single engine planes, are they really that dangerous?
S. Manzo
I live in the city of seattle and every nw and then a single engine plane
crashes on a lake out side of the city. And some body told me that sort
of plane aren't safe at all and only those who dare or of low income dare
to fly them. Does any one know anything about this topic?
Rebecca Cutri-Kohart
Well, I can summarily deny the low-income part of flying a single engine
plane. Its the only hobby more expensive than running for Congress.
Any activity has the possibility of being fatal and dangerous. But
seriously, no, single engine planes aren't all that dangerous. If you
are worried about the engine failure (with no backup engines for
reduncy), don't. In the off-chance there is an engine failure, a pilot
of a single engine plane can guide it to the ground gliding. We
practice such manuvers during our training. As a matter of fact, a
reasonable portion of our training is devoted to learning how to cope
with emergency situation. I can quote the statistic that is often
repeated when speaking of flying - it is much safer than driving. Many
hours of training are required before your instructor (and the FAA)
trusts you to control of the airplane. It is sad to hear of the general
aviation accidents near in your area. But before you right of
single-engine pilots as impoverished thrill-seekers, take an
introductory flight at your local airport, and I'm sure you will see the
concern with safety and control that is necessary to fly an airplane..
_________________________________
\ \ ___ ______ |
\ Rebecca Cutri-Kohart \ / \___-=0`/|0`/__|
\ art...@resnet.gatech.edu \_______\ / | / )
/ "Know Thyself" / `/-==__ _/__|/__=-|
/ / * \ | |
/_________________________________/ (o)
Rick Wagner
S. Manzo wrote:
> I live in the city of seattle and every nw and then a single engine
> plane
> crashes on a lake out side of the city. And some body told me that
> sort
> of plane aren't safe at all and only those who dare or of low income
> dare
> to fly them. Does any one know anything about this topic?
Yes – They can be unsafe, but do not have to be. The aircraft are sound
and reliable – Its the pilot that makes the predominate difference in
operational safety. The primary reason single-engine airplanes crash
is a direct result of pilot error, not income level or that some
aircraft are more or less "stronger" than others. Improper planning,
flying into hazardous weather or intentional violation of rules and
regulations are often the primary ingredients to a fatal incident.
Seldom do you find an incident of mechanical failure that renders the
aircraft uncontrollable. A road or field may have to become a
make-shift runway in the rare event of engine mechanical failure but in
most cases these off-airport landings result in minor damage or injury,
if any. The number one reason for off airport landings is sadly –
running out of fuel – normally a direct result of improper planning or
poor pre-flight inspection.
Single-engine aircraft incidents may appear to be more dangerous to the
average person at first blush but there are two factors that need to be
considered. In many cases there are a significant higher number of
single engine aircraft operations in contrast to twin engine aircraft
and, multi-engine aircraft are operated by persons who ordinarily have
significantly more experience and training – in addition to having
additional equipment to increase the operational envelope of the
aircraft. That is not to say that multi-engine aircraft are safer –
either can be as dangerous given the capacity of the pilot operating it.
Often the currency of the pilot is an issue. The average private pilot
license holder flies only 40 some hours per year which is not
unreasonable to stay proficient in normal operations under “normal”
conditions, but it is seldom that incidents are attributed to normal
conditions when outside of the arena of poor preparation and poor
planning. If your only flying 40 hours a year it is doubtful if that
person is spending much time practicing for power, instrument or
navigation failures for those “not normal” situations.
Truth is - we all make mistakes, single and multi-engine, prop planes
and jet pilots - its how often, how serious or how close to the ground
that will make the difference.
Not unlike driving down the freeway – Its often obvious to identify
those who know what their doing and those who think they do. Those
same people are flying airplanes and it doesn't matter if its someone
driving a BMW or a Chevrolet.
--
Rick Wagner
CP-AMEL/SEL IA
PA-22-135 N1507P KANE Minnesota
USPA Master Skydiver D-15865
Skydiver Driver
Freefall Cameraman
One Lucky Guy
Check out my FLIGHT Page http://www.goldengate.net/~rwagner
P@Pilot
S. Manzo wrote in message ...
>I live in the city of seattle and every nw and then a single engine plane
>crashes on a lake out side of the city. And some body told me that sort
>of plane aren't safe at all and only those who dare or of low income dare
>to fly them. Does any one know anything about this topic?
>
Well, any kind of activity has it's own dangers. Overall, aviation is one of
the safest forms of transport there is. The only problem is that, when there
is a plane crash/accident, it is usually overpublicized by the media. After
all, for every plane crash, there are THOUSANDS of automobile accidents. And
personally, I feel a lot safer being in the air than driving a car.
As for flying a single engine aircraft, well, obviously, if you lose an
engine, you are now a glider. But these light aircraft are relatively easy
to land in any open field with no or minor damage. If you are talking about
flying single engine in the night time, well, the chance of having a
successful forced landing decreases dramatically.
Overall, single engine aircraft are VERY safe. But you must come to realize
that accidents do happen, no matter what you do.
As for the low income thing, well, I do not have a low income, and I like to
fly bugsmashers from time to time, they are a lot of fun & I don't ever
worry about accidents (If I did, I'd never go flying). But if an emergency
happens, I AM ALWAYS READY FOR IT. You have to realize that pilots usually
are an exceptional bunch of people who treat their flying/driving/operating
anything with the highest amount of situational awareness. They anticipate
emergency situations and avoid them if possible, when they are unavoidable,
they will deal with it in the most professional manner.
-Pat
QFI Canadian Air Force
http://www.geocities.com/yosemite/4381
A SUPERIOR pilot is one who uses his SUPERIOR judgement in order to avoid
situations that might require him to use his SUPERIOR flying ability.
Rick Wagner
P@Pilot wrote:
> S. Manzo wrote in message ...
> >I live in the city of seattle and every nw and then a single engine
> plane
> >crashes on a lake out side of the city.
>
> Well, any kind of activity has it's own dangers.
<snipped - everything I agree with>
> You have to realize that pilots usually
> are an exceptional bunch of people who treat their
> flying/driving/operating
> anything with the highest amount of situational awareness. They
> anticipate
> emergency situations and avoid them if possible, when they are
> unavoidable,
> they will deal with it in the most professional manner.
Although I would like to agree with this unconditionally, but is it not
the fact that just the opposite is true as it applies to the higher
percentage of reported GA accidents?
In regards to professional manner:
I use to think that pilots were - in general - a cut above the rest.
But have you ever left your GPS or flight calculator in a rental
aircraft and been able to return the next day to find it turned into the
lost and found? I have - and it wasn't. Have you every gone out and
untied a rental or club plane to find some un-reported damage to a
flight control or other essential item that would make flight
"awkward". How about the majority of GA aircraft mechanics that won't
ride in the airplanes they work on. How about the guys who continually
schedule the airplane for an hour and return it after two? Ever had
your car broken into while you were out flying? How about the right
hand pattern guys at the left hand airports? Or the instructor doing
tear drop patterns to get the most touch and go's for the rental buck?
Ever have a FBO want you to pre-pay to receive a minimal discount and
show up one day to find a sign on the door "closed - permanently".
.......
I don't think pilots are any worse than non-pilots, but so far I've
found them not to be any better than the rest of the persons at this
level of the food chain.
--
Rick Wagner
Duck Tape Flyer
Keith Arnold
On Sun, 25 Jan 1998 16:14:29 -0800, "S. Manzo" <sma...@u.washington.edu>
wrote:
>I live in the city of seattle and every nw and then a single engine plane
>crashes on a lake out side of the city. And some body told me that sort
>of plane aren't safe at all and only those who dare or of low income dare
>to fly them. Does any one know anything about this topic?
========>
Naw and yah. I'll let others comment further.
ô¿ô - Keith - 182L/STOL N3431R - Chino, California
N33° 58' 46" W117° 38' 41"
Kathy Lankford
Have you looked at why they crash? A two-engine craft isn't much advantage
if the reason for the accident was "out of gas", which seems to be pretty
common. I can think of several other very common causes of small craft
accidents where a second engine wouldn't help near so much as a bit more
good judgement would.
Are any other students as surprised as I am to find out how many accidents
are caused by doing things your instructor told you over and over not to
do?
Wendy B G
>Are any other students as surprised as I am to find out how many accidents
>are caused by doing things your instructor told you over and over not to
>do?
Seems to be human nature to ignore good advice.
How many people do you know who have made a hash out of their lives by
violating basic rules (like the Ten Commandments)?
--Wendy
Andrew Boyd
S. Manzo <sma...@u.washington.edu> wrote:
> I live in the city of seattle and every nw and then a single engine plane
> crashes on a lake out side of the city. And some body told me that sort
> of plane aren't safe at all and only those who dare or of low income dare
> to fly them. Does any one know anything about this topic?
Nope. This is exactly why I don't drive a car, ride a bicycle, order a
meal
in a restaurant, or walk across the road, because all of these activities
are inherently unsafe [people have *died* doing these things] and I am
guaranteed by the constitution a risk-free existence, or so I am given to
understand by what the american trial lawyers association says.
--
ab...@igs.net ATP "One Good Troll Deserves Another"
Roy Smith
"P@Pilot" <nospa...@sk.sympatico.ca> wrote:
> Well, any kind of activity has it's own dangers. Overall, aviation is one of
> the safest forms of transport there is.
You know, I'm all for promoting aviation, but let's not lie with statistics.
There is no doubt that flying part-121 transport jets (i.e. scheduled
airlines like United, American, Northwest, etc) is extremely safe. Safer
than pretty much any other form of transportation you could find.
Certainly safer than private car by a long shot.
But, you're lumping general aviation in privately operated single-engine
light airplanes (i.e. the typical Cessnas and Pipers people fly for fun)
into that same pot. Only an idiot would try to claim that the accident
statistics for this type of aviation is comparable to scheduled airlines.
I'm not saying that general aviation is any more dangerous than a lot of
other things people do for fun. They ride motorcycles. They ski. They
race sailboats. They bungee jump. They climb mountains. They play
rugby. They engage in recreational sex. All of these can be fatal if an
accident happens, but people do them anyway because it's fun. But let's
not twist the statistics by lumping GA into "Overall, aviation is one of
the safest forms of transport there is".
--
Roy Smith <r...@popmail.med.nyu.edu>
New York University School of Medicine
550 First Avenue, New York, NY 10016
Andrew M. Sarangan
Does anyone have the statistics of airplane accidents broadly classified
into (1) fuel starvation (2) weather (3) engine failure etc... ?
Does any government agency classify it that way ?
--
Andrew Sarangan
PP-ASEL-IA
nightjar
Kathy Lankford <ka...@col.hp.com> wrote in article
<6ai0oq$kdr$1...@nonews.col.hp.com>...
>
> Are any other students as surprised as I am to find out how many
accidents
> are caused by doing things your instructor told you over and over not to
> do?
>
I agree Kathy. Looking at the UK statistics, at least 60% of the most
common accidents are due to pilots failing to follow common sense rules.
Colin
Jim McCarthy
On Sun, 25 Jan 1998 16:14:29 -0800, "S. Manzo"
<sma...@u.washington.edu> wrote:
>I live in the city of seattle and every nw and then a single engine plane
>crashes on a lake out side of the city. And some body told me that sort
>of plane aren't safe at all and only those who dare or of low income dare
>to fly them. Does any one know anything about this topic?
Most people who ask this question are concerned about an engine
failure in flight. When acquaintances imply that I must be nuts to
fly a single engine airplane, I ask them "When was the last time you
were cruising on the Interstate and your engine just quit for any
reason other than running out of gas?". So far the response has
always been "Never" . I'm sure it happens, but not very often. And
modern automobile engines are far more complex (read "prone to
failure") than aircraft engines.
Jim McCarthy
Tampa, FL
PP-ASEL
Morris Bernstein
In article <34ce0e7b...@news.citicom.com>,
Actually, it happened a couple of times in my old Civic which I owned
for 7 years. Once when I was cruising along at speed of traffic,
about 120 (kilometers per hour) when the engine lost power for no
apparent reason. I started to pull over to the side of the road, but
the thing kicked back into life as if nothing had happened. I never
did figure out what/why it happened.
Another time, it was after a long descent when I was using engine
compression to keep control speed (I know, it's power for descent and
elevator for speed). The engine trouble lamp went on. I pulled over
to the side of the road and shutdown the ignition. After a couple of
minutes, I restarted and everything was fine.
John, tell us again how many forced landings you've had?
Morris
--
Morris Bernstein mor...@pobox.com
"Science requires equal amounts of awe and skepticism"
Spammers beware: I may respond in a way you _won't_ like
Mike Wei
For one thing, is there any driver here strictly following the
maintanence schedule on their cars? Especially, how many car owners
change their timing belt every 60,000 miles (or whatever the
recommendation is)?
If cars are regulated like airplanes, I bet most cars can run for 25
years or a million miles, without many breakdowns.
--Mike
Morris Bernstein wrote:
> Actually, it happened a couple of times in my old Civic which I owned
> for 7 years. Once when I was cruising along at speed of traffic,
> about 120 (kilometers per hour) when the engine lost power for no
> apparent reason. I started to pull over to the side of the road, but
> the thing kicked back into life as if nothing had happened. I never
> did figure out what/why it happened.
>
> Another time, it was after a long descent when I was using engine
> compression to keep control speed (I know, it's power for descent and
> elevator for speed). The engine trouble lamp went on. I pulled over
> to the side of the road and shutdown the ignition. After a couple of
> minutes, I restarted and everything was fine.
>
> John, tell us again how many forced landings you've had?
>
> Morris
> --
> Morris Bernstein mor...@pobox.com
> "Science requires equal amounts of awe and skepticism"
>
> Spammers beware: I may respond in a way you _won't_ like
--
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
Mike Wei
nightjar
Jim McCarthy <jmca...@citicom.com> wrote in article
<34ce0e7b...@news.citicom.com>...
> Most people who ask this question are concerned about an engine
> failure in flight. When acquaintances imply that I must be nuts to
> fly a single engine airplane, I ask them "When was the last time you
> were cruising on the Interstate and your engine just quit for any
> reason other than running out of gas?". So far the response has
> always been "Never" . I'm sure it happens, but not very often. And
> modern automobile engines are far more complex (read "prone to
> failure") than aircraft engines.
