Slashdot Mirror
Australian Team Working On Engines Without Piston Rings
JabrTheHut writes "An Australian team is seeking funding for bringing an interesting idea to market: cylinder engines without piston rings. The idea is to use small grooves that create a pressure wave that acts as a seal for the piston, eliminating the piston ring and the associated friction. Engines would then run cooler, could be more energy efficient, and might even burn fuel more efficiently, at least according to the article. Mind you, they haven't even built a working prototype yet. If it works I'd love to fit this into an older car."
This is 2014, where's my flying car?
Oh wait, I can't afford it.
Please give me grooves for an extra 2 miles a gallon in a way that the local shop can fix (looking at you, battery/hybrid-CVT/regen-braking monster).
I'm sorry but the energy density of hopes and dreams is nowhere close to that of gasoline.
fnord.
But hopes and dreams are of endless supply. Gasoline not so much.
Extra fuel efficiency would be nice, but I am most excited about the prospect of the engine itself lasting longer. Less friction = less heat, less wear & tear, etc. A cool, frictionless engine could potentially last for half-million miles before needing replacement. At my paltry 10-20k miles per year, I could potentially never have to buy another car again.
Agreed. No chance this is feasible.
The piston would need to have a coefficent of thermal expansion which was in keeping of that of the bore liners. If not massive friction forces or blow-by/lack of compression would ensue as the engine warmed up.
However, if the above could be controlled the piston material would need also need to have a very low coeeficient of friction to render the use of rings obsolete.
On the whole it is, at present, an unfeasible idea.
Trust me, I have a PhD in engineering.
Would you care to expand upon that? Or is this the scenario we are looking at below?
If an elderly but distinguished scientist says that something is possible, he is almost certainly right; but if he says that it is impossible, he is very probably wrong. -- Arthur C. Clarke
Or perhaps we simply have a loose troll?
much of left-wing thought is a kind of playing with fire by people who don't even know that fire is hot - George Orwell
So, the idea is that the grooves in the piston will create little eddies of air that separate the combustion chamber from the oil galley, right?
Here's the problem - the air that forms said eddies has to come from somewhere, and there's only two options: the combustion chamber, or the oil galley.
Still, to a gear head such as myself, it's still a pretty cool idea.
An enigma, wrapped in a riddle, shrouded in bacon and cheese
But we already have an engine that doesn't use piston rings. And it's not like this idea hasn't been tried before either on reciprocating piston engines, usually with a whole series of problems. Mostly compression issues.
Om, nomnomnom...
I'm sorry but the energy density of hopes and dreams is nowhere close to that of gasoline.
That's catchy, but I'll reformat it.
I'm sorry but ....
the energy density of hopes and dreams
is nowhere close to that of gasoline.
much of left-wing thought is a kind of playing with fire by people who don't even know that fire is hot - George Orwell
Only works in theory? Don't tell me, rubber pistons?
Table-ized A.I.
If they haven't even built a working prototype then how can they be seeking funding to bring it to market? surely they are just seeking funding to prototype to see if it is even viable to bring to market?
Is the no ring design coupled with a spherical rotary head. What ever happened to Coates International?
I'm sorry but the energy density of hopes and dreams is nowhere close to that of gasoline.
I'm sorry but the energy density of gasoline (36 MJ/L) is nowhere close to that of Uranium-235 (1,546,000,000 MJ/L).
Another advantage of Uranium is that while having a lot of oil will get you invaded, carrying even a little bit of Uranium means only another madman would dare approach you.
Trust me, I have a PhD in engineering.
Heh heh. Posting anonymously when resting your authority on the strength of your name rather than the validity of your argument. Have to feed the troll on this one.
Science advances one funeral at a time- Max Planck
Forget hopes and dreams, power it on a person's sense of self-satisfaction. Although low yield, it's in vast abundance.
Science advances one funeral at a time- Max Planck
They are re-inventing labyrinth seals. They come in a variety of shapes and sizes. They've been used for decades in jet engines and other applications where the pressure drop across the seal in not large. They have not proven practical in applications with higher pressure drops across the seal because they don't seal completely. There is always some leakage.
They shouldn't test in Australia. Down there, piston engines convert smog into petroleum.
Table-ized A.I.
Gasoline's energy density is nothing special, the advantage it has is in procurement, having resulted from millions of years of energy collection which means the effort of getting to it is trivial.
And compared to the alternatives, it's a messy bit of junk.
From TFA:
A 'virtual model' equates to 'proof-of-concept'? Since when?
Put ALL effort into engines that don't use fossil fuel at all. Thanks.
Exactly, since the internal combustion engine has no future at all in the long term, such a breakthrough is not exactly "news that matters". Now, a great breakthrough in battery technology, or, even better, a nuclear fusion electrical generation station would be something worth thinking about. High storage capacity batteries that can be fully charged in only a few minutes and last for hundreds of kilometers of high-speed driving would kill the internal combustion engine for most vehicles. But nuclear fusion would make energy so cheap that people could still use their internal combustion engines if they really wanted to, but they wouldn't because fuel cell-based cars are mechanically much simpler and more reliable... and should be cheaper.
It's really quite a simple choice: Life, Death, or Los Angeles.
I thought this was about this article which uses a pistonless pressure wave and makes all the same promises.
Slashdot's rate-of-post filter: Preventing you from posting too many great ideas at once.
My reading comprehension may be failing me here. Does the article say Benz and BMW are already using this technology?
"It’s the ideal set-up to make the most of each spark, already used in advanced engines by the likes of Benz and BMW for the win-win it produces in boosting performance while cutting consumption and emissions."
So... in other words, you're saying that the whole thing is blowing a bunch of hot air?
Science advances one funeral at a time- Max Planck
You sound like the people in my grandmother's village in 1905 when the first car drove in - "It won't last - you can't feed it like you can a horse".
But no prototype. I am not a physicist, but I ran it through a little thought experiement. If it is some sort of standing pressure wave, it would have to move with the piston, that may be possible, but difficult. The problem I see is that any type of wave would hbe dependent on the frequency/speed of the piston in the cylinder. Therefore, it would have to be there across the entire operating range of the engine, not just it's peak power band. That is a large range. If it falls off anywhere along this range then you get oil control issues, compression issues, or both just as if you had bad rings. Oil control leads to plug/combustion chamber issues and expensive oil replacement. Compression issues lead to huge ineffeciencies, that would offset some or all of the gains from reducing friction. In addition, while the friction may be less, this pressure wave would by its nature have to exert some pressure on the piston and cylinder walls to seal. It may be less friction and less metal to metal contact, but not zero friction. In short a laudable goal, but seems more like a funding grab than a workable idea.
