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Efficiency? Think Racing Cars, Not Hybrids
Gordonjcp writes "A renowned racing car designer has said that car manufacturers should be looking at making cars lighter to improve efficiency, rather than adding complex drive trains. In this article on the BBC News website, Professor Gordon Murray explains that a weight saving of 10% in a normal car would make more difference than switching to a hybrid engine and motor combination. Could this be the next nail in the SUV's coffin?"
This amuses me to no end, and I've heard it repeated from people at the Budget rental place as well as talking heads on TV. What possible use is seeing over traffic if you're still stuck in it? Are you following too closely and not paying attention to your surroundings or something?
It doesn't mean much now, it's built for the future.
Hybrids get their benefits in two ways: reclaiming power that would otherwise be lost during braking, and the fact that electric motors have a flat torque band. You generally can't do either that with an internal combustion engine alone.
However, there are a few ways to do both the above without an electric motor. One way is to have a flywheel connected to a CVT on the drive shaft. When you hit the brakes, the flywheel spins up. You can then release that power again when you accelerate. The flywheel will also act as a gyroscope, so you need to have some way of tilting it so you can go through corners with it spun up (which has the side effect of increasing handling). This method is being put on F1 cars soon.
The other way is to have an air compressor, which again is run off the drive shaft when you hit the brakes. On acceleration, the compressed air could either run the drive shaft, be dumped into the intake to increase boost, or dumped into the exhaust manifold to eliminate turbo lag. This is probably easier to design than a tilting-flywheel system, though it won't make handling better.
The compressor could also run off turbines using inlets around the car's body that are opened when braking. This particular use is probably illegal for F1 and other types of race cars (which often ban variable body shape systems), but could easily be used in road cars.
Both the above don't require any particularly exotic materials (though carbon fiber or nanotubes would be nice for the flywheel), and shouldn't be as heavy as an electric motor/battery system.
Not a typewriter
- One that I only drive to and from work, maybe grab a 12-pak of Diet Dr Pepper®
- One that has ONE seat, maybe 2 in tandem for carpooling, thus a narrower front for lower drag coefficient, maybe a tripod
- One that gets a55-load MPG, on regular gas
- One that is enclosed against rain, maybe even snow.
- save weight by removing the automatic transmission, power steering, power brakes, Bose Stereo, the GPS, the air bags, spare tire. Make the tank small enough to weigh little and still get me through the work week without refilling
- Actually, remove ALL safety features except the brakes and the brake lights! Save weight. no OnStar, no Lojack, no side curtains.
- Cut us some slack on emissions. Yes, commuters are the bulk of the problem, but not if we are burning half of the fuel that we would have been.
- it has to be CHEAP! Like $2000. Cheap to insure. Cheap to replace panels if we bump each other. Easy to park.
- if you want to get REALLY froggy, give us tax breaks, or our own LANE on the freeway. Watch people buy em like hotcakes.
Ok, so I just described a 1982 Suzuki, full face helmet and a rain suit, except for the 3-wheel stance.My point is really this. We need a small, commuter-only vehicle, unfettered from the legal burdens that add weight and reduce gas mileage. And yet still capable of highway speed and 200 mile range. Take an F1 car, make it 3-wheeled with a Jet cockpit. End of problem. It's not rocket science...
What about not driving absolutely everywhere? I see a lot of people drive from my apartment complex to the convenience store next to it. Total time to walk is about 2 minutes. When you add up going to the underground parking, starting your car, exiting the underground parking, waiting for traffic to turn onto the main road, drive down 30 feet of road, and then wait for traffic again as you drive into the parking lot of the store. It takes more time to just get to the store than if you walk. Sure that short drive isn't going to cost too much in gas, or cause too much harm to the environment, but the whole attitude of having to drive absolute everywhere is just terrible.
Anthropic principle: We see the universe the way it is because if it were different we would not be here to see it.
I did a UI course back in 2002 and we happened to be talking about steering wheels as the UI input device. The prof happened to be a Psychology/Comp. Sci. cross, and he went off on a tangent wrt a certain thought experiment:
The hypothesis says: the higher the chance of death, the lower your speed. If the chance of death in a moving car were 100%, no one would drive. If the chance of death were 0, then everyone would drive as fast as the car could go.
What happens if you put a spear sticking out of the steering wheel aimed at your chest?
I own two cars designed with the exact same goals in mind and built in the same factory 45 years apart:
1963 Mini - 1300lbs, 850cc engine, 37hp, ~55mpg.
2008 MINI - 2600lbs, 1600cc engine, 98hp, ~42mpg.
So the weight doubled, the engine capacity doubled to make up for it - and surprise, surprise, the mpg got worse. It ought to have been a lot worse than that - but engine technology, drag reduction, drivetrain friction and other things improved.
While the modern MINI is 2 feet longer, more than a foot wider and nearly a foot taller - there is actually LESS rear legroom than the '63 model. Trunk capacity and front legroom are comparable. Handling is comparable. The modern car also has a radio! Safety, top speed and accelleration improved immensely over 45 years - handling stayed about the same (which is remarkable given that the weight doubled!), comfort improved a little.