>
I've had two car engines fail on me in use that I can recall. One from a
con rod exiting though the side of the block. One on a new car from a minor
fault that should have been picked up on the pre flight errm.. pre delivery
inspection. I also have had a partial failure from one piston top breaking
up, after which it started to use nearly as much oil as petrol.
I fly a twin, just in case.
Colin Bignell
Dylan Smith
nightjar wrote:
> I've had two car engines fail on me in use that I can recall. One from a
> con rod exiting though the side of the block. One on a new car from a minor
> fault that should have been picked up on the pre flight errm.. pre delivery
> inspection.
However, cars are not subject to the sort of inspection and TBO
that aircraft engines are! Looking at the NTSB or AAIB reports,
there are very few where the engine just quits cold. Most of
the times the engine quits seem to be from induction icing
(which will get both engines in a twin if you don't catch it!)
or running out of fuel.
Also, car engines are far higher stressed than aircraft engines.
A C172 has a massive 320 cubic inch engine (about 5.3 litres)
which only produces 160 bhp. My old Ford Sierra had an engine
one third of that size, but produced 110 bhp. A Chevrolet
Corvette has a 5.7 litre engine producing around twice as
much power as the good old O-320. Of course, if you want
to see real high output per litre, then look at a Japanese
motorcycle...
--
Email: dy...@vnet.IBM.COM
Dylan Smith 1810 Space Park Drive, Houston, TX 77573
Standard disclaimer applies.
Anti-spam - Change 'r' to raleigh, 'i' to ibm and 'c' to com.
Andrew M. Sarangan
In article <34D09...@r.i.c>, Dylan Smith <dy...@r.i.c> wrote:
>
>Also, car engines are far higher stressed than aircraft engines.
>A C172 has a massive 320 cubic inch engine (about 5.3 litres)
>which only produces 160 bhp. My old Ford Sierra had an engine
>one third of that size, but produced 110 bhp. A Chevrolet
>Corvette has a 5.7 litre engine producing around twice as
>much power as the good old O-320. Of course, if you want
>to see real high output per litre, then look at a Japanese
>motorcycle...
>
Dylan,
The majority of the time, auto engines operate far below their maximum rated
power. The high power is used only during brief periods of accelerations.
If a car engine were to operate at its maximum power continuously then it
would not last for more than a few hours. On the other hand, an aircraft engine
operates at its full power most of the time, and it lasts several thousand
hours. Therefore, a 100HP aircraft engine has to be built to withstand a
lot more stress than a 100HP auto engine.
I am no expert in engines, but that was my impression.
--
Andrew Sarangan
PP-ASEL-IA
Jeff Oslick
Dylan Smith wrote:
> Also, car engines are far higher stressed than aircraft engines.
> A C172 has a massive 320 cubic inch engine (about 5.3 litres)
> which only produces 160 bhp. My old Ford Sierra had an engine
> one third of that size, but produced 110 bhp. A Chevrolet
> Corvette has a 5.7 litre engine producing around twice as
> much power as the good old O-320. Of course, if you want
> to see real high output per litre, then look at a Japanese
> motorcycle...
I disagree. Few auto engines spend a lot of time putting out anywhere near their
maximum rated horsepower, while aircraft engines spend most of there time near
75% power, and several "high stress" minutes per flight at 100% (takeoff climb,
poor air cooling). Air cooled aircraft engines are also suffer from relatively
poor heat distribution across the cylinders, compared to liquid cooled auto
engines, a can easily be subjected to shock cooling when flown by an imprudent
pilot. While auto engines do indeed have higher hp/displacement ratios, they in
fact have lower overall mechanical stress.
__________________
Jeff Oslick..................................PP-ASEL
Dept. of Geological Sciences
Brown University
Providence, RI
nightjar
Dylan Smith <dy...@r.i.c> wrote in article <34D09...@r.i.c>...
>
> However, cars are not subject to the sort of inspection and TBO
> that aircraft engines are!
From the mileage done and normal average speeds achieved, I estimate that
the one that put the con rod out the side had done less than 1,000 hours.
It was also in the days when the slightest odd noise would have me digging
around the car innards with a tool set in hand. Maybe the inspections were
not as regularly scheduled, but they were very thorough.
>
> Also, car engines are far higher stressed than aircraft engines.
> A C172 has a massive 320 cubic inch engine (about 5.3 litres)
> which only produces 160 bhp.
That huge volume is more a result of needing to produce maximum power at
less than 3,000 rpm so that the propeller can be stuck on without the need
for a reduction gear. Because car engines can rev much faster, they are far
more efficient, and do not need the big capacity to achieve power. If they
are more highly stressed then it is because 'value engineering' is a motor
industry buzz word where 'safety' is the one preferred by the aero
industry. The Porche Mooney engine used high speed to achieve good
efficiency from a relatively small capacity engine, but the weight of the
reduction gear needed lost any gains made.
Colin
Dylan Smith
Andrew M. Sarangan wrote:
>
> In article <34D09...@r.i.c>, Dylan Smith <dy...@r.i.c> wrote:
> >
> >A C172 has a massive 320 cubic inch engine (about 5.3 litres)
> >one third of that size, but produced 110 bhp. A Chevrolet
> >Corvette has a 5.7 litre engine producing around twice as
> >much power as the good old O-320. Of course, if you want
> >to see real high output per litre, then look at a Japanese
> >motorcycle...
>
> power. The high power is used only during brief periods of accelerations.
> If a car engine were to operate at its maximum power continuously then it
> would not last for more than a few hours. On the other hand, an aircraft engine
> operates at its full power most of the time,
Hmmmm.... I operate our club's C172 at 65% power most of the time.
I only use full power during brief periods (takeoff, go-around etc).
Long periods of cruise power are actually less wearing on the
engine than stop and go (like driving in a traffic jam). I would
argue that most aero engines have a much easier life than
most car engines.
My old Sierra was certainly operating at at least 65% power out
on the open road, and it was very reliable, yet the horsepower
being produced per litre at that power was over twice of that
that a Lycoming O-320 is producing at 65% power. Also, it had
to do that at around 3500 rpm where as the O-320 even at full
power redlines at 2700 rpm (so the 2-litre unit in the Sierra
was undergoing far more wear cycles per hour in use). The Sierra
engine is also an overhead cam unit (most modern engines in
cars are OHC, or even DOHC) which has a timing belt that
is a lot more prone to failure than the gear that drives
the camshaft in a pushrod engine like the O-320.
New cars produce even more hp per litre.
As an extreme example, consider the Japanese motorcycle with
about 110 horsepower - they usually have 1.3 litre engines or
therabouts, and the owners usually get the most out of them!
Yet they seldom quit cold. When they do quit it's often
due to poor maintenance or running out of gas.
The other thing with aircraft is the system that produces the power
(engine and prop) is much simpler than in a car, plus the systems
that go wrong most frequently (electrical) are dual.
In my Ford F150, the complexity is awesome compared to a C172.
It has a computer controlled engine, a clutch, a transmission,
lots of different sensors for the EEC IV module, fuel pumps etc.
automatic ignition timing etc, distributor, high voltage coil
for the spark. Not to mention other transmission parts like
the differential, and associated other bits that would disable
your car if they failed on the highway like the balljoints
and suspension parts.
In a car with auto transmission it is even more complex because
it has a nasty box filled with voodoo machinery like torque
converters, nasty little brake bands and clutches and a planetary
gearset. All are just more things waiting to go wrong, plus
a road vehicle doesn't get nearly the maintenance schedule
that the average C172 gets.
A C172 just has a simple carburetted engine, and the trasmission
consists of a solid piece of metal going to the propellor. The
spark is generated by a magneto which is a very simple device
which essentially spins a permanent magnet past some windings.
The suspension of a C172 is only in use on the ground, and
consists of a single oleo strut for the nose, and a stout
piece of bendy steel for the mains.
The only simpler engines I have come across are the ones that
power lawn mowers (which incidentally use magnetos too). They
are only really simpler because they use side valves and
therefore don't have pushrods.
Gregory Travis
In article <01bd2cf0$975efd80$3883f2c2@default>,
nightjar <nigh...@pavilion.co.uk> wrote:
>That huge volume is more a result of needing to produce maximum power at
>less than 3,000 rpm so that the propeller can be stuck on without the need
>for a reduction gear. Because car engines can rev much faster, they are far
>more efficient, and do not need the big capacity to achieve power. If they
>are more highly stressed then it is because 'value engineering' is a motor
>industry buzz word where 'safety' is the one preferred by the aero
>industry. The Porche Mooney engine used high speed to achieve good
>efficiency from a relatively small capacity engine, but the weight of the
>reduction gear needed lost any gains made.
Very good points. I would only add that "efficiency" as Colin is using it
to refer to auto engines is PACKAGING efficiency, not fuel efficiency.
HP per Cubic inch ratios come into play when considering the engine package
(weight and size). Higher HP to CI allows the engine to be physically
smaller and lighter (where all other aspects are equal). It comes from
spinning the engine faster which has a negative effect on fuel
efficiency.
Colin's point about "value engineering" is an excellent one. Because of
their production scales, Ford/Toyota/GM can each realize tens of millions
of dollars in added income per year just by shaving a few bucks here and
there off the cost of manufacturing engines.
Shaving those costs involves converging on a design which is, from a
manufacturing point of view, totally optimized for the road. It might
make good economic sense, for instance, to shave a couple ounces and a
dollar off of each connecting rod, or to use cast crankshafts, even if
the warranty claims suffer slightly, in return for $10 million per year
which is probably about 100 jobs (all in customer service :-)).
A company with a new volume production rate like Lycoming, however, could
easily increase or decrease the cost of manufacturing each new engine by
over $200 each without affecting total earnings by more than about $200,000 -
or about 1% of net income (about 2 jobs).
Thankfully aerospace, due to the volume demands, is insulated from value
engineering (and the inherent conflict of interest with safety that it
implies) pressures to a degree that the auto industry could only dream
about. The Ford Pinto fuel tank was one modern wonder of value engineering.
greg
Gregory Travis
In article <34D0DE...@r.i.c>, Dylan Smith <dy...@r.i.c> wrote:
>Hmmmm.... I operate our club's C172 at 65% power most of the time.
>I only use full power during brief periods (takeoff, go-around etc).
>Long periods of cruise power are actually less wearing on the
>engine than stop and go (like driving in a traffic jam).
Stop and go takes a far harder toll on your brakes than on your engine.
The "stop" part of "Stop and go" represents idle time for your engine - a
period in which (if not continued too long) there is no wear at all.
> I would
>argue that most aero engines have a much easier life than
>most car engines.
The absolute hardest thing for any engine is inactivity. Given that, what
has it harder: The car in the driveway that gets started several times a
day or the plane in the hangar that sometimes goes weeks without running?
>My old Sierra was certainly operating at at least 65% power out
>on the open road, and it was very reliable, yet the horsepower
>being produced per litre at that power was over twice of that
>that a Lycoming O-320 is producing at 65% power.
I don't know what a Sierra is but the average sedan will require about
15-35% percent of the engine's maximum power to maintain 55MPH on
the open highway (lower for sleeker, smaller, sedans).
65% power from an auto engine would propel just about any automobile
so far past the legal speedlimit that you would never get out of jail.
Automobiles must have a large difference between cruise horsepower needs
and maximum horespower available in order to have acceptable acceleration
characteristics. In other words, the engines are designed around the
15-35% power average but are capable, for short times, of producing
a large fraction of the maximum in order to provide acceptable acceleration.
>New cars produce even more hp per litre.
>As an extreme example, consider the Japanese motorcycle with
>about 110 horsepower - they usually have 1.3 litre engines or
>therabouts, and the owners usually get the most out of them!
>Yet they seldom quit cold. When they do quit it's often
>due to poor maintenance or running out of gas.
I dare you to run 71.5 HP continuously for even an hour on a motorcycle,
any motorcycle on any road anywhere.
>The only simpler engines I have come across are the ones that
>power lawn mowers (which incidentally use magnetos too). They
>are only really simpler because they use side valves and
>therefore don't have pushrods.
You say this as if it's a bad thing.
greg
Andrew M. Sarangan
In article <34D0DE...@r.i.c>, Dylan Smith <dy...@r.i.c> wrote:
>>
>>
>> The majority of the time, auto engines operate far below their maximum rated
>> power. The high power is used only during brief periods of accelerations.
>> If a car engine were to operate at its maximum power continuously then it
>> would not last for more than a few hours. On the other hand, an aircraft engine
>> operates at its full power most of the time,
>
>I only use full power during brief periods (takeoff, go-around etc).
>Long periods of cruise power are actually less wearing on the
>argue that most aero engines have a much easier life than
>most car engines.
>on the open road, and it was very reliable, yet the horsepower
>being produced per litre at that power was over twice of that
>to do that at around 3500 rpm where as the O-320 even at full
>power redlines at 2700 rpm (so the 2-litre unit in the Sierra
>was undergoing far more wear cycles per hour in use). The Sierra
>engine is also an overhead cam unit (most modern engines in
>cars are OHC, or even DOHC) which has a timing belt that
>is a lot more prone to failure than the gear that drives
>the camshaft in a pushrod engine like the O-320.
Dylan,
One of the most important difference between an auto and an aircraft engine
is the RPM. A car engine has reduction gears allowing the engine to spin
a lot faster than the wheels. The peak power output of an auto engine
usually occurs at very high RPMs (ie when you are on 1st gear). A high
RPM setting with a high load makes it very easy on the engine.
On the other hand, an aircraft engine does not have reduction gears. The
propellor is directly connected to the crankshaft. Since the propellors are
not very efficient at very high RPMs, you need to have an engine that
produces high power at low RPM setting. This is why aircraft engines are
different from auto engines. It is like having a car which has only one
gear. Imagine that. It is like trying to drive up a steep hill in your car
on 4th gear. It will stress the heck out of your engine, and probably
even break it. But that is what an airplane does every time it takes off.
That is also why the airplane engines are also significantly more expensive.
Many homebuilders are now trying to put auto engines into their airplanes
because they are cheaper. In order for that to work they have to invariably
introduce a reduction gear between the crankshaft and the propellor.
This adds some complexity to the system, but many people have used it
quite successfully.
Also you are comparing auto vs aircraft engines, you are comparing
modern Japanese engines and 1950's technology. Of course your club's
1960 C-172 is going to have an archaic engine compared to the 1998 Hondo
Accord. There is no arguing about that.
