OT Interesting video - Page 11 - Cycling Mob: Road Cycling, Mountain Biking and More

01-20-2007, 11:58 AM

>> Actually the sources can be pinpointed pretty well. Certainly there
>> are lots of sources, but the lion's share of air pollution is from
>> motor vehicles.
>
>Given that air and air pollution are globally distributed and do not
>keep pollutants segregated, it is impossible to pinpoint sources in a
>practical way. "Hmm, that smells like pollution from a 1978 Chevy
>Caprice" is not really a doable proposition.

In th e U.S. at least, it's very practical to estimate what portion of the
overall pollution is from that 1978 Chevy Caprice.

Chris Neary
[Only registered and activated users can see links. ]

"Science, freedom, beauty, adventure: what more could
you ask of life? Bicycling combined all the elements I
loved" - Adapted from a quotation by Charles Lindbergh

01-20-2007, 12:26 PM

Mark Hickey writes:

>> As a classic car buff, I learned fast that total production is a
>> BIG factor in whether or not you can afford the thing. My Corvairs
>> went to nearly two million copies and many service parts are shared
>> with all Chevy sixes (1955~1980) so they are cheap to run and hop
>> up. Every piece you want is available and cheap. These mills are
>> currently powering brand new sport planes (November cover Sport
>> Flying) 38 years after 'death'.

> That reminds me of one of the actual real advantages of a rotary, at
> least for aircraft use. If you lose the cooling system on a
> water-cooled aircraft motor, you can get into big trouble - you
> won't get far before the piston engine gets too hot to continue
> running, and then if you're not within gliding distance of a
> suitable landing place, you're gonna make the evening news.

That sound like the introduction of the Wankel to cars, offering great
advantages that seem not to have materialized. In spite of the fewer
parts and claimed lighter weight, it does not compete economically
against the piston engine, from manufacture to life on the road.

> A rotary OTOH will continue to run virtually forever (at a somewhat
> reduced power level) until you can get the plane safely on the
> ground. It'll be a "throw-away" at that point, but would have
> potentially saved the aircraft and the pilot/passengers.

Could you explain how that works? This engine has a cooling problem
when working normally. I don't believe there is a working air cooled
version for that reason.

> Another benefit of the rotary is that they have a very smooth power
> output at the crankshaft. This has huge benefits for an aircraft,
> and the PSRU (Propeller Speed Reduction Unit) which gears down the
> prop speed allowing the engine to run in its efficient RPM range
> without sending the propeller tips into the (noisy and inefficient)
> supersonic range (that's the noise you hear when aerobatic planes do
> vertical dives). The lack of extreme "power pulses" puts a lot less
> stress on the PSRU and propeller (which can be destroyed by the
> pulsating power output of a piston engine in certain situations).

It has three ordinary power pulses per rotation of the rotor and has
an output roughly like a two-stroke per chamber.

[Only registered and activated users can see links. ]

# Unlike a piston engine, where the cylinder is cooled by the incoming
# charge after being heated by combustion, Wankel rotor housings are
# constantly heated on one side and cooled at the other, leading to
# very high local temperatures and unequal thermal expansion. This
# places high demands on the materials used. A further problem caused
# by the shape of the seals in Mazda engines is that carbon particles
# can become trapped between the seal and the casing, completely
# jamming the engine and requiring a partial stripdown to rectify.
# Such engines should never be started and run unless the engine will
# reach operating temperature; most such instances of jammed engines
# occur when a car is started and moved a few meters, e.g. from a
# garage to a driveway. In these situations it is better to manually
# push the car.

This is only a short piece of a fairly exhaustive and positive
analysis of the Wankel. After reading this, the question arises, why
these engines are not in general use. As I said, it sounds much like
the recumbent bicycle description. If it is really so good, why
aren't they taking over the market?

Jobst Brandt

01-20-2007, 12:28 PM

[Only registered and activated users can see links. ] wrote:
> Bill Sornson wrote:
>> Tom Keats wrote:
>>
>>> It's all my fault.
>>
>> Frank agrees! LOL
>>
>> (See, that's deceptive snipping. Oh, never mind...)
>
> Hmm. I _could_ point out that such "deception" would always be
> ineffective, because we can always read the thread to see exactly what
> was being said.

If that's the case, then why leave any quoted material at all?

> But if I pointed that out, it would be repetitious. We've told you
> this many, many times.