Silence is a state of mime.
Soylent gas be okay?
rewriting history since 2109
My 'hopes and dreams' are 92% nitro-methane you insensitive clod.
John McAfee 'It was like that time I hired that Bangkok prostitute; to do my taxes, while I fucked my accountant'
Put ALL effort into engines that don't use fossil fuel at all. Thanks.
Then effort doesn't go into 'engines' - It goes into energy storage solutions that have the weight / energy capacity of gasoline.
Gasoline's energy density is nothing special, the advantage it has is in procurement, having resulted from millions of years of energy collection which means the effort of getting to it is trivial.
And compared to the alternatives, it's a messy bit of junk.
Its pretty special.
Even discounting cost, there are virtually no other fuels that come close.
Sig Battery depleted. Reverting to safe mode.
Who says it needs to run on fossil fuel? Alcohol runs just fine as a fuel in an internal combustion engine with little modification needed.
Seems like a lot of extra work. Why not just mod an existing design with their piston?
Never let a lack of data get in the way of a good rant.
Are you sure they didn't say you can't BREED it like you can a horse?
If that were the case, they were correct.
Find me two cars you can rub together and get a third, without losing anything from the prior two.
And all for the cost of not mowing your lawn.
Sig Battery depleted. Reverting to safe mode.
This also removes the piston-to-liner pathway as a way of cooling the piston head - the hardest part of an internal combustion engine to keep cool.
Put ALL effort into engines that don't use fossil fuel at all. Thanks.
Gasoline, diesel, etc don't have to be Fossil Fuels. We can make them with a biological process for example. These processes are basically carbon neutral since the carbon emitted during internal combustion recently came out of the atmosphere.
How the ringless piston works:
In place of the rings, each piston has numerous small, angled grooves, semi-circular at their apex. With the small clearances between them, the movement of the piston creates high-speed eddies -- air pressure working like metal rings to cut leakage and loss during the compression and combustion strokes.
“That means there’s no metal-to metal contact between the pistons or rotors and their mating cylinders or housings. Virtually no friction means the mechanism needs no lubrication and there’s no wear and tear on major components,” said Trigg.
There’s an important by-product here, too. Putting an “air cushion” around the periphery of the combustion chamber creates a stratified air-fuel charge – an injection profile that enriches the mixture in the centre of the chamber and leans it up towards the periphery.
It's not a typo if you understood the meaning!
That makes this Slashdot-worthy.
A boxster engine.... are they looking to fix the Subaru STi ringland problem ? Some stock and modified Subaru STi haves piston rings failures from cylinder 2 and 4.
I wouldn't dismiss this right away.
If the physical features on the piston provide resistance to gas flow along the piston/cylinder annulus similar to that provided by piston rings, they wouldn't need a close-fitting piston - therefore no expansion coefficient headaches. It may also be that the hydrodynamics tend to center the piston in the cylinder, which would reduce contact events and scuffing wear.
You could probably get a feasibility go/no check with a few weeks' worth of modeling. The resonance interactions in the piston grooves when the combustion pressure front reaches them would be very interesting to see.
Gasoline's energy density is nothing special, the advantage it has is in procurement, having resulted from millions of years of energy collection which means the effort of getting to it is trivial. And compared to the alternatives, it's a messy bit of junk.
You are confusing storage not collection. The energy was collected over the very short time span of a plant in a swamp. The millions of years that turns this into crude oil is just chemical transformation and storage.
Gasoline is a simple molecule that can be created in a variety of ways. One way is the distilling of crude oil. Another is biological production via engineered photosynthetic organisms. Same energy source of the fossil fuels, the sun, however carbon is coming from the current atmosphere not carbon sequestered millions of years ago. Its a much greener process.
Soylent gas be okay?
Isn't that the solution to pension plan problems and social security?
The shepherds did so well protecting the flock that the sheep no longer believed that wolves existed.
What about when the piston is motionless or slow?
Then effort doesn't go into 'engines' - It goes into energy storage solutions that have the weight / energy capacity of gasoline.
Why ignore the inefficiency of internal combustion? Are you seriously saying that putting effort into more efficient motors is advancing energy storage solutions? That sounds imbecilic to me.
Achieving equivalent energy density isn't required if more efficient motors and/or transmission methods are discovered and/or utilized. You're not seriously putting forth that, say, mag-lev trains, or the hyper-loop are applications of "energy storage solutions with the weight / energy capacity of gasoline", are you? Energy density would already be high enough for a hybrid solutions whereby inductive charging supplements existing electric energy storage -- The effort here is going into "energy storage with the weight / energy capacity of gasoline"? No. Not unless you conflate storage with transmission. Take a look next to damn near any road you're driving on for the power line.
Also, burning things should be avoided, not just "fossil fuel". However, better gasoline engines while transitioning to other fuels still helps -- no need for a false dichotomy. Next time don't be absolutists. It makes you both sound like morons.
Trust me, I have a PhD in engineering.
Would you care to expand upon that? Or is this the scenario we are looking at below?
I'm an engineer too, but without PhD. I don't know what he was thinking of (or even if he is an engineer at all), but I can say one major flaw that I noticed. The piston rings serves two functions and they only consider one.
The article deals with combustion, which is on top of the piston. It never mentions what is below, which is the piston rod and the crankshaft. The connection between those two needs to be well lubed, but the construction makes it really tricky to lube a "run away" bearing. The solution is to make an "oil fog", which sticks to everything, including the cylinder below the piston. When the piston moves downwards, the piston rings scrape off the oil from the cylinder and provides a clean surface for the combustion.
When running an engine with cracked piston rings, lube oil will start to enter the combustion. This will produce toxic black and foul smelling exhaust and the engine "will be burning oil". Even worse the oil burns badly and leaves behind soot, which will damage/block the valves. Some of it will stick to the cylinder wall and not be removed by the piston rings, which mean it ends up in the lube oil. The higher the amount of soot in the oil, the worse lubing ability it has. Eventually you have an engine with enough oil, but no lubing.
In short: no piston rings will destroy every valve and bearing in the entire engine and replacing it could be cheaper than repairing it.
