OT Interesting video

On 2007-01-19, [email hidden] <[email hidden]> wrote:
[snip]

Quoted message said:

At the time I mentioned to the engineers to mark my words, that this
engine will not survive, to their utter amazement... and that of all
the others who wanted to believe in it. My thermodynamics Professor
had shown us running rotary prototypes in the lab from years past and
explained why they cannot work. They all have the same feet of clay
as they address only the mechanical part of the machine and fail to
see that this is a heat engine and thermodynamics its main focus.

Essentially one spark plug for multiple rotating combustion chambers
is what kills it. At the spark plug, temperatures in the 1000's degF
occur if the engine has any reasonable efficiency, while the intake
zone is below freezing (carburetor icing). Both areas remain a steady
state.

Interesting point, so do you mean the engine casing around the spark
plug is what heats up, effectively warming the fuel/air mixture before
it's ignited?

Whereas in a four-cylinder engine, the area around the plug and the
plug itself get a chance to cool down while the other three cylinders
take their turns?

Quoted message said:

It's the reciprocation that makes it work. We use aluminum pistons in
a mundane engine block with steel valves that see temperatures from
freezing to flaming in one cycle. The average temperature when seen
through a boundary layer of gas is mundane. Meanwhile the Wankel
burns up! To make it work, compression had to be low giving poor
performance, requiring higher engine speed to make up for that poor
performance. The result is a short lived machine with poor fuel
economy.

I assumed the low compression ratio was a consequence of the difficulty
of sealing the things. Although the Wankel engine seems simpler in
concept, when you add the requirement of keeping lubricant and
combustion materials where they're supposed to be and not where they're
not, a four-stroke piston engine with a head gasket suddenly starts to
look almost like the more elegant solution.

You also have to consider the amount of effort that has gone into
optimizing the piston engine over the years. Things like subtle changes
in the intake port design to make the gas swirl around and burn just
right. It seems like all that needs to be done again for the Wankel, and
only Mazda (and Norton?) are working on it.

In article <[email hidden]>,

Quoted message said:

Michael Press said:

Quoted message said:

> But how about this concept:

http://www.starrotor.com/Engine.htm

Quoted message said:

Quoted message said:

After gazing at hundreds of "miracle engine" articles over the
years, I've decided to ignore any reports that don't include tests
of working models. The only one of those hundreds of designs that
gained any traction was the Wankel, and it didn't set the world on
fire.

Quoted message said:

Essentially one spark plug for multiple rotating combustion chambers
is what kills it. At the spark plug, temperatures in the 1000's degF
occur if the engine has any reasonable efficiency, while the intake
zone is below freezing (carburetor icing). Both areas remain a steady
state.

It's the reciprocation that makes it work. We use aluminum pistons in
a mundane engine block with steel valves that see temperatures from
freezing to flaming in one cycle. The average temperature when seen
through a boundary layer of gas is mundane. Meanwhile the Wankel
burns up! To make it work, compression had to be low giving poor
performance, requiring higher engine speed to make up for that poor
performance. The result is a short lived machine with poor fuel
economy.

Quoted message said:

The Wankel is dead!

E pur si muove:

http://www.mazda.co.uk/Showroom/RX-8/

--
Ryan Cousineau [email hidden] http://www.wiredcola.com/
"I don't want kids who are thinking about going into mathematics
to think that they have to take drugs to succeed." -Paul Erdos

In rec.bicycles.tech said:

Bill Westphal said:

Quoted message said:

> BTW, a lot of people laugh at 43 about his pronunciation of the
> word "nuclear", and I did too (quietly) when I joined the nuclear
> navy and noticed some highly educated people doing the same, until
> I figured out that's the legitimate pronunciation on the east
> coast, or at least in parts of it.... never thought I'd be
> defending him!

http://en.wikipedia.org/wiki/Alfa_class_submarine

Quoted message said:

Quoted message said:

That's interesting. What do these people say when they discuss
nucleation and that the nucleus of an atom does thus and so. It
seems to me to be much line the people who cannot say length or
strength, saying lenth and strenth instead. I'm nut sure they have
the musical ear to discern the difference.