Anyway, I am not very clear on why introducing a reduction gear into the
aircraft is necessarily a bad thing. With a variable reduction gear (like
in a car) *and* a variable-pitch propellor, I don't see why an auto engine
cannot be successfully installed in production aircrafts. If anyone knows
the answer to this, I would like to hear from them.
Thanks!
--
Andrew Sarangan
PP-ASEL-IA
Dylan Smith
Gregory Travis wrote:
> The absolute hardest thing for any engine is inactivity. Given that, what
> has it harder: The car in the driveway that gets started several times a
> day or the plane in the hangar that sometimes goes weeks without running?
I wish our C172 would have that...perhaps I'd be able to schedule
it a bit more often! (Our club's 172 flies between 50-70 hrs/month)
> I don't know what a Sierra is but the average sedan will require about
> 15-35% percent of the engine's maximum power to maintain 55MPH on
> the open highway (lower for sleeker, smaller, sedans).
The Sierra is the Merkur XR4Ti in the US. It is a European built
Ford. The speed limits in the UK where the car was owned are 70 mph
on the highway, and you can get away with doing 85 there (so I did!)
I must admit that I was assuming around 65% for that speed - it
was a bit of a WAG (wild assed guess). But this IS usenet...
> >The only simpler engines I have come across are the ones that
> >power lawn mowers (which incidentally use magnetos too). They
> >are only really simpler because they use side valves and
> >therefore don't have pushrods.
>
> You say this as if it's a bad thing.
I'm saying it as that it is a GOOD thing. The simplicity of
the aero engine makes it have fewer things that can critically
fail when compared to the highly complex computer managed auto
engines today.
Dylan Smith
Andrew M. Sarangan wrote:
> Many homebuilders are now trying to put auto engines into their airplanes
> because they are cheaper. In order for that to work they have to invariably
> introduce a reduction gear between the crankshaft and the propellor.
> This adds some complexity to the system, but many people have used it
> quite successfully.
Do the engines have dual magneto ignitions? In my experience with
the cars I've driven by far the most unreliable part is the
ignition.
<off to muse the possibility of a tuned Corvette engine in
a C-172 airframe, probably completely impractical...>
john....@schwab.com
In article <01bd2c4e$53381ee0$5f83f2c2@default>,
"nightjar" <nigh...@pavilion.co.uk> wrote:
>
>
>
> I've had two car engines fail on me in use that I can recall. One from a
> con rod exiting though the side of the block. One on a new car from a minor
> fault that should have been picked up on the pre flight errm.. pre delivery
> up, after which it started to use nearly as much oil as petrol.
>
> I fly a twin, just in case.
>
I've had two aircraft engines go silent on me. One restarted, one did
not. After the second one, the NTSB guy said that it was a "one in a
million" kind of failure. I would've preferred to win the lottery
instead :-)) I really don't trust aircraft engines as much as I used to.
Instead, I now fly as though the next "one in a million" event is right
around the corner. Something I did not do early on because of the
knowledge that engine failures were such rare events.
I can't afford a twin :-(
Fly Safe,
John Galban=====>N4BQ (PA28-180)
-------------------==== Posted via Deja News ====-----------------------
http://www.dejanews.com/ Search, Read, Post to Usenet
Sriram Narayan
Dylan Smith (dy...@r.i.c) wrote:
: A C172 just has a simple carburetted engine, and the trasmission
: consists of a solid piece of metal going to the propellor. The
: spark is generated by a magneto which is a very simple device
: which essentially spins a permanent magnet past some windings.
: The suspension of a C172 is only in use on the ground, and
: consists of a single oleo strut for the nose, and a stout
: piece of bendy steel for the mains.
The propeller is one huge load that can wreak havoc when
it is not properly balanced. The auto engine typically
has a relatively small "moment" on the crankshaft which
puts much less stress on bearings than a typical aircraft
engine. With direct drive in the aircraft engine, there is
nothing to isolate this load. Since HP = torque * RPM,
with low RPM's of a/c engines, torque must be high. This
implies greater "forces", which I imagine will result in
greater stresses. Large torques are easier achieved with
large displacement than stroke length (where space inside
the cowling is a premium). There must also be other
considerations like relative mass of propeller to engine
mass (so that spool up time is reduced), cooling, compression,
CG, etc.. in what dictates engine size.
--
sriram narayan sriram....@technologist.com http://www.dsp.net/narayan
pp-asel:san francisco bay area:vfr flight planner:av articles:photo:sw dxing
Gregory Travis
In article <34D0EB...@r.i.c>, Dylan Smith <dy...@r.i.c> wrote:
>The Sierra is the Merkur XR4Ti in the US. It is a European built
>Ford. The speed limits in the UK where the car was owned are 70 mph
>on the highway, and you can get away with doing 85 there (so I did!)
>I must admit that I was assuming around 65% for that speed - it
>was a bit of a WAG (wild assed guess). But this IS usenet...
Can't get the actual data (bowling's server is down) but I would be surprised
if 85MPH in that car was 25% power.
greg
Gregory Travis
In article <6aqpmk$ae...@musca.unm.edu>,
Andrew M. Sarangan <sara...@unm.edu> wrote:
>Also you are comparing auto vs aircraft engines, you are comparing
>modern Japanese engines and 1950's technology. Of course your club's
>1960 C-172 is going to have an archaic engine compared to the 1998 Hondo
>Accord. There is no arguing about that.
What're the technical differences between the "modern Japanese engines" and
the "1950's technology?" and how to they relate to operation in aircraft?
>Anyway, I am not very clear on why introducing a reduction gear into the
>aircraft is necessarily a bad thing. With a variable reduction gear (like
>in a car) *and* a variable-pitch propellor, I don't see why an auto engine
>cannot be successfully installed in production aircrafts. If anyone knows
>the answer to this, I would like to hear from them.
How about:
1. Weight
2. Reliability
3. Fuel efficiency
Where do you want to start?
greg
Ron Natalie
Dylan Smith wrote:
> Do the engines have dual magneto ignitions? In my experience with
> the cars I've driven by far the most unreliable part is the
> ignition.
Magneto ignitions aren't the most reliable things either.
That's why there are two. The spark is weak. Your average
electronic car ignition will blast through any crud on the
plug. Two ignitions on one set of plugs is a frequent
configuration on auto engines adapted to air use.
tony
On Thu, 29 Jan 1998 14:49:34 -0600, Dylan Smith <dy...@r.i.c> wrote:
>> >The only simpler engines I have come across are the ones that
>> >power lawn mowers (which incidentally use magnetos too). They
>> >are only really simpler because they use side valves and
>> >therefore don't have pushrods.
>
>I'm saying it as that it is a GOOD thing. The simplicity of
>the aero engine makes it have fewer things that can critically
>fail when compared to the highly complex computer managed auto
>engines today.
>
I have a question. what about a plane that uses no pistions? like
using a Radial engine from the Mazda RX-7 I would think that this
configuration would be much more agreable due to its lack of
components, it power to weight ratio, weight to thrust ratio, and its
Power to torque ratio. Has any one herd or know of any one using this
particular engine for the air?
this is just a question, I dont know what I would do with the info,
but it posses an interesting question no?
tony
Dylan Smith
tony wrote:
> I have a question. what about a plane that uses no pistions? like
> using a Radial engine from the Mazda RX-7 I would think that this
> configuration would be much more agreable due to its lack of
> components,
I did see something about a piston engine that had fewer
parts by having the pistons (12 of them) mounted on some
sort of cam arrangement, which cut the number of moving
parts dramatically.
Has anyone ever fitted a rotary engine to an aircraft?
Jon Gross
gr...@sherrill.kiva.net (Gregory Travis) writes:
There is a tripacer (I believe) based at BFI that has a
mustang 6 cylinder engine in it, so it is done occasionally.
--
- jo...@watchguard.com: patron of the arts, ditch digger,
and Lord High Integration Wizard...........
Andrew M. Sarangan
gr...@sherrill.kiva.net (Gregory Travis) writes:
> In article <6aqpmk$ae...@musca.unm.edu>,
> Andrew M. Sarangan <sara...@unm.edu> wrote:
>
> >Also you are comparing auto vs aircraft engines, you are comparing
> >modern Japanese engines and 1950's technology. Of course your club's
> >1960 C-172 is going to have an archaic engine compared to the 1998 Hondo
> >Accord. There is no arguing about that.
>
> What're the technical differences between the "modern Japanese engines" and
> the "1950's technology?" and how to they relate to operation in aircraft?
What I meant to say was "modern auto engines", not necessarily Japanese.
Anyway, there are many differences and improvements between the early
auto engines and today's auto engines. The fundamentals of the internal
combustion engine may not have changed much since its invention, but its
efficiency and safety has clearly improved.
For example, take fuel injection. It makes an engine safer, better and more
efficient. It doesn't get iced up like the carburator. I don't think they
make cars with caburatored engines anymore. The new C-172 uses fuel injection.
Another "modern" feature is automatic fuel mixture adjustment. This too
results in safe, and more efficient operation. The Katana DA-20 has this
feature.
It is no secret that the new auto engines emit almost no carobon monoxide
or other bad stuff. CO is a major concern for pilots even if you are not
an environmentalist.
Modern engines are far more fuel efficient by having fancy exhaust gas
recirculations to burn off any unburnt hydrocarbons. The older engines
did not have any EGR.
>> >Anyway, I am not very clear on why introducing a reduction gear into the
>> >aircraft is necessarily a bad thing. With a variable reduction gear (like
>> >in a car) *and* a variable-pitch propellor, I don't see why an auto engine
>> >cannot be successfully installed in production aircrafts. If anyone knows
>> >the answer to this, I would like to hear from them.
>>
>> How about:
>>
>> 1. Weight
>> 2. Reliability
>> 3. Fuel efficiency
>>
>> Where do you want to start?
Weight is clearly an issue for aircraft engines, and this one of the areas
where aircraft engines still have an advantage. However, I don't think
the next-generation light-weight engine is going to come from the aircraft
industry. Ceramic engines are already being explored by the major auto
makers. If it becomes a success, that will change a lot of things the way
airplanes are powered.
I don't think an aircraft engine is any more reliable than an *equally*
maintained auto engine. In fact, I would dare to guess that a well
maintained auto engine will significantly outlast an aircraft engine.
Some of the new cars don't need any kind of maintanence for 100,000 km.
That is well over 1000 hours of operation, and we are not talking about TBO!
I don't think aircraft engines are anywhere close to the fuel efficiency
of auto engines.
IMO, the main reason why there is still a market for aircraft engines
is because of the unique low-rpm hi-power requirement, and the sustained
hi-power operation required from aircraft engines. It loses in every other
respect to auto engines.
--
Andrew Sarangan
PP-ASEL-IA
Sean Franklin
tony wrote in message <34d1079b...@news.netisle.net>...
>I have a question. what about a plane that uses no pistions? like
>using a Radial engine from the Mazda RX-7
I think there was a thread on the Mazda rotary in rec.aviation.homebuilt a
few months back... you might do a search on http://www.dejanews.com with
'mazda' and 'rotary' keywords on that group. Auto conversions are a common
subject in r.a.h
--
Sean Franklin
Indianapolis / Plymouth, Indiana
Gregory Travis
In article <6ar6v8$19...@musca.unm.edu>,
Andrew M. Sarangan <sara...@unm.edu> wrote:
>gr...@sherrill.kiva.net (Gregory Travis) writes:
>
>> In article <6aqpmk$ae...@musca.unm.edu>,
>> Andrew M. Sarangan <sara...@unm.edu> wrote:
>>
>> >Also you are comparing auto vs aircraft engines, you are comparing
>> >modern Japanese engines and 1950's technology. Of course your club's
>> >1960 C-172 is going to have an archaic engine compared to the 1998 Hondo
>> >Accord. There is no arguing about that.
>>
>> What're the technical differences between the "modern Japanese engines" and
>> the "1950's technology?" and how to they relate to operation in aircraft?
>
>What I meant to say was "modern auto engines", not necessarily Japanese.
>Anyway, there are many differences and improvements between the early
>auto engines and today's auto engines. The fundamentals of the internal
>combustion engine may not have changed much since its invention, but its
>efficiency and safety has clearly improved.
>
>For example, take fuel injection. It makes an engine safer, better and more
>efficient. It doesn't get iced up like the carburator. I don't think they
>make cars with caburatored engines anymore. The new C-172 uses fuel injection.
Fuel injection, on aircraft engines, has been around for roughly 75 years.
It's nothing new. Continental pioneered "modern" fuel injection on opposed
aircraft engines back in the 1950s - thirty years before it was widely
adopted for auto use.
>
>Another "modern" feature is automatic fuel mixture adjustment. This too
>results in safe, and more efficient operation. The Katana DA-20 has this
>feature.
>
A feature available via AMC bellows on Bendix aircraft injection units of
the 1940s through the 1990s. A feature available on Continental engines,
using their fuel injection system, since at least the mid 1960s.
>It is no secret that the new auto engines emit almost no carobon monoxide
>or other bad stuff. CO is a major concern for pilots even if you are not
>an environmentalist.
What do you know about aircraft engine emissions? When operated at best
economy, aircraft engines pollute very little with the major pollutants
being oxides of nitrogen (a problem with all lean-burn engines). There
is also the lead issue but that's a fuel problem.
>Modern engines are far more fuel efficient by having fancy exhaust gas
>recirculations to burn off any unburnt hydrocarbons. The older engines
>did not have any EGR.
You're confusing exhaust emissions with fuel economy. EGR system REDUCE
fuel economy and power. They address pollution problems that are
somewhat unique to automotive use (i.e. pollution at very low and
idle load).
>Weight is clearly an issue for aircraft engines, and this one of the areas
>where aircraft engines still have an advantage. However, I don't think
>the next-generation light-weight engine is going to come from the aircraft
>industry. Ceramic engines are already being explored by the major auto
>makers. If it becomes a success, that will change a lot of things the way
>airplanes are powered.
We've been hearing about ceramic engines for thirty years now. Guess
what? They still don't work. The big three are going diesel for the
next big push.
>I don't think aircraft engines are anywhere close to the fuel efficiency
>of auto engines.
Aircraft engines, largely because of a lack of emissions equipment as
well as low internal friction, usually beat the pants off of auto engines
in terms of fuel conversion efficiency.
That's with conventional carburetors and fixed ignition. Add balanced
injection ($700.00) and electronic ignition (~$2000.00) to an aircraft
engine and there isn't an auto engine on the planet that can touch it
from a fuel efficiency point.