"We" have, Frank? You mean my betters, Mastah? LOL

> Furthermore, if I pointed that out, I'd be pretending you'll
> eventually learn. That's just too unrealistic.

Right, Frank, I just don't get this Usenet thing at all. Hope is gone.

> So, never mind! :-)

If only.

01-20-2007, 12:30 PM

In article <45b1c627$0$80118$[Only registered and activated users can see links. ]>,
[Only registered and activated users can see links. ] wrote:

> Matt O'Toole writes:
>
> >> You can't pinpoint current air quality problems from a single
> >> source or even a single nation. There are lots of contributors.
> >> Cars. Trucks. Coal fired powerplants. Industry.
>
> > Actually the sources can be pinpointed pretty well. Certainly there
> > are lots of sources, but the lion's share of air pollution is from
> > motor vehicles.
>
> I can recall when trains were pulled by steam engines that often
> belched huge plumes of thick black smoke. However, we had not yet
> experienced smog, although media mentioned it with respect to Los
> Angeles.

Los Angeles basin is smog central. The inhabitants
before the Spanish noted that cooking fire smoke
ascended ~1000 ft then spread horizontally.

--
Michael Press

01-20-2007, 01:01 PM

In article <[Only registered and activated users can see links. ]>,
Chris Neary <[Only registered and activated users can see links. ]> wrote:

> >> Actually the sources can be pinpointed pretty well. Certainly
> >> there are lots of sources, but the lion's share of air pollution
> >> is from motor vehicles.
> >
> >Given that air and air pollution are globally distributed and do not
> >keep pollutants segregated, it is impossible to pinpoint sources in
> >a practical way. "Hmm, that smells like pollution from a 1978 Chevy
> >Caprice" is not really a doable proposition.
>
> In th e U.S. at least, it's very practical to estimate what portion
> of the overall pollution is from that 1978 Chevy Caprice.

Really? Please demonstrate.

01-20-2007, 01:04 PM

In article <dMtsh.728185$5R2.506737@pd7urf3no>,
"nash" <[Only registered and activated users can see links. ]> wrote:

> "Tim McNamara" <[Only registered and activated users can see links. ]> wrote in message
> news:[Only registered and activated users can see links. ]...
> > In article <bnhsoe.mn6.ln@bud.garden.local>, [Only registered and activated users can see links. ]
> > (Tom Keats) wrote:
> >
> >> And it's their own air pollution they're complaining about.
> >
> > We all own the air pollution as we are all economically complicit
> > in its creation.
>
> I am not. But if you want to see how much pollution you create go to
> One Tonne Challenge. Averaged out we make 5 tons a year. Myself I
> only make 2 and that was before I stopped using transit to work. I
> am at home and only ride the bike as I have since I was 8. So my
> life time contribution has almost been nil to those averages of 5T/y

Congratulations. What you lack in pollution you make up for in self
righteousness.

Unless you eat a raw foraged diet, do not live in a heated home, do not
use electricity, do not buy consumer goods, do not have a job, etc., you
are economically implicit in the pollution of the Earth. Some people
have a marginally larger share than others. If you live in the United
States your pro-rated share is higher than any other group of people in
the world.

01-20-2007, 02:06 PM

[Only registered and activated users can see links. ] wrote:

> It is at the low partial power range that most automobile engines are
> operated and it is there that the diesel achieves its fuel economy.
> We don't drive with the pedal all the way, or even half way down to
> the floor, and that is where fuel economy shows up in the diesel.
>
> [Only registered and activated users can see links. ]
> [Only registered and activated users can see links. ] [Only registered and activated users can see links. ]
>
> To make up for that, I have seldom been in a diesel car where the
> owner didn't mention that the car is much smoother running than the
> older ones... but you can usually notice it or the subject wouldn't
> have been mentioned. The Germans have the best description of it:
> nageln and klingeln... driving nails, and bell ringing, quite aside
> from the vibration at low speed caused by a 20:1 compression ratio.

