Nnnnnnnnnnnyeeeeeowwww

28 July 2013 — dan

A reader writes:

I was watching an awesome Honda ad featuring the ghost of Ayrton Senna and his 1989 car...

...and I noticed people arguing in the comments on Jalopnik about Doppler effect, which I think you can hear in the video as the "car" goes past the camera.

Per your previous writing about "common sense" and concepts that "slither out of people's mental grasp", can a series of speakers set up around a racetrack and playing the sound of a car actually create the same Doppler effect as the actual car did?

Ron

No, they can't.

The Doppler effect happens when a moving object emits something, in this case sound waves. When each new wave is emitted in front of the sound source, it's closer to the previous wave than it would have been if the emitter were stationary. Behind the emitter, each new wave is a bit further from its predecessor than it would be if the emitter weren't moving.

This works for light as well, hence "redshift" and "blueshift".

We don't notice redshift or blueshift in everyday life because Doppler shift is a proportional effect, and the speed of light is so high that no light-emitter that humans normally deal with moves at an appreciable fraction of lightspeed relative to us. The speed of sound, however, is relatively low (about 340 metres per second close to standard temperature and pressure), and the human ear is quite sensitive to changes in pitch. So we can easily hear this effect on the sound of a car engine...

...or horn, when that car passes us at speed.

(My favourite example of car-horn Doppler shifting, which includes a lot of moderately comprehensible cursing, is this one.)

If you set up a bunch of speakers to imitate the sound of a passing car, none of them are moving, so there will be no Doppler shift from the point of view of a stationary observer. You could create the same effect by deliberately adding pitch shifts to the sound being played so that it sounds correct from a given listening location, but that'll make it sound wrong to listeners somewhere else. Doppler changes are caused by waves being bunched up and spread out by motion, and that just doesn't happen if neither listener not sound-emitter are moving. There's nothing about the order in which speakers play sounds that change what the sounds are.

(OK, there might be some interference effects audible at various listener locations. But that wouldn't sound Doppler-y.)

There actually would be Doppler effects if you were in your own car driving around the racetrack during the ghost-of-Senna performance, though. A moving listener creates Doppler shift in exactly the same way as a moving source:

Again, though, the pitch-shifts wouldn't sound right. They'd entirely depend on your speed relative to whatever stationary speakers are sounding at a given moment.

A related concept to this is the idea of the faster-than-light laser dot.

Consider flicking the dot of a laser pointer across, say, the face of the moon. (Presume you've got a laser that's well enough collimated that it still has a small dot at that distance.)

If the dot crosses the moon in, say, a hundredth of a second, and even if you ignore its curvature the moon is about 3,400 kilometres across, then that dot is going about 340,000 kilometres per second, which is faster than light. Address for delivery of Nobel Prize in Physics will be provided on request.

Unfortunately, and to the chagrin of a great many cats, a laser dot is not a "thing". It's just where photons happen to be falling and bouncing off at any given moment. Moving a dot faster than light is indeed perfectly theoretically possible, but you might as well give two blokes each a flashlight with an accurate timer built in, have them synchronise timers and then move a thousand kilometres apart, and then turn their flashlights on and off so that one light-pulse happens a thousandth of a second before the other. Presto, now a dot has moved at a million kilometres per second, more than three times the speed of light!

Except that doesn't mean anything, because that dot of light is not a thing moving faster than light. You could fill the space between those two flashlights with a trillion more flashlights timed to give a wonderfully smooth movement of the dot, but the dot would still not be a thing travelling faster than light. A spinning lawn sprinkler may have a contact point between droplets of water and the circumference of its spray pattern that goes round and round at a quite impressive speed, but that's just where the water hits the lawn, it's not an actual separate moving object.

(By the way, smart alecks, relativistic time dilation does not mean the flashlight timers would get significantly out of sync if the flashlight-carrier on one end got to his assigned location on foot, taking weeks, and the other got to his by rocket-sled at ten thousand kilometres per hour. At 10,000km/h your clock will tick slower than that of a stationary observer, but only by a factor of 1.0000000000429. The fastest object humanity has ever made is the Helios 2 probe, at 70,220 metres per second relative to the sun; it achieved a time dilation factor all the way up at 1.000000027!)

A further extension of this idea is to say, "OK, what if I've got a stick a million kilometres long, and I hold one end of it and spin it around my head in a circle in, say, five seconds? The circumference of a circle with radius one million kilometres is 6,283,185 kilometres, and the tip of the stick it will go all the way around that circumference in five seconds, which is 1,256,637 kilometres per second. The tip of the stick is a thing and not just a dot of light, so it's really going at that speed, which is 4.2 times the speed of light, NOW can I have my Nobel prize?"

No, you still can't.

Ignoring the obvious issues regarding the construction and inertia of a million-kilometre broomstick, there is no way for one end of an object to know what's happening to the other end at faster than the speed of light. Motion of the object occurs when the molecular bonds that hold it together are stretched and pull the molecules along, and there's nothing about those molecular bonds that causes them to influence each other faster than light. Otherwise you could make an instantaneous communication system by taking your very long magic broomstick and tapping on the end of it in Morse code or something.

So even if your very long stick were made of alien indestructium with an infinite tensile strength, spinning the middle of it round and round would just cause the whole thing to start wrapping up into a spiral. You could then try cracking it like a whip if you wanted, because you're Cowboy Galactus or something, but the other end of the object would still not travel faster than light, because no "information" within the object, in this case the information regarding the location and motion of its component particles, can travel faster than light either.