I consider this to be a far more serious problem than anything the article mentions and I find it rather shady that they completely avoid this rather serious issue. It isn't like it is an unknown problem. If you run big engines like trains or ships, then you will periodically test the oil for soot (and other stuff related to other defects) to detect faulty piston rings before the engine is wrecked. Anybody working in the engine industry should know this.
If I had to pick whom to trust more, AC or Cryacin, I would pick AC. Ignoring my obvious bias, I've made way more posts than you have and for a lot longer too. Again, I am way more trustworthy than you are (especially if you ignore my dissociative identity disorder).
No Ph.D. here, but I used to was a mechanic.
TFA is not quite right. Piston ring friction is not the reason an engine needs a cooling system. Quite a lot of heat is produced by the combustion! So much so that the piston rings' are used to transfer heat from the top of the piston to the cylinder wall; typically pistons are made of aluminum alloys which melt around 2000 F. Combustion temps are much. much higher than that. If the metal piston ring didn't conduct heat, the piston would melt.
Solve that with an air seal!
You'd have to keep the CR low enough to not overcome the pressure wave of the ringless design. That means you'd lose efficiency in the engine. Reducing friction is a great concept but I'd still like to see the math involved as to how they'd get the efficiency out of the engine vs. a traditional design and how they'd keep the crankcase temps down and the oil clean. Most of that black/brown gunk in your oil at an oil change is blow-by, products of the combustion process. Even with piston rings you get a certain percentage of this and it raises the temps of the engine not just with friction but with hot gasses escaping into the crankcase. Don't get me wrong, I'd love to see internal combustion go beyond what we have today but it seems that there are already advances in direct injection and forced induction that are making smaller more efficient designs more powerful. If you want an internal combustion engine without rings (or wipers in a Wankel) then why not a turbine engine? It was tried before but I guess people were worried about melting the asphalt with the exhaust gas temps.
Harrison's Postulate - "For every action there is an equal and opposite criticism"
The biggest barrier to the adoption of ringless pistons is pre-existing technology
which is mature ( and works as needed ) and which has already paid for its development costs.
Billions of dollars and millions of man-hours have been consumed
in the development of Otto Cycle engines. Existing engines do not fail
because the piston rings are worn. They most often fail due to poor maintenance
practices, negligence, or abuse, which would kill an engine using ringless pistons just as quickly.
Additionally, whether this ringless technology is adopted hinges on
whether money is made available to develop it to the point where it
can be used in mass-produced vehicles. When a manufacturer can
meet its goals using an engine which has piston rings and spend less
money , or spend significantly more money using ringless pistons
which give marginal improvements at best, it is extremely unlikely that
a manufacturer will choose the ringless technology which involves more
risk for a reward which is not proportional to the risk.
There is an old patent on such ringless tech. There really are
very few new ideas in internal combustion engine tech.
http://www.google.nl/patents/US3745890
Much larger gains in power and efficiency are available by using electrical
or pneumatic devices instead of camshafts to control the movement
of valves in an engine. If I had to bet on what would be the most likely
tech to actually be used in production engines this is where I'd put my
money. Such tech IS used in engines of both Formula 1 cars and MotoGP
racing motorcycles. But all those engines ( on which hundreds of millions of
development dollars / Euros / yen have been spent ) still use piston rings.
That ought to tell you something. Of course it is possible that the engineers
at Ferrari and Honda and Renault and BMW are not as sharp as the folks in
Australia with their ringless pistons, but smart money would not bet on that
being the case.
Finally, if you REALLY want your engine to last, use the best synthetic oil available
and perform all other maintenance as indicated by the manufacturer, and you will
probably get bored with the vehicle long before it wears out.
=
Turbulent obturation rings of this kind (well, technically I guess these are obturation cannelures) have been used in a lot of applications because they have some interesting properties. For instance they are used in mortar shells. When you drop the shell down the mortar barrel, you essentially want it to fall without retardation so the primer gets a good hard strike and the propellant ignites 100% of the time. However you want as much as possible of the propellant gas to do the job of propelling the projectile, without blowing past it in the barrel. You ALSO want it to be as consistent as possible so the CEP of where the projectile lands relative to the target is as small as possible. So this isn't impossible, but it's not easy either.
-1, you forgot "Burma Shave!"
or were you going for haiku format? Too many syllables in that one for a haiku.
Learning HOW to think is more important than learning WHAT to think.
Whereas the majority of other peoples' are between 5% and 50% ethanol.
Learning HOW to think is more important than learning WHAT to think.
That has been solved for a while. Oil jet to to bottom of the piston. They have been doing that for a long time in racing and motorcycle engines.
See my blog http://ilovecookes.blogspot.com/ for light hearted technical information.
So will this mean that sleeve valves will be practical.
See my blog http://ilovecookes.blogspot.com/ for light hearted technical information.
That's how the Prius works. It's partly powered by smug.
That I'm right, and you don't like it, doesn't mean I'm a troll.
Eyeroll. "In the long term we are all dead". For the lifespan of everyone who is alive to read this today (discounting a war that destroys industrial civilization), the internal combustion engine will be the dominant powerplant for transportation. Deal with it.
From the TFA:
"... that an absolute seal isnâ(TM)t that important, and eliminating the friction generated by the rings on the cylinder wall can have far-reaching effects on engine design on the whole "
" ... that the whole thing is blowing a bunch of hot air?"
If they _ CAN _ use that bunch of hot air to form a seal, and achieve a drastic reduce of friction in between the piston ring and the bore itself, I feel that it's time for the return of the ceramic engine.
The chief reason why ceramic engine doesn't make it into the mainstream despite having had under research since the 1970's is that the friction in between the piston ring and the wall of the bore itself result in the wearoff of the ceramic material in the form of a pile up of fine ceramic dust inside the chamber.
If what the vendor said is proven to be true, then we should bring the ceramic engine back to the fore-front.
Muchas Gracias, Señor Edward Snowden !
It is nothing special from a volumetric energy density (MJ/L) point of view. It's in the same general range as all primarily petroleum based fuels which are liquid at room temperature and atmospheric pressure; more toward the lower end of the range. It is substantially more than liquefied gases and solids such as coal and wood.
Petrodiesel 37.3 MJ/L
Crude Oil 37.0
Gasoline 34.2
Gasohol E10 33.2
Jet A 33.0
Biodiesel 33.0 for comparison
Diesel is both cheaper (in normal countries, not the ridiculous US pricing structure) and higher energy density.
