Thursday, June 7, 2012

Lit Motors. Or was it 'bongs'?

So, I have to wonder what, exactly, the creators of the 'Lit C1' gyro-stabilized motorcycle and web meme were actually on when they had their big idea. And, by the way, what their PR firm was on, suggesting that Lit should go public with a concept that's completely unresolved, not to mention a spec-sheet that is laughably optimistic.


Oh, it's cute alright. Very stylish. And on the face of it, a motorcycle that can't tip over probably has an intrinsic appeal for non-motorcyclists -- who presumably think that 'tipping over' is a big problem for us.

It may come as a shock to Lit, but their motorcycle is not the first one to have two gyros that prevent it tipping over. There's another motorcycle on the market that has two gyros that keep it upright. It's the... all of them.

Look, I hate* to be the guy who calls the emperor naked here, but...

(*Actually, I love being that guy.)


Motorcycles turn by leaning. Note that the Lit prototype is not fitted with car tires, it's fitted with motorcycle (i.e. toroidal) tires. That shape is essential if your vehicle is going to turn like a motorcycle, by leaning over.

This thing, this leaning thing, that we all implicitly love and understand, is actually pretty complex if you try to turn it into a physics lesson. If you're scientifically 'lit'erate, feel free to read the Wikipedia entry on bicycle and motorcycle dynamics. If that makes you dizzy, though, all you really need to remember is that at most speeds, camber thrust is the dominant force turning a motorcycle. It explains why a motorcycle that's leaned way over can turn sharply, with a much smaller steering angle than, say, a car would need to negotiate a turn with the same radius.

Camber thrust is trivial at walking speeds. At walking speeds, motorcycles' and cars' turning dynamics are the same -- you turn by steering in the direction you want to go, not countersteering. (At those speeds, motorcycles are unstable; a vertical-axis gyro that spun up only at walking speed would serve a purpose. It would help prevent those embarrassing parking-lot tip overs we all have as beginners.)

Why I point that out is, all the demonstration videos of the Lit C1 prototype in use show it traveling at less than ten miles an hour. You hardly have to lean it to turn it at those speeds, but as soon as you get that thing up to useful speeds, if it isn't going to lean at all, it would be far better to fit it with a car tire with a 'flat' contact patch and a carcass construction intended to transfer a very different set of forces. (Look at the tires on sidecar racing outfits. Those are motorcycles that don't lean. None of those guys would dream of running normal motorcycle tires.)

Lit already has a very stylish and well resolved... web site. On this page with nine bios of key personnel, though, I found a single mention of the word 'motorcycle,' and it was in the context of styling, not engineering. I found no evidence at all that there's any one on this team who's remotely capable of launching a viable brand. They say, "What you don't know won't hurt you," but I've got news for high-tech start-ups: What you don't know that you don't know will kill you.

Summary of this part of the rant: If it is going to steer like a car, it needs a car tire (and a lot more steering lock, which is not evident in photos of the front suspension.) If it's going to steer like a motorcycle, it needs to lean.

I'm assuming that the steering wheel, as opposed to a handlebar, is a nod to the fact that Lit expects this thing to steer like a car, not countersteer like a motorcycle. If that's the case, those motorcycle-profile tires will help the Lit to roll slightly out of the turn (as cars do) because the gyros won't** keep it dead level. When it rolls out, however slightly, the same camber thrust that turns a bike into the corner when it's leaned in, will actually promote radical understeer.
(**Unless the gyros are actively 'counter-tilting' in real time to compensate for roll forces -- a complex system that would require powerful servos to overcome gyro inertia and which, in the event of failure, would cause a guaranteed crash.)

A note from the Dept. of Things They Should Have Thought Of: I'm guessing that two-wheeled configuration makes the Lit C-1 a motorcycle, for the purposes of traffic laws.

The upside to that is, Lit won't have to submit it to car crash testing, and meet current safety regulations with things like air bags, saving investors millions of bucks. The downside: you will need a motorcycle license to operate it. i.e., the only people who will buy it are probably already motorcyclists. That's already a small market, made smaller because you're appealing to motorcyclists who don't want to feel things like wind, and leaning into turns... which are why a lot of people take up the sport.

Steering wheels on single-track vehicles? Already been done. By a crazy dude I see pedaling around KC.
Lit's CEO Daniel Kim, who says it won't tip over even if it's T-boned by an SUV, obviously doesn't remember the physics he learned at Reed College. From the looks of the prototype, the 'drivers' shoulder would be about 5 inches from the SUV's grille. If the Lit only weighs a few hundred pounds, it would be safe to assume that an SUV that hit you from the side at 20 mph would cause the driver to sustain a momentary acceleration of, oh, let's say 100gs. (Calculation on a Post-It Note, your results may vary.) Even if the vehicle's bodywork retained its shape, the driver would be dead inside it. (I note that there are no crash helmets evident anywhere on the Lit web site, in the many slick photos of their mock-up, parked in street contexts with stylish riders hopping out...)