This seems bizarre, but again this is because we're talking about scales far larger than those on which humans normally operate. On the very large scale, nothing is particularly solid. If planets and stars and even galaxies run into each other, the energies involved may be unimaginably large, but all of the actual objects behave pretty much as if they were made of blancmange.

(Actually, in galaxy collisions, few to no actual collisions of the objects that make up the galaxies are likely to happen, because galaxies are mostly empty space.)

If Unicron were actually the size of even a small planet, no material that even theoretically exists in the universe would be stiff enough for him to be able to transform like his car-sized distant relatives. (Well, maybe if he's made of some kind of degenerate matter and has magical technology to prevent himself from collapsing into a black hole. Once you can cancel gravity, you might as well move information faster than light, too. It never seems to take a Transformer or Decepticon much more than twenty minutes to get to anywhere in the universe, after all.)

To reward anybody who managed to get to the end of this post, the ghost-of-Senna ad sounds pretty good, but the Shell-Ferrari one from a few years ago is much better:

(I think that version's the best one on YouTube in both resolution and sound. Aspect ratio's wrong, though.)

Psycho Science is a... sort of... regular feature here. Ask me your science questions, and I'll answer them. Probably.

And then commenters will, I hope, correct at least the most obvious flaws in my answer.

Posted in Cars, Machinery, Psycho Science, Science. 7 Comments »

Constructive criticism

24 December 2012 — dan

A reader writes:

From: Al
To: "dan@dansdata.com"
Date: Sun, 23 Dec 2012 14:25:11 -0700
Subject: A little knowledge

I read your Dan's Data on the subject of power chips and must say you have lots to say about a subject you know nothing about. You state that engine timing before top dead centre will cause problems and can destroy the engine. Fact is every engine operates with timing set to vary from 15 to 5 degrees before top dead centre depending on load and rpm. I don't know where you pick up your information but do some serious research before you stick it on the web. I do agree chips are a bunch of hokey.

You're quite right, Al; I've fixed the article. Thanks!

I am gratified to note that now that I have fixed the one mistake you could identify on that page, I have presumably graduated from knowing "nothing" about this subject, according to your intriguing system of evaluation, to knowing everything about it. Will you send me my Ph.D in Automotive Engineering right away, or do you require a small processing fee?

(It's also interesting that that guy from the chip company who offered me handsome remuneration in return for writing a "white paper" about their products didn't notice the mistake either.)

Posted in Cars, Shop talk. 10 Comments »

Fins! Fins, everywhere!

15 September 2012 — dan

An update to yesterday's post about the "Gaspods" fuel-saving vortex fins for cars:

Until I read jaypeabey's comment pointing to a series of articles on the AutoSpeed blog, I had no idea that a bunch of commercial products similar to GasPods already exist, and that they're well-known in aeronautical applications, too.

Fuelsavers vortex generator

These are "VG Fuelsavers", "As Seen On the ABC's 'NEW INVENTORS'"! (That's not necessarily a point in your favour, guys.)

VG Fuelsavers appeared on The New Inventors in 2006. AutoSpeed contacted the Fuelsavers people shortly after that, and offered to actually, you know, test them, which The New Inventors doesn't do.

This offer was, silently and mysteriously, rebuffed.

The Fuelsavers site claims a "6% to 9%" reduction in fuel consumption", which is plausible, if you do almost nothing but highway driving.

Even a 6% gain for a car mainly driven in city traffic, though, does not seem likely to me. Even at highway speeds it's difficult for a drag-reducing aerodynamic modification to give a fuel-economy gain of more than about 60% of the drag reduction. Since drag increases with the square of speed, aerodynamics are very important to racing cars, and moderately important for highway driving, but almost irrelevant at low speeds. (This explains why you don't see a lot of aerodynamically-designed bulldozers.)

Airtab vortex generator

Airtab vortex generators

These ones are called "Airtabs". They may be the first gizmo I've ever seen that claims some connection with NASA, and is actually telling the truth. (See this, for instance, for the usual situation. Or this, for the similarly-common military version. Some people, though, will believe anything.)

AutoSpeed tested the Airtabs, but not very well. The test wasn't blinded or well-controlled, and the only test vehicle they actually measured fuel consumption on was a Honda Insight. If it was the first-generation model, then it started out with a coefficient of drag of only 0.25. That's about as good as production cars have ever managed, so it's arguable that it can't be improved very much more, and certainly not by just sticking on some little fins.

To be fair, a facility that can do proper drive-cycle tests probably can't do them on aerodynamic devices, because drive-cycle tests are usually done on a stationary dynamometer. You need a wind-tunnel to test aerodynamics thoroughly, and they're a lot rarer than dynos.

But, as AutoSpeed points out in their first article about vortex gizmoes, you can get a good idea of the structure of the airflow over a car by sticking bits of yarn all over it. And it's also possible to get decent numbers, by doing the rolling-down-a-hill-in-neutral test I mention in the Gaspods post. You can even do it with only one test car. And if I were doing it, I'd start with a "normal" car with a CD of 0.3 to 0.35. It would also be instructive to test a vehicle with quite lousy aerodynamics, like a van or pickup truck.

(You can actually even estimate your car's coefficient of drag by rolling in neutral.)

Aerotech vortex generators

These are "Aerotech" vortex generators, sold in sets of 50 for truckers. The rectangular-prism end of a truck trailer is an aerodynamic disaster area, and fuel economy is something of an obsession for many truckers. Anything that reduces drag even a little bit for a long-haul trucker is likely to be worth quite a lot of money; the Aerotech page claims an improvement of "as much as 1%".