Exactly. They know what the hell they are doing, or even if they don't exactly know, they have a hell of a lot better idea of what's going on than you arm-chair engineers. Always naysaying because being a "skeptic" is all the hipster rage these days. I am so glad that an engineer like you could tell us what the functions of a piston's ring are and how a team who knows so much about how a ring works hasn't even thought about the lubrication aspects of their function.
Oh wait, it's in the TFS. Guess what function of the ring is no longer needed if friction is eliminated? Good thing you posted AC.
Why not eliminate the engine completely? Just aim in the direction of the destination, detonate, and surf the pressure wave.
With the engine-less car you can't take it with you, but if you don't make it on the first shot you won't be around to care.
Hardly imbecilic to me. It depends on how you define volumetric energy density. If based on the simple energy release of combustion, then yes the engine is not a factor. If based on the actual energy put to useful purpose (turning wheels), then it is directly proportional to engine/drivetrain efficiency.
2010 Corolla - it'll last forever, which is long after you'll fall asleep at the wheel from boredom...
I seem to remember running those well beyond the typical life of a current car engine. In fact, I remember my roommate pulling his squareback into a VW small local shop: 15 minute swap, a week to rebuild, another 15 minute swap - and good for another 100K...
Ethanol has only about 2/3 the energy density of gasoline, and methanol less than half. Whether you call that "running fine" depends on your point of view. And modification most certainly is required. The stoichiometric air/fuel ratio for alcohols is majorly different from that of gasoline. If using a carburetor you need to rejet, if electronic fuel injection you must remap the mixture in the ECU. Also, the requirements for seals in the fuel system is different.
I thought they were shutting down thte Australian car plants (by 2017)
If the pistons don't make contact with the cylinder bore, they can both be made from the same material and the CoE will be the same. Or you can just use a coating on the bore, like they have been for 50 years, and not worry about it at all. Sleeveless cylinders are not a new thing.
Or a sleeveless cylinder; 50 year old technology.
Find me two cars you can rub together and get a third, without losing anything from the prior two.
Or tractors.
This is why the Amish are smart... and wealthy.
That I'm right, and you don't like it, doesn't mean I'm a troll.
There are no economically feasible systems like you say in use any place on Earth, so you are incorrect, you should have prefaced your flippant comment with, "Theoretically".
How do I know, because I'm part of a working group to do just that, we're in contact with scientists and companies world wide and nobody can make it happen on a large scale at cost, let alone at a profit, which is the only way that technology will become available.
One of the reasons for going from 2-stroke to 4-stroke was heat. So the "fix" to your problem is to go to 6-stroke engines, with extra strokes for cooling. Also, water injection was used to fix that issue in other engines as well. There are lots of ways to fix that. No oil in the chamber doesn't mean you can't spray the back of the piston with a cooling agent (oil in today's cars). I can fix that problem easily in any of a hundred ways (finding the most efficient would be the trick), and you've proposed no other solution to the problem fixed by the air seal.
Learn to love Alaska
Looking for funding without a physical proof of concept?
How much would it cost to create a prototype? Get a used lawnmower engine, find a piston from a slightly larger used lawnmower engine (up to here you spent about $50), then turn some grooves in there and see how it purrs.
What are we talking about? a couple hundred bucks?
It would cost way less to try this in real life than all the computer simulations. Something smells fishy.
I'm not switching from gasoline until someone makes an engine that will run on distilled suffering of hippies.
Violence is like duct tape. If it doesn't solve the problem, you didn't use enough.
The important part, anyways. The Valvular Conduit - patent # US 1329559 A
http://www.google.com/patents/US1329559
Without rings, there would be no seal, so you either machine the gap to within a single atom, or you lose the pressure/increase friction.
I can see them collecting a lot of money to fund such a device, but it won't work how they're saying they will do it.
>>> Put ALL effort into engines that don't
>>> use fossil fuel at all. Thanks.
>> Then effort doesn't go into 'engines' -
>> It goes into energy storage solutions
>> that have the weight / energy capacity of gasoline.
> Why ignore the inefficiency of internal combustion?
What is an example of an internal combustion enginet that doesn't use fossil fuels?
I'm thinking if you had a micrometer sized spiral grove going up the cylinder wall the oil would stay in the grove to act as a fluid bearing and seal. I think part of the problem is that pistons and cylinder walls expand and contract with temperature.
This is still vapurware...
Work like no one is watching. Dance like you've never been hurt. Make love like you don't need the money.
As opposed to the falling for the bullshit, hype and PR?
BMW tried this on their cars and they leaked a lot of oil. Toyota removed the rings on the Tacoma and after 120,000km the engine was really loud with valve noise.
It is a good idea to reduce the friction in the engine but you will have some nasty results if things go wrong.
Hey, that's DOCTOR troll to you, bub. ;-)
Being a sceptic is good. New ideas need to be proven. Otherwise gullible consumers start putting magnets on their fuel lines.
IT specialists and software developers *ARE* the hippies of the engineering world.
What a come back, armchair engineer. I see the error of my ways. Nothing will work as scientists say because the Slashtards said so. I don't even know why they bother experimenting anymore. They can just post an Ask Slashdot and we'll show them the error of their ways!
I have mod points and would mod you up but I fucking hate you. You're right for once though. Maybe one of your other Slashtard buddies can mod you up.
Good luck making an electrically powered ship or airplane...
Which matters not. He said what his dreams are but you couldn't hold back speaking for the rest of us in a vain attempt at being smug. How many Priuses can you fit in your ass? Don't say you don't know. We all know you do.
Well, technically, pistons without rings. The piston and cylinder are machined precisely enough that they don't need rings. But here's the catch to what the Aussies are talking about as well as lots of other exotic engine designs. If it can't be made for the same or less money than present engine designs, it'll never get off the ground. And if it can't be maintained for the same cost, it'll eventually fade away. Popular Science and Popular mechanics are littered with unusual game-changing engine designs e.g. the 6-stroke engine that has a steam cycle to make use of the wasted heat energy or the Wankel.
A whole team is working. Yet no prototype has been produced. What's their main activity then? Pushing pencils? Having meetings to organise funding? It all sounds a bit strange.
I hadn't the slightest objection to his spending his time planning massacres for the bourgeoisie... (P.G. Wodehouse)
Who the FUCK got ahold of your account login credentials? YOU are telling these guys not be absolutists? Hysterical! Go read your postings again if you are having difficultly figuring out what I am referring to. To summarize vortex's posts, everyone who doesn't think like me, shit like me, and jack off like I do needs to go die in a fire. I am honestly surprised you didn't figure out how to bring Republitard talking points into this or is "not being an absolutist" the new term for "bipartisan efforts?"
