Yes but the the last paragraph in the OP mentions economic limits and that’s probably one reason the A380 failed.
What’s it called?
I took a 380 from Toronto to Dubai once. For comfort and service on this plane, even in economy class, Emirates was head-and-shoulders above the rest.
Maybe, but those limits are hard to discern. The double pendulum is the quintessential example of a chaotic, non-linear system, and yet there are control systems that can not only balance a triple pendulum on end, but invert it from a hanging position:
In terms of aircraft, the past couple of decades has seen the rise of cheap quadcopter drones. These are completely unstable under all conditions, and yet control systems that cost a few dollars make them flyable by any child.
It’s certainly true that making any unconventional airframe stable requires a lot more than slapping a computer onto it (though I’ll note that current open-source drone software like Ardupilot works on an immense number of configurations). And even quadcopter-style configurations, which are well understood now, still aren’t quite ready for commercial passenger use (though a number of companies are working on it). Still, it’s disappointing that we haven’t seen even mildly unconventional commercial aircraft yet.
I posit that companies like Boeing and Airbus are simply not very good at software, which makes them dependent on conventional stability characteristics, which implies conventional aircraft designs. New entrants might be better, but you need a few tens of billions just to start playing the game. And it’s not that high-margin a business, so there’s not much attraction for venture capital.
I k now I’m a little late, but actually wings ARE attached with bolts. At least, 747 ones are. And the bolts aren’t as large as you’d think.
And folding-wing carrier planes such as the Corsair use pins to hold the wings when they are unfolded.
From what I have read, it was competition from smaller planes with better engines that killed the A380, along with airline operational changes that took advantage of these newer, more efficient smaller planes.
When the A380 was designed, airlines were using the hub and spoke model. You would fly from hub to hub on large planes like the A380, then would fly on smaller planes along the spokes to get to your final destination. It made sense. It gets very congested at large airport hubs, so it is much more efficient to have fewer planes that each hold more passengers.
The problem with that is that people don’t like layovers. You waste a lot of time sitting around at airports waiting for your next connection.
People prefer to fly point to point and not hub and spoke. With newer, more efficient engines, planes like the 767 could fly further than previous aircraft of that size and use less fuel while doing it. All of a sudden the point to point model becomes a lot more practical and therefore a lot more attractive to the airlines. And so passengers start filling up on these smaller planes that go directly to their destination, avoiding busy hubs and their associated long delays. The giant A380s, which were designed to carry a lot of passengers from hub to hub, no longer have enough passengers to fill their massive number of seats.
The A380 was economical when its seats were filled, but a half-empty A380 is extremely inefficient, especially with those four fuel-hungry engines. If you aren’t filling your A380s, you are much better off replacing them with smaller two-engine planes that can go the same long distances.
Dubai really loved the A380 because Dubai is basically a hub for that part of the world, even in modern times when folks do a lot of point to point flying. So they kept the A380 going longer than most.
The Boeing 747 had the same issue as the A380, but it managed to find new life as a cargo hauler. The A380 couldn’t do that as easily due to its design. Boeing expected air travel to eventually shift to some sort of supersonic airliner, so the 747 was designed from the start to be both a cargo hauler and a passenger jet. If the passenger market dried up (as Boeing expected it to) they would just switch over to hauling freight.
The A380 was designed purely for passengers and doesn’t work as well in a cargo hauler capacity. The A380 was also designed with the idea that it would have an even larger bigger brother using a lot of the same parts. And so the A380 is heavier than it needs to be, which reduces the cargo weight that it can carry. If you try to haul cargo on an A380 you’ll run out of weight capacity long before you run out of space on the plane. That extra weight on the A380 ended up being a complete waste. The bigger brother (the A380-900) was never built, again due to reduced demand for large passenger haulers as the airlines changed from hub and spoke to point to point.
Technical issues with the A380-800 also drained the company’s finances a bit.
It’s called FlightRadar24 on my iPhone…
Select AR mode and point the camera toward a plane (even indoors where all you see is walls) and it will give you the aircraft info - From, To, aircraft type…
There’s also a mode where it shows all the aircraft in an area on the (zoomable) world map. There’s been a few cases where smaller planes (like Dash-8) don’t register…
I’ve been thinking about this, and it’s definitely quite impressive, but are we certain that a triple pendulum is more complicated than a double pendulum? The limiting case for an n-segment pendulum, as n gets large, is a chain or a rope, and we know how those behave: They’re just superpositions of normal modes, with each mode being a Bessel function.
I mean, obviously there are special cases of the triple pendulum that are indistinguishable from a double pendulum, but maybe there are also special cases that are easier than the double pendulum, where carefully-selected lengths can cancel out the chaotic effects. And maybe the pendulum in that video is such a one.
This is a fair point; one could probably just say that a double pendulum is “chaotic enough” and that more segments may appear to give wilder behavior but fundamentally isn’t actually more chaotic. Like a 4-body system isn’t really more chaotic than 3-body; aside from special cases, they’re both far away from the stable/chaotic boundary, and a solver doesn’t get more complicated with more points (it just takes longer to run). That said, all else being equal, I’d guess the triple pendulum is harder in a practical sense.
Maybe, but I don’t get that impression. I skimmed one of his papers a while back; I don’t remember a whole lot, but energy management was a big component. That makes sense: energy is conserved, and not chaotic at all. The stable state has potential energy at a maximum and kinetic at zero, and while the flow from one to the other is likely still chaotic, it might be easier to solve compared to looking at the detailed motion. I believe the initial pumping action is to put enough energy into the system to equal the final stationary state. This is all easy to measure with angle/velocity sensors.
Here is a new video from my favorite aviation YouTuber about the state and fate of the original AN-225 and the possibility of getting the second one flying. (Sadly, not very likely.)
Phew. You have not all been replaced by pod people. I was just catching up on a thread that I hadn’t encountered before and I thought for a few moments that in 80 posts no SDMBer had made the “on a big treadmill” response. Frankly I’m still a little disappointed that it only came at post 19. Maybe in 2007 the GQ mods were meaner.