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'[TECH]:: Fuel efficient vehicles'
2008\12\15@015516 by apptech

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Hijacked from thread: [OT] Economy is not in a bad state

From: "Danny Miller" <spam_OUTdannymTakeThisOuTspamaustin.rr.com>
> The Goodwin guy makes a lot of claims.  Most of which don't seem to be
> possible from an engineering standpoint.  For example, a 1960 Lincoln
> Continental cannot be made astoundingly more efficient because it's got
> so much weight, rolling resistance, and drag.  You can't reduce that
> very much without changing the exterior and frame at which point it's no
> longer a 1960 Lincoln Continental.

I hadn't looked at the website(s) but had my severe doubts.
I still haven't and still do.

Rolling resistance can be reduced to almost nothing with enough
engineering - and isn't too bad already in most cars.

The overwhelming energy loss at speed is drag.
Drag increases with the CUBE of velocity.
Travelling at half the speed reduces your drag losses by a factor of 8.
There's a fuel efficieny clue.

Here's an old rule of thumb which is very useful.

       "It takes 30 HP to ton"

ie a motorcyle with a beleathered rider well tucked in can reach 100 mph
with 30 HP.
You can then play with frontal area and Cd (drag coefficint) to reach some
reasonably decent results.

Drag = 0.5 x Cd x Rho x A x V^2.

      Drag = Newtons or arcane measure of your choice
     Cd = drag coefficient = 1 for flat plate
     Rho =~ air density = 1.3 kG/m^3 for air.
     A = frontal area
     V = velocity

Energy = Force x distance.
Power = Energy/time.
V = distance/time, so
Power = V x Drag, so ....

  Power =  0.5 x Cd x A x V^3 Watts

Plugging in some ISO whatever units as a sanity check.
100 kph ~= 30 m/s
3 m^2 frontal area
Cd = 0.5

Power = 0.5 x 0.5  x 3 x 30^3 =~ 20 kW = 27 HP.

Let's try the 100 mph motorcycle.

100 mph = 44.4 m/s
A = 1 m^2 say
Cd = 0.4 say

Power = 22.8 kW = 29.9 HP.

:-)

I didn't cook it. Honest! Really.
Obviously some assumptions must be wrong :-).

So.
*IF* said Lincoln is not presently getting hot wheel bearings or super super
hot tyres then there is no way to achieve the gains that are claimed.

Sadly.

> So he must be claiming that he's
> going to make a power plant that is 4x-5x more efficient, which is
> difficult since that would probably exceed even the theoretical
> thermodynamic efficiency limit of internal combustion.  Ah good luck
> with that.

In fact it would exceed absolute available energy.
An auto engine currently gets around 2x% afaik.



  Russell




2008\12\15@030322 by William \Chops\ Westfield

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On Dec 14, 2008, at 10:54 PM, apptech wrote:

> I hadn't looked at the website(s) but had my severe doubts.

Supposedly turbine-electric hybrid with supercaps.  A turbine charges  
batteries and/or supercaps, and the electric motor provides motive  
power.  Turbines are supposed to be more efficient than IC engines,  
right?  I too have severe doubts, though.

Of course, if what they really mean is that it gets 100mpg, not  
including plugging it into the wall every night to max out the main  
batteries, they wouldn't be the only ones making such misleading  
claims (or questionable "conservation" decision.)

But the energy crisis is over, right?  Gas (in the US) is back down  
below $2/gallon, people will be driving their Hummers again, and the  
US automakers just need short loans of a couple 10s of billions of  
dollars until people start buying the same old gas guzzlers again...

BillW

2008\12\15@041852 by Vitaliy

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"William "Chops" Westfield wrote:
> But the energy crisis is over, right?  Gas (in the US) is back down
> below $2/gallon,

$1.55/gal in Phoenix. Can't remember the last time I saw gas at this price.


> people will be driving their Hummers again, and the
> US automakers just need short loans of a couple 10s of billions of
> dollars until people start buying the same old gas guzzlers again...

OPEC should adjust their policies to make things normal again. There are too
many governments that based their budgets on the $100/barrel price, and are
currently running deficits.

Vitaliy

2008\12\15@091950 by Neil Cherry

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William "Chops" Westfield wrote:

> But the energy crisis is over, right?  Gas (in the US) is back down  
> below $2/gallon, people will be driving their Hummers again, and the  
> US automakers just need short loans of a couple 10s of billions of  
> dollars until people start buying the same old gas guzzlers again...

Nah this is just Bush's last parting shot, he wants history to
think better of him. ;-)

Now I'll run and hide as the conspiracy theorists come out of the
wood work. ;-)

--
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http://www.linuxha.com/                         Main site
http://linuxha.blogspot.com/                    My HA Blog
Author of:            Linux Smart Homes For Dummies

2008\12\15@124948 by M.L.
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On Mon, Dec 15, 2008 at 1:54 AM, apptech <apptechspamKILLspamparadise.net.nz> wrote:

> The overwhelming energy loss at speed is drag.
> Drag increases with the CUBE of velocity.
> Travelling at half the speed reduces your drag losses by a factor of 8.
...
>
> Drag = 0.5 x Cd x Rho x A x V^2.


I'm unsure how you went from **3 in your text to **2 in your equation.
I have been under the impression that as the speed increased, as did
the exponent
2 --> 3(+?)

-
ML

2008\12\15@165320 by Sean Breheny

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I think that the formula below is a formula for drag FORCE, not power.
The power needed to maintain speed against this drag force is v*force,
which would raise the exponent on V to 3.