When you give me an example of what an "enginet" is, I'll show you. Is that like a cute little mini-engine or something? Like the 3 cylinder Geo engine?
Umm...?
http://en.wikipedia.org/wiki/Electric_aircraft
http://en.wikipedia.org/wiki/Electric_boat
Carbon build-up.
Eventually, all engines suffer some form of carbon build-up that effects both engine compression and the internal exhaust pathways. For example; the exhaust valve pathways and EGR. Even with modern engines, proper fuel metering, and modern additives (polyetheramine), crap and crud still builds up over time.
Life is not for the lazy.
The Flintstone's car. It'll make a comeback.
Life is not for the lazy.
We already have engines that work based on air holes.
http://gamehacking.org/vb/threads/12747-nensondubois-codes http://twitter.com/nensondubois_
http://en.wikipedia.org/wiki/Nuclear_pulse_propulsion
Why do you hate me, and who are you? If the post is good, mod it up, I'm at karma cap anyway, so it won't help me as a person (not that slashdot karma is a big deal).
Learn to love Alaska
When running an engine with cracked piston rings, lube oil will start to enter the combustion. This will produce toxic black and foul smelling exhaust and the engine "will be burning oil".
You mention an engine where a specific feature, specifically the piston rings, has failed, so it's no surprise that it's operation would be undesirable. I will counter with 2 stroke and wankel/rotary engines, which burn oil by design. Burning oil isn't as much of a problem if you design for it.
The Australians are working on a design where the piston rings won't be necessary. It could end up that they need a new lube system for the piston rod/crankshaft, or it could end up being an insurmountable problem(for now). I like that they're looking into it though. It reminds me about how HD platter arms are suspended by air flow from the rotating platters. High enough pressures might cause the air to act more like a liquid.
I don't read AC A human right
how do keep the piston cool? seems like spraying oil would get into the grooves and stop the air waves from being formed.
'm sorry but the energy density of gasoline (36 MJ/L) is nowhere close to that of Uranium-235 (1,546,000,000 MJ/L).
Now, if only somebody would develop an engine that could run on a cubic millimeter (a microliter) of U-235 (roughly equivalent to a tank of gas). Or even a completely sealed unit with a milliliter of U235 buried somewhere in its innards (a few hundred thousand miles' worth).
-- Alastair
The physics of the carburetter seem absolutely stupid to me... Why would they not just squirt a fuel air mix in?
The answer is because it's fucking difficult, and the carburetter lasted for over 100 years in production cars because of this.
Just because something is fucking difficult, does not mean it will not be done, eventually.
Slashvertisement.
Also will meet a grim fate in stop-and-go driving if fielded when they carbon up.
"This post is an artistic work of fiction and falsehood. Only a fool would take anything posted here as fact."
Infinite amounts of zero is still zero.
Mine is 0% ethanol.
Electric motors are already over 90% efficient.
What's wrong with burning hydrogen? The by-product is water.
I thought Soylent Gas was what you got after eating Soylent Green tacos from Taco Bell.
Fuel injected cars are quickly learn a new fuel map when the fuel changes.
Even 10+ year old cars do that to an extent. My turbo charged engine has two maps. There is the basic programmed map and a learnt one based on readings from the knock sensor, so it can handle fuel of varying octane ratings.
Dynex has brought the technology to the proof-of-concept phase, in which virtual modelling of the âoeair-sealingâ principle looks promising enough to get to work on the real thing.
So, they haven't gone beyond a computer simulation of this? Yet,...
Weâ(TM)ve reached the point where we need to secure corporate backing to push the project through the development stage towards international commercialisation,
They think that a computer model is good enough to get this thing into mass production? Without even building a single prototype engine? What the hell, am I missing something here?
Nearly all small model aircraft engines run air cooled with pistons without rings. I built control-line aircraft models in the early 70s that used .049 cc and .20 cc and .35 cc displacement engines that had no rings. These engines were mass produced by Cox, Enya, SuperTigre. So what is the big deal here?
A horse.
Give it another hundred or so years... We might find that horses end up more popular than gasoline filled vehicles again. Not saying that horses will regain their former dominance though.
I don't read AC A human right
Lower fuel energy density doesn't matter that much between gasoline/ethanol, though. Energy density is still high enough that you simply put a 15 gallon tank where you currently put a 10 gallon tank.
I do agree that 'little modification' is a rather large understatement. While you can convert by 'simply' changing jets/remapping fuel mixture in the ECU, and a lot of seals are already compatible, I feel that in order to do alcohol *properly* you need to design the engine from the ground up to use it - alcohol has advantages as well as disadvantages, it's possible to make up some of the energy difference by creating a high compression engine that takes advantage of ethanol's high octane.
I don't read AC A human right
Interesting to see how the pistons will last under the heat of combustion without no active cooling via rings to cylinder wall.
What the heck are you talking about? Piston rings are there to save money by not requiring precision honing of the bore and piston. If you select the materials correctly you have never needed piston rings.
Just about every model airplane engine now uses a piston with no rings, and it scales perfectly well. It's just a matter of how much it costs, and the cost has been prohibitive.
And yes, you do need to match the coefficients of expansion in some combinations of materials, and also taper the bore so that it doesn't "bell-mouth" from expanding more that the top, where it's hot, than the bottom. Either that, or allow it to be mismatched, put in even more taper, and allow heat and expansion to create the proper fit. In either case, chrome the bore, or put on a hard anodized surface to keep it from wearing out prematurely.
People knew this all 50-60 years ago, and used it in some cases. It's not cost-effective, but it's certainly feasible.
Brett
Trust me, I have a PhD in engineering.
Model aircraft engines have been using grooved pistons since the 60s, and it worked fine. I have seen it on bigger engines too - but usually backed by at least one conventional piston ring.
There is nothing new in using grooves instead of rings - it is simply a case of optimising the groove design to make it work better for larger pistons.
(And contrary to what another poster has said, cooling is not an issue either - it is easy to oil cool pistons, if required.)
Model airplane engines don't have piston rings because those would be cost prohibitive, not because it's better technology. Model airplane engines wear extremely fast, have a low efficiency when you compare the burn energy to the output of motion and are extremely polluting.
