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The Glaring Flaw in That "Land Airbus" Concept Everyone's Talking About
See if you can spot why the concept, as rendered, is physically impossible
Years ago we showed you this concept for an elevated, tunnel-like bus that would not interfere with ordinary road traffic:
Enter a caption (optional)Conceived of in China by engineer Song Youzhou, the concept was unveiled in 2010 and scuttled thereafter for being unworkable. But now Song is attempting to resuscitate the project, and the blogosphere has been gamely playing along, circulating this video from 2012:
As rendered, what you're seeing in the video is physically impossible. The issue is one of turning radius. If you've ever seen a limousine, a city bus or a tractor trailer try to get around a corner on your average city block, the problem becomes obvious.
Enter a caption (optional)
Enter a caption (optional)You have what's known as the actual radius versus the effective radius, which is to say, when a long-wheelbased vehicle makes a turn, there comes a point at which the midpoint of the wheelbase is cutting a radius different from the arc that the wheels are describing. This presents a problem if there are vehicles, or guardrails, alongside the vehicle.
In short, it would be impossible for Song's vehicle to navigate the impossibly-tight radii depicted in the video. Take a look, for instance, at these stills:
Enter a caption (optional)
Enter a caption (optional)
Enter a caption (optional)
Enter a caption (optional)In those shots, you can clearly see he's got the vehicle bending, as if it's made of rubber rather than steel.
This physics problem means that the vehicle either needs to be articulated every few feet along its length, or have articulating points with an extreme differential where the carriages meet. That will be tricky to execute given the vehicle's width--at seven meters it is nearly three times as wide as your average 2.5-meter-wide articulating bus--but not impossible to accomplish. Indeed, at the Beijing International High-Tech Expo, where Song presented a working scale model earlier this month, he has opted for the latter approach:
In those final frames you can see the extremely sweeping radius--far wider than what's depicted in the first video--required to get the concept to work. If roads are built to accommodate in a wide-avenue city like Beijing, the concept ought to be workable. But it's unlikely to be suited for anything other than straight-line travel in a city riddled with your average right-angle intersections.
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Current articulating buses do fine. You're not going to drive this thru the old streets of Milan. Any routes would accommodate the corners needed or be designed to do so. As for people making turns into the sides of the bus, it looks like on one video that the bus lane would have dedicated guard rails where it needs to contact the ground. If drivers can manage a two lane road, there shouldn't be an issue. Take the top away and you have two additional lanes of traffic on either side (or very long motorcycles). After that it is an issue of managing intersection traffic. Rain Noe's issue with the turning is short sighted and easy to look past. Any industrial designer knows not to shoot down ideas so early and to leave mechanical issues up to engineers ;) Yes, the person who made the "bending" bus render did a poor job but not something worth writing an article about.
I disagree. First off, I think leaving "mechanical issues up to engineers" where basic geometry is concerned is what gives industrial designers a bad name. Secondly, this bus was *designed* by an engineer. So who ought he leave it up to? Thirdly, when I see a video presenting a concept that defies simple physics--12-meter sections of steel bending around a radius, then magically straightening again--I don't think of that as a "poor job" of rendering, but as an indication that there are some basic issues that have not been thought out and resolved.
I don't think it is great either.
"I think leaving "mechanical issues up to engineers" where basic geometry is concerned is what gives industrial designers a bad name."
My problem with articles such as this, is that it shuts down the idea without actually exploring it's concept. It is a great idea, and yes, it does have a few issues to work through. However, it is still in proposal phase. This means that while many of the issues we are talking about haven't been fully articulated, that doesn't mean that they haven't been thought through. If we never proposed ideas that played on the verge of possible, then great ideas would never exist. Don't shut down the idea, but rather think about the solutions that could work. Your article was less convincing about the failure of the project than the plausibility of it.
I'm dissapointed to read this, although I have to agree the idea has flaws and is misrepresented in the renders and models, I feel this is not the glaring omission it's made out to be. Moreover ideas like hyperloop I feel have way larger design issues and that's not stopping it's development.
About the supposed issue, by simplifying the issue to a rectangle on rails the option of independently turning wheels is excluded, although this a know solution to this problem. Streetcars have been using it for years. You shortly touch up on this but
About hitting the guide rails, yeah that could happen if you build them too close, and therefore the idea is misrepresented in it's renders, but it doesn't do this idea justice to discredit it based upon a visual misrepresentation, while it hasn't been developed since 2012
I think that this article would've been a way more enjoyable read if it was an exploration of what was still necessary to make it work, or maybe even proposed as a question to the Core77 community/readers so everyone can pose ideas to solute a possible problem instead of discussing whether the problem is actually a problem.