>IMO, the main reason why there is still a market for aircraft engines
>is because of the unique low-rpm hi-power requirement, and the sustained
>hi-power operation required from aircraft engines. It loses in every other
>respect to auto engines.
Auto engines have a singular advantage over purpose-built aircraft engines
and that is perceived cost.
greg
Jim Miller
I've had a rod exit through the side of the block. It was a real
bummer, but the engine being a Ford 360 I was still able to drive it
home (about 75 miles!).
The Jap bikes indeed have impressive HP/Displacement ratios. I used to
own a Honda V65 Sabre - 116HP out of 1100 ccs. I don't think it would
last 2000 hours at 10,500RPM.
-Jim
Dylan Smith wrote:
>
> nightjar wrote:
> > I've had two car engines fail on me in use that I can recall. One from a
> > con rod exiting though the side of the block. One on a new car from a minor
> > fault that should have been picked up on the pre flight errm.. pre delivery
> > inspection.
>
> However, cars are not subject to the sort of inspection and TBO
> that aircraft engines are! Looking at the NTSB or AAIB reports,
> there are very few where the engine just quits cold. Most of
> the times the engine quits seem to be from induction icing
> (which will get both engines in a twin if you don't catch it!)
> or running out of fuel.
>
> Also, car engines are far higher stressed than aircraft engines.
> A C172 has a massive 320 cubic inch engine (about 5.3 litres)
> which only produces 160 bhp. My old Ford Sierra had an engine
> one third of that size, but produced 110 bhp. A Chevrolet
> Corvette has a 5.7 litre engine producing around twice as
> much power as the good old O-320. Of course, if you want
> to see real high output per litre, then look at a Japanese
> motorcycle...
>
Uwe Hale
Gregory Travis :
> What're the technical differences between the "modern Japanese engines" and
> the "1950's technology?" and how to they relate to operation in aircraft?
dual overhead cams instead of pushrods/rockers
4 or 5 valves per cylinder instead of 2
Electronic (Computer controlled) Fuel injection vs carburators
Electronic (Computer controlled)ignition vs magneto
regarding aircraft, add
consistant cylinder temperatures on water cooled engines vs varying temperatures on air
cooled engines.
Uwe
Uwe Hale
Gregory Travis :
> Automobiles must have a large difference between cruise horsepower needs
> and maximum horespower available in order to have acceptable acceleration
> characteristics. In other words, the engines are designed around the
> 15-35% power average but are capable, for short times, of producing
> a large fraction of the maximum in order to provide acceptable acceleration.
Not always. I often run my 4cyl nissan truck loaded with dirt bikes, gear,
etc. at full throttle doing about 70-80mph for hours at a time. Even have to
downshift going up hills when it slows down. The original motor got 180,000
miles including this kind of abuse.
Uwe
Roberto Waltman
>> I have a question. what about a plane that uses no pistions? like
>> configuration would be much more agreable due to its lack of
>> components,
A "radial" engine does have pistons, located in plane "radially"
from the center of the engine, hence the name. (Look at any
Stearman biplane to get the idea...) The RX-7 has a Wankel
*rotary* engine. And of course, some of the earlier aircraft
engines were radial and rotary.
>I did see something about a piston engine that had fewer
>parts by having the pistons (12 of them) mounted on some
>sort of cam arrangement, which cut the number of moving
>parts dramatically.
The Dyna-Cam engine.
>Has anyone ever fitted a rotary engine to an aircraft?
Yes, the Norton and Mazda have been installed in a few aircraft.
Sorry, I am not close enough to my pile of Experimenters to check
out the names.
RW.
DEAGLE844
Subject: single engine planes, are they really that dangerous?
From: "S. Manzo" <sma...@u.washington.edu>
Date: Sun, Jan 25, 1998 19:14 EST
Message-id:
<Pine.A41.3.96a.98012...@dante29.u.washington.edu>
I live in the city of seattle and every nw and then a single engine plane
crashes on a lake out side of the city. And some body told me that sort
of plane aren't safe at all and only those who dare or of low income dare
to fly them. Does any one know anything about this topic?
>
I don't think they are that dangerous. As my buddy used to
say, "the second engine gets you to the crash site faster".
Glenn Scherer
On 29 Jan 1998 20:18:35 -0500, gr...@sherrill.kiva.net (Gregory Travis)
wrote:
<snip long debate with good points on both sides>
Those of you on this group that don't also follow r.a.homebuilt may
not realize that this question has been debated at great length for
several years on r.a.h. Greg Travis follows both groups and his points
are well taken and accurate. You might all want to do a DejaNews
search on r.a.h to see the debate. Although I have not (yet) attempted
such a conversion myself, I have drawn the following general consensus
from those that have.
1. It *can* be done successfully.
2. It *will* be a *major* project, there are no "bolt a prop on it and
fly" answers, even the engines with an semi-established history such
as the 3.8 Ford and the VW will take extensive tinkering to produce
acceptable performance.
3. It *will* be heavier than an aero engine of comparable power.
4. It will be marginally cheaper for original install than an aero
engine. The size of the margin will depend on how much personal skill
you can bring to the project. The more you can do for yourself, the
greater the margin.
5. It will be significantly cheaper on overhaul. Once again, how much
cheaper depends on how much you can do yourself.
THE MOST IMPORTANT THING IS!, if you're not doing this on an
experimental category aircraft, don't even waste your time thinking
about it. You cannot put a non-certified engine in your type-certified
aircraft without accepting flight restrictions that most of us would
choke on!
Bottom line? If you just want to fly, don't mess with it. If you want
to build an experimental category aircraft, AND you love to tinker
with engines, you can do it, save *some* money, and have fun doing it.
Glenn
_
| | Glenn Scherer
__| ^~~~: Farmersville, TX USA
\ ^ ) sche...@airmail.net
\/\ /
\_(
Gregory Travis
I'm sorry but full throttle has little or nothing to do with full
power.
greg
Ron Natalie
Gregory Travis wrote:
> >
> >Another "modern" feature is automatic fuel mixture adjustment. This
> >too results in safe, and more efficient operation. The Katana DA-20
> >has this feature.
> >
>
> A feature available via AMC bellows on Bendix aircraft injection units
> of the 1940s through the 1990s.
My Bendix pressure carb on my 1950 Navion has a similar auto
adjustment. The only thing the mixture control does in my
plane is stop the engine.
Mark
Andrew M. Sarangan wrote:
> different from auto engines. It is like having a car which has only one
> gear. Imagine that. It is like trying to drive up a steep hill in your car
> on 4th gear. It will stress the heck out of your engine, and probably
> even break it. But that is what an airplane does every time it takes off.
That analogy doesn't ring true to me. After all, an automobile engine
has to move the drivetrain, which in turn is carrying the load of the
vehicle. I believe the only work an airplane engine has to do is spin
a balanced propeller. The work will be different at different RPMs
and airspeeds, but I expect even at its worst (short-field takeoff,
e.g.) it's probably not that bad.
If I'm wrong, I have confidence that someone will correct me. ;-)
Rick Macklem
Morris Bernstein (mor...@animal.blarg.net) wrote:
: Actually, it happened a couple of times in my old Civic which I owned
: for 7 years. Once when I was cruising along at speed of traffic,
: about 120 (kilometers per hour) when the engine lost power for no
: apparent reason. I started to pull over to the side of the road, but
: the thing kicked back into life as if nothing had happened. I never
: did figure out what/why it happened.
I had the same thing happen a few times in an old Toyota I had. One time
I yanked the air cleaner off as soon as I had pulled over and, sure enough,
the ice was still sitting in the carb, melting away. No doubt it was carb
ice in my case.
Have fun flying, rick
Roger Halstead
Mark wrote in message <34D1FD...@SpamBGon.mddmr.fc.hp.com>...
<G> I hope I get this straight now...
There is far more load on the engine from the propeller than most think.
For instance with a fixed pitch prop at full take off "throttle" you should
notice that the RPM (That with out an "s" for those that insist on calling
it RPMs -- Revolutions Per Minute(s) ??) does not come up all the way to
redline. Yet after a short roll the RPM does start climbing.
You will notice a similar phenomena when pulling up from flying straight
and level. The engine will "lug" down. Push the nose down and the RPM will
climb quite high and in some cases can exceed redline at full throttle.
Pretty much like trying to drive in just one gear. At slow speeds the
engine will "lug" and at high speeds (nose down descending, or a dive) the
engine RPM will climb just like going down hill in a car without changing
gears.
With a "Constant speed prop" (one where the pitch of the blades varies to
control engine RPM) full throttle with the prop control all the way in
produces the maximum RPM (in most cases) allowed, or the so called redline.
This could be thought of as an automatic transmission which shifts down
(blades at fine pitch) for takeoff and high gear (coarse pitch) for level
cruise.
It's called a constant speed prop because you set the RPM with the prop
control and then the blade pitch will automatically change (by the prop
governor) to maintain that RPM whether climbing or descending. Pull the
nose up and instead of the engine lugging the blades will go to a finer
pitch to maintain the rpm and reduce the load on the engine. Shove the nose
over and the prop will go to coarse pitch to keep the RPM down at the
desired setting.
This becomes most noticeable under the hood as with a fixed pitch prop one
of the attitude clues is the pitch or sound of the engine. You don't get
that when using a constant speed prop.
So... When in level cruise with the prop adjusted to give the desired RPM
and the throttle adjusted to give the desired manifold pressure you could
think of the prop as an automatic transmission.
Roger Halstead K8RI and EAA Chapter 1093 Historian
N833R World's oldest Debonair? S# CD-2
http://members.tm.net/rdhalste
Jean Richard
> >> The majority of the time, auto engines operate far below their maximum rated
> >> power. The high power is used only during brief periods of accelerations.
You are probably living in USA where cars use big 6 to 8
cylindre engine of 3 litres and above, and where speed limit
on highways is below 100 km/h. Go in Europe and when you
will see 1 litre cars overpassing you at 150 km/h, you will
have a different idea.
> >> If a car engine were to operate at its maximum power continuously then it
> >> would not last for more than a few hours.
It can be true with a Formula 1 engine that give more than
five times the power of a Lycoming O-320 with less than
half the cubic capacity. But once again, cars with more
than 300 000 kilometres are not uncommon in Europe and those
are often used at more than 75 % of power on autoroutes,
autobahn...
> On the other hand, an aircraft engine
> >> operates at its full power most of the time,
Here in Northern regions (Canada), airplanes used for
training in winter, and specially when doing touch and
goes, have a lot more engine trouble than those used for
cruising. Many flying schools don't allow touch and goes
training at temperatures below minus 10 because it's
putting too much wear and trouble on engines. Compare
that to car that we stop and start many times a day in
temperatures that sometimes go below minus 30. A cold
start at minus 20 degrees is estimated to do the same
wear on the engine as a 800 to 1000 kilometre trip at
cruising speed on the highway.
> I would
> >argue that most aero engines have a much easier life than
> >most car engines.
And I agree, at least where winter exists.
> On the other hand, an aircraft engine does not have
> reduction gears. The
> propellor is directly connected to the crankshaft.
Except the Rotax 912...
Direct drive (Lycoming style) is part of a solution and part
of a problem. A problem ? Yes because everything is shaking
together, from the piston to the propeller. It contribute
to wear on the crankshaft, on the engine mount, on everything,
including to noise level and vibrations. People flying for
the first time in Rotax 912 powered airplanes are always
surprise to see how it's smooth and somewhat quieter than
a Continental or Lycoming powered airplane in the same range
of power. The same is true from the ground too. I observed
a Cessna 152 and a Pélican 912 doing touch and goes together.
The only time you can hear the Pélican from the ground was
when the C152 was on final with engine idling.
But something that work properly within a given scale cannot
always be extrapoled easily for a different scale. Gearboxes
work very well with small Rotax. They are not 100 % trouble
free, but still very reliable. With bigger engines like the
210 hp Porsche, it seems that builders still have to work on
design to improve reliability without adding too much weight
and costly maintenance. For that reason, builders seem to
stick with the direct drive solution.
> Since the propellors are
> not very efficient at very high RPMs, you need to have an engine that
> produces high power at low RPM setting. This is why aircraft engines are
> different from auto engines. It is like having a car which has only one
> gear. Imagine that. It is like trying to drive up a steep hill in your car
> on 4th gear.
Not really. It's like engine having only a torque converter
but no gearbox. Low speed means a lot of lost energy in the
hydraulic torque converter. But very different from trying
to start a direct clutched car in 5th gear without making
the clutch slip (and smoke...).
> It will stress the heck out of your engine, and probably
> even break it. But that is what an airplane does every time it takes off.
It's like you are trying to say that you start your take off
run with full power, but with engine running only a 400 rpm.
> That is also why the airplane engines are also significantly more expensive.
What make aircraft engines more expensive are :
- small scale production
- high cost of research and development
- high cost of certification
- American lawyers (the last but not the less)
Raw aluminium and steel just add a few dollars...
> Also you are comparing auto vs aircraft engines, you are comparing
> modern Japanese engines and 1950's technology.
1950's technology ? Take 10 to 20 more years. It's
1940's technology and even late 1930.
> 1960 C-172 is going to have an archaic engine compared to the 1998 Hondo
> Accord. There is no arguing about that.
Both can be greatly improved. They are still converting
less than 30 % of polluting fuel in useful energy. It's
a poor ratio. Worst, the C172 is using fuel to cool down
its valves. Try leaning the mixture while doing glider
towing and you will see what I mean. Cooling an engine
with unburned fuel (and partly with air) is not exactly
environment friendly. You can be happy that US government
still believe that atmospheric pollution reduction must
be left to other countries, because Lycoming wouldn't be
allow to build "fuel cooled" engines, using forbidden
leaded fuel and spreading in the sky a lot of undesirable
fumes...
If we want to keep flying small airplanes in the next
century, maybe it's time to adapt before being bannished.
J. Richard
Jean Richard
An auto engine has been developed for airplanes and got
certification. It's the FAM 3000, which is based on a
V6 3 litre engine found a few years ago on Peugeot,
Renault and Volvo cars.
That engine has been flown on a Robin R3160 (metal
4 seater) and compared to a Lycoming O360 (which
normally equip that airplane). The results are the
following :
- better performance on take off and climb with
the FAM (the FAM give 185 cv against 180 for the
Lycoming) ;
- fuel consumption 15 to 20 % less with FAM ;
- very significant noise level reduction, inside
and outside ;
- cleaner engine (can work with autogas) ;
- less vibration due to gearbox reduction (direct
drive means all sources of vibration in phase)...
