warren@ihnss.UUCP (Warren Montgomery) (06/19/84)
(Fuel for the flamethrowers) I beg to differ with a recent posting (on the 55mph limit) claiming the fuel shortage to be the biggest farce ever. It is still true that the world is using up ~40M barrels/day of oil. Virtually no new oil is being created, and the rate of use still exceeds the rate at which new deposits are being discovered. We may have pushed too hard on the panic button 11 years ago, but barring some unforseen scientific discovery, sooner or later the world will run out of gas. The dates for this remain about the same as were envisioned 11 years ago as well (some time early next century). Please don't confuse the factors that drive the short term panic/glut reaction cycle with the long term problem. I don't like the 55mph limit any better than you do, and I don't know if it saves gas in the country as a whole (It did make a significant difference in my Toyota, which did noticably better on tires as well as gas when I stopped driving at 70-75), but I wish people would stop trying to promote the view that there is no energy problem and no reason to conserve gas as an argument against the 55mph limit. -- Warren Montgomery ihnss!warren IH x2494
knutson@ut-ngp.UUCP (06/19/84)
Yes, you may have better gas mileage at 55 compared to 75, but did you notice that your Toyota also gets better gas mileage at 62 than it does at 55? Ours does. This was verified by a trip from Central Texas to the Virginia coast and back. The average distance was about 3 mpg. It's not much but every bit helps. The real point is that the technology exists now to produce cars and engines that have better gas mileage at 70, 80, 90, ... than they do at 55. Todays cars are designed for running best at somewhere close to 55 so obviously they do worse at 70. If the speed limit is switched back to 75 or above then auto manufactures will just change the design a little and now you have a fuel efficient car running at 75. Now, why don't we discuss why we don't go the autobahn method of unlimited or nearly unlimited speeds on limited access divided highways. Another reason for the 55 speed limit was the death rate. However, this was partly due to crossing lanes into oncoming traffic on the old highway system where highways were not yet divided and colliding head on with another car. The other factor in deaths was drunk driving and such which had nothing to do with the speed limit. Since we now have divided highways, that should eliminate the problem of head on collisions. That just leaves adverse weather and drunks. Drunks have nothing to do with the speed limit and anyone doing 70+ mph in a downpour deserves to slide off the road.
mth@drutx.UUCP (Hamilton) (06/20/84)
If there is, or is going to be, a fuel shortage; Where are all those 100 MPG carbs? Probably still on the corporate shelf of Exxon or ??? Mark Hamilton Denver, CO
bees@drutx.UUCP (DavisRB) (06/20/84)
If speed traps were converted to tire pressure traps to insure that everyone kept their tires properly inflated, we would save more fuel than reducing the speed limit. Ray Davis
ziegler@lzmi.UUCP (06/21/84)
> If there is, or is going to be, a fuel shortage; > > Where are all those 100 MPG carbs? Probably still > on the corporate shelf of Exxon or ??? I've got one of those 100 MPG carbs right here that I'll sell to you. I also can get you a great deal on a bridge in Brooklyn and some ocean-front property in Arizona! I don't have the little smiley face on that, because I assume everyone can recognize it as sarcasm. If you're looking for a miracle engine fix to end all our oil problems, FORGET IT! There ain't no such thing. Exxon, or any other oil company would just love to sell you a device to get 100 MPG. Then they'd just jack up their gas prices to cover the loss in volume. It's much easier and more profitable for them that way, and you'd end up paying less in dollars per mile, so everybody would be happy. I'm surprised people still believe these crazy stories. Joe Ziegler {ihnp4, hogpc}!pegasus!lzmi!ziegler
piety@hplabs.UUCP (Bob Piety) (06/21/84)
Talk of "100 MPG carburetors" annoys me! Has anyone calculated the energy contained in a gallon of fuel compared with the energy required to overcome friction, wind resistance, etc??? A carburetor is hardly the weak link, folks! from the 100 MPG keyboard of Bob
tbul@trsvax.UUCP (06/21/84)
#R:ihnss:-210400:trsvax:55200080:000:241 trsvax!tbul Jun 21 12:10:00 1984 Just a few figures for all you over 55 mph, ah, people. Your chances of surviving an accident at 70-75 mph is 50-50. At 55-60 mph, the chances of surviving are raised to 31 to 1. (I am one of those old fashioned people who obeys the law.)