Sean


On Mon, Dec 15, 2008 at 12:49 PM, M.L. <.....mKILLspamspam.....lkeng.net> wrote:
{Quote hidden}

> -

2008\12\15@172102 by Danny Miller

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Well there's the Capstone Microturbine, which has a built-in generator
head and has no mechanical shaft output.  AFAIK they're
state-of-the-art.  Its stated efficiency they keep quoting (like 80%) is
for "cogeneration", water heating plus electrical output.  MOST of that
is water heat you have no use for so this is not even a relevant
number.  A piston engine could be 80%-90% "efficient" like that too if
you just ran the exhaust through a heat exchanger.

The actual electrical efficiency is there, and should yield gains, but
not ENORMOUSLY higher than piston engines.  The cycle efficiency of
batteries and the motor efficiency are their own issues.

The Capstone Microturbine was used in a fleet of hybrid buses for
awhile, but the project was not entirely "successful" and they have
since been scrapped.  I don't know the reasons.  I've seen the buses'
Capstones on eBay before.

So if that Johnathan Goodwin dude wants to say he's going to using an
outstanding new small turbine technology, great... what brand and why
haven't we heard about it.  Something that verifies his plans instead of
these claims of "all sorts of tweaks and mods".  He doesn't seem to be
the type to invent a new turbine tech all on his own then only use it to
power a single vehicle.

Danny

William "Chops" Westfield wrote:
{Quote hidden}

2008\12\15@213649 by microsoftwarecontrol

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I checked my car. It is running at too rich codition and using 20% more gas.

!t not make engine light on, only reduce mileage per filling tank.

I read, o2 sensor can decade!
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2008\12\15@221936 by Bob Blick

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microsoftwarecontrol wrote:
> I checked my car. It is running at too rich codition and using 20% more gas.
>
> !t not make engine light on, only reduce mileage per filling tank.
>
> I read, o2 sensor can decade!

What test did you perform to determine it is running too rich?

Because if an O2 sensor is bad enough to change the mixture, it is
likely bad enough to trigger the check engine light an any fuel injected
car.

Mileage is a poor indicator of mixture. Anything can affect the mileage.
Snow. Alcohol in the fuel. The nut behind the wheel.

Cheerful regards,

Bob

2008\12\15@223259 by apptech

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>> The overwhelming energy loss at speed is drag.
>> Drag increases with the CUBE of velocity.
>> Travelling at half the speed reduces your drag losses by a factor of 8.
> ...
>>
>> Drag = 0.5 x Cd x Rho x A x V^2.

> I'm unsure how you went from **3 in your text to **2 in your equation.
> I have been under the impression that as the speed increased, as did
> the exponent
> 2 --> 3(+?)

Typo.
Read th erest and it should be clear enough.
POWER rises with V^3.
Drag with V^2.
Interestingly energy for a given distance travelled rises with V^2 and not
V^3 (self evidently on consideration) as the more V you have the less time
it takes.


  Russell

2008\12\16@091638 by Carl Denk

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We recently had on 2 occasions where after filling up, the mileage on
our 2002 Cougar went down to 26 MPG, and remained there several
tankfuls, and the after taking on fuel at a  certain brand station in
Ohio, mileage went back to normal. This is on a 700 mile trip that we do
frequently with usual fuel stops. The vehicle's on board instantaneous
and average mileage computer readings were confirmed when our first fuel
stop was 60 miles short of our usual stop. I blame it on poor quality
fuel which likely was gasohol.

Briggs & Stratton Engine have a $8 alcohol percentage checker, it is
basically a calibrated cup that one adds water.

Bob Blick wrote:
{Quote hidden}

2008\12\16@122125 by microsoftwarecontrol

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my car suddenly eaten quater more gas, till now!

o2 sensor decade should be over 25%, to trig engine light!
I guess lots car driving in front of you, give you so bad gas smell, is due
to o2 decade.

it seems, car fule/air control loop is not "advanced" one.
Now I believe, it works like this: air flow mass / 14.7  is fuel amount;
then o2 sensor make
second adjustment, output: fuel trim.

it is easy to put a pic to correct o2 decade in output voltage.


{Original Message removed}

2008\12\16@133443 by Brooke Clarke

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Hi:

There is another factor to fuel economy besides aerodynamic drag and that's the
rolling resistance of the tires.  Larger diameter tires have lower rolling
resistance than smaller tires.  This is different than the coefficient of
friction of the tire that relates cornering and the power needed to smoke the
tires.  Under inflated tires result in wasted gas.

Gas engines have a "throttle" that creates a vacuum in the intake manifold to
slow down the engine.  It takes horsepower to overcome that vacuum.  A diesel
engine does not use a throttle and uses a different chemical cycle so is more
efficient, hence their use for commercial vehicles.  The energy in a liquid
fuel is closely related to it's density.  Maybe a measuring cup and scale are
need to shop for fuel?

A basic computer program that uses numerical integration to determine the 1/4
mile elapsed time and velocity is on web page:
http://www.prc68.com/I/CSX3282.shtml#ET
Tire growth with speed is also included so the program works for AA Fuel dragsters.

The vehicle description gives an idea of the factors needed:
http://www.prc68.com/I/Images/Cob_RMB1.txt
http://www.prc68.com/I/Images/Cob_RMB2.txt < vehicle description
http://www.prc68.com/I/Images/Cob_RMB3.txt
http://www.prc68.com/I/Images/Cob_RMB4.txt
http://www.prc68.com/I/Images/Cob_RMB5.txt
http://www.prc68.com/I/Images/Cob_RMB6.txt
output
http://www.prc68.com/I/Images/Cob_RMBas.jpg
http://www.prc68.com/I/Images/Cob_RMBbs.jpg
http://www.prc68.com/I/Images/Cob_RMBcs.jpg

--
Have Fun,

Brooke Clarke
http://www.prc68.com

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