Quoted message said:

You got me curious. These were Naval Academy grads and full-fledged
navy nuclear officers (as all submarine officers are). And they
were otherwise normal, with no other speaking anomalies. And I
recall they were easterners, although most other easterners
pronounced it normally, and I never brought it up because no one
ever blinked an eye, and I thought maybe I was off-kilter, so I just
accepted it, and went with my theory all these years. But Wiki (via
Bartleby) has another interesting theory. I didn't realize
Eisenhower, Reagan, AND Carter had the same "affliction" (according
to Bartleby). (And Carter was a Navy Submarine nuke officer
himself.)

http://en.wiktionary.org/wiki/nuclear

That article doesn't answer my question or say that these people are
otherwise linguistically skilled.

Let me add Meriam Websters take on it, from the "nuclear" entry:

usage: Though disapproved of by many, pronunciations ending in
\-ky&-l&r\ have been found in widespread use among educated speakers
including scientists, lawyers, professors, congressmen, United States
cabinet members, and at least two United States presidents and one
vice president. While most common in the U.S., these pronunciations
have also been heard from British and Canadian speakers.

(Look up "hoosier" in wiki dictionary or any unabridged for a clue on
the vp id.)

Quoted message said:

I wonder how many of them spoke
more than one language. One who masters English and French, for
instance, must have a keen ear for pronunciation.

No mention of linguists or musicians. Beethoven wrote his greatest
work (IMO) stone deaf. But I don't know if writing op. 106 makes him
smart, or how he pronounced nuclear.

Quoted message said:

A monolingual
person can get by without ever questioning form or sound and could be
imitating his closest peers.

If he lives in a closet, or works at the factory by day and watches
the idiot box by night. Or the Peter Principle has kicked in. OR he
just doesn't give a [censored]. Some great (and ordinary) people just have
a stunning gap somewhere. The trick is discerning whether the gap is
from carelessness, or beyond the persons control. Some very smart
people spendtheir lives fighting that gap, and lose. I think the key
in this case is that it's just the one word, and has nothing to do
with anything else.

Quoted message said:

I related the story of the young
engineering officer who described an impact area as being strewn with
"derbis" and had in all his life gotten away with it, possibly talking
to people who knew neither what debris or derbis was.
I found that so elegant a faux pas that ever since I usually say
"derbis" among friends and family.

My wife is native Rusky/Ukrainsky, english-2'nd language and very
astute at it, yet comes up with some doozies that I adopt for
in-house/family/friend kidding-factor usage that I then accidentily
use on the "outside" and find myself apologizing for. In our Israeli
vs. Arab political arguments there are the "mussels".

Quoted message said:

I've mentioned that those who were
among the highest GPA's in college were on occasion not gifted with
great intelligence but rather good short term memory, persons I would
not ask to explain a complex concept. Just because some great people
have great leadership skills, we should not expect them to be equally
skilled in other areas.

No one will disagree with you there, esp me, since that (ability to
recall arbitrary and trivial lists) is a great weakness. But many
organizations are led by people with those abilities (Navy tech,
e.g.), and their successors choosen to emulate those qualities, and
their education systems designed to teach and test for those
qualities, creating masses of morons running things. Take this
country. Charlie Rose tonight had recipients of the annual McCarthur
"genius award", and a spirited discussion of exactly what genius is.
Part of it is the ability to drive at something with interminable
will, like "will the steel stick to the steel". I suspect some of
these people have gaps in their general competency as a result of
their specialization, but there are only so many hours to the day. I
wouldn't be terribly surprised if some certified genius somewhere
mispronounces "nuclear".

