Now what if there were a treadmill inside the tunnel?
True. The F-117 stealth fighter is the most famous example, but lots of newer generation fighter aircraft are actively unstable aerodynamically and have to be continually stabilized by small inputs from the computer. It makes them easier to maneuver quickly.
The difference is: fighter planes are designed for killing, whereas passenger planes are designed for not killing.
Commercial aircraft are already equipped with auto-landing features. But it’s never a good idea to put solid objects near the flightpath of an airplane. Doing so means that small errors, deviations, air current shifts, unexpected runway congestion, etc. become deadly emergencies instead of everyday occurrences.
It doesn’t matter how many bombs your plane can carry if it kills the crew. Fly-by-wire systems started on test aircraft in the late 1950s (a guy by the name of Neil Armstrong worked on them), and have since migrated to commercial aircraft. With the increase in fuel prices, and the need to pack more and more [del]cattle[/del] people onto airplanes, the nature and complexity of systems on aircraft is only going to grow, with human control of the planes becoming less and less. We’re now starting to see it on cars, and there’s plenty of Dopers who’re chomping at the bit to get a “self-driving” car, should one be built.
Of course, one of the reasons for that is that human reaction times are so slow, do you honestly think that in 50 years computer technology won’t have advanced to the point its so superior to human ability (in things like flying a plane/driving a car) that we won’t be relying on it to land planes in ways currently considered too dangerous today?
The majority of people will not be ready for aircraft without a pilot in the cockpit or one who can not over ride the automatic systems 50 years. It will need top be some other system of travel that they do not have this history of fear already ingrained with. YMMV
Who will build a system that if it ever hurts someone, that there is no defense what so ever about the builder being 100% responsible? Who will insure it, what government will force the people to accept it?
In transportation, trying to make it work in MORE hazardous situations with more complexity is the wrong direction to be moving IMO. Moving away from hazardous operating conditions is the direction to go.
The airplanes are not the problem, the system we use (hub & spoke) them in is wrong. Big can of worms that… And of course our expectations of the service providers…
A missed approach would be a bit of a bitch, wouldn’t it? At the moment, there’s (often, anyway) the opportunity to pull up, go round and try again. Not so if you’re approaching the mouth of a tunnel.
Sort of why you’d not want a human at the controls.
I’m sure somebody said that about elevators and trains.
Sort of why I’d just not want to fly into a tunnel, really.
Robot control systems will be subject to wind shear too.
The trouble with underground airports is they have no advantages. So why build one? Large aircraft for hauling masses of humanity have to be safe, cheap and efficient. They probably won’t be VTOL because that necessitates an extra drive system/ducting that can breakdown and contributes useless weight for the majority of the trip.
Now underground taxiways/plane storage/boarding ramps… that’s a good idea. I’m seeing a futuristic airport being three or four actual runways with planes taxing out of underground structures. That would mean the actual size of the airport is the footprint of the runways. I assume computer control would make it very efficient to taxi planes up to the runway and into position, so it would probably take much less time and necessitate less physical runways than today. But that would be true whether the support buildings are underground or not.
But this assumes that space is at such a premium that huge subterranean vaults are economical to construct. And with robot construction equipment, it will no doubt get cheaper, but again, is it cheaper than buying the actual space above ground?
And unlike humans, they won’t need to figure out what that alarm means, they’ll be able to respond instantly (or at least a lot faster than a human could).
This is a good spot, I think, to trot out the old statement by Bill Gates that no computer would ever need more than 640K of RAM.
Didn’t they fill in part of the harbor in Hong Kong to build more runways some years back? Didn’t Boston just bury the interstates leading into the city? Think environmental regulations are going to get any easier?
Is that quick enough to not hit the side of the mountain you’d have them be flying into? Robots have to obey physics for the time being and a 300 ton Futurejet™ traveling at a hundred MPH doesn’t turn on a dime.
Are you envisioning anti gravity? Ducted fans? Does your future aircraft use jets or jet like technology to generate thrust? Yeah if you assume magic anti-gravity or other against the laws of physics technology then VTOL makes total sense.
But economically if the cost of hauling the VTOL components of the aircraft is more than the amount saved by building very small VTOL runways they aren’t going to use them. And the fuel cost of hauling the VTOL components is continuing while the cost of a runway is more or less one time.
I certainly think there will be a niche for VTOL transports in the sci-fi future, but are they going to be cheap and fast enough to compete with jet-like aircraft of today for hauling the family to Disney World?
What does any of those things have to do with what we’re talking about?
Futuristic runways will likely be smaller and fewer of them will be needed because computer control can have planes landing and taxing very efficiently in real time. I don’t see any need for a dangerous approach into a very expensive mountain for no benefit.
How about better radar and other systems which are able to more accurately predict wind shear conditions and take action before it becomes a hazard?
So, you’re thinking that better materials, which are lighter, stronger, and more versatile than anything we have now are out of the question, then? Putting VTOL on a jet opens up more landing possibilities. One of the issues with the A380 is that the jet cannot land at certain airports, because they either don’t have long enough runways, or they cannot accommodate the width of the jet. A VTOL or STOL system means that a jet doesn’t need so long of a runway. The question is: Will the amount of air traffic increase to the point where that’s seen as a viable option?
People thought that Henry Ford was crazy when he stated that he wanted to make cars that every American could afford. Mass production does wonders as far as bringing the cost of something down.
You asked would it ever make economic sense to bury an airport. Those were all large scale engineering projects done in unusual ways because of space limitations. As for the environmental regulations, I seriously doubt that you could get away with filling in part of a harbor in the US for environmental reasons. Environmental regulations are only going to get tighter, both in the US and the rest of the world. Burying an airport deep underground is going to have minimal impact on the surface, and will preserve, much of habitat of the area.
There are limits, however, to how closely you can pack planes together in the sky. It doesn’t matter how good your computer is, things like jet wash, and wing turbulance dictate that aircraft will always have a minimum distance apart. You’ve also got to be able to handle situations where something goes wrong with one of the craft, which puts a limit on how many planes you can have landing at any one time, simply because of how long it will take to clear a runway.
That’s awesome. But that doesn’t mean it will happen before we get robot jets or ever. Flying into a mountain is a bad idea.
Nowhere did I say that. What you don’t seem to understand is that VTOLs will be made of better futuristic stuff, so will conventional jets. It’s the relative cost that matters not the absolute number. If VTOLs cost 10% more to operate, the airline industry will be taking that into account.
Yeah and putting a laser on a shark’s head makes them freakin’ terrifying.
How much less efficient will they be is the question. Do we have an aircraft engineer in the house? If VTOLs cost more to operate their benefit must be greater than that. Every pound of VTOL could be a pound of paying passenger or that many less pounds of fuel.
You’re scattering the