But the engine is not in production and probably
will never be, even if it got certification. Why ?
- too small market to interest industry people ;
- and the presence of Renault who is going back
to aviation (long long time ago, Renault was
building aircraft engines).
Renault is working on a diesel aircraft engine in
the near 200 cv range. But even if Renault is a
somewhat large car and truck builder, and with a
lot of experience with diesel engine, people
choose to build an airplane engine from zero and
not from a car engine (even if the experience
built with so many year in cars (including racing
Formula 1 up to this year) will surely be applied
to aeronautical).
It can make sense to design an aeronautical engine
exclusivly for aircraft instead of trying to adapt
a car engine. Only the future will tell us if
Renault did the right choice. It's true that in
that power range, not only the FAM 3000 will stay
an orphean, but Porsche also failed a few years
ago, but it's also true that in less powerful range,
we have many excellent engines with auto heritage.
Think about the Rotax 912, the Limbach, the JPX.
J. Richard
Jean Richard
Dylan Smith wrote:
> Do the engines have dual magneto ignitions? In my
> experience with the cars I've driven by far the most
> unreliable part is the ignition.
It seems that you are still driving a 1954 Chevrolet
Belair or a 1955 Meteor Rideau... You must be a very
careful driver to keep your cars so long.
The last time I got trouble with ignition in my car
was near 25 years ago. The car didn't have an electronic
ignition, but the fact was that it was difficult to see
the engine under the hood because it was full of wet snow.
Don't tell me it's because I'm owning Diesel cars because
it was true only for one month. I've owned European,
Japanese and even one American cars.
I would like to try to start a Lycoming with those
two magnetos hard packed in snow...
But even with less than 400 hours flying time in motor
airplanes, I know what is a non working magneto... And
I know why they choose to install two of them...
J. Richard
Uwe Hale
Gregory Travis :
> I'm sorry but full throttle has little or nothing to do with full
> power.
Eh? At what throttle do you make full power? 1/4??? You're statement makes no
sense. I just read some of your other posts. Carbureted, aircooled, pushrod
aircraft engines are more efficient than modern automobile engines? Yeah right!
ROFLMAO.
Uwe
Morris Bernstein
In article <34CF45...@research.bell-labs.com>,
Mike Wei <w...@research.bell-labs.com> wrote:
>For one thing, is there any driver here strictly following the
>maintanence schedule on their cars? Especially, how many car owners
>change their timing belt every 60,000 miles (or whatever the
>recommendation is)?
I wound up getting rid of the Civic just before it was time to change
the timing belt. It was also due for a new clutch and new tires.
Until that point, I did follow the manufacturer's recommendation. The
engine was almost brand new. Unfortunately, the frame was starting to
rust out.
>If cars are regulated like airplanes, I bet most cars can run for 25
>years or a million miles, without many breakdowns.
Not in Montreal where they spread so much salt in the winter the cars
are biodegradable :-(.
>Morris Bernstein wrote:
>
>> Actually, it happened a couple of times in my old Civic which I owned
>> for 7 years. Once when I was cruising along at speed of traffic,
>> about 120 (kilometers per hour) when the engine lost power for no
>> apparent reason. I started to pull over to the side of the road, but
[snip]
Morris
p.s. I've been away for a few days and and came back to find a few
hundred messages on the server. So far not a single flame. Way cool!
--
Morris Bernstein mor...@pobox.com
"Science requires equal amounts of awe and skepticism"
Spammers beware: I may respond in a way you _won't_ like
GJ...@webtv.net
Rodger wrote < you could think of the prop as an automatic transmition >
Sounds more like cruise control on your car.
GJ
GJ...@webtv.net
I read somewhere, Buzzmans troubleshooting page I think, that the
biggest problem is the prop destroys the crankshaft bearings and the
crankshaft. With or without a reduction gear. That the materials in the
autos component parts wont take the stress that the a/c engine will. The
big three saves a buck wherever they can you know :-)
GJ
Roger Halstead
GJ...@webtv.net wrote in message
<6auaev$blj$1...@newsd-161.iap.bryant.webtv.net>...
Rodger wrote < you could think of the prop as an automatic transmition >
Sounds more like cruise control on your car.
Mmmm no, not quite, as the prop directly controlls the engine RPM and only
indirectly aircraft speed.
Maybe a cruise control *plus* as it only works that way in level flight.
Push the nose up and the airspeed will fall off where in a car with cruise
control it will remain the same (well it's supposed to). Shove the nose
down and the airspeed will go up, but again the RPM remain the same.
You can still adjust the throttle to differing Manifold pressures to get
more or less airspeed as well, yet the RPM still stays the same.
However there is often a wide range of throttle (Manifold pressure) and prop
(Engine RPM) settings for any given HP.
Roger Halstead K8RI and EAA Chapter 1093 Historian
N833R World's oldest Debonair? S# CD-2
http://members.tm.net/rdhalste
GJ
James M. Knox
In article <VA.00000b5b.00880104@sct>, Uwe Hale <ha...@sct-inc.com>
wrote:
>> I'm sorry but full throttle has little or nothing to do with full
>> power.
>
>Eh? At what throttle do you make full power? 1/4??? You're
statement makes no
>sense.
My news server seems to have missed whatever came before, but Greg's
statement is quite correct (with an assumption). Full throttle may
or may not produce full engine power, depending on mixture and
ignition timing. More important, full throttle most definitely does
NOT equate to full thrust power -- just look at a plane with
variable pitch prop.
jmk
Uwe Hale
James M. Knox :
> My news server seems to have missed whatever came before, but Greg's
> statement is quite correct (with an assumption).
Ok, a huge, grand canyon leap, kind of assumption.
> Full throttle may
> or may not produce full engine power, depending on mixture and
> ignition timing.
Full throttle is going to produce the maximum engine power compared to
any other throttle setting.
> More important, full throttle most definitely does
> NOT equate to full thrust power -- just look at a plane with
> variable pitch prop.
Agreed. Thrust was never the issue.
The previous messages were about the durability of engines. Greg
stated that an automobile engine could not be run at full power for any
length of time. I replied that I run my nissan full throttle for hours
at a time and the original engine lasted 180K mi.
I just find it funny that someone is actually trying to argue that 50
year old engine technology is superior to what's available today.
BTW, Please don't send me duplicate messages to e-mail and the
newsgroup. If I posted on the newsgroup, reply there. thanks.
Uwe
Q Salt
> What do you know about aircraft engine emissions? When operated at best
> economy, aircraft engines pollute very little with the major pollutants
> being oxides of nitrogen (a problem with all lean-burn engines). There
> is also the lead issue but that's a fuel problem.
good post greg. It`s worth noting that Lead is itslef not a big problem in
emmisions. The reason lead is removed from fuel is that it screws up
catalytic convertors. The stuff they put in it`s place is actually worse
than the lead was! I have a paper outlining this somewhere, I`ll see if I
can find it if anyone`s interested.
Q
Gregory Travis
In article <VA.00000b6b.0694688b@ws>, Uwe Hale <ha...@sct-inc.com> wrote:
>
>James M. Knox :
>> Full throttle may
>> or may not produce full engine power, depending on mixture and
>> ignition timing.
Those are not even the most crucial factors. See below
>Full throttle is going to produce the maximum engine power compared to
>any other throttle setting.
This is an incorrect assumption, see below.
>The previous messages were about the durability of engines. Greg
>stated that an automobile engine could not be run at full power for any
>length of time. I replied that I run my nissan full throttle for hours
>at a time and the original engine lasted 180K mi.
And I replied that full throttle is no guarantee that your engine is
producing full power.
POWER = FREQUENCY (RPM) x TORQUE
Your engine will have been rated at a certain maximum horsepower AT
A CERTAIN RPM. For you students, THIS is why an aircraft with a
constant-speed propeller has a more spritely takeoff and climb than an
aircraft with a fixed-pitch prop. Those aircraft engines are rated for
their maximum power at a certain RPM (2700 typically for Lycomings). They
cannot make that power if the prop doesn't allow them to turn that
fast. A fixed-pitch prop will limit takeoff/climb RPM to something around
2400-2500RPM (typically). Therefore, even with full throttle, the engine
with a fixed-pitch prop is NOT developing full power.
By definition, if your engine is NOT turning at its rated maximum horsepower
RPM then it is NOT producing full power. Note that throttle position
never came into the discussion. Throttle position has an effect on the
amount of torque produced but not, necessarily, on the RPM. If the RPM
can be varied (i.e. with a controllable prop, an automotive transmission,
or on a dynomometer) it is >possible< to produce MORE power at a lower
throttle position than at a full throttle position.
Flooring your throttle, in your Nissan, doesn't equate to maximum power
unless a whole lot of other conditions are met. One of those conditions is
that the engine be at its maximum power RPM. At what RPM was your engine
running when you were driving around with the hammer down?
Again, I posted information that should have made this point clear but you
chose to ignore it. Your Nissan will need about 25% of your engine's
maximum horsepower to maintain 60MPH on a freeway. How fast do you think
you would be going if you used all 100% of your engine's horsepower?
>I just find it funny that someone is actually trying to argue that 50
>year old engine technology is superior to what's available today.
Well, while you're chuckling to yourself, consider that the Otto cycle
engine was invented roughly a century ago and that development and
refinement of the engine peaked at the end of World War II. What's
"available today" is what was available 50 years ago for cars and
planes. The technology matured well before I (and I suspect you) was
born.
If you have data that contradicts what I've posted here then why don't
you cough it up? I have lots of dynomometer data, done under controlled
conditions, of both aircraft and auto engines. They all say the same
thing: There's no replacement for displacement and that aircraft engines
are far more efficient, in general, than auto engines at converting
chemical energy into kinetic energy.
Quick Quiz, which should be easy if you've been paying attention:
Q. Which engine has the lower BSFC?
1. The 1997 Ford SHO engine, with EFI
2. The 1984 Continental IO-550 engine, with CFI
greg
John R. Johnson
On Mon, 2 Feb 1998, Uwe Hale wrote:
>
> Full throttle is going to produce the maximum engine power compared to
> any other throttle setting.
>
That is not even necessarily true. Full throttle may be providing a
poor fuel mixture and the engine is held below maximum power RPM by a
prop that is too steep, and you could actually get more power by easing
the throttle a little.
Maximum power only occurs at maximum manifold pressure and the maximum
power RPM. NO fixed pitch propellor aircraft can get maximum power at
a standstill even with the throttle all the way open. If the propellor
allowed the RPM to go high enough the engine would overspeed as soon as
the airplane started to move. Even with a constant speed propellor, the
low pitch stop will normally not allow full power RPM while static, even
though you should attain it shortly into the takeoff roll. My own
airplane will reach my max HP RPM at about 50 mph during the takeoff
roll. At higher speeds the governor will start increasing the pitch to
keep the engine from overspeeding!
By the way, aircraft engine technology is neither olded nor less efficient
than auto engine technology. It just has different problems to solve, and
the solutions are correspondingly different.
John
Anton Verhulst USG
>Rodger wrote < you could think of the prop as an automatic transmition >
>Sounds more like cruise control on your car.
No, Rodger (sp?) has it right. A constant speed prop allows the engine to
develop full rpm at low airspeed. With a fixed pitch prop plane, look at your
tach at full power when you start your take off roll. Not anywhere near
redline, right? With a constant speed prop set at max rpm (little pitch)
it will be at the redline and, hence, develop more power.
Tony V.
Gregory Travis
In article <VA.00000b4f.27477fcd@sct>, Uwe Hale <ha...@sct-inc.com> wrote:
>Gregory Travis :
>
>> What're the technical differences between the "modern Japanese engines" and
>> the "1950's technology?" and how to they relate to operation in aircraft?
>
>dual overhead cams instead of pushrods/rockers
How is this an advance rather than simply a difference? Dual overhead
cams contribute significant additional friction to the engine, which
must be overcome with fuel. They also demand a much more complex drive
system than a pushrod/rocker system. This, of course, reduces reliability.
Finally, they are not weight competitive with a pushrod system.
So, for less reliability, more parts, more weight, and more friction we
get what? A little better breathing? How important is that for an
engine that maxes out at 2700 RPM and has valves the size of most automobile
pistons?
>4 or 5 valves per cylinder instead of 2
Twice as many valves to fail, twice as much valve friction that must be
overcome with additional fuel. Again, this is an optimization for a
low-displacement, high-RPM engine. It is not a cost effective
solution for a large-displacement, low-RPM engine.
>Electronic (Computer controlled) Fuel injection vs carburators
How does EFI compare, efficiency-wise, with continuous mechanical injection
in a steady-state, high output application? It's a wash with the EFI
coming out with a higher parts count, more failure modes, and more expense
for no increase in fuel efficiency.
>Electronic (Computer controlled)ignition vs magneto
Check out Lightspeed or LASAR for solutions for your aircraft engine.
>regarding aircraft, add
>consistant cylinder temperatures on water cooled engines vs varying
>temperatures on air cooled engines.
Which affects what? Not fuel efficiency. On the other hand, you
don't have to lug around 20-30 pounds of water pumps, radiators, hoses,
and coolant with an air-cooled system.
greg
Uwe Hale
Gregory Travis :
> How is this an advance rather than simply a difference?
People usually don't make things different if it isn't an advance.
> Dual overhead
> cams contribute significant additional friction to the engine, which
> must be overcome with fuel.
No they don't. Where do you get this from? With overhead cams, you are
eliminating the friction of the lower pushrod to lifter, upper pushrod to
rocker, rocker arm, and rocker arm to valve contacts. Modern engine's camshaft
lobe to bucket to valve has less moving/rubbing parts, mass, and less friction.
> They also demand a much more complex drive
> system than a pushrod/rocker system.
Wrong again. The pushrod/rocker drive system is much more complex. Lets count
the parts. 4 cylinder aircraft has 1 timing chain, 1 cam, 8 lifters, 8
pushrods, 8 rockers for a total of 26 moving parts (not counting dozens of
needle bearings in the rockers and lifters). A modern 4 cylinder has 1 timing
chain(or belt), 2 cams, 16 buckets for a total of 19 moving parts.
>This, of course, reduces reliability.
Of course. Thanks for making my point.
> Finally, they are not weight competitive with a pushrod system.
If the cams are hollow, the second cam should be just as light as all the
pushrod parts.
> So, for less reliability, more parts, more weight, and more friction we
> get what? A little better breathing?