Quoted message said:

Jobst Brandt

Bill Westphal

Ben C said:

Interesting point, so do you mean the engine casing around the spark
plug is what heats up, effectively warming the fuel/air mixture before
it's ignited?

Whereas in a four-cylinder engine, the area around the plug and the
plug itself get a chance to cool down while the other three cylinders
take their turns?

It's more about the general shape of the combustion chamber. Wankel having a fairly flat, shallow and long one vs piston engine ones are - well, more or less cylindrical. With a better volume to surface ratio the piston engine can achieve a better burn than the wankel. There are details like flame front propagation, spark plug position, and the big cooling area.

There's been recurring talk about how the introduction of a really good engineering ceramic material would, at some point resurrect the wankel by solving both the seals issue and the incomplete burn at the same time. So far though it seems to remain merely talk.

dabac said:

Ben C said:

Interesting point, so do you mean the engine casing around the spark
plug is what heats up, effectively warming the fuel/air mixture before
it's ignited?

Whereas in a four-cylinder engine, the area around the plug and the
plug itself get a chance to cool down while the other three cylinders
take their turns?

It's more about the general shape of the combustion chamber. Wankel
having a fairly flat, shallow and long one vs piston engine ones are -
well, more or less cylindrical. With a better volume to surface ratio
the piston engine can achieve a better burn than the wankel. There are
details like flame front propagation, spark plug position, and the big
cooling area.

There's been recurring talk about how the introduction of a really good
engineering ceramic material would, at some point resurrect the wankel
by solving both the seals issue and the incomplete burn at the same
time. So far though it seems to remain merely talk.

Oh yes the incomplete burn problem, I remember from the days when I
owned an RX-7 that thing put out some nasty emissions, particularly when
the engine was cold. As I recall it had dual catalytic converters. Makes
me wonder how Mazda ever managed to get it certified by the epa.

Ken
--
The bicycle is just as good company as most husbands and, when it gets
old and shabby, a woman can dispose of it and get a new one without
shocking the entire community. ~Ann Strong

Paul Cassel said:

Qui si parla Campagnolo said:

At least it was a diesel truck, the real future of internal combustion
engines....

and source of our current nasty pollution.

Nope, new low sulfer diesel plus smaller, powerful, less expensive to
maintain PLUS diesel-hybrid.
'Our current nasty pollution' is from cars, gas cars, not a relativley
small portion of trucks with diesel PLUS bio-fuels, much easier with
diesel than gas-type.

Bill Westphal said:

Quoted message said:

A monolingual
person can get by without ever questioning form or sound and could be
imitating his closest peers.

If he lives in a closet, or works at the factory by day and watches
the idiot box by night. Or the Peter Principle has kicked in. OR he
just doesn't give a [censored]. Some great (and ordinary) people just have
a stunning gap somewhere. The trick is discerning whether the gap is
from carelessness, or beyond the persons control. Some very smart
people spendtheir lives fighting that gap, and lose. I think the key
in this case is that it's just the one word, and has nothing to do
with anything else.

And he could be better read than social - the common freshman issue of
coming out of high school with a vocabulary picked up from reading
with little feedback from peers on how to pronounce the words
properly. I can still revert to a horrible pronunciation of
'clandestine' without much encouragement.

I've seen my share of tech people that have more reading vocabulary
well into their adult lives than they use with any degree in
conversation. At least most don't intersperse "and, uh" throughout
their speech. If someone speaks in complete sentences, I'll cut them a
lot of slack. And correct them later clandestinely, clandestin, uh, in
private.

Curtis L. Russell
Odenton, MD (USA)
Just someone on two wheels...

Ken C. M. said:

dabac said:

Ben C said:

Interesting point, so do you mean the engine casing around the spark
plug is what heats up, effectively warming the fuel/air mixture before
it's ignited?

Whereas in a four-cylinder engine, the area around the plug and the
plug itself get a chance to cool down while the other three cylinders
take their turns?