For a car, that's not worth paying for, which presumably is why sellers of vortex gadgets for cars tend to be more... optimistic... about their products. One per cent is worth paying for for a trucker, though.

Note that there are also "vortex generators", also known as "turbulence generators", that claim to create a vortex in the air going into the engine, rather than the air flowing over the car. Turbulence generators have been sold in umpteen forms over the years, and have never done a damn thing, except they often do restrict airflow into the engine and thus reduce its maximum power.

This actually often will save some fuel, because now pushing the accelerator all the way to the floor will only give you, say, 80% of what full throttle used to be. Just not pushing the pedal to the floor will do the same thing, though, and still let you have all the horsepower you paid for when you want it.

In light of the panoply of aerodynamic, possibly-actually-effective vortex gadgets on sale, I clearly should have done more research before writing that blog post. As, of course, should the journalists who wrote those happy-clappy articles about the GasPods, never mentioning that they're not actually a new idea.

As that article jaypeabey linked to says (quoting the Bosch Automotive Handbook), you can reasonably expect a given reduction in drag to give you a bit more than half as large a reduction in fuel consumption, at highway cruise speeds. Quite a bit more than half as large a reduction if you're driving really fast, legally or otherwise; no gain worth paying for if you're driving much slower, in traffic.

This is what AutoSpeed found in their dodgy test with the Insight, and, as I said in the GasPods post, there's no strong reason to presume that any of these devices even can somehow give you a larger fuel-economy gain than the drag reduction they deliver.

They're not snake oil, but they do seem to me to be rather oversold.

Posted in Cars, Science. 5 Comments »

Cars need more fins

14 September 2012 — dan

A reader writes:

"Gaspods" - what's your take?

I've got no intention of buying these things, so no money's at stake either way, but I was curious what you thought of this very excited article in Wired today.

Glen

I read "gaspods" and I thought, oh, lord, is someone claiming they're the seeds of the gasoline tree?

Wait, no - perhaps they're packaged doses of a magic fuel additive, presented like those coffee-pod things or the little sealed cups of UHT milk.

Gaspods

Actually, thank goodness, GasPods are little stick-on aerodynamic modifier things for cars, designed by one Bob Evans, who seems to have relevant qualifications. Chief among said qualifications is the "Force Fin" swimming flipper, which appears to have been favourably evaluated by the US Navy (I'm not sure why they had to file a Freedom of Information request to get those results, but it'd hardly be the most annoying interaction a business has yet had with a government body...) and also in a university study, although I'm not sure whether that study's ever been published anywhere, which is odd.

But never mind. Dude that made the things has various hydrodynamics qualifications, and hydrodynamics and aerodynamics are similar fields. Good so far.

Commenters on the Wired article weren't very impressed, not least because the article claims Bub Evans has managed to achieve "a 5 percent boost in efficiency for his Volvo Cross Country XC70", which by some wizardry means "a trip that would consume three-quarters of a tank now uses only half". Which would, of course, require a rather more than 5% improvement.

OK, let's presume the journalist misquoted the guy, and Wired's fact-checkers aren't all that they might be.

What claims does the actual GasPods site make, and what evidence do they provide?

On every page, the GasPods site says "Field testers' results exceed the 5% savings predicted by computational aerodynamic performance tests". The About page has a testimonial video claiming a better-than-20% fuel-economy gain in an Audi A4. And the Research page says "Initial Field Studies validate the computational results with participants realizing fuel savings of between 4% and 19%".

Those "computational results" on the research page are the entirety of the actual objective evidence that GasPods do anything at all. Simulated wind-tunnel tests allegedly reduced "the vehicle's drag coefficient by around five percent (5%)," and "Adding GasPods along the rear side of the vehicle further reduced its drag coefficient by an additional 1.6%, to increase the aerodynamic efficiency of the vehicles tested by 6.7%."

But, somehow, GasPods customers are reducing their fuel consumption by up to 19%.

The energy required to push a car through the air increases approximately with the square of the speed, because that's how aerodynamic drag increases. Drag is pretty much irrelevant in stop-start city traffic (unless you're pushing through a really fast headwind...), but the faster you go on the highway, the more drag matters.

Drag is not all that matters for highway fuel consumption, though. The most important other factor is the car's rolling resistance, caused by friction and deformation of the tyres on the road, but in the real world also including the friction and other energy loss in the whole of the rest of the drivetrain. There's also energy used for things other than propulsion, like power steering, electrical systems, the cooling system, air conditioning and so on.

Overall, drag is likely to account for rather more than half of highway-speed fuel consumption, a lot more than half if your vehicle is aerodynamically terrible, and proportionally more and more as you go faster and faster. But it's certainly not the only factor, and reducing drag won't change any of the other factors. (The crazier kinds of automotive talisman are claimed to improve not just drag or engine power, but umpteen other things, up to and including magically cleaning your car.)

The drag of a particular car design, expressed as the "coefficient of drag" or CD, has been a brochure selling point for a long time now. The equation to determine the actual value of the drag for a given car at a given speed is:

FD = 0.5 * p * v2 * CD * A

...where FD is the drag, p is the fluid mass density, v is the velocity, A is the reference area and CD is the coefficient of drag.

