vehicle. Other factors include type of road, drive cycle (stop-and-go vs. highway) and vehicle features, which can be negative (air conditioning) or potentially beneficial (regenerative braking).
A heavier car can regenerate more energy with braking than a light car, and of course the more often brakes are used the more chances there are to recapture energy. Hybrid systems are most effective for buses and delivery trucks, which are heavy and stop frequently. On the other hand, if a car is used with very few stops the regeneration system is only added weight.
Conventional cars have become really heavy. Partly this is due to the weight of equipment needed to meet emissions and safety requirements, partly it is due to feature creep – the weight of motors and brackets for fully adjustable seats, for example – and partly because weight begets weight. The size and stress put upon each component of a car is a function of the total weight of a car; this is obvious in the need for a more powerful engine or larger brakes in a heavier car but the concept applies to many other vehicle parts.
Therefore is harder to take weight out of a car than to design a new one; the Very Light Car is light because it is light.
Reader Comments (2)
Compliments to the web site folks. Nicely done, but comment text is a little weak in the dark background.
On the subject of weight, you dismiss hybrid advantages a little too quickly. They are not limited to regenerative braking, which itself is a little under-credited. A fallacy there is that if the car makes very few stops, heavy vehicles are not so disadvantaged either, at least in respect to the inertial effects.
More importantly, the electric system makes it possible to much reduce the power output requirement for the engine. Acceleration for starting and passing, and hill climbing are burdens on the engine that force high horsepower capability which much of the time is not needed. If the intermittent power needs are provided from battery storage, then the engine needs only to supply the average power needs. Thus, it only has to be modestly higher in capacity than it would need to be for steady speed, level operation, such that battery power reserves would be assured.
A further advantage of electric apparatus is that it enables stabilizing arrangements so that the main weight can be positioned much lower than is conveniently done with a central engine. Of course, it the body is kept close to the ground, that might not be a problem, but the aerodynamic penalty of keeping the body close to the ground is huge -- like about 45% increase in Cd or more.
Aerodynamic drag force is far larger than rolling resistance force at higher speeds - - and it is important to note that most people, especially Americans have always insisted on going fast. For those of us who value our time, this is a real priority. And not only do we not like to ride butt-dragging puny, we also do not like dragging up in the rear. So, maybe more emphasis is due to aerodynamics than to weight (Note, I say emphasis; this is not to ignore weight).
A reminder to your aerodynamicist who actually knows this very well, but the drag coefficient of the airship (see USS Akron, Freeman, NAC reports, 1932) is .04 in free flow conditions. Check Morelli's paper, 1982 to see what has to be done to get a car to work that well when it is close to the ground, which is where we got the Morelli shape (aka the Aptera shape).
Look at details at www.miastrada.com to see how free flow conditions could be achievable. And no, it does not have to be as wide as an 18-wheeler.
I have some ideas, thank you for sharing, I really like
louis vuitton agendas bag or purse. Welcome to browse Louis Vuitton replica Cruise Collection handbag from our fabulous collection of Cruise Collection, these Louis Vuitton knockoff replica Louis Vuitton Agendas Collection are nothing short of excellence. We aim to provide our customers with high quality replica handbags of the latest spring and summer fashion so that they can fully display their glamour in this vigorous season, but with stunningly cheap prices that they would like to pay, and always come back for more. Pleased and satisfied customers are what we desire, and we firmly believe that our first-class service can satisfy all their louis vuitton cruise collection handbag needs.replica louis vuitton handbags cheap louis vuitton handbags discount louis vuitton handbagsluxury handbagwww.moodhandbags.comreplica louis vuitton handbagscheap louis vuitton handbagsdiscount louis vuitton handbagsluxury handbagwww.iv-bag.comThe fashion Louis Vuitton Cruise 2010 Collection bags and purses will bring you the newest fashion wind from the romantic south France.Our Louis Vuitton Damier Canvas is a perfect combination of classics and fashion, a vibrant mix of style and pleasure, offering you exact copies of the original LV handbags, wallets and purses. Those high quality replica Cruise Collection handbags will assure you of a cool and most welcomed change to your style, a change you certainly deserve. Please choose one of those exquisite bags offered in our fabulous louis vuitton damier canvas bag online outlet with fantastic discount. In addition, various other Louis Vuitton knockoffs are waiting for your visitation and selection.
mbt walking shoesmbt shoesdiscount mbt shoes