It's more about the general shape of the combustion chamber. Wankel
having a fairly flat, shallow and long one vs piston engine ones are -
well, more or less cylindrical. With a better volume to surface ratio
the piston engine can achieve a better burn than the wankel. There are
details like flame front propagation, spark plug position, and the big
cooling area.

There's been recurring talk about how the introduction of a really good
engineering ceramic material would, at some point resurrect the wankel
by solving both the seals issue and the incomplete burn at the same
time. So far though it seems to remain merely talk.

Oh yes the incomplete burn problem, I remember from the days when I
owned an RX-7 that thing put out some nasty emissions, particularly when
the engine was cold. As I recall it had dual catalytic converters. Makes
me wonder how Mazda ever managed to get it certified by the epa.

My RX-7 had not two, but three exhaust pipes. I wondered if the third
one (which was smaller, and tucked away a bit) was designed to spew the
really nasty stuff while they unwittingly put the gas-tester up one of
the others.

Actually though I think that third pipe is to vent surplus air pressure
from a fan-belt driven air pump with various functions one of which
might have been to apply a bit of back-pressure to the intake.

It also had two spark-plugs per rotor, the purpose of the second one I
think was just to burn the exhaust to make it a bit cleaner, and perhaps
to give the rotor a small amount of additional impulse in the process.

Ben C said:

Ken C. M. said:

dabac said:

Ben C Wrote:
> Interesting point, so do you mean the engine casing around the spark
> plug is what heats up, effectively warming the fuel/air mixture before
> it's ignited?
>
> Whereas in a four-cylinder engine, the area around the plug and the
> plug itself get a chance to cool down while the other three cylinders
> take their turns?
It's more about the general shape of the combustion chamber. Wankel
having a fairly flat, shallow and long one vs piston engine ones are -
well, more or less cylindrical. With a better volume to surface ratio
the piston engine can achieve a better burn than the wankel. There are
details like flame front propagation, spark plug position, and the big
cooling area.

There's been recurring talk about how the introduction of a really good
engineering ceramic material would, at some point resurrect the wankel
by solving both the seals issue and the incomplete burn at the same
time. So far though it seems to remain merely talk.

Oh yes the incomplete burn problem, I remember from the days when I
owned an RX-7 that thing put out some nasty emissions, particularly when
the engine was cold. As I recall it had dual catalytic converters. Makes
me wonder how Mazda ever managed to get it certified by the epa.

My RX-7 had not two, but three exhaust pipes. I wondered if the third
one (which was smaller, and tucked away a bit) was designed to spew the
really nasty stuff while they unwittingly put the gas-tester up one of
the others.

Actually though I think that third pipe is to vent surplus air pressure
from a fan-belt driven air pump with various functions one of which
might have been to apply a bit of back-pressure to the intake.

It also had two spark-plugs per rotor, the purpose of the second one I
think was just to burn the exhaust to make it a bit cleaner, and perhaps
to give the rotor a small amount of additional impulse in the process.

Well my 85 just had a single muffler with two out lets, but now that you
mention that air pump I think the purpose of that was to introduce some
fresh air into or just before the converter which I think reduced
emissions somewhat. Yeah and those 4 spark plugs were expensive! As I
recall they cost like 5 dollars each, and that was back in the early
90s. I liked the body design and other aspects of the car, but the
engine wasn't very reliable, but one good thing I can say about it was
that it ran very smooth at higher rpm.

Ken
--
The bicycle is just as good company as most husbands and, when it gets
old and shabby, a woman can dispose of it and get a new one without
shocking the entire community. ~Ann Strong

In article <[email hidden]>,

Qui si parla Campagnolo said:

Paul Cassel said:

Qui si parla Campagnolo said:

At least it was a diesel truck, the real future of internal
combustion engines....

and source of our current nasty pollution.

Nope, new low sulfer diesel plus smaller, powerful, less expensive to
maintain PLUS diesel-hybrid.