So, for instance, if your car has an unremarkable CD of 0.35, and you're driving at 120 kilometres per hour (75 miles per hour, 33 and a third metres per second), through air with a density of 1.2 kilograms per cubic metre, and your car is 1.5 metres high and two metres wide, giving it a "reference area" - sort of its frontal footprint - of three square metres, the drag works out as 0.5 * 1.2 * 33.33^2 * 0.35 * 3, which in this case adds up to the suspiciously round number of 700 newtons of drag force.

For our current purposes, it doesn't actually matter what the drag for a given car is, though. What this equation really tells you is that drag force, all other things being equal, is directly proportional to the coefficient of drag. There's nothing sneaky, like squaring of the CD, going on.

So if you reduce the coefficient of drag by 10%, drag drops by 10%, all other things being equal.

This puts a hard limit on the possible engine-load reduction from a given CD reduction; that limit is equal to that CD reduction, even if drag force is the only thing the car's engine has to work against, and thus the only thing determining fuel consumption.

We know, though, that drag at highway speed may account for more fuel consumption than all other factors put together, but it still doesn't account for all of the fuel consumption. Even if you manage to get a quite large reduction in CD, like 20% for instance (remember, the best computer-simulated reduction the GasPods site mentions is only 6.7%), the best you could reasonably expect that to give you in highway-speed engine-load reduction is about 15%.

A testimonial on the GasPods research page claims a highway-mileage improvement in a 2006 Ford Escape Hybrid from a rated 23 miles per gallon to 29.1mpg, a 26.5% improvement not just in drag, but in actual fuel consumption.

Eeeeeexcept it isn't, because the rated economy is an EPA drive-cycle number (I'm not sure which one; there are several variants of that car), not what you'll actually get in a given long drive. Everybody knows a car will get unusually good fuel economy in a long, flat drive with little accelerating or braking; it's often easy to beat the official "highway" number in a drive like that. For some reason the GasPods page doesn't take pains to point out that 23 miles per gallon was the government-rated fuel economy, not what the car actually got on the exact same drive before installation of the GasPods.

The GasPods people also invite buyers to join the "Test Team" and submit detailed mileage logs, in return for a discount and the warm and pleasant feeling of helping to save the environment.

This is better than the usual magic-car-gadget testimonial standard of "'Ah strapped them magnets on mah fuel line and now mah car sure do go faster!', says Steve No-Last-Name, allegedly of Jackson, Mississippi", but it's still subject to the problems that make uncontrolled, unblinded tests of car-enhancing devices fundamentally useless. Unless you don't know when the magic gadget or potion is being used, with someone swapping it in and out through the test period without your knowledge, and then you average large amounts of driving numbers with and without the gadget or potion, you're not going to get even slightly reliable results from an uncontrolled, non-drive-cycle, test. And blinded testing of a device that's clearly visible on the outside of the car is... difficult.

Without blinded testing, even if you average out large amounts of data rather than just eyeballing the fuel gauge and how fast your car "feels", you're still only going to generate yet another worthless testimonial. People are not calibrated testing mechanisms; you can't become unbiased by just trying to be.

Wait, that's not quite right. Testimonials may be worthless to anyone who wants to know whether the thing being tested actually works, but they can be really useful to people trying to sell that thing. Glowingly positive testimonials are essential advertising material for just about everybody in the woo-woo business, and they're plentifully useful for that, because most consumers don't know how worthless testimonials of this sort are.

Personally, having run into so many big ol' pages of testimonials on Web sites for countless mutually contradictory gadgets, medicines, religions and get-rich-quick schemes, I now take the presence of such testimonials on any site as strong evidence against the validity of the claims being made, even if they've got some real evidence in their favour as well.

I also find it very suspicious that the GasPods people, like the makers of numerous other magical car accessories, seem to be mysteriously allergic to actually doing their own proper tests. Or, heaven forfend, getting a reputable third party to do some tests for them.

For pity's sake, just take two identical cars, put GasPods on one of them, put them both at the top of a hill in neutral and see which one rolls further! (Then run the same test several more times to reduce confounding factors, making sure to test GasPods on both cars in turn, to correct for differences in weight, tyre pressure, bearing condition and so on. You could still get this done in a day, at minimal expense.)

Do these simple tests, use the results to persuade a third party - like a minor university, say - to do better tests without charging you much, use those results to claim the first small share of the billions of dollars per year that a device that really does reduce automotive fuel consumption by a significant fraction is worth, and use that revenue to move on to more and more reputable testers and users. Before you know it, you'll be the first fuel-saving product that the US government actually endorses!

But no. Like every other seller of magical car-enhancement devices and potions, the GasPods people have some skimpy allegedly empirical evidence from tests they did themselves, and plenty of testimonials, and they just sell their wares to anybody who's persuaded by this. (Between $US79.95 and $US124.95 plus shipping for a set of nine Pods! Order today!)

The only rational way to salvage the testimonial claims on the GasPods site is by speculating that reducing engine load by a given amount will reduce fuel consumption by a greater amount - so great an amount, in fact, that it allows an X-per-cent drag reduction to create a greater-than-X-per-cent fuel-consumption reduction, even when you take into account the unchanging rolling resistance and parasitic loads.

Such non-linear relationships do exist, especially at the extreme ends of engine load. When a car's sitting stationary at idle its fuel economy is of course zero, and when it creeps forward in stop-start traffic its miles-per-gallon will be terrible, too. Likewise, heavy load at wide-open-throttle consumes a disproportionately large amount of fuel per distance; a basic fuel-economy tip is to avoid accelerating up hills.