I was promised a flying car. Where is my flying car?
Since posting quickly is one of the tricks round here, I forgot another problem - oil control. Without oil scraper rings, the oil sprayed on the bottom of the pistons (which only partly solves the heat problem) and oil thrown purposely on the lower cylinder walls to lube the piston on its bottom excursions will find itself in the combustion chamber in large quantities, probably large enough to foul the spark plug but certainly enough to produce huge clouds of pollutant-laden, oily smoke.
Do I have a solution? Not yet.
But I can cry "bullshit" when I hear it, can't I?
To add on to what user Firethorn has said, try imagine an engine that needs no cooling.
The very reason we need to COOL our engine because the metal that we use in our engine can withstand heat up to a certain limit, and beyond that, the engine starts to melt.
Ceramics don't have that problem. Some ceramic compounds can withstand thousands of degrees of heat (and for that they have been used as shields for the Space Shuttles) and they are excellent insulators !
Serious research has been carried out on ceramic engines since before 1970's, by almost all the developed countries (America, Europe, Japan) and prototype engines had been developed.
The main problem so far is that, unlike metal, ceramics are not as durable against friction. Very fine ceramic dusts will fall out as a result of the friction, and combined with the fuel, it become "sludge"-like, jamming up the chamber.
There are a lot of places inside an engine where there are frictions, but the MAIN place which friction takes place is in between the piston ring and the bore wall.
If what the TFA says is true - that they can manipulate the air to become a "force" and takes the place of the piston ring, which means, the friction in between the piston ring and the wall of the bore is gone, then, the number one problem facing the ceramic engine is solved !
Muchas Gracias, Señor Edward Snowden !
That applies now.
The only reason it is not economically feasible is because it is so cheap to dig fossil fuels out of the ground.
Allegedly, we are now past peak oil, and the price of fossil fuels should start going up. Eventually it will be economical to produce synthetic hydrocarbon fuels using solar/nuclear/other power and either biomass or CO2 and water - either because the technology has improved, or the products have risen in value, or more likely, both.
I'm guessing that wasn't on their radar screen...
I'm not switching from gasoline until someone makes an engine that will run on distilled suffering of hippies.
Not all 'hippies' are created equal. I tend to consider myself as somewhat hippy-ish. I believe in peace, love, understanding, environmentalism, nuclear power, GMO foods, high-technology, and the idea that we can - in a perfect world - eliminate the need for work allowing people to concentrate on the betterment of themselves and their fellow man.
Note that the vast majority of 'hippies' disagree with me vehemently on nuclear power and GMO foods (and some disagree on the high-tech). From my point of view as a scientifically minded person though, I see these as being the sensible environmental low-impact choices of the present day.
As for your gas-guzzler (and mine) - I look forward to the day they no longer exist.
My book about LSD and Self-Discovery
Also on facebook as: DroppingAcidDaleBewan
Now , dont be too hasty in condemning this as fruitless.
The Aussies were merely formulating a way to slowly burn off that nasty engine oil. Why, they would only end up changing it and winding up with a bucket of old dirty motor oil. This way it is vaporized along with gasoline and any remnants of it are spread invisibly through the atmosphere. Theyve eliminated a very messy product to deal with.
Imagine how tough they will look with their vehicles blowing a manly stream of black smoke in their wake.
All perspective.
*Repent!Quit Your Job!Slack Off!The World Ends Tomorrow and You May Die!
All iron block engines are sleeveless as are most modern aluminum blocks. Do you mean sleeve valve engines maybe?
See my blog http://ilovecookes.blogspot.com/ for light hearted technical information.
Why isn't there a car refurbishment industry, or at least a cottage industry?
There are always those models of cars which through design refinement seem to reach a "bullet-proof" stage where the major mechanicals are extremely durable and are produced in massive scale, like the Camry.
Assuming they don't rust out (which seems to be less a function of corrosion than mistreatment and unrepaired body damage), you would think that someone would be in the business of refurbishing them to a near-new kind of state.
There's a ton of third-party new parts and the cars were produced in such numbers that there's a lot of spare parts from other vehicles, too. Seats could be rebuilt and reupholstered. About the hardest part to "fix" would be dashes and interior door panels, but these could come from spares.
US labor is probably too expensive, but it's not hard to see the rebuilding of components (engines, transmissions, seats) happening overseas and assembly happening here, or just do it all overseas and ship them back by the shipload.
For the clearances to be right at operating temperature, they have to be far greater when cold. On cold starts, the blow-by will probably pretty bad - enough to fail US federal emissions limits; doubly so for California's.
distilled suffering of hippies
Isn't that what gasoline and the other long chain hydrocarbon fuels are?
Time to offend someone
I have a PhD in engineering too. Computer Engineering. So I’m probably just as unqualified as the AC to comment on this. :)
BTW, you should look at the comments on the article. They’re more interesting than the article. Apparently this idea of ringless pistons has been known since the 1950’s.
Until we start manufacturing gasoline from atmospheric CO2 and water, then, yeah kinda it is. Seriously, close the loop, you get the energy density of gasoline, and don't need to further burn new hydrocarbons. We pick an optimum CO2 density, bring the atmosphere to that (where ever it may be), and moderate total production to maintain that level.
Well there isn't much gain to be had for electric motors. Cheap crappy ones can be had that get 85%, good ones get around 90%, and I think I read a while back that someone had one that was something like 98% efficient. The biggest problem with electric vehicles is the amount of power needed to drive a vehicle. Gasoline has something like 33KWh of energy in each gallon about 10KWh is actually used to make the car move, the other ~2/3 of that energy is lost as waste heat (friction and combustion).
If we compare a couple of vehicles lets say my 02 BMW 325i and a 2013 Nissan Leaf. My car has a 16 gallon tank which provides me with about 160KWh of usable energy to make the car move and if run from full to empty on the interstate would probably get me something like 500 to 550 miles from where I started. Now looking at a Nissan Leaf with its 24KWh battery and estimated range of 84 miles (EPA estimate which is in the middle of the range). For the leaf to go 500 miles it would need a battery about 6 times the size with a capacity of 144KWh. Also of note the leaf has better aerodynamics so it gets a benefit my car doesn't. So it looks like for a reasonable sized vehicle you do need about 150KWh of energy to go 500 miles. So if you want an electric car with better range you would only see at best a 15% increase in range from better electric motors, but still would need an additional 5x increase in battery capacity to match the range of my car.