Ridden your bike behind a diesel truck lately? They still suck with
massive output of particulates. There are diesel designs that are very
efficient and clean-burning, but they are not in widespread use. The
University of Minnesota has a diesel development program that has
resulted in diesel engines with very low emissions. I spent a very
interesting hour talking with one of the lead engineers in that project
a couple of years ago.

http://www.me.umn.edu/centers/cdr/

Quoted message said:

'Our current nasty pollution' is from cars, gas cars, not a
relativley small portion of trucks with diesel PLUS bio-fuels, much
easier with diesel than gas-type.

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.

At this point we are still buying into the illusion of "profit, profit
uber alles" as the mantra for our economic model.

The rotarys didn't have cats, at least through the '70's when I was
working on 'em.They had a thing called a thermal reactor.Burned at @2k
F. They did pollute like crazy when cold and they couldn't meet warm up
emissions in, IIRC, '75 and weren't imported.
BTW, we rebuilt and or shortblocked a bunch of 'em in a recall by
Mazda. Before we'd pull the motors we'd put french fries or sometimes
part of a BigMac on the carb secondaries and rev 'em and when the
secondary flap opened whatever was on it would get sucked through into
the reactor. The shop smelled like Micky-D's for most of that recall
campaign.

--
bg

Matt O'Toole said:

Ken C. M. said:

Michael Press wrote:

Quoted message said:

Quoted message said:

Can you can tell me why gas turbine engines are not practical? They
have run well in races.

Quoted message said:

Ask Chrysler they tried to get one to work in a prototype back in 70s
and it went nowhere fast.

Turbines are actually less efficient and pollute more than modern diesels,
so they're a non-starter for car/truck use.

I think you are thinking about a specific application - aircraft
engines. A well-built turbine should come out near twice the
efficiency of a diesel with the same output. But it would cost several
times as much to make.

If diesels were more efficient, we would not use turbines in power
plants, where even tiny efficiency advantages make significant profit
differences.

Quoted message said:

On top of that, they're expensive, run at too-high RPM, and have a narrow
RPM operating range. They're more suited for constant speed, high load
applications, like generators and aircraft/marine propellers.

A constant speed, high-RPM case could be made for turbine-electric
hybrids, but if it really would work, I would expect diesel-electric
locomotives to be replaced with turbine-electric.

Austin

Quoted message said:

Turbines are well suited for aircraft because of their light weight,
compact size, reliability, and relative efficiency. Light weight and
compact size makes for a smaller plane which requires less power, etc.

An Indy race car is a relatively constant speed, high load application,
where light weight and compact size are important too. Thus Granatelli's
effort in the 60s, which would have won if not for a broken fuel pump.

Matt O.

"AustinMN" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

I think you are thinking about a specific application - aircraft
engines. A well-built turbine should come out near twice the
efficiency of a diesel with the same output. But it would cost several
times as much to make.

If diesels were more efficient, we would not use turbines in power
plants, where even tiny efficiency advantages make significant profit
differences.

Have you seen the efficiency of big diesels, as used in eg ships (the 2
stroke scavenging ones)? It's astonishingly high (55%?). Gas turbines plus
steam turbines in a combined cycle manage to beat it, but it's pretty close.

cheers,
clive

Ben C? said:

[snip]

Quoted message said:

Quoted message said:

At the time I mentioned to the engineers to mark my words, that
this engine will not survive, to their utter amazement... and that
of all the others who wanted to believe in it. My thermodynamics
Professor had shown us running rotary prototypes in the lab from
years past and explained why they cannot work. They all have the
same feet of clay as they address only the mechanical part of the
machine and fail to see that this is a heat engine and
thermodynamics its main focus.

Quoted message said:

Quoted message said:

Essentially one spark plug for multiple rotating combustion
chambers is what kills it. At the spark plug, temperatures in the
1000's degF occur if the engine has any reasonable efficiency,
while the intake zone is below freezing (carburetor icing). Both
areas remain a steady state.