Over small portions of the power range of most engines, though, the relationship between load and fuel economy is pretty close to linear. And this is relevant to the GasPods claims; a drag reduction of 10% or less at highway speeds is obviously not going to make a big difference to engine load, because the engine was far from fully loaded to start with. It might matter to a drag racer, but not to a highway driver. At normal highway speeds you're certainly not going to reduce fuel consumption by almost 20% by reducing your drag coefficient by less than 10%.

So the explanation that reducing drag by a given amount reduces fuel consumption by a larger amount sounds completely demented to me. But it's the only explanation possible for the more impressive GasPods testimonials, besides "these testimonials are rubbish, like almost all other testimonials".

So, do GasPods do something? Quite possibly. The notion that odd changes to the shape of a vehicle can reduce its fuel consumption...

...is not at all implausible.

And, unlike most magic car gadgets and potions, GasPods don't rely for their operation upon the negation of fundamental theories of physics and automotive engineering.

Do GasPods do enough to make them worth the money, though?

Well, the people selling them have no good evidence to suggest this, and the evidence they do offer is very much the same physically-implausible unblinded-test anecdotal testimonial claptrap that's presented in favour of countless ridiculous automotive gadgets and potions.

This is a new product, so maybe they'll have proper evidence to show us soon.

Until that happens, though, I'd keep my money in my pocket.

UPDATE: It would appear that GasPods are not as remarkable, or at least as unusual, as their creators claim. There are actually quite a few vortex-fin products for cars and trucks.

Posted in Cars, Science. 6 Comments »

On hobbies, and countries

13 August 2012 — dan

A while ago, I figured out why it is that Top Gear hate caravans.

It's not just because being stuck in a four-mile tail-back behind a Morris Oxford towing a 1986 Chateau La Car is even more frustrating when you're attempting to review a 900-horsepower quad-turbo Lamborghini Testicoli Enormi. It's also because Top Gear are in the UK, and I think caravanning in the UK is like metal-detector-ing in Australia.

There are few places in the UK that are worth dragging a little mobile house to. Cornwall's nice enough, but it has hotels, as do the other parts of the UK that try with varying plausibility to present themselves as holiday destinations.

OK, maybe you enjoy being able to have a fry-up breakfast out of the rain and then tramp around a different soggy piece of Scotland every couple of days. But this is stretching it.

Here in Australia, on the other hand, we have large amounts of beach and forest and low-but-wide mountain ranges that are not within convenient distance of a motel. You can easily spend a year driving around this place and still have failed to come within a hundred kilometres of enough land area to make up what most people call a country. OK, a signficant amount of that area is one of our many great expanses of nothing much...

Gunbarrel Highway

...but there's still a lot of Australia out there.

The whole area of the United Kingdom, plus southern Ireland, is about 314,000 square kilometres. That's a little less than the two smallest Australian States, Victoria and Tasmania, put together.

The whole of Australia has an area of more than 7.6 million square kilometres. But Australia's population is less than 23 million, versus 62 million and change for the UK. (Australia's population is about 15% more than that of New York state.) And most of the Australian population is crammed into little strips on the coast.

Result: An awful lot of wilderness where you could play with a howitzer for weeks without hitting anyone. If you're crossing those distances, a little towed house can be convenient.

If you make a hobby out of metal-detecting in Australia, though, you're not likely to find anything very interesting. Humans have been here for tens of thousands of years, but until Europeans showed up and commenced doing what they usually do, the indigenous Australians didn't have any metal at all.

You can find plenty of stuff if you swing a metal detector around in any vaguely habitable part of Australia, but the most antiquitous items you're likely to locate are ring-pulls.

Oh, and you're not going to find any gold, either. There are still plenty of places in Australia where you can pan for gold successfully - which is to say, at the end of the day you'll have a clearly visible collection of gold-specks in a little vial, which may be worth as much as fifty cents. But our most recent gold rush was well over a century ago. You're more likely to find a fist-sized meteorite than you are to find a gold nugget, and you are not likely to find a fist-sized meteorite.

If you live in the UK, on the other hand, then just going into your back garden and digging a hole will very probably find you some Roman pottery, or even coins. The pottery will probably be worthless broken shards and the coins will probably be equally worthless lumps of corroded bronze, but they'll still be more than a thousand years old.

If Tony Robinson et al came to Australia to dig places up, they might be able to find something a couple of hundred years old in Sydney, or perhaps an interesting geological specimen out in the sticks, but that's about it.

Am I missing something, here? I invite comments from any Britons who gain deep fulfilment from caravanning the Grampians, or Australians who metal-detected a gold bar on Coogee Beach.

Posted in Cars, Toys. 14 Comments »

Hey presto, an old fuel saver is new again!

29 April 2012 — dan

Remember the Moletech, or possibly MTECH, Fuel Saver?

Pretty much your standard magical catalyst-or-something, it got pimped by the Sydney Morning Herald, and those guys who say every hokey fuel saver in the world works said it works too. And then the Herald article disappeared in a way that basically said THIS ARTICLE HAS DISAPPEARED IN A SUSPICIOUS WAY, even as the Australian Government department that was alleged to be testing the device told me they'd never heard of it.

And then the Herald covered their tracks with the professionalism of a small child attempting to rearrange eight cupcakes to conceal the fact that there used to be twelve cupcakes.

(If Asher Moses wants me to ever forget he wrote that piece, and more importantly that he or one of his Herald workmates then stumbled around incompetently trying to pretend the article never existed instead of just saying "whoops, sorry" like a sensible person, he's going to have to kill me. It would appear that Twitter and the SMH actually are a bit similar, dude.)