Note I actually like electric vehicles and this was not to diminish their usefulness. The next car that gets purchased will probably be an electric for my wife since she has the ideal driving profile for someone who should be using an electric car. Also both cars could be substantially lighter which would extend the range of both of them.
Time to offend someone
It is more than a little modification. If you are looking to go for miles per gallon ethanol and especially methanol suck compared to gasoline and diesel. They are however excellent fuels for race or performance applications as you can release more energy for a given air charge than you can with gasoline or diesel. Those alcohols also have a higher octane rating and a higher latent heat so you can run higher compressions or higher boost. As far as modifications to properly utilize them you need to adjust the fuel air mixture (bigger injectors or jets if carbureted), adjust the timing, make the fuel system alcohol safe (E100 or M100 are completely different monsters than the E10 blend sold everywhere), this includes the tank, lines filters, pumps, injectors or carburetor, and valves(there is some debate on this). Alcohol vehicles are also harder to start when cold, and I don't even mean cold like it is now when they probably wouldn't start unless you installed a glow plug like system as well. While these things are doable (doing it on my project car that I am doing a full restoration on) they aren't exactly simple on an existing vehicle. Granted you could just adjust the timing and fuel air mixture and call it good but you will have to replace the rest of the stuff when it does fail. The flex fuel vehicles wouldn't need the replacement of parts but they are a compromise since they can run on E0 up to E85 and don't seem to do any of it well.
Time to offend someone
While this is true alcohols will push it very far out of either of those bounds. Using a lower octane fuel your car may be dumping an additional 10-15% more fuel in. Now using an alcohol fuel it could be dumping in close to 2 (ethanol) to almost 3 (methanol) times the fuel which would probably put your injectors out of their duty cycle range at the pressure you are running them at. So your options are to either put in bigger injectors, or put in a higher pressure fuel pump, and you should probably put in a higher volume fuel pump any way since you will be moving a substantially larger volume of fuel all the time.
Time to offend someone
Wikipedia covers it pretty well but it's an average of RON and MON.
http://en.wikipedia.org/wiki/Octane_rating
It may work...
With oil weights getting thinner and thinner, the clearances between the piston and piston wall may be so thin, that such an action can occur. However, how do you keep the compression if there is no piston ring there? If it is only the oil, then that air will simply push that out of the way and you loose compression, which is currently a sign of a worn piston ring.
Oil is getting pretty thing, all due to fuel economy. We are about to see a consumer grade of 0w16 oil! Now that's thin!
I've never had an engine fail due to piston ring wear.
Most haven't but that doesn't mean something potentially better than piston rings isn't worth trying. Piston rings work pretty well but their very design is sort of a workaround solution. In theory they shouldn't be necessary at all. A design that could eliminate them altogether could in theory be a very big improvement in engine efficiency and reliability.
Oh and I have had a piston ring fail. Even if they don't fail they will cause wear which results in reduced efficiency over time.
Seems to me this may be an idea looking for a problem.
Only if you don't understand the engineering tradeoffs being made. Piston rings generate friction, they require complicated lubrication systems, they can and do fail sometimes, they are expensive to replace, they complicate engine assembly and design which adds cost, etc.
I consider this to be a far more serious problem than anything the article mentions and I find it rather shady that they completely avoid this rather serious issue. It isn't like it is an unknown problem. If you run big engines like trains or ships, then you will periodically test the oil for soot (and other stuff related to other defects) to detect faulty piston rings before the engine is wrecked. Anybody working in the engine industry should know this.
What does this remind me of? Oh, yes. New York Times, January 13, 1920.
[...] It is when one considers the multiple- charge rocket as a traveler to the moon that one begins to doubt and looks again, to see if the dispatch announcing the professor's purposes and hopes says that he is working under the auspices of the Smithsonian Institution. It does say so, and therefore the impulse to do more than doubt the practicability of such a device for such a purpose must be--well, controlled. Still, to be filled with uneasy wonder and express it will be safe enough, for after the rocket quits our air and and really starts on its longer journey, its flight would be neither accelerated nor maintained by the explosion of the charges it then might have left. To claim that it would be is to deny a fundamental law of dynamics, and only Dr. Einstein and his chosen dozen, so few and fit, are licensed to do that.
That Professor Goddard, with his "chair" in Clark College and the countenancing of the Smithsonian Institution, does not know the relation of action to reaction, and of the need to have something better than a vacuum against which to react--to say that would be absurd. Of course he only seems to lack the knowledge ladled out daily in high schools.
Bring back the rotary, without ANY APEX or side seals.....
I am the unwilling control for my Origin.
and the idea that we can - in a perfect world - eliminate the need for work allowing people to concentrate on the betterment of themselves and their fellow man.
Has it occurred to you that in many cases work IS a way for people to concentrate on the betterment of themselves? Work is not some horrible thing to be eliminated or feared.
What about Butanol? May not smell so nice though, but better energy density than ethanol and at lower temperature.
Gasoline, diesel, etc don't have to be Fossil Fuels. We can make them with a biological process for example.
All so-called fossil fuels come from biological processes. The only real difference the ones we make and the ones we dig up is when they were made. The ones we dig up were biological processes that took place a long time ago. This means it requires comparatively little energy to get them because we just dig them up. If you want to make them the energy required for processing becomes a MUCH bigger piece of the economic and chemical equation.
These processes are basically carbon neutral since the carbon emitted during internal combustion recently came out of the atmosphere.
No they will not be carbon neutral because the conversion process will not be 100% efficient. The processing of the fuel will require energy which baring some unexpected breakthrough in energy technology will result in net carbon being emitted.
Wouldn't going to a 6-stroke design greatly reduce power output, all else being equal? Much like going to 4-stroke from 2 made it harder to generate horsepower.
When I think of knock, I think of bad bearings, main or rod. Pre-ignition I call pinging.
Knock and pinging are synonyms per standard usage. Pre-ignition is technically a separate phenomenon. Knocking is when fuel/air explodes outside the normal envelope of the combustion front. Pre-ignition is when the fuel/air explodes prior to the spark plug firing. It's common for people to confuse the two and to use the terms interchangeably but among us engineers this is technically not correct.
Er, wasn't that the OP's point? No current battery, flywheel, natural gas, etc. provides the energy density of liquid petroleum, regardless of the refinery technique. People use oil for transportation because it's easy to transport and handle (compared to, say, LOX), and the fuel weight to payload ratio is very small. We're not stupid, as they said in Trainspotting...