So if low vibrations are on top of your list the rotary engine comes
into play again. Sorry, could not resist, but I wonder if you had the
opportunity to drive an European car with one of the more recent Diesel
engines by Peugeot/Citroen or Volkswagen. They really do have much
improved and are very easy and nice to drive with high torque at low
RPM. It is not just fuel economy and lower fuel taxes for Diesel in
some countries but also the contentment of drivers that have led to a
market share of Diesel cars in Europe that already results in problems
for the petrol industry to produce the right mixture of Diesel and
gasoline. But until now your huge SUV's with low mileage take up the
extra gasoline :-)

x'post rec.bicycles.misc,rec.bicycles.tech
follow up to rec.bicycles.tech

Günther

01-20-2007, 02:07 PM

[Only registered and activated users can see links. ] hatte geschrieben:

> Peter Chisholm writes:
>
>>>> Isn't the RX-8 a rotary engine? And I owned a RX-2..2 plugs per
>>>> rotor, btw, not one.
>
>>> They are both in the same place and fire at the same time. Putting
>>> more of them there does not move the "combustion chamber" away from
>>> that hot spot.
>
>> I guess my point was the reference to how "Wankel' engines are both
>> dead and use 1 spark plug per rotor... but not dead and use 2...
>
> So if we used +4 spark plugs, it would have eight by your logic. It's
> not the number of gaps but that there is only one ignition point. I
> suppose the adverse shape of the combustion chamber made this design.

Not being an expert in the design of combustion engines I still can't
see why it should not be possible to redesign the engine with multiple
spark plugs and multiple injection nozzles for direct injection. This
might solve some of the problems inherent in this design. Technology
has evolved since the time of Wankel and the concept might well profit
from the more recent progress in conventional engines.

> So why do you suppose there aren't a wide variety of small or large
> cars offered with these engines?

Well, the automotive industry is conservative and has good reasons to be
so. So why there are no two-stroke engines with direct injection in
small cars? This technology is very interesting for low cost and low
weight vehicles. Still no major company sells it.

x'post rec.bicycles.misc,rec.bicycles.tech
follow up to rec.bicycles.tech

Günther

01-20-2007, 02:42 PM

>> In th e U.S. at least, it's very practical to estimate what portion
>> of the overall pollution is from that 1978 Chevy Caprice.
>
>Really? Please demonstrate.

Here's a report generated from 1999 data for Franklin County, Ohio, note the
section on "Mobile Sources":
[Only registered and activated users can see links. ]

Currently, there are just over 1 million motor vehicles in Franklin County
(Source: [Only registered and activated users can see links. ])

So our 1978 Chevy Caprice with Franklin County tags is responsible for
roughly 0.3 tons of CO, 0.06 tons NO2, etc. Assumptions made:

* Model discounts other mobile sources such as aircraft or off-road
vehicles, thereby overestimating the contribution from the Caprice

* Model assumes the Caprice creates pollution at the average rate for motor
vehicles, thereby underestimating the contribution from the Caprice

* Model assumes the Caprice is driven the average miles/year for the all
motor vehicles, which may over or underestimate the contribution from the
Caprice.

* Model is based on 1999 pollution data, which may over or underestimate the
contribution from the Caprice

You get the idea.

While some locations are more prone to absorbing pollution from other
regions (the Southern San Joaquin Valley comes to mind) in general the
significant sources of pollution are local.

Chris Neary
[Only registered and activated users can see links. ]

01-20-2007, 05:44 PM

In article <[Only registered and activated users can see links. ]>,
Chris Neary <[Only registered and activated users can see links. ]> wrote:

> >> In th e U.S. at least, it's very practical to estimate what
> >> portion of the overall pollution is from that 1978 Chevy Caprice.
> >
> >Really? Please demonstrate.
>
> Here's a report generated from 1999 data for Franklin County, Ohio,
> note the section on "Mobile Sources":
> [Only registered and activated users can see links. ]
> 39049#em issions_summary
>
> Currently, there are just over 1 million motor vehicles in Franklin
> County (Source: [Only registered and activated users can see links. ])
>
> So our 1978 Chevy Caprice with Franklin County tags is responsible
> for roughly 0.3 tons of CO, 0.06 tons NO2, etc. Assumptions made:
>
> * Model discounts other mobile sources such as aircraft or off-road
> vehicles, thereby overestimating the contribution from the Caprice
>
> * Model assumes the Caprice creates pollution at the average rate for
> motor vehicles, thereby underestimating the contribution from the
> Caprice
>
> * Model assumes the Caprice is driven the average miles/year for the
> all motor vehicles, which may over or underestimate the contribution
> from the Caprice.
>
> * Model is based on 1999 pollution data, which may over or
> underestimate the contribution from the Caprice
>
> You get the idea.

Yes. It can't be done.