chim@ncsu.UUCP (06/21/84)
100mpg carburetors may be too optimistic but >70 mpg carburetors are not. There was some gentleman in the state of Washington that had such an animal. The gas mileage was not the problem with the carburetor, it was safety. From the newspaper article I read on the topic, a gasoline preheater was used. By the time it got to the air-fuel mixture chamber, a manufacturer would have been crazy to literally or figuratively stand behind the product. The inventor developed it, and, according to the article, the carburetor got incredible mileage. But who wants a carburetor that may cause a gasoline explosion. Bill Chimiak
tron@fluke.UUCP (Peter F. Barbee) (06/23/84)
Two items of disagreement (I agree that 55 stinks but not for the same reasons)
1) The major drag force at speed (anything over 45 or so) is aerodynamic drag.
This force is proportional to the velocity squared. I know that the
effective coefficient of drag is, for many new cars, much lower than it
used to be but this doesn't change the fact that the drag force is increasing more than the velocity. Let's look at some facts;
F= cd * A * p * V**2 / 2 where F = drag force
cd = coefficient of drag
A = projected area
p = fluid density
V = velocity
now let's compare the following situations;
car 1 : cd=.45 , V=24 meters/sec (55mph)
car 2 : cd=.32 , V=34 m/s (75 mph) , and A= .85*A of 1
so .45(24**2)/2 * Ap = F (car 1) = 129.6 Ap
and .32(34**2).85/2 * Ap = F (car 2) = 157.22 Ap
I believe car 1 is representative of older cars, say a '75 Nova, and
car 2 is a similarly sized (interior room) modern aerodynamic car. I
did not take engine friction, or wheel bearing friction, or tire friction
into account as they increase linearly with velocity. Also note that the
velocity here is relative free steam velocity, so the situation is worse
witha headwind, and better with a tailwind.
2) It seems obvious that in the event of an accident more damage will be
done if the cars are going faster. They simply have more stored energy
(call it inertia, potential energy, or momentum) to dissipate. Since
many accidents occur with both cars going the same direction you could
argue that it's the relative speed that mattered but I disagree. Usually
the cars will come to a stop, they are usually out of control, and therefore
are likely to hit something. I can also mention the effects of reaction
time, you travel farther (27%) in a given time at 75 than at 55. I don't
think many more accidents would occur if the limit were raised, I just
think they would be worse.
Peter Barbee
decvax-+-uw-beaver-+
ihnp4--+ allegra-+
ucbvax----lbl-csam-+--fluke!tron
sun-+
ssc-vax-+knutson@ut-ngp.UUCP (Jim Knutson) (06/26/84)
I would have to say, the analysis by Peter Barbee was rather well done.
However, I have to disagree with a few points.
First of all, I think cars on the highway today tend to be smaller than
the .85 of a Chevy Nova. Secondly, the .32 drag coefficient could be brought
down even further if the public didn't mind the shape of the new cars.
Now, if we took the Honda CRX as an example of what is happening now, we
get:
car 3 (CRX) : cd=.32 , V=34 m/s (75 mph) , and A= .65*A of 1 (Nova)
so .32(34**2).65/2 * Ap = F (car 3) = 120.22 Ap
which is less than the Nova at 55mph. Now we can all argue facts and figures
all day long, but the idea is that smaller and slippery cars are making
he 75 speed limit viable.ciampa@wivax.UUCP (Robert Ciampa) (06/27/84)
At 55-60mph chances of surviving 31 to 1?????
I think your statistician should have his calculator
checked. Unfortunately, I've been a witness to too
many fatal accidents at that speed to take it
seriously.
--
Robert A. Ciampa {apollo, cadmus, decvax, linus, masscomp}!wivax!ciampa
Wang Institute (617) 649-9731 x372