Aaaaanyway, rejoice, for the Moletech-or-whatever fuel saver still stands ready to relieve you of a few hundred bucks while for-a-certainty paying for itself really really soon with amazing mileage gains. Entirely according to the usual script for BS molecular-magic fuel savers, the Moletech people have opened new marketing vistas and evaded any disappointing online commentary from clearly crazy people who suggest their product might not work by changing the product's name, to "Greentech".

Any doubts you may have about this clearly-unassociated-with-that-Moletech-thing-that-didn't-work product are sure to be dispelled by the new Greentech Web site, whose FAQ page currently contains the following hard evidence:

Q: How does it work?
A: Immediately effect will be observed as soon as the contact between the fuel and Greentech Molecule Enhancer was established.

The Greentech doodad comes in two parts, too, one for the fuel and one for the air intake. I think the Moletech gadget only had one. This makes all the difference, I'm sure.

On the somewhat less... slender... "Main Functions" page, the Greentech people explain that their product does all of the things that magic quantum magnetic moonbeam fuel-saving devices are always claimed to do (plus, oddly, apparently the magical removal of pollen and tobacco smoke and other such things that human beings do not like breathing from the air going into the engine, even though an engine doesn't give two slim shits about whether a bit of pollen made it through the air filter).

How is the Greentech thingy meant to do this?

Why, by reducing Van der Waals forces between fuel molecules, of course! A Canadian distributor rabbits on about this at greater length.

This, as usual, would be either study-of-physics-revolutionising instant-Nobel-prize material, or cause a slow but inevitably apocalyptic unravelling of the very fabric of the planet, depending on whether your view of fuel-saver-company quantum flapdoodle tends more towards the Larry Niven/Iain M. Banks or Peter Watts/J. G. Ballard ends of the sci-fi spectrum.

If it didn't kill us all by next year and actually did what they claim - more power, less fuel consumption, lower exhaust emissions, just like all the rest - then the Greentech doodad would, yet again, be a zillion-dollar product for sale to every maker of internal combustion engines, not something sold to end-users on the Internet.

The Greentech people are proud that they've been selling this thing for more than a decade now, but in all that time they've neither inked monster contracts with Toyota and General Motors, nor been erased by the conspiracy that's the only thing that could possibly have stopped them from doing so.

The abovementioned Canadian distributor hoped for a Sydney-Morning-Herald-like response to their product from Wheels.ca.

They didn't get it.

Posted in Cars, Scams, Science. 4 Comments »

Oh, all right. One more fuel additive.

2 October 2011 — dan

A reader writes:

I've read all your various fuel-additive debunking pieces, and while I'm assuming that this is Just One More Of The Same, I would like your opinion:

http://www.ecofuelsaver.com/

Big, flashy web page. Graphics and embedded videos. And not only testimonials, but actual Lab Results!!!

The How It Works web page sounds awfully dodgy to me, though, and the FAQ page makes me even more skeptical. On the other hand, they go to great lengths to differentiate themselves from being just another engine cleaner, and give myriad details about how to properly do testing so you can see the results for yourself. Also, the information given in their "EPA & CARB certified Lab Results" page is big on scientific rigor, discussing the need for consistent baseline runs and blind testing so the driving habits do not affect the outcome. (Of course, it could all be made-up hooey, but that's the chance we take.)

Point is, they sound good. And the product is being sold by Canadian Tire, a very large Canadian retail outlet.

(Canadian Tire is an institution in Canada. They are a Wal-Mart like store, but have been around for some 90 years. For 50 years have a 'store loyalty' program called Canadian Tire money, where some small percentage of your purchase is refunded to you in Canadian Tire Money. This 'money' is of *very* high quality; it is, in fact, better (better paper and ink, stronger security measures) than the national currency of some countries I have travelled. It is gladly accepted by charities, frequently given in larger denominations as wedding gifts, and is often used as a sort of alternate currency, trading at par among friends or even friendly strangers. Thus endeth the lesson.)

Anyway, since Canadian Tire is endorsing the stuff, I expect that many folks are going to be trying it. I know you have seen many scams of this nature, so I beseech you to train your skeptical and knowledgeable eyes on this potential snake-oil from the Great White North.

Shane

Yeah, here we go again.

This outfit does indeed have a better spiel than most fuel-additive sellers, but there on their How It Works page is the usual claptrap about raising octane rating.

Raising a fuel's octane rating above what an engine's compression ratio and ignition timing requires will, for an absolute certainty, do nothing at all, and certainly not improve an "incomplete burn", a concept which the Eco Fuel Saver people also share with dozens, if not hundreds, of other fuel-additive companies.

Modern engines all burn very very nearly all of the fuel, or else they fail emission testing and/or set the catalytic converter on fire.

And on it goes, blah blah blah, and then there are those nifty PDF test datasheets you mentioned - which are, once again, of a quality well above the norm for these outfits, and not even from California Environmental Engineering!

This post has been sitting on my to-do pile for rather a while; when I first replied to Shane I observed that the "Gasoline" test-results document said that the tests were done in 2006. And here we were, years later, and this hundred-billion-dollar product was still being sold over the counter to individual motorists. On account, perhaps, of a Conspiracy.

