Being that these older vans (mine is a G10 from the early 80s) are so not aerodynamic, shouldn't there be a way of utilizing the oncoming wind (through a series of fans mounted strategically on the front, sides and roof of the vehicle) to increase the amount of mileage you get from a gallon?
Sure sounds like a perpetual motion device to me.
The electric motor in a hybrid assists the ic engine. Why can't wind generators do the same?
JustMe wrote in news:b18cf2fd-9852-4e68- snipped-for-privacy@a1g2000hsb.googlegroups.com:
You probably could do that, but would the gains outweigh the costs? Look how expensive gas/electric hybrids are compared to regular cars.
Plus, how big would those fans have to be in order to generate enough torque to drive a generator at the speeds you'd actually drive? Those giant bird-chopper turbine blades you see at "wind farms" are that big for a big reason.
In article , Tegger wrote:
But of course, the point is moot - There just isn't any way to make it "pay off".
Where is the energy that turns these hypothetical fans coming from?
Unless you're always driving into the wind (the wind one would measure if one were sitting still, not that caused by the fact that you're in motion) then the "wind" driving the fan(s) is a direct result of the engine burning fuel and moving the vehicle. Which means that, if any, the juice made by a generator attached to the fan is going to be the result of burning fuel, with AT LEAST three layers of lossy conversion between the gasoline and any "help" that might be created - Burning fuel to spin the engine - Conversion 1. And a pretty inefficient conversion, at that. Rotation of engine converted to forward motion - Conversion 2. Also lossy, if only (and it's *NOT* "only", but for the sake of simplicity, let's ignore that fact) due to friction in the gear-train that takes the rotation from the engine to the tires. Relative motion of the vehicle pushing through the (relatively) still air - Conversion 3. Even worse losses there to MANY factors - friction, turbulence, possibly even the fact that the wind is from behind, and therefore cuts the effective speed that the fan blades "see". The inefficiency of the pseudo-wind as it tries to drive the fan blades is going to introduce even more loss. The frictional losses to the shaft bearings of both fan and generator (and let's skip how much MORE loss will come from trying to multiply the speed of the fan through gearing or belts/pulleys if somebody mistakenly thinks that might make up for all the losses so far...) and finally, the losses of converting the rotation of the fan(s) into electricity in the genny, etc, etc, etc...
In a nutshell, you'd be better off, if only from a "conversion losses" standpoint, by simply driving a genny straight off the engine - Which pretty well defeats the purpose of using fans/turbines to try to help with gas consumption.
The important point here is, that in order to get some additional energy out of the wind, for a non-aerodynamic car, one needs to /replace/ the drag force with fan spinning force. If you just add fans and whatever, for example on the roof, if this increases the total drag, it will /not/ produce any improvement - exactly for the conversion reasons that Don Bruder outlines. If one wants improved efficiency by fan generators, one must keep the total aerodynamic drag the same. This can happen only if you decrease the drag of the car itself - by installing an aerodynamic snout, for instance - and catch the wind in a fan inlet, so the total drag stays the same. But, by the same Don Bruder reasoning, it will be even better if you just install an aerodynamic snout and spoilers, and do /not/ install any fans. This will insure maximum improvement in gas mileage.
Difference between dissipative and non-dissipative forces. The generator part of a hybrid has very low losses (generators and electric motors can be VERY efficient). Unfortunately, a wind turbine has some drag of its own, and it is almost impossible for the design of a wind turbine to reduce the inherent drag of the vehicle (the inherent drag CANNOT be recovered).
Another way to look at this. Regenerative braking does NOT recover the energy from normal coasting, only that due to braking. It is replacing the normally dissipative friction brake with a generator. When you use a generator do generate electricity, the torque needed to turn the generator increases greatly. This increased torque is used as a brake. The energy involved in the braking is recovered as electricity that CAN be stored in a battery.
Note that a Prius has a very low drag coefficient. One cannot make a very good hybrid from a car with a lot of aero drag (or ANY form of drag).
Why not put up a mast and a sail?
"Steve Austin" wrote
Line 3+4... "oncoming wind". Great for backing up, not so good for going forward.
In article , "MasterBlaster" > > wind (through a series of fans mounted strategically on the front,
What? You never heard of sailboats tacking into the wind? :)
Honest, Ossifer... I'm not as think as you drunk I am. I wan't weaving back-n-forth-n-back-n-forth... *hic* across 4 lanes of traffic 'cause of the 14 beers, I was, umm... tacking into the wind, yeah, that's it!
In article , "MasterBlaster" I wan't weaving back-n-forth-n-back-n-forth... *hic* across 4 lanes
Ahhh, how refreshing! Somebody got it! :)
Chop it, slam it, and flame it.
Guaranteed to increase its fuel economy. The trade offs? Lousy head room... reduced load carrying capacity... lousy ride on anything but billiard table smooth roads... some chicks don't find large flame decals appealing.
On Aug 10, 3:10 am, Patok wrote:
Nothing is free. The cooling system on light aircraft involves air flowing into openings behind the propeller, through the engine's cooling fins and so on, and out the bottom. The whole thing is designed to create a high-pressure zone on top of the engine and a low-pressure zone beneath. Funny thing is that when the bottom opening is closed when the engine doesn't need all that airflow, the airplane's overall drag decreases and it goes faster. Air going around the cowling creates less drag than that going through the cooling system, since the cooling system reduces the airspeed of that air. Adding a fan to the front of a vehicle will gain absolutely nothing except more drag. There are better ways available that cost much less and make more sense: shaping the car properly is one. Strangely, I don't see many cars with tapered-off rear ends; most of them are chopped-off rather square, something a pilot recognizes as a big source of drag. Is it unfashionable or something to have a tapered- off tail? Getting the air that was divided by the car's approach to flow back together with a minimum of turbulence is the key here, and we can see that principle used on all aircraft wings, fuselages and tails. More drag: those phony little wings and spoilers we see on some cars. Fashion over function, again, indicating that the marketing guys often have the last word over the engineers.
snipped-for-privacy@r66g2000hsg.googlegroups.com:
True. The Kamm tail is not better than the "shape of least resistance," the optimum shape. However, the Kamm tail will make a lighter, more practical car. The difference in drag is small.
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