Last but not least, the Lit spec sheet is laughable. I admit that the vehicle's shape and layout will result in a far lower drag coefficient than you'd find in any other electric motorcycle. And, the longer wheelbase with a lower c.g. may make it easier to recover energy in braking (by transferring more brake bias to the rear, where it's easier to engineer a KERS.) But the claimed battery size, top speed & acceleration, and range just don't square with anything that's ever been experienced in the real world. The claims are disingenuous at best.

Note to Lit Motors: See that registered trademark of BMW? No, not the blue and white roundel, but the vehicle name just below it? How do you think BMW, which is working on its own electric version of the C1, feels about the name you've picked? I'll be surprised if your desist letter isn't in the mail.
By the way... I've often been pretty critical of Michael Czysz, Segway, and their electric dreams. But there's no taking away from MotoCzysz' achievement yesterday on the Isle of Man. I thought that Mugen was the team to beat, and I guess they were; Michael Rutter did just that. A well-deserved congratulations, then, to the Oregonians. A 105 mph lap is no small achievement. 

Now, let's tone down the, "The electric bikes did in four years what it took the ICE bikes fifty years to do..." rhetoric. First of all, the EVs piggybacked their designs on 100+ years of established motorcycle architecture. And second, when that Norton Manx lapped at over 100 miles an hour, it did it in a six-lap race. It would take the MotoCzysz an entire day to put in six 100mph laps, because it would involve five multi-hour pit stops.

5 comments:

  1. Actually, it has to lean to turn, and it will have to lean just as much as a motorcycle, otherwise it will fall over to the outside of the turn.

    I agree it is very expensive, and its benefits over a motorcycle (and a SmartCar) are slim.

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    1. I think it would be pretty easy to build a gyro-stabilized single-track vehicle that could successfully resist *falling over* to the outside of the turn. It would be vastly harder to make such a vehicle handle acceptably. Fitting it with motorcycle tires makes that challenge exponentially more difficult, since unlike car tires motorcycle tires are designed to generate camber thrust...

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  2. The gyros could be spun up only at low speeds, and deactivated once you slip into the regime where a bike countersteers. It's pretty clear from their videos that they do expect it to lean into turns.

    This could be a problem if an SUV smashed into the side of the bike when the bike is traveling at 40 mph. But that's a problem on any bike.

    There is some type of provision for motorcycle type vehicles that don't require helmets. Aptera went this route. It also screwed them when it came to the DOE funding awards .. hard to have your cake (motorcycle safety requirements) and eat it (car licensing requirements) too.

    "it would be safe to assume that an SUV that hit you from the side at 20 mph would cause the driver to sustain a momentary acceleration of, oh, let's say 100gs."

    Let's say 10-20g .. and since they're not requiring helmets, let's hope they're covering all surfaces that could be impacted with the driver's head. Not sure I follow the necessity of driver death; after all, our heads are inches away from a car's A pillar, and people seem to usually survive (low speed) side impacts.

    The Monotracer MTE-150 claims 180 miles @ 75 mph from a 20 kWh battery .. so around 110 Wh/mile. That's on the low side of what the Lit could expect without a front wheel fairing.
    http://peraves.files.wordpress.com/2012/03/monotracer_e_brochure_usa_mid.pdf

    The Zero S (340 lbs) claims 70 Wh/mile in city riding.

    The Lit prototype is around 600 lbs IIRC. I would expect to see around 90-100 Wh/mile in the city (depending on gyro power consumption), 130-140 Wh/mile on the highway. From an 8 kWh pack that gives you (generously) 90 miles city, 60 miles highway.

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  3. The difference between getting T-boned in the Lit, and in a conventional car where the driver's head is near the B-(not A-)pillar is that the car you're in weighs five times what the Lit weighs. So, the Lit will scoot sideways about twice as fast as a full-sized car. And, I doubt they plan to fit the Lit with side-curtain air bags, which are now pretty common. And, I doubt there will be anywhere near as much crush space between the oncoming vehicle and the driver of the Lit as there is, even in most small cars. I figure the Lit driver's spine will accelerate from 0 mph in the direction of SUV travel to 20 mph in about eight inches. Very bad situation. My point isn't that that is a survivable crash on regular bikes, my point is that Lit's being disingenuous suggesting its survivable in their bucket.

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  4. Wake me up when they show the prototype going from 0 to 60 round a roundabout, through an S Bend and back to 0 again. You might want too also throw in a few pot holes given that it appears to have zero suspension travel at either end.

    What is it about electric concept vehicles that make them so prone to huge amounts of hyperbole and PR Fluff? And what the hell is Lit's business model?

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