Correction/addition:
*You shortly touch up on this but quickly dismiss it as to big an issue to even try
Independently driven and steered wheels could overcome a lot of this. Combined with a couple of points of articulation, you can do some amazing maneuvers.
David, that tractor trailer's wheels are steering so that the inside edge of the trailer moves further from the center of the radius. That means the *outside* edge of the trailer would then scrape the guardrail on the other side. To understand the geometry, cut a rectangle out of a piece of paper, draw two parallel arcs that are slightly wider than the rectangle, then try maneuvering it in between. You'll quickly see that a rigid rectangle simply cannot round a tight radius without touching what's on either side of it.
I understand the geometry just fine. Im just pointing out that in the real world, there is more free space available than in your example, so moving the rectangle to the outside of the arc a fair amount is possible. The video I linked shows what is actually being done with only limited rear wheel starring to move large rectangles around corners in the real world.
Altering the wheels would not solve the central problem: Each carriage is, seen in plan view, a rigid rectangle 12 meters long. When you drag something with straight sides along an arc, the sides wind up inside the arc. It's basic geometry.
I almost commented an idea that involved an elaborate canal lock like system, then I realized it'd be far easier to just have a raised track at intersections. Yeah, it'd be a compromise from the original point, but it'd probably still be cheaper than a full-on elevated/underground train system.
Not if the rear wheels steer in the opposite directions of the front, guiding the rear to the outside of the turn. With independently powered and steered wheels, a vehicle can reverse direction in its own length. This video shows a real world example of vehicle with a very limited range of four wheel steering.
They built a scaled model, and it turns corners. Okay, not smoothly, but it did manage the corners. Those that cannot envision an articulating undercarriage/suspension and think the carriage itself must bend really have no ability to imagine the possibilities. This is design and engineering. Give us a problem, and let the minds find the way to solve it.
Rigid trains have managed to make bends in the tracks for quite a long time. I can envision each wheel on a strut that rotates through a turn.
Sure. The video is a stretch, but the big picture concept is what's important. The mechanical wrinkles can always be ironed out later.
Many people commenting have not been on the G4 Beijing, nor seen the immense 50-lane thoroughfares there (yes. FIFTY LANES WIDE). This concept would work very well from Beijing to Hong Kong, even if only for workers hoping to bypass a few miles of traffic in a straight line. To simply label the invention a "bus" and dismiss it outright, seems rather closed-minded. I would consider it an elevated light rail system, that would save many millions of dollars in infrastructure.
some shots it has a 3rd rail others don't, which is it? what does it do at intersections and when cars are changing lanes across the rail paths? seems super dangerous for the lower vehicles to always have to be aware of it's position and know how and when to move or get out of its way.. maybe it needs to wait til all cars have AI controls and can cross-communicate? Wouldn't it be safer, more efficient, and more cost effective to make a raised train system? One that doesn't need to stop at crosswalks.. or run the risk of every street based car, truck, bike, person, etc running under it at the wrong time, or bumping into that (maybe 3rd rail)???
this concept is so wrong at so many levels:
You're right, as designed, this doesn't turn. But it's simple to make it work- not articulable but having a multi car cab and trailer design. Your critique of engineering problems on a concept are a little overblown.
Its not simple to make it work. Because of the width of the vehicle it would be very difficult to make each section short enough to articulate the amount required.
Here is the more recent video that prompted me emailing you about this.
I didn't see your article on this from 2010, but I'm so glad you touched on it again this time. I'll admit I didn't notice that the renderings were showing the bus flexing around corners, which I agree is ridiculous. The video I had seen showed a mostly straight path in all the examples. I agree with David that fantastical renderings aside, the wheels could be made more flexible and articulating than the rest of the carriage.
Jason, the problem of the surrounding drivers is easy to solve. What I'd do is line the supporting members of the bus with a series of large chainsaws, ideally oscillating in an up-down motion, that could mangle them before they got too close to the bus. I'd then have a powerful photon beam, mounted to the undercarriage, blast the mangled wreckage away from the bus in order to keep the path clear. If this happened even once and they posted video of it to YouTube, they'd get so many hits they could probably fund the bus system just with the ad revenue.
Not a bad idea, and it's probably cheaper than duct-taping Jedi to the front. Those guys charge through the roof!