Now they've got documents from 2011 on the lab-results page, though, and all they say is that their additive doesn't ruin the fuel, and in fact changes it in almost no way at all. Then, puzzled, you might try their "Results" page instead, but all you'll find there is a list of variably plausible excuses for the additive doing nothing noticeable. But don't be fooled - Eco Fuel Saver will "increase BTU, octane and lubricity in your fuel", so never mind our own PDF test results that proudly indicate an octane change, for instance, of less than half of one per cent, and the fact that even a large octane increase makes no difference unless your current fuel is causing knock or making your fancy computer-controlled engine retard its spark; just clap your hands, children, and wait for Tinkerbell.

I could dig further into this, but it's like investigating every new prophecy of the end of the world or dude who reckons he's channelling a million-year-old alien, yet is mysteriously unable to even tell you pi to ten significant digits, let alone anything of scientific interest that millions of human high-schoolers don't already know.

It's up to the makers of all of these products to demonstrate the value of their incredibly valuable, if true, claims. It's not up to us to sort through the numerous claimants and their countless claims to see whether perhaps, this time, the magical mileage elixir or perpetual-motion machine is real.

The fact that Canadian Tire sell this product indicates, I think, that Canadian Tire reckon people will buy it. Similarly, Wal-Mart sells those magical "Power Balance" wrist bands (and several similar products, not to mention a particularly spiffy-looking magical engine potion).

And just about every pharmacy sells homeopathic remedies (as does Walmart!). And so on, and so forth.

Posted in Cars, Scams, Science. 7 Comments »

Today's mechanical conundrum

16 May 2010 — dan

A reader writes:

As soon as I heard about "Steve Durnin's D-Drive, [possibly] the holy grail of infinitely variable transmissions", my BS meter activated and the needle swung to "Possible thermodynamics violation".

But in his favor he's got an actual physical prototype...

...and is attempting to have a metal model made so its input and output power can be tested.

What do you think of the concept, and can you tell how on earth it works? I'm still trying to figure out how this is too different from CVT, other than maybe a wider range.

I'm still wondering if this is somehow impossible, but personally I'm open to the possibility that it's a similar step such as CVT and the in-article claims are typical science-journalism overestimations.

David

Oh no - it's another New Inventors prize-winner!

Fortunately, though, an infinitely-variable transmission (IVT) is not actually in any way related to perpetual motion. All it is, is a continuously-variable transmission (CVT) that has some way to run its variable "gear ratio" all the way down to infinity-to-one, also known as a "driven neutral".

(This is, by the way, not the same as just running the gear ratio up so much, billions or trillions to one, that the final gear in the train is functionally immobile, and could be embedded in concrete without having any effect on the load of the driving motor for some years. A true "driven neutral" could be driven at a trillion RPM for eleventy frajillion years, and never turn the output at all. A transmission that bottoms out at zillion-to-one gearing would, however, be perfectly usable as a real-world infinitely-variable transmission.)

Because it can gear down to infinity-to-one, this does indeed mean that this transmission doesn't need a clutch, which does indeed reduce complexity. Whether a real-world version of the D-Drive would be too big or too heavy or inadequate in some other more complex way for real-world duty, though, I don't know. But there's nothing crackpot-y about the basic idea.

As the video makes clear, the big deal here is making an IVT - actually, a mere CVT, that still needed a clutch, would do - that uses standard gearbox-y sorts of components, or can in some other way handle lots of power and torque without being unmanageably big, expensive and/or quick to wear out.

Normal CVTs have been available in low-torque machinery like motor-scooters for some time, and are now showing up in some mainstream, full-sized cars as well. But they're still a fair distance from ideal.

It's easy to make a CVT, you see. Here's one made out of Lego. It's hard to make a CVT that can handle lots of power. And yes, the fact that most CVTs contain some sort of friction-drive device is a big part of the reason for this.

Note, however, that there's a big difference between dynamic-friction CVTs like this one or the Lego one, in which friction between moving parts transfers power, and static-friction CVTs like this one, in which friction locks components together (as in a clutch!), and they don't wear against each other.

But even here, real-world elements muddy the water and make it hard for someone who doesn't actually work at the engineering coalface to tell whether they're looking at something genuinely new and useful, or something that's not new at all, and/or won't work. Here, for instance, is the NuVinci transmission, a friction-based CVT that spreads the friction stress between numerous relatively lightly-clamped spheres - it's related to the "ball differential" with which R/C car racers are familiar. The NuVinci's makers claim it's useful for high-power, high-torque applications. And maybe they're right. I don't know.

For an excellent example of the ugliness that can happen when somewhat specialised knowledge is repurposed by people who, at best, don't know what they're talking about, look at this particular piece of "water-powered car" nonsense, where the well-known-to-jewelers electric oxyhydrogen torch is claimed to be some sort of incredible over-unity breakthrough. This sort of thing happens all the time - it's just, usually, not quite such a blatant scam.

As the Gizmag article mentions, many commercial CVTs are also deliberately hobbled by car manufacturers. They force the transmission to stick to only a few distinct ratios, and also to want to creep forward when at rest, just like a normal automatic transmission. This isn't a limitation of existing CVT technology, though; it's just deliberately bad implementations of it.

(The manufacturers do this so that people who're used to normal autos won't be freaked out by a CVT. Those of us who'd like the superior technology we pay for to be allowed to actually be superior just throw up our hands, and cross those cars off the worth-buying list.)

I think one trap for the D-Drive could be the second motor that handles the ratio-changing - that might need to spin really, really fast in certain circumstances.