Quoted message said:

Interesting point, so do you mean the engine casing around the spark
plug is what heats up, effectively warming the fuel/air mixture
before it's ignited?

Thermally, we have no materials that work at these temperature
extremes and above all, no lubricants. The rotor experiences all four
strokes of the power cycle, but the housing is static and sees steady
state. As I said, that is the failing of all the rotary IC engines
that have been designed.

Quoted message said:

Whereas in a four-cylinder engine, the area around the plug and the
plug itself get a chance to cool down while the other three
cylinders take their turns?

It's not so much a chance to cool down, but rather never experiencing
the full high temperature consistently. The atmosphere in the
cylinder, above the piston experiences all four strokes of the IC
cycle and sees them through a boundary layer of gas that is constantly
changing temperature.

Quoted message said:

Quoted message said:

It's the reciprocation that makes it work. We use aluminum pistons
in a mundane engine block with steel valves that see temperatures
from freezing to flaming in one cycle. The average temperature
when seen through a boundary layer of gas is mundane. Meanwhile
the Wankel burns up! To make it work, compression had to be low
giving poor performance, requiring higher engine speed to make up
for that poor performance. The result is a short lived machine
with poor fuel economy.

Quoted message said:

I assumed the low compression ratio was a consequence of the
difficulty of sealing the things. Although the Wankel engine seems
simpler in concept, when you add the requirement of keeping
lubricant and combustion materials where they're supposed to be and
not where they're not, a four-stroke piston engine with a head
gasket suddenly starts to look almost like the more elegant
solution.

That is not a problem. Seal failure occurred because there is no
lubricant that can withstand the extremely high temperatures that are
practically steady state on the housing where the four strokes of the
IC cycle are stationary as the rotor passes.

Quoted message said:

You also have to consider the amount of effort that has gone into
optimizing the piston engine over the years. Things like subtle
changes in the intake port design to make the gas swirl around and
burn just right. It seems like all that needs to be done again for
the Wankel, and only Mazda (and Norton?) are working on it.

You can spend all the time you like, but thermodynamics won't change.
All the advances made in IC engines don't help the rotary one bit.
More time and money won't help. Those who don't study history are
doomed to repeat it. That applies here entirely. I was surprised
that Felix Wankel either did not study the history of the rotary or
recognize it when it was explained to him, as it surely must have
been.

Jobst Brandt

Ryan Cousineau said:

Quoted message said:

Quoted message said:

>> But how about this concept:

http://www.starrotor.com/Engine.htm

Quoted message said:

Quoted message said:

Quoted message said:

> After gazing at hundreds of "miracle engine" articles over the
> years, I've decided to ignore any reports that don't include tests
> of working models. The only one of those hundreds of designs that
> gained any traction was the Wankel, and it didn't set the world on
> fire.

Quoted message said:

Quoted message said:

Essentially one spark plug for multiple rotating combustion chambers
is what kills it. At the spark plug, temperatures in the 1000's degF
occur if the engine has any reasonable efficiency, while the intake
zone is below freezing (carburetor icing). Both areas remain a steady
state.

Quoted message said:

Quoted message said:

It's the reciprocation that makes it work. We use aluminum pistons in
a mundane engine block with steel valves that see temperatures from
freezing to flaming in one cycle. The average temperature when seen
through a boundary layer of gas is mundane. Meanwhile the Wankel
burns up! To make it work, compression had to be low giving poor
performance, requiring higher engine speed to make up for that poor
performance. The result is a short lived machine with poor fuel
economy.

Quoted message said:

Quoted message said:

The Wankel is dead!

Quoted message said:

E pur si muove:

I don't understand your comment, "and also one moves"?

http://www.mazda.co.uk/Showroom/RX-8/

It will remain as a boutique experiment and appeal to those who seek to
be different. As a useful engine, it is dead for the reasons cited.
It has not made any advances in IC propulsion and remains a problem
that has not been solved.