No. Along with much better breathing (better filling and scavenging = better
efficiency) you also get more reliability, less parts, probably less weight,
and less friction.
> How important is that for an
> engine that maxes out at 2700 RPM and has valves the size of most automobile
> pistons?
Not important if you are going to max out at 2700. But very important if you
are wanting to the most power and efficiency out of a motor. Most engine
applications have a gearbox so that the engine can be run at it's most
efficient state or it's maximum output regardless of the required output speed.
Aircraft engines are designed according to a desired output speed (low rpm)
and not for most efficient operation. Otherwise, all our cars would be powered
by 1940s VW motors.
> Twice as many valves to fail, twice as much valve friction that must be
> overcome with additional fuel.
These "valves the size of most automobile pistons" are also much heavier than
valves in multivalve engines. This requires much stiffer springs to get them
to close and seal(not bounce). Stiffer springs will create more friction along
the valve train than smaller lighter valves with softer springs - even with
twice the number of smaller lighter valves. Also think about the amount of
mass including lifters, pushrods, rockers, and huge valves that have to be
accelerated, stopped, and reversed every other engine revolution. Add up all
that weight times distance traveled and calculate the amount of power used by
the engine just to actuate the valve train.
> How does EFI compare, efficiency-wise, with continuous mechanical injection
> in a steady-state, high output application?
Mechanical injection and carburetors do not adjust themselves to the fuel
requirements of each individual cylinder 100s of times per second. It simply
squirts fuel in according to rpm and some other inputs. It cannot consistently
provide a 1/14.7 fuel/air ratio. The better EFI units use direct port
injection where the fuel is mixed (pulsed) with the air just in front of the
valves. This eliminates the fuel separation problem that carburetors and some
fuel injection systems have as the fuel/air mix has to go around bends in the
intake manifold. Around the corners, the fuel separates and enters the
combustion chamber as large unburnable droplets. EFI pulsed injectors also
prevent fuel puddling compared to mechanical constant injection. You end up
having to run a richer mixture (more fuel) to compensate for all the unburnt
fuel getting dumped out the exhaust.
> It's a wash with the EFI
> coming out with a higher parts count, more failure modes, and more expense
> for no increase in fuel efficiency.
But the parts are electrical and IMHO more reliable than anything mechanical.
And they are much more efficient as I pointed out in the last paragraph.
> Check out Lightspeed or LASAR for solutions for your aircraft engine.
Why isn't that stuff standard? No aircraft engine here, thermals are much more
fuel efficient.<g>
And if the displacement(bore) was smaller, the rpm higher, and a decent squish
band was designed in the head (like modern engines), you wouldn't need the dual
ignition system/plugs to overcome the problems with the slow flame front
propagation.
> >regarding aircraft, add
> >consistant cylinder temperatures on water cooled engines vs varying
> >temperatures on air cooled engines.
>
> Which affects what? Not fuel efficiency.
Yes, fuel efficiency. Some cylinders will run leaner than others due to
temperature differences. Some might be prone to pre-ignition. So you have to
run the mixture rich for the leanest cylinder. This will make other cylinders
run rich and waste fuel. EFI would also help in this situation by monitoring
each cylinder individually and adjusting the fuel/air ratio accordingly.
> On the other hand, you
> don't have to lug around 20-30 pounds of water pumps, radiators, hoses,
> and coolant with an air-cooled system.
True, but you also don't have to replace cracked cylinders all the time either.
It's a tradeoff, do I want to carry extra weight while flying or do I want to
be in the hangar working on a light engine.
Uwe
Gregory Travis
In article <VA.00000b89.1388f29e@ws>, Uwe Hale <ha...@sct-inc.com> wrote:
>Gregory Travis :
>
>> How is this an advance rather than simply a difference?
>
>People usually don't make things different if it isn't an advance.
You've obviously never heard of marketing.
>> Dual overhead
>> cams contribute significant additional friction to the engine, which
>> must be overcome with fuel.
>
>No they don't. Where do you get this from?
Gee, any one of a half-dozen beginning and advanced textbooks on tribology
and engine design? You might want to check out Taylor for a graph of pushrod
valve train drive torque vs. some alternatives.
> With overhead cams, you are
>eliminating the friction of the lower pushrod to lifter, upper pushrod to
>rocker, rocker arm, and rocker arm to valve contacts. Modern engine's
>camshaft lobe to bucket to valve has less moving/rubbing parts, mass,
>and less friction.
And you add several camshaft journal bearings, a belt or gear drive, etc.
Again, I could go on into the reasons why the overhead cam design is less
efficient but it's easier to state that the research and data simply
don't support your view. If you're interested in reading more I can
point you to the relevant textbooks and SAE papers.
>Not important if you are going to max out at 2700. But very important if you
>are wanting to the most power and efficiency out of a motor. Most engine
>applications have a gearbox so that the engine can be run at it's most
>efficient state or it's maximum output regardless of the required
>output speed.
The most efficient state for a reciprocating engine, if you're talking
about RPM and mechanical friction, is 0 RPM. Above that value mechanical
friction, which must be overcome with additional fuel, rises in proportion
to RPM. The only reason for running a reciprocating engine at high
RPM is if you want to reduce its package size and if you expect that the
engine will run at a much lower percentage of its maximum RPM the majority
of the time. Does that sound like an automotive application?
Some of the most efficient reciprocating engines in the world are shipborn
diesels with pistons the size of manhole covers running approximately
100 RPM (that's one hundred) direct drive to the prop. Believe me they
are SENSITIVE about fuel burn on ships and if they thought they could
get better efficiency by running a smaller engine faster, through a
gearbox, they would.
>Mechanical injection and carburetors do not adjust themselves to the fuel
>requirements of each individual cylinder 100s of times per second. It simply
>squirts fuel in according to rpm and some other inputs. It cannot
>consistently provide a 1/14.7 fuel/air ratio. The better EFI units use
>direct port injection where the fuel is mixed (pulsed) with the air just
>in front of the valves. This eliminates the fuel separation problem that
>carburetors and some fuel injection systems have as the fuel/air mix has
>to go around bends in the intake manifold. Around the corners, the fuel
>separates and enters the combustion chamber as large unburnable droplets.
The continuous injection systems on aircraft are also the "port" injection
type and inject fuel just before the intake valve. It's also not important,
in an aircraft application, to adjust the fuel/air ratio several times
per second. That's important in the dynamic conditions encountered during
street driving but it simply adds cost and no value to an aircraft application
where you are cruising at a steady-state for hours.
Again, the dyno data bear this out. The CAFE foundation independently
measured the Continental IO-550 aircraft engine at a BSFC of 0.38 a
couple of years ago. No auto engine can touch that.
>EFI pulsed injectors also
>prevent fuel puddling compared to mechanical constant injection. You end up
>having to run a richer mixture (more fuel) to compensate for all the unburnt
>fuel getting dumped out the exhaust.
Huh? How do they do this?
>> Check out Lightspeed or LASAR for solutions for your aircraft engine.
>
>Why isn't that stuff standard? No aircraft engine here, thermals are much
>more fuel efficient.<g>
Because the manufacturers aren't sure that the economics are justified. If
the LASAR system shaves 0.04BSFC off the fuel burn of a typical O-360 then
that means that the O-360 will consume approximately 1,677 gallons less
fuel over its TBO run of 2000 hours. That's approximately $3000.00 over
ten years (a typical TBO run time). The LASAR system costs over
$2,000 up front. $2000.00 invested at even a modest interest rate will
yield well over $3000.00 at the end of ten years. It's cheaper to burn
more fuel.
>And if the displacement(bore) was smaller, the rpm higher, and a decent
>squish band was designed in the head (like modern engines), you wouldn't
>need the dual ignition system/plugs to overcome the problems with the
>slow flame front propagation.
That must be why Alfa Romeo, Nissan, and Toyota have all come out with
dual plug auto engines.
The question you should be asking yourself is not "Why do aircraft engines
have two plugs?" but "Why DON'T auto engines have two plugs?" The answer,
my friend, is cost. Auto engines don't have two plugs not because it
wouldn't make them more efficient but because, at approximately $4.00
per engine to implement it (the manufacturer's cost), it represents hundreds
of millions of dollars per year that doesn't go back to the stockholders.
>> On the other hand, you
>> don't have to lug around 20-30 pounds of water pumps, radiators, hoses,
>> and coolant with an air-cooled system.
>
>True, but you also don't have to replace cracked cylinders all the time
>either.
I've never replaced a cracked cylinder. You know why? Because I replace
them with new at every overhaul instead of trying to get by with junkyard
junk in an aircraft engine.
Look, you can speculate all you want with smooth glossy data from auto
manufacturer marketing departments. On the other hand, if you've got
actual comparative data, regarding fuel burn, between auto and
aircraft engines that contradicts what I've posted here then put your
money where your mouth is and out with it.
greg
John R. Johnson
On Thu, 5 Feb 1998, Uwe Hale wrote:
> Gregory Travis :
>
> > How is this an advance rather than simply a difference?
>
> People usually don't make things different if it isn't an advance.
>
I certainly wouldn't say that. Do you think plastic upholstery is an
advance over leather?
In my experience most changes were done to make things cheaper. They
even call it "Value Engineering" when you make it just barely good
enough to do its job until it is paid for.
John
Dave Stadt
Uwe Hale wrote:
>
> Gregory Travis :
>
> > How is this an advance rather than simply a difference?
>
> People usually don't make things different if it isn't an advance.
Not to pick on GM but have you ever heard of the Vega, GM diesel or the
Cadillac V8-6-4? Somehow different and advanced don't go together
when I think of these.
CHOP CHOP
Jean Richard
John R. Johnson wrote:
>
> On Thu, 5 Feb 1998, Uwe Hale wrote:
>
> >
> > > How is this an advance rather than simply a difference?
> >
> > People usually don't make things different if it isn't an advance.
> >
> upholstery is an advance over leather?
Yes it is ! Why ? For sure, Rolls Royce is still using leather
in its cars, just like Mercedes Benz for some of theirs. But
how many Rolls are sold every years ?
How many millions of cars are built every year ? How many
animals would we need to be able to used all leather
seats and garnitures in them ?
> In my experience most changes were done to make things
> cheaper.
Not sure. Radial tyres are more expansive to make than those
old cheap tyres still found on American production up to
the late 70's. Disk brakes are also more expansive, just like
are overhead camshaft and most of the modern engine
technology.
What we read now from the defenders of old airplane engine
1930 technology, we heard it a few years ago when more
advanced European cars started invading North America,
followed by Japanese car (less innovative than European,
but still in advance on N.A. production).
How many people want to go back to old V8 Buick and likes ?
Not a lot. Because what modern technology gave to us is :
- cars with a fuel consumption of 5 to 8 litres/100 km
where those Buick took 20 to 30 for the same speed and
useful load ;
- cars that only burn fuel and not oil - adding a litre
of engine oil for every two gaz tank filling was common
with big V8
- engine that last easily two times longer than those big
V8, and being almost trouble free compared to them
- engine that start in cold weather when big V8 refuse
to do it at near -20 degrees
- atmospheric pollution lowered by 200 % in some major
N.A. cities while the car trafic increases by 300 %
I still remember my father's 1956 Dodge Regent. He bought it
brand new. Four year later, it was a wreck. So rusty than
part of the body were falling out. Exhaust fumes were blue.
And like most of the cars of that era, trouble was a common
law. Trouble with engine, with gearbox, with heather, wipers,
radio, name it... He sold it with only 140 000 km.
Nothing to compare with my 1995 Toyota Tercel (the bottom
at Toyota). It would be hard to find even a single part of
my Toyota that's not improved compared to what we have on
the old Dodge.
Airplane are the same. I know a lot of people who bought
airplanes and sold them after a while because they represent
a lot of trouble, costly maintenance and so on. They are
old Dodge 1956, that's it.
Light airplanes missed almost all the research and
development needed to make them modern, efficient and
reliable like cars. Of course, both world cannot be
compare all the way. But trying to defend what is killing
light aviation is a nonsense.
What worked for cars can work for airplane, even if it
cannot be done the same way. Thinking that we cannot improve
airplanes because they reached the perfection with Cessna and
Lycoming is ridiculous. Thinking that engineers and designers
only want to change products for marketing reasons and
cannot have any desire to improve things is also ridiculous.
J. Richard
John R. Johnson
On Thu, 5 Feb 1998, Jean Richard wrote:
> How many millions of cars are built every year ? How many
> animals would we need to be able to used all leather
> seats and garnitures in them ?
>
However, decent fabric is excellent and not at all hard on the animal
population. Besides, you talk like we kill the animals for their hide.
We don't. We kill them to EAT. The hide is a byproduct. If you don't
choose to use it, it is still there. I see many rotting hides because
it is too much trouble to TAN them.
> > In my experience most changes were done to make things
> > cheaper.
>
Been in a Wal-Mart Store lately?
> Not sure. Radial tyres are more expansive to make than those
> old cheap tyres still found on American production up to
> the late 70's. Disk brakes are also more expansive, just like
> are overhead camshaft and most of the modern engine
> technology.
>
Not any more. They were more expensive when all the tire machinery
was still built for making bias ply tires. Disk brakes are another
example. Why should a disk brake be more expensive than a drum.
> What we read now from the defenders of old airplane engine
> 1930 technology, we heard it a few years ago when more
> advanced European cars started invading North America,
> followed by Japanese car (less innovative than European,
> but still in advance on N.A. production).
>
I have no idea what you are talking about.
> How many people want to go back to old V8 Buick and likes ?
> Not a lot. Because what modern technology gave to us is :
>
> - cars with a fuel consumption of 5 to 8 litres/100 km
> where those Buick took 20 to 30 for the same speed and
> useful load ;
That is not because of improvements is the specific fuel consumption
of the engines. That is merely because the cars are smaller and lighter
so you have less metal to ship around with you. There have been some
improvements in materials, fit, and lubricants, and they would help the
V-8's even more than they help the little engines that have to turn too
fast to make their power. Without those advances the little engines
were not possible because they wouldn't remain together at all.
> - cars that only burn fuel and not oil - adding a litre
> of engine oil for every two gaz tank filling was common
> with big V8
Not with reasonable maintenance. However, in any case most of that
change was a result of improved seals.
> - engine that last easily two times longer than those big
> V8, and being almost trouble free compared to them
Once again. Using the same materials with the V-8 they would last far
longer than with the overreved and overloaded tiny engines they are using
now to keep costs down.