The trouble with adding weight is that more weight means that you need more engine which adds yet more weight - your fuel consumption gets worse so you need a bigger gas tank - and when it's full, that's more weight. You have to absorb more energy in a collision - so you need more structure - which adds more weight. It becomes a positive feedback situation where increasing the weight by a little bit ends up increasing it a lot.
But the good part of that is that stripping out a little weight saves more weight which saves more weight.
The concerns are real, but I don't know if they're valid concerns when I looked at the actual crash stats. What I've seen in the stats is that SUVs and trucks were statistically more dangerous to ride & drive in than a mid-sized car.
It's the weight and the high center of gravity that play against the safety of the trucks. The mid-sized cars can swerve better and brake faster, and the cars are far less likely to roll over than trucks & SUVs. Basically, while trucks & SUVs can better protect the passengers in the event of a collision, they're more likely to get into collisions.
The only reason why this is is because we were sold on the idea of living in the suburbs 50 years ago and the cities funded most of that movement of their tax base to the suburbs with all the money there were supposed to spend on infrastructure. cities like seattle that never spent a dime outside of its own city limits have an amazing infrastructure. we were sold a consumerist dream and bought it hook line and sinker. now its time to pay up and we're going to have to go back to the way we were before this whole fiasco and live in the cities close to our works and stay the hell out of other peoples business.
Odd - slashdot managed to eat my post during preview.
In any case, here's the equation you want: E=0.5m*v^2. Know that the weight of a Miata is 940 Kg and that of an excursion is 3261kg. For the Miata to have the same kinetic energy as the Excursion at 30 mph, the Miata has to drive at 55 mph.
Who is the idiot who is driving 55 in a 30 mph zone?
Those who can, do. Those who can't, sue.
Smart car crash test...
http://pl.youtube.com/watch?v=Y1NHXiGd0rQ
Which driver suffered more?
No sig today...
Actually, VW/Audi's new automatic tranny, the DSG (Dual Shift Gate) is only slightly heavier than a traditional manual tranny and is more efficient.
It uses 2 clutches, a split fly wheel (inner and outer), and two input shafts. It can always keep 2 gears engaged with only 1 clutch engaged. Up-shifting takes a tiny fraction of a second as the two clutches switch states and the newly disengaged input shaft engages the next gear to be shifted into. Down shifts can take a hair longer, but are still in the sub-second range.
The down side though is that you can't (currently) feed it much over 250 ft-lbs of torque since the surface area on the flywheel is split between two clutches, you'll slip the clutch in no time with too much power and weight. But for a commuter car that isn't going to be taking a tuned engine and hard launches, the DSG is an amazing piece of engineering.
-Rick
"Most people in the U.S. wouldn't know they live in a tyrannical state if it walked up and grabbed their junk." - MyFirs
The problem is America picks heavy and cheap without bothering with the safe.
Take a look at this picture. Same speed. Same impact.
The Mini crumpled its whole engine bay. A total write-off. But the passenger compartment is barely touched.
The F-150 has a beautifully intact engine. It's unfortunately inside the cab where the people-puree would be oozing out.
Add on pickups having a consistently 20% higher fatality rate per million miles driven and you suddenly realize that stupid engineering combined with being in a hulking great target that can't get out of the way really doesn't compete with a small, light, quick to accelerate car that's simply not where the accident happens in the first place.
Case in point: About two weeks ago, my wife was in her Mini Cooper S in a parking lot, looking for a space. A Dodge (oxymoron if ever there was one) Ram (ah, far more accurate) reversed out without looking, straight at her. Had she been in an SUV, the back end of the Dodge would have gone through the side of it before the idiot had time to react and hit the brakes. The Dodge would have been trashed, she'd be dead or in a coma from the injuries. In the Mini, he put her foot down and was somewhere else while her SUV driving friend in the passenger seat asked, "How the hell did you do that?"
So, given the choice, I'd rather be in a well built car that folds the parts I'm not in when it gets hit, light enough to avoid more of the accidents anyway, than the hunk of American steel that deforms that steel in to right where I'm sitting.
I work in London, UK. Gas is $10 a gallon.
Our public transport is OK, not great, but it costs $15/day and takes 45 mins on the train, compared with $35 fuel, $15 congestion charge and $25 parking to drive - for 1 hour 50 mins.
(And the housing beyond insane - you could not buy a home of any sort for less than $1 million within 30 miles of my office)
You will get this eventually in your big US cities. LA is the size of London, and starting to run of space to build 10 lane highways. New York is probably already like it.
"Those who cast the votes decide nothing; those who count the votes decide everything." (attrib. Joseph Stalin)
This is the reason flywheel energy storage is not used in vehicles. The flywheels turn at super-high rpms, amplifying this issue. AFS Trinity (formerly American Flywheel Systems, I think...) worked on the AFS-20 as a prototype flywheel car back in the mid 90s. They never got it working. The problem is that when you are driving, and you turn, precession causes a large amount of friction against your flywheel bearings as it resists the turn.
Last I heard, they were working on magnetic bearings, instead of physical ones, but there's been little progress released to the public so far.
The main advantage of a flywheel is that it can handle rapid charge / discharge, but ultracapacitors are another way to gain that benefit without the disadvantages of flywheels.