Jobst Brandt

Quoted message said:

Quoted message said:

One of my best friends in engineering school couldn't correctly

pronounce "aluminum."

and Americans can't spell aluminium!

(;-)

pk

Quoted message said:

Ryan Cousineau said:

Quoted message said:

>>> But how about this concept:

http://www.starrotor.com/Engine.htm

Quoted message said:

Quoted message said:

Quoted message said:

The Wankel is dead!

Quoted message said:

Ryan Cousineau said:

E pur si muove:

http://www.mazda.co.uk/Showroom/RX-8/

Quoted message said:

I don't understand your comment, "and also one moves"?
It will remain as a boutique experiment and appeal to those who seek to
be different. As a useful engine, it is dead for the reasons cited.
It has not made any advances in IC propulsion and remains a problem
that has not been solved.

He was paraphrasing Galileo Galilei who, after being convicted of heresy
for disputing that Earth was the fixed center of the universe, is said
to have muttered, "And yet it moves".

http://www.usgovernetics.com/Fri-to-Geo/galileo.php

Cute but not exactly germaine to Wankel.
IIRC it's usually 'Eppur si muove' but I'm not an expert
--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971

Isn't the RX-8 a rotary engine? And I owned a RX-2..2 plugs per rotor,
btw, not one.

Quoted message said:

Michael Press said:

Quoted message said:

> But how about this concept:

http://www.starrotor.com/Engine.htm

Quoted message said:

Quoted message said:

After gazing at hundreds of "miracle engine" articles over the
years, I've decided to ignore any reports that don't include tests
of working models. The only one of those hundreds of designs that
gained any traction was the Wankel, and it didn't set the world on
fire.

Quoted message said:

Quoted message said:

That page is way too full of phrases like "...is projected to
have...", "...should be...," "...is expected to be..."

Quoted message said:

Can you can tell me why gas turbine engines are not practical? They
have run well in races.

Interestingly, the Wankel first found real fertile soil at NSU in
Neckarsulm (from which the name arises) just north of Stuttgart where
I was working at the time. n R&D engineer came rolling in into our
shop at Porsche to demonstrate this new concept.

At the time I mentioned to the engineers to mark my words, that this
engine will not survive, to their utter amazement... and that of all
the others who wanted to believe in it. My thermodynamics Professor
had shown us running rotary prototypes in the lab from years past and
explained why they cannot work. They all have the same feet of clay
as they address only the mechanical part of the machine and fail to
see that this is a heat engine and thermodynamics its main focus.

Essentially one spark plug for multiple rotating combustion chambers
is what kills it. At the spark plug, temperatures in the 1000's degF
occur if the engine has any reasonable efficiency, while the intake
zone is below freezing (carburetor icing). Both areas remain a steady
state.

It's the reciprocation that makes it work. We use aluminum pistons in
a mundane engine block with steel valves that see temperatures from
freezing to flaming in one cycle. The average temperature when seen
through a boundary layer of gas is mundane. Meanwhile the Wankel
burns up! To make it work, compression had to be low giving poor
performance, requiring higher engine speed to make up for that poor
performance. The result is a short lived machine with poor fuel
economy.

When I read about propelling bicycles with the arms in a sprint or why
mechanical stress relieving doesn't work, I recall these engineering
moments where conventional thinking stymies understanding. You can be
sure that I found no takers at Porsche. Professor Kays at LSJU had it
right, although I believe his class failed to see the importance of
his lecture and that was years before Felix Wankel presented his
engine. That's often the way school is.

The Wankel is dead!

Jobst Brandt

qui si parla Campagnolo said:

Isn't the RX-8 a rotary engine? And I owned a RX-2..2 plugs per rotor,
btw, not one.

Here is the answer:
http://www.automotive.com/2005/12/mazda/rx-8/specifications/index.html

Yes it is rotary.