> - engine that start in cold weather when big V8 refuse
> to do it at near -20 degrees
Clearly you didn't know how to do it. My big old V-8's always started
when I liven in northern Minnesota and had to park them outside in -45
degree weather. I would drive ten miles before the tires warmed up
enough for the flat spot to go away. But those old V-8's STARTED. My
modern Toyota's often fail to start in below zero weather and the darn
heaters don't work at all unless I block off the entire radiator with
a blanket so air can't go through it.
> - atmospheric pollution lowered by 200 % in some major
> N.A. cities while the car trafic increases by 300 %
>
Entirely a result of smaller cars requireing less power to move about.
NOTHING to do with "technology advances" except for a very small
contribution from computer controlled tuning that makes up for people
who couldn't be bothered to keep their engines in tune.
> I still remember my father's 1956 Dodge Regent. He bought it
> brand new. Four year later, it was a wreck. So rusty than
> part of the body were falling out. Exhaust fumes were blue.
> And like most of the cars of that era, trouble was a common
> law. Trouble with engine, with gearbox, with heather, wipers,
> radio, name it... He sold it with only 140 000 km.
>
Still a heck of a lot better than the 1956 Cinzano sign Citroen or a
Renault. Not to mention the british cars. Japanese cars in 1956 were
really bad. Give credit where credit is due.
> Nothing to compare with my 1995 Toyota Tercel (the bottom
> at Toyota). It would be hard to find even a single part of
> my Toyota that's not improved compared to what we have on
> the old Dodge.
>
Depends on what you call improvement. As I say, lubricants, metallurgy,
and fit have improved, as have paints and finishs. However, your Toyota
Tercel is nowhere near as quiet or comfortable.
> Airplane are the same. I know a lot of people who bought
> airplanes and sold them after a while because they represent
> a lot of trouble, costly maintenance and so on. They are
> old Dodge 1956, that's it.
>
Bullshit. That is really comparing apples to kumquats.
I have an "old" airplane that is regularly flown. My maintenance on that
has been LESS than the maintenance on my Toyota car.
> Light airplanes missed almost all the research and
> development needed to make them modern, efficient and
> reliable like cars. Of course, both world cannot be
> compare all the way. But trying to defend what is killing
> light aviation is a nonsense.
>
That is what is nonsense. Light airplanes have missed NONE of that
research and most of the people I know are using modern lubricants,
their engines use modern seal technology, and there are many state
of the art improvements in an aircraft engine. Compare the current
Lycoming O-320 for its predecessor, the Lycoming O-290. The O-290
weighs more, produces less power, and requires more maintenance.
Don't make the mistake of equating Progress with Change. Most of the
"high tech" changes in automobiles would provide NOTHING to aircraft.
> What worked for cars can work for airplane, even if it
> cannot be done the same way. Thinking that we cannot improve
> airplanes because they reached the perfection with Cessna and
> Lycoming is ridiculous. Thinking that engineers and designers
> only want to change products for marketing reasons and
> cannot have any desire to improve things is also ridiculous.
>
And claiming that all changes IMPROVE the product is really rediculous
and thinking that Cessna and Lycoming at STATIC and Toyota is NOT is
the height of purposeful and selective blindness.
John
Dylan Smith
John R. Johnson wrote:
> That is not because of improvements is the specific fuel consumption
> of the engines. That is merely because the cars are smaller and lighter
> so you have less metal to ship around with you.
Ford's largest car (not talking SUV's here) today - the Lincoln
Town Car has better gas mileage than their smallest car of 20
years ago (the Pinto). The modern Town Car is still a big heavy
land yacht compared to the Pinto.
> There have been some
> improvements in materials, fit, and lubricants, and they would help the
> V-8's even more than they help the little engines that have to turn too
> fast to make their power. Without those advances the little engines
> were not possible because they wouldn't remain together at all.
That's why I like the big displacement, low hp engines. Until
the tranny finally died on my old Dodge pickup, that V8 was
still going strong at around 140,000 miles and not burning oil
either.
However, little engines were possible back in the 60's. A car
I used to own (and my student car) was a remarkable vehicle.
It had an 850cc engine and had done about the same mileage as
the Dodge. It was a 1969 model, and I drove it until 1995.
The vehicle was the good old Austin Mini (one of the British
cars you are maligning - some of them _were_ good, and the
Mini has quite a following - do a Webcrawler search and
see what one is).
--
Email: dy...@vnet.IBM.COM
Dylan Smith 1810 Space Park Drive, Houston, TX 77573
Standard disclaimer applies.
Anti-spam - Change 'r' to raleigh, 'i' to ibm and 'c' to com.
John R. Johnson
On Fri, 6 Feb 1998, Dylan Smith wrote:
> John R. Johnson wrote:
> > That is not because of improvements is the specific fuel consumption
> > of the engines. That is merely because the cars are smaller and lighter
> > so you have less metal to ship around with you.
>
> Ford's largest car (not talking SUV's here) today - the Lincoln
> Town Car has better gas mileage than their smallest car of 20
> years ago (the Pinto). The modern Town Car is still a big heavy
> land yacht compared to the Pinto.
>
And it weighs about the same as the Pinto.
> > There have been some
> > improvements in materials, fit, and lubricants, and they would help the
> > V-8's even more than they help the little engines that have to turn too
> > fast to make their power. Without those advances the little engines
> > were not possible because they wouldn't remain together at all.
>
> That's why I like the big displacement, low hp engines. Until
> the tranny finally died on my old Dodge pickup, that V8 was
> still going strong at around 140,000 miles and not burning oil
> either.
>
> However, little engines were possible back in the 60's. A car
> I used to own (and my student car) was a remarkable vehicle.
> It had an 850cc engine and had done about the same mileage as
> the Dodge. It was a 1969 model, and I drove it until 1995.
> The vehicle was the good old Austin Mini (one of the British
> cars you are maligning - some of them _were_ good, and the
> Mini has quite a following - do a Webcrawler search and
> see what one is).
>
I have many miles in both the Austin Mini and the Cooper Mini. I have
spent a lot of time driving around in the UK. Neither are imported
into the US anymore, if ever, because they will not meet the emission
requirements.
John
Dylan Smith
John R. Johnson wrote:
> I have many miles in both the Austin Mini and the Cooper Mini. I have
> spent a lot of time driving around in the UK. Neither are imported
> into the US anymore, if ever, because they will not meet the emission
> requirements.
The reason I had heard was that it was safety issues rather than
emissions. The modern Mini meets the European standards which are
just as strict as the US ones. However, safety standards are
different and it probably wouldn't be worth Rover's (now BMW's)
time to try to make the car fit in a market where it probably
wouldn't sell. A pity really, the Mini was the most enjoyable car
I've owned. It had character. Of course, my old Dodge truck
had character too, but it was a rather bad one ;-) Oh well, we
are wandering a bit off topic here, but what pilot isn't a bit
of a motorhead?
Jean Richard
John R. Johnson wrote:
> Besides, you talk like we kill the animals for their hide.
> We don't. We kill them to EAT.
Would you like to have airplane seats from chicken
leather ;-))
> Been in a Wal-Mart Store lately?
Never. I keep away from that kind of stores. Maybe it help
me to have a different view of our modern world.
> Why should a disk brake be more expensive than a drum.
Compare both and you will see why.
> > Not a lot. Because what modern technology gave to us is :
> >
> > - cars with a fuel consumption of 5 to 8 litres/100 km
> > where those Buick took 20 to 30 for the same speed and
> > useful load ;
>
> That is not because of improvements is the specific fuel consumption
> of the engines. That is merely because the cars are smaller and lighter
> so you have less metal to ship around with you.
O.K. Then compare oranges with oranges. My 1985 Toyota Tercel
gave me a 7,1 litres/100 km fuel consumption (I always keep
record of all my fuel bills). My 1989 Tercel gave me 6,7 for
the same kind of use. My 1995 Tercel now gives me 5,7, while
it's the most powerful of the three. Will you tell me that
the 7,1 to 5,7 is only due to weight reduction ?
> Clearly you didn't know how to do it.
>My modern Toyota's often fail to start in below zero
>weather and the darn heaters don't work at all unless
>I block off the entire radiator with a blanket so air
>can't go through it.
Clearly you don't know how to do it ;-)))
> Don't make the mistake of equating Progress with Change.
I won't, as so long you won't do the opposite.
> And claiming that all changes IMPROVE
Words like ALL or NOTHING belongs to you, not to me ;-((
Now, maybe one thing we forget when comparing airplanes
engines to cars ones is the way game was played. While
there was several players from different parts of the World
in the car game, airplane engine game was almost a single
player game. In car world, you have big names from Europe,
(Volkwagen, Renault, Fiat, Peugeot, Citroën, British
Leyland, Volvo, Saab..),Asia (Toyota, Honda, Nissan,
Mitsubishi...) and North America (GM, Ford, Chrysler...)
playing a hard game. In Europe, it was a technological
game, in N.A. a marketing game and in Japan, a mix of both.
In light aviation, things were different. For political
reasons, Japan stayed out of the game. Europe stay with
small engines, mostly for non certified airplanes (Rotax,
Limbach, JPX...). In USA, for a while there was two players,
Lycoming and Continental, but Lycoming is now claiming that
it has 85 % of the piston certified engine market.
That one player game may have contribute to keep the airplane
engine technology in the 1940's era. There's too many people
who joined the winner thinking that it will be the way to be
winners themselves. Not so sure !
In a David against Goliath game, there's people to support
David while there's more people who feel more confortable
staying on the Giant side.
For David supporters, the come back of Renault in light
aviation engine world is welcome, as is also welcome the
Teledyne Continental project (with a supporting name like
NASA) of a 200 hp jet fuel diesel engine. The TC project
is still very young, but the Morane-Renault is not very far
from certification.
It's easy to believe that the MR project may have boosted
the TC's one. The "non US" MR project may have contributed
to the participation of the NASA (yes, fundings from public
money in a private project, in USA... You can see a smile
on the face of many non USA people).
Nobody want to see Morane-Renault or Teledyne Continental
holding 85 % of the market. But there's a hope to see a new
multi-player game where the real winner will be the
customer, because the force balance will be different from
now. After all, Lycoming is the "Microsoft" of light
aviation. We have to stop monopoly.
J. Richard
JStricker
Greg,
As usual, you make some very convincing and accurate comments regarding the
a/c engine vs.. auto engine debate. We all have our biases, myself
included, that show up occasionally though.
Gregory Travis wrote in message <6bckjd$dkg$1...@sherrill.kiva.net>...
>In article <VA.00000b89.1388f29e@ws>, Uwe Hale <ha...@sct-inc.com> wrote:
>>> Dual overhead
>>> cams contribute significant additional friction to the engine, which
>>> must be overcome with fuel.
>>
>>No they don't. Where do you get this from?
Point for Greg. I suggest anyone that doubts him, do a test. Take a
dial-type torque wrench and turn over the cam of an engine and read it.
Now, do the same thing with the cams of an OHC engine of the same # of
cylinders and valves/cylinder. Add the totals of all the cams in the OHC
engine. I don't remember where, but I read somewhere that a SOHC will have
about 180% of the drag and a DOHC over 225% and that sounds reasonable to
me. (I'm assuming a V or flat cylinder arrangement here, as I think Greg
is. Where you would need 2 cams to replace one using pushrods. The
argument doesn't work for inline 4's, etc. and that's why you saw them used
in those engines first.)
The ONLY reason an OHC arrangement is selected (well, almost) is for
valvetrain control. Not as many pieces flopping around in the wind, so to
speak, at high rpm. From everything I've seen, it's just not worth it until
you get over 6,500 rprm or so.
>
>>Mechanical injection and carburetors do not adjust themselves to the fuel
>>requirements of each individual cylinder 100s of times per second
>>EFI pulsed injectors also
>>prevent fuel puddling compared to mechanical constant injection. You end
up
>>having to run a richer mixture (more fuel) to compensate for all the
unburnt
>>fuel getting dumped out the exhaust.
>
>Huh? How do they do this?
>
>>> Check out Lightspeed or LASAR for solutions for your aircraft engine.
>>
>>Why isn't that stuff standard? No aircraft engine here, thermals are much
>>more fuel efficient.<g>
>
>Because the manufacturers aren't sure that the economics are justified. If
>the LASAR system shaves 0.04BSFC off the fuel burn of a typical O-360 then
>that means that the O-360 will consume approximately 1,677 gallons less
>fuel over its TBO run of 2000 hours. That's approximately $3000.00 over
>ten years (a typical TBO run time). The LASAR system costs over
>$2,000 up front. $2000.00 invested at even a modest interest rate will
>yield well over $3000.00 at the end of ten years. It's cheaper to burn
>more fuel.
This is one of my areas of disagreement with you Greg, but not a major one
and only partial disagreement. The big advantage to a good EFI on the
conventional a/c engines would be taking the operator out of the fuel
management loop. I think you're right. That a properly leaned conventional
engine really won't benefit much, but you know as well as I that proper
leaning is at best done 50% (by the average pilot) of the time and that is
at cruise. We all run the engines full rich (for the most part) on takeoff
and that is NOT the most efficient way to run them. We're just a little
busy at that time to really lean correctly, even if we knew how to do it as
the leaning procedure for max power or climb power I think would be
significantly different than at cruise.
A TIMED EFI could reduce puddling, if the the intake was prone to standing
waves at certain RPM, but I've never heard of that being a problem on any
a/c engine. This is a theoretical question in reality as the mechanical
injection currently available is really well sized and with properly placed
ports that don't let this happen. That may not be true in a carb'd engine,
but now we're getting into apples and oranges.
To me, the only reason that Lyc/Continental haven't used EFI is that they
don't see anyway to recoup the massive R&D money, not to mention the money
to get all those systems certified, with the low volume of new engines being
built and sold right now. It's one thing to have GM or Ford spread the
expense out between several hundred million units (over several years) and
another for the a/c engine mfg. to do it over at most several thousand a
year. How many a/c engines did Continental and Lyc. build last year? Do
you know Greg? I'll bet it didn't amount to a good 2 weeks of production
out of Detroit.
>
>>And if the displacement(bore) was smaller, the rpm higher, and a decent
>>squish band was designed in the head (like modern engines), you wouldn't
>>need the dual ignition system/plugs to overcome the problems with the
>>slow flame front propagation.
>
>That must be why Alfa Romeo, Nissan, and Toyota have all come out with
>dual plug auto engines.
I expected a better argument from you than this Greg. ;8-) If you're going
to use this one, then it would be perfectly fair to say the same thing for
OHC's and EFI. You can do better than that.
>
>The question you should be asking yourself is not "Why do aircraft engines
>have two plugs?" but "Why DON'T auto engines have two plugs?" The answer,
>my friend, is cost. Auto engines don't have two plugs not because it
>wouldn't make them more efficient but because, at approximately $4.00
>per engine to implement it (the manufacturer's cost), it represents
hundreds
>of millions of dollars per year that doesn't go back to the stockholders.
>
I don't buy this argument Greg. The reason there are 2 plugs per cylinder is
safety. A side benefit is you are getting twice the fire in the hole. One
of the reasons you have drop on the mag check is because NEITHER plug is in
the ideal spot to initiate combustion. The other is you are losing some of
the igniting capability. This is a carryover from the old old days of
aviation where fuel was much more unreliable and components and materials
weren't as sophisticated.
I'm of the opinion that if a head could be designed correctly with lot's of
testing, a second plug would be entirely unnecessary. But, little things
like intake/exhaust ports and valves, water jackets, pushrod slots, head
bolts, and a host of other items tend to block the best spot so the
engineers do the best they can. I'm sure it's possible to design an engine
with the optimum placement by starting at the plug. Now, which combustion
chamber do you use?? There are so many different types, all with their own
strong and weak points that it's an argument in itself. Some are good for
max HP, some are good for flat torque cureves, some are good for emissions.
Rarely do the types overlap. Compromise, compromise, compromise. There is
no best for all applications, in this or any other engineering problem.
Only the best compromise of all the factors.
>>> On the other hand, you
>>> don't have to lug around 20-30 pounds of water pumps, radiators, hoses,
>>> and coolant with an air-cooled system.
>>
>>True, but you also don't have to replace cracked cylinders all the time
>>either.
>
>I've never replaced a cracked cylinder. You know why? Because I replace
>them with new at every overhaul instead of trying to get by with junkyard
>junk in an aircraft engine.
Maybe you haven't Greg, but tell us about the remarkable reliability of the
cylinders in the Cont. TSIO-360-FB in the Turbo Arrow. ;8-) OK, I know,
the most common cause was overboosting and shock cooling, both pilot error.
Another good argument for electronic engine controls, IMHO. The more we
stress any engine, a/c included, the more prone they're going to be to fail
from improper use. I think that the same engine, equipped with electronic
controls, would routinely run to TBO. And while I'm sure there are some,
I've never seen a TSIO-360 that ran to TBO. Not picking on Continental
either. Lycoming has the same problems with their version in the 337,
especially in the back engine.
>
>Look, you can speculate all you want with smooth glossy data from auto
>manufacturer marketing departments. On the other hand, if you've got
>actual comparative data, regarding fuel burn, between auto and
>aircraft engines that contradicts what I've posted here then put your
>money where your mouth is and out with it.
>
>greg
OK, I'm off my soapbox. I have no doubt that Greg could take a likely
candidate (like the Soob, V-6 Ford, whatever) and work with it and make it a
perfectly acceptable a/c engine. No doubt at all.
And when he got done, he'd have a water-cooled engine that MIGHT get a
little better fuel efficiency and cost several thousand man-hours to do from
scratch. And most likely not be as reliable.
Although I disagree with him on occasion, he always makes good and valid
points. I don't have any plans currently to fly behind or in front of an
auto conversion. But I wouldn't be afraid of one that was done well either.
Personally, I'd like to see some of the auto engine guys develop an EEC for
Lyc 360. Think about that for a minute. And I'm not talking about a
piecemeal deal here. Total engine control of fuel and ignition, all solid
state, sold as a replacement package. No development time in the mechanical
aspects of the engine. Could even go DIS if you liked. Dual DIS would be
just as reliable as mags as long as there was some battery left.
Computerized engine management could even control the prop. No great
stretch there. Ever hear of Cruise Control? If guys want to experiment
with auto conversions, more power to you. But like Greg, show me the
benefits. I see lot's of potential benefits to modernizing an existing a/c
engine though.
John Stricker
--
Remove the "nosp..........." Oh hell, you folks know what to do and
why I had to put it in. If one of you real humans wants to contact me:
"I didn't spend all these years getting to the top of the food chain
just to become a vegetarian"
Gregory Travis
In article <B2968440627647D8.9E695191...@library-proxy.airnews.net>,
JStricker <jstr...@odsys.NOSPAM.net> wrote:
>Greg,
>
>As usual, you make some very convincing and accurate comments regarding the
>a/c engine vs.. auto engine debate. We all have our biases, myself
>included, that show up occasionally though.
I'm a Historian. I'm immune from bias. They taught me that in school so
it must be right.
>This is one of my areas of disagreement with you Greg, but not a major one
>and only partial disagreement. The big advantage to a good EFI on the
>conventional a/c engines would be taking the operator out of the fuel
>management loop. I think you're right. That a properly leaned conventional
>engine really won't benefit much, but you know as well as I that proper
>leaning is at best done 50% (by the average pilot) of the time and that is
>at cruise. We all run the engines full rich (for the most part) on takeoff
>and that is NOT the most efficient way to run them. We're just a little
>busy at that time to really lean correctly, even if we knew how to do it as
>the leaning procedure for max power or climb power I think would be
>significantly different than at cruise.
As a Historian, I have data that supports your position. Both of the big
two piston aircraft manufacturers built and experimented with EFI systems
in the early 1980s. Lycoming flew theirs in a Comanche.
What they found was three things:
1. The system did nothing to improve fuel consumption during cruise
against a competent pilot who knew how to use the mixture knob.
2. They could, however, improve block-block fuel consumption by
up to 10% because most pilots don't lean sufficiently during
climb or descent (i.e. when they are busy with other stuff).
3. The system was not economically viable at the time.
>A TIMED EFI could reduce puddling, if the the intake was prone to standing
>waves at certain RPM, but I've never heard of that being a problem on any
>a/c engine.
Virtually all of the so-called sequential EFI systems with which I am familiar
basically revert to a constant injection system at moderate to high power.
They only time the injection to coincide with intake valve opening at idle
and off-idle power (where that's most efficient for a smooth idle and
good environmental properties).
The injectors simply aren't large enough to intermittently flow fuel at
higher outputs. The "injector open" time increases so that the injector is
actually open (or modulating) fuel for most of the time. If they sized the
injector so that it could deliver enough fuel in only the time the intake was
open at high speed, it would have very poor spray/atomization properties
at low speed.
Against that, I don't see how timed EFI is going to help, over continuous
injection, at higher powers. And the data bears that out.
>To me, the only reason that Lyc/Continental haven't used EFI is that they
>don't see anyway to recoup the massive R&D money, not to mention the money
>to get all those systems certified, with the low volume of new engines being
>built and sold right now.
Well, see above for a little background. Times have changed and there are no
less than three companies working on full FADEC-type EFI for aircraft engines.
>How many a/c engines did Continental and Lyc. build last year? Do
>you know Greg? I'll bet it didn't amount to a good 2 weeks of production
>out of Detroit.
Each manufacturer "produces" about 300-400 engines per month. Of this total
almost virtually all are overhauls or remans. Lycoming produces about 100
new engines a month and Continental a little less.
This has, of course, changed slightly for Lycoming with Cessna coming
back on line. Lycoming was, until very recently, building about 10
engines a day (with salaried and mercenary labor (i.e. while suffering under
a lockout strike)) but has recently cut back to 5 due to production
problems at Cessna (and Lycoming with the strike).
At the height of GA production, Lycoming built around 1200 NEW engines, on
three shifts, a month. I believe their largest ever month was about 1700
new engines. Continental's numbers were similar.
>I don't buy this argument Greg. The reason there are 2 plugs per cylinder is
>safety. A side benefit is you are getting twice the fire in the hole. One
>of the reasons you have drop on the mag check is because NEITHER plug is in
>the ideal spot to initiate combustion. The other is you are losing some of
>the igniting capability. This is a carryover from the old old days of
>aviation where fuel was much more unreliable and components and materials
>weren't as sophisticated.
This is all true. However, that does not mean that an additional plug in
your auto engine wouldn't make IT run better. You've never done a "mag
drop" test in your auto engine because it's not equipped with two plugs. But,
if you could, I think you would be surprised at the results.
>>I've never replaced a cracked cylinder. You know why? Because I replace
>>them with new at every overhaul instead of trying to get by with junkyard
>>junk in an aircraft engine.
>
>
>Maybe you haven't Greg, but tell us about the remarkable reliability of the
>cylinders in the Cont. TSIO-360-FB in the Turbo Arrow. ;8-) OK, I know,
>the most common cause was overboosting and shock cooling, both pilot error.
No one, particularly me, is going to argue that there aren't some real
turkey aircraft engines out there. The TSIO-360-FB is one.
>I've never seen a TSIO-360 that ran to TBO. Not picking on Continental
>either. Lycoming has the same problems with their version in the 337,
>especially in the back engine.
The IO-360 in the 337 is the same Continental engine. No Lycoming ever went
into the 337.
>Personally, I'd like to see some of the auto engine guys develop an EEC for
>Lyc 360. Think about that for a minute.
It's happened before and it's happening again.
Good discussion,
greg
Ron Natalie
> >I don't buy this argument Greg. The reason there are 2 plugs per cylinder is
> >safety.
Because magnetos are weak spark sources. The modern auto emisions
aren't
anywhere near as prone to plug problems.
> This is all true. However, that does not mean that an additional plug in
> your auto engine wouldn't make IT run better. You've never done a "mag
> drop" test in your auto engine because it's not equipped with two plugs. But,
> if you could, I think you would be surprised at the results.
In at least Nissans case, the reason for dual plugs was emissions.
The 1980 NAPS-Z engine (the first dual plug one they had) was
unique at the time for getting the same gas milage in the
California model as it got in the rest of the country.
They only put two plugs in it if you got one set up
for california, my east coast one only had the single.
Starting with 81 on, everybody got the dual plug version.
Gregory Travis
In article <34DB68...@sensor.com>, Ron Natalie <r...@sensor.com> wrote:
>> >I don't buy this argument Greg. The reason there are 2 plugs per cylinder is
>> >safety.
>
>anywhere near as prone to plug problems.
Actually, they're only weak at low RPM. While not as powerful as a modern
CD electronic ignition, an aircraft magneto at speed will easily outpower the
mechanical points/coil or hall-effect/coil ignition systems used on
automobiles through the 1970s.
Race car drivers used to use magnetos exclusively for this very reason -
regular auto coil systems just couldn't cut it ignition-wise under
high load. They ripped out the conventional coil ignition and replaced it
with magnetos made by various manufacturers.
But a CD type electronic ignition delivers the punch you need at starting
while also equalling, and usually bettering, the punch a mag makes at
speed.
greg
dhs...@ingr.com
You dare mention Fiat, British Leland and car in the same sentence?
I might have believed some of what you said up to that point.
Oh, and Disc brakes have a lot less parts and require much less assembly
and adjustment time.
Dave "Ex-Fiat and Triumph with Lucal Electrics owner" S.
In article <34DB4F...@sympatico.ca>,
Jean Richard <j.ri...@sympatico.ca> wrote:
>
> John R. Johnson wrote:
>
> > Besides, you talk like we kill the animals for their hide.
> > We don't. We kill them to EAT.
>
> Would you like to have airplane seats from chicken =
>
> leather=A0;-))
>
> > Been in a Wal-Mart Store lately?
>
> Never. I keep away from that kind of stores. Maybe it help
> me to have a different view of our modern world.
>
> > Why should a disk brake be more expensive than a drum.
>
> Compare both and you will see why.
>
> > > Not a lot. Because what modern technology gave to us is :
> > >
> > > - cars with a fuel consumption of 5 to 8 litres/100 km
> > > where those Buick took 20 to 30 for the same speed and
> > > useful load ;
> > =
>
> > That is not because of improvements is the specific fuel consumption
> > of the engines. That is merely because the cars are smaller and lighter
> > so you have less metal to ship around with you.
>
> O.K. Then compare oranges with oranges. My 1985 Toyota Tercel
> gave me a 7,1 litres/100 km fuel consumption (I always keep
> record of all my fuel bills). My 1989 Tercel gave me 6,7 for
> the same kind of use. My 1995 Tercel now gives me 5,7, while
> it's the most powerful of the three. Will you tell me that
> the 7,1 to 5,7 is only due to weight reduction ?
>
> > Clearly you didn't know how to do it. =
>
> >My modern Toyota's often fail to start in below zero =
>
> >weather and the darn heaters don't work at all unless
> >I block off the entire radiator with a blanket so air =
>
> >can't go through it.
>
> Clearly you don't know how to do it ;-)))
>
> > Don't make the mistake of equating Progress with Change.
>
> I won't, as so long you won't do the opposite.
>
> > And claiming that all changes IMPROVE
>
> Words like ALL or NOTHING belongs to you, not to me ;-((
>
> Now, maybe one thing we forget when comparing airplanes =
>
> engines to cars ones is the way game was played. While =
>
> there was several players from different parts of the World
> in the car game, airplane engine game was almost a single
> player game. In car world, you have big names from Europe,
> (Volkwagen, Renault, Fiat, Peugeot, Citro=EBn, British
> Leyland, Volvo, Saab..),Asia (Toyota, Honda, Nissan,
> Mitsubishi...) and North America (GM, Ford, Chrysler...)
> playing a hard game. In Europe, it was a technological
> game, in N.A. a marketing game and in Japan, a mix of both.
> In light aviation, things were different. For political
> reasons, Japan stayed out of the game. Europe stay with
> small engines, mostly for non certified airplanes (Rotax,
> Limbach, JPX...). In USA, for a while there was two players,
> Lycoming and Continental, but Lycoming is now claiming that
> it has 85 % of the piston certified engine market.
>
>CHOP CHOP
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Keith Arnold
On Tue, 3 Feb 1998 11:10:45 -0600, "John R. Johnson" <jo...@siu.edu>
wrote:
>By the way, aircraft engine technology is neither olded nor less efficient
>than auto engine technology. It just has different problems to solve, and
>the solutions are correspondingly different.
>
>John
========>
And, John, the certification process (cost) are different.
ô¿ô - Keith - 182L/STOL N3431R - Chino, California
N33° 58' 46" W117° 38' 41"