What was once true, is no longer so
Oh wait, it's in the TFS. Guess what function of the ring is no longer needed if friction is eliminated? Good thing you posted AC.
They plan to reduce/eliminate friction between the piston head and cylinder walls , the link between the piston head and the piston rod still needs to be lubricated which is what the gp was pointing out that they didnt consider or didnt mention in the article.
maybe you should read the comment you are replying to.
$ unzip, strip, touch, finger, grep, mount, fsck, more, yes,fsck,fsck,fsck,umount, sleep
Makes me think it's junk that will never work right.
Trust me, I have a PhD in engineering.
Heh heh. Posting anonymously when resting your authority on the strength of your name rather than the validity of your argument. Have to feed the troll on this one.
Hey, Cryacin, that's quite a profound statement coming from someone that doesn't seem to realize they are hiding behind a pseudonym, too.
Appropriate captcha: identify
This will starve a lot of people in the UAE and surrounding countries if a replacement for petroleum is found. Don't do this.
If the engine is designed for it (ECU has the code to learn the correct map, fuel system has the additional capacity), what's the problem?
I didn't read the details, but whatever works as "rings" on the top, could be used as rings on the bottom as well, or just reduce, but not eliminate the rings. Perhaps there's a lube that burns clean, so you lube with gasoline (probably not literally, but something that burns close enough to that) and all your listed problems go away.
Learn to love Alaska
The loss of power comes from pumping losses and friction. If you greatly reduce the friction losses with elimination of rings, and keep the valves closed for the last 2 cycles, you'll not be reducing power "greatly" (from an efficiency perspective), but would be reducing it from a power per displacement perspective, but that's less important than efficiency.
Maybe there's be a hybrid where it's 6-stroke for "normal" operation and when running hot, and 4-stroke for when cool enough and extra power is required.
Learn to love Alaska
Properly maintained, the common internal combustion engine can keep going for a very, very long time - I've seen several that passed the half-a-million mile mark, a few of which are still going strong today.
FWIW, and again assuming proper maintenance, your car's engine is one of the least likely parts to fail. Except maybe the floorboards.
An enigma, wrapped in a riddle, shrouded in bacon and cheese
Now, if only somebody would develop an engine that could run on a cubic millimeter (a microliter) of U-235 (roughly equivalent to a tank of gas). Or even a completely sealed unit with a milliliter of U235 buried somewhere in its innards (a few hundred thousand miles' worth).
Wouldn't it be safer and more efficient to do it centrally on a bigger scale and simply pipe the resulting electricity to the cars over the existing electrical grid? They could even be plugged in recharge overnight!
*cheekygrin*
..Mullah or Pope, Preacher or Poet, who was it wrote: "Give any one species too much rope and they'll fuck it up"?
Here is a list of Internal Combustion Engine vehicles that use Hygrogen.
You can't take the sky from me
Yeah, uh, you're stupid.
Case 1: Random moron newspaper editor states (in an editorial) that Goddard's proposal are impossible based on an objection widely known to be wrong and dumb and stupid at the time of writing. (No 1920 physicist would have supposed that a rocket in a vacuum would be ineffectual, nor did you need an Einstein to tell you so. p=mv was rather an old equation at that time.)
Case 2: Engineer with specific relevant domain knowledge states an objection to hype about friction-reducing ringless pistons based on knowledge of what the other function of piston rings is -- keeping oil out of the combustion chamber. Does not use any obviously false evidence or reasoning. Doesn't go so far as to assert impossibility but makes awfully good points about this being a rather obvious problem which is completely un-addressed by what appears to be a bit of hopeful trolling for investors. (Seriously, nothing but simulation, no physical prototypes? Better do your homework before putting money in...)
One of these things is not like the other.
He did say little modification needed.
They stopped using carburetors on production cars in the 80's (although there were a few GMs and the Japaneese Honda Civic that you could get into the mid 90's).
Ethanol will not harm cars built from about 85 forward (fuel injected cars don't use cork gaskets).
You can't take the sky from me
Not if you use water injection!
You would steam clean that baby!
I currently use it on my turbo 2.3 with great success.
You can't take the sky from me
Carbon build-up.
Perhaps a ceramic engine could run hot enough, that carbon at critical places will burn. Perhaps ceramics can be made with surface which resists carbon-build up. Perhaps ceramic material can be made so that it catalyzes burning of carbon. Perhaps some space can be reserved and gas flow around the piston can be designed so that carbon build-up happens at places where it does not matter. Perhaps increasing efficiency enabled by higher temps will simply allow so clean burning, that amount of unburnt carbon is reduced to the tenth of current minimum and it will not become a problem until it's necessary to overhaul the engine anyway.
To summarize, I'd wager carbon build-up is just an engineering challenge.
Had me thinking though.. and ones that could create a pressure wave might not work at high RPMs , due to the time required to build up the air cushion. Since they haven't built a working model, never mind prototype, I guess they haven't cracked that egg yet.
Why not revisit rotary if they're going to waste all their time on the ICE? OTOH, I'm a garage junkie from the 60s and I love the smell of gasoline, and the best days of my life were spent doing things like helping to install a chromed GMC 6/71 blower on a hemi in a loud hot garage.
Yet ... Even *I've* gone electric. Mind you, I've disconnected the governor and installed plus size Tesla batteries on a wee li'l scooter ;-)
Eventually, all Internal Combustion engines suffer some form of carbon build-up
compressed air and steam engines just to name a couple don't suffer from carbon build-up in the cylinders
do NOX users fart nitro-methane?
http://en.wikipedia.org/wiki/Gunpowder_engine this count?
gosgog:
Interesting thought but wait 'till they build & put at least 100,000 miles on it. Speaking of U.S. Built cars (late 60's) , Mustang, & Cougar were great but then went to Toyota sold it because of planned on a job move to Vancouver, they wanted to tax all my stuff so didn't go.
I bought a used 66 Cadillac 4 door, with about 35,000 miles. Moved from Portland, Ore, to Houston Texas to live (great city). I finally got rid of it after elec windows & some other minor stuff, final mileage close to 400,000 miles! A few years later with my own business based in Houston I leased a used Lincoln town car...finally close to three hundred thousand miles. Sold it 'cause I needed money to buy an airplane for my business, and bought an old pickup to get back & forth to my local airport. Today (retired) I live in Asia, & currently drive a used Nissan sedan.