There's also the fact that this is only really an infinitely-variable transmission at one end of the ratio scale. The D-Drive can gear down an infinite amount, and right on through zero to negative (reverse) ratios. But unless I'm missing something, I don't think it can gear up at all. So the output shaft can't ever turn faster than the input shaft. This is a problem if you want to do low-power flat-highway cruising, when the engine's turning quite slowly but the wheels are turning very fast.

Normal cars have significant gear reduction in the differential, though - the "final drive ratio". Perhaps if you make the diff a 1:1 device, which shouldn't make it that much bigger, the D-Drive's output-ratio limitation won't matter.

The reason why I'm saying "might" and "perhaps" so often is that I, like the New Inventors judges, am not actually an expert on the very large number of mechanisms that the human race has invented over the centuries. The simplicity of the D-Drive makes me particularly suspicious. The D-Drive's mode of operation may be a little difficult for people who don't work with mechanisms all day to intuitively grasp, but there aren't many components in there, and none of them are under 100 years old. Actually, that's probably a considerable understatement; I'm not sure when epicyclic gearing became common knowledge among cunning artificers, but I can't help but suspect that a master clockmaker in 1650 wouldn't find any of the D-Drive's components surprising.

Sometimes someone really does invent some quite simple mechanical device, like the D-Drive, that nobody thought of before. But overwhelmingly more often, modern inventors just accidentally re-invent something that was old when James Watt used it.

To get an idea of the diversity of mechanical movements and mechanisms, I suggest you check out one of several long-out-of-copyright books full of the darn things. I think Henry T Brown's 507 Mechanical Movements, Mechanisms and Devices is the most straightforward introduction; it's a slim volume available for free from archive.org here.

(If you'd like a paper edition, which I assure you makes excellent toilet reading, you can get the one I have for eight US bucks from Amazon. Here's a version of it for four dollars.)

And then there's Gardner Dexter Hiscox's Mechanical movements, powers, devices, and appliances, whose full title would take a couple more paragraphs, which is also available for free.

Both of those books carry publication dates in the early twentieth century, but many of the mechanisms in them were already very, very old. Like, "older than metalworking" old. But several of them are still, today, unknown to practically everybody who's not able to give an impromptu lecture about the complementary merits of the cycloidal and Harmonic drives.

(You may, by the way, notice rather a lot of mechanisms in those old books that do the work of a crank. That's because one James Pickard patented the crank in 1780 - plus ça change. This forced James Watt, and many other early-Age-Of-Steam engineers, to find variably practical Heath-Robinson alternatives to that most elegant of mechanisms to get the power of their pistons to bloody turn something. Watt's colleague William Murdoch came up with a kind of basic planetary gearing to replace the crank. Planetary gears have, in the intervening 230-odd years, found countless applications - including the D-Drive!)

Getting back to Mr Durnin and The New Inventors, they both currently allege that the D-Drive is a "completely new method of utilising the forces generated in a gearbox". According to this Metafilter commenter and this patent application, that may not actually be the case, since 18 of the 19 formal Claims made in the application appear to have been turned down. But, again, I could be getting this wrong, because somewhere behind the impenetrable thicket of legalese I suspect the "Written Opinion" may be saying that the final Claim actually is patentable as a separate worthwhile thing. (See also this forum thread.)

This all has me thinking, again, about the repeatedly-demonstrated gullibility of The New Inventors. When I can bring myself to watch the show, I keep thinking - OK, actually sometimes shouting - about how I'd spoil the party by asking at least one out of every four inventors "would you be willing to make a small wager that your device is not fundamentally worthless, or a duplicate of something that's been in production for years?"

(Sometimes, I'd just say "Have you always dreamed of being a rip-off artist, or is it a recent career development?")

The New Inventors seem to not have much of a peer-review system to keep the show free of crackpots, scammers and ignorant inventors who're unaware that their baby was independently invented in 1775. Or maybe there's just a shortage of interesting inventions, like unto Atomic magazine's shortage of interesting letters, so they let even the dodgy ones onto the show as long as they look impressive.

Perhaps the people on the judging panel just studiously avoid saying anything that might attract legal action from an inventor outraged that someone dared to point out that his magic spark plugs strongly resemble 87 previous magic spark plugs out of which the magic appeared to leak rather quickly.

Personally, I suspect that some insight into the newness or otherwise of the D-Drive may lurk in the various kinds of differential steering used in tanks. (Many of those have also been implemented, needless to say, in Lego.) And don't even ask about differential analysers.

It doesn't even take a lot of searching to find other IVTs. Here's one that, like the D-Drive, has no friction (or hydraulic) components. Its highest input-to-output gear ratio is quoted as "five to one", which is weirdly low; perhaps it's meant to be the other way around.

I hope, I really do hope, that the D-Drive turns out to be a proper new and useful device. We can always use another one of those.

But I remain very unconvinced that something this simple, aiming to do this straightforward a task, really is useful, let alone new.

UPDATE: As mentioned in the comments, Gizmag have a new post about this.

To summarise: The D-Drive does not remove all friction components from the drivetrain, because it can only ever be a part of that drivetrain, and needs supporting stuff that'll probably need friction components. And yes, it would need a motor just as powerful as the "main" one to drive the control shaft.

And Steve Durnin is apparently proud of independently coming up with a system similar to Toyota's Hybrid Synergy Drive "Power Split Device". I must be missing something, there, seeing as if this is the case then the D-Drive probably isn't patentable, and probably wouldn't even be particularly marketable.

Posted in Cars, Hacks, Machinery, Science. 22 Comments »
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