Ken
--
The bicycle is just as good company as most husbands and, when it gets
old and shabby, a woman can dispose of it and get a new one without
shocking the entire community. ~Ann Strong

Quoted message said:

Ben C? writes:

[snip]

Quoted message said:

Quoted message said:

Quoted message said:

Essentially one spark plug for multiple rotating combustion
chambers is what kills it. At the spark plug, temperatures in the
1000's degF occur if the engine has any reasonable efficiency,
while the intake zone is below freezing (carburetor icing). Both
areas remain a steady state.

Quoted message said:

Interesting point, so do you mean the engine casing around the spark
plug is what heats up, effectively warming the fuel/air mixture
before it's ignited?

Thermally, we have no materials that work at these temperature
extremes and above all, no lubricants. The rotor experiences all four
strokes of the power cycle, but the housing is static and sees steady
state. As I said, that is the failing of all the rotary IC engines
that have been designed.

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Whereas in a four-cylinder engine, the area around the plug and the
plug itself get a chance to cool down while the other three
cylinders take their turns?

It's not so much a chance to cool down, but rather never experiencing
the full high temperature consistently. The atmosphere in the
cylinder, above the piston experiences all four strokes of the IC
cycle and sees them through a boundary layer of gas that is constantly
changing temperature.

I think I get it now.

In the rotary engine we have three distinct areas of the housing, one
around the intake port, one around the spark plug, and one around the
exhaust port. In the piston engine, all four parts of the cycle happen
in one place (for each cylinder), so there will be constant changes of
gas temperature, and the changes are rapid enough that the head remains
somewhere around the average temperature. But in the rotary we tend to
end up permanently hot around the plug, cold around the intake port, and
I suppose somewhere in between around the exhaust port. The housing
around the combustion area is only prevented from reaching full
combustion temperature in the 1000s of deg F by the coolant and
conduction through the head. The only way to keep the temperature it
reaches within workable limits for the materials and lubricants is to
use a low compression ratio and hence we get a fuel inefficient engine.

[snip]

Quoted message said:

Quoted message said:

I assumed the low compression ratio was a consequence of the
difficulty of sealing the things. Although the Wankel engine seems
simpler in concept, when you add the requirement of keeping
lubricant and combustion materials where they're supposed to be and
not where they're not, a four-stroke piston engine with a head
gasket suddenly starts to look almost like the more elegant
solution.

That is not a problem. Seal failure occurred because there is no
lubricant that can withstand the extremely high temperatures that are
practically steady state on the housing where the four strokes of the
IC cycle are stationary as the rotor passes.

They did also suffer from failure of the side seals, which are possibly
not exposed to such high temperatures.

An advantage of the four-stroke piston engine is that you keep the oil
below the piston rings and the combustion above them, and it's quite
easy to keep a good oil seal on the rings. The Wankel needs to pump oil
to the seals through narrow channels in the rotor, which sounds like a
lot more trouble.

Two-strokes have a similar problem with getting the oil to the seals. In
that case you often just mix the oil in with the fuel.

Quoted message said:

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You also have to consider the amount of effort that has gone into
optimizing the piston engine over the years. Things like subtle
changes in the intake port design to make the gas swirl around and
burn just right. It seems like all that needs to be done again for
the Wankel, and only Mazda (and Norton?) are working on it.

You can spend all the time you like, but thermodynamics won't change.
All the advances made in IC engines don't help the rotary one bit.
More time and money won't help. Those who don't study history are
doomed to repeat it. That applies here entirely. I was surprised
that Felix Wankel either did not study the history of the rotary or
recognize it when it was explained to him, as it surely must have
been.

Didn't Felix Wankel invent the Wankel engine? So presumably at that
point it had no history to learn from.

There are always going to be some hurdles with any idea. The
reciprocating engine is not without its problems either, but most of
them have been overcome one way or another.

The arguments for Wankels (fewer moving parts, simplicity) cut it less
now than they probably did in the 50s and 60s since the reliability of
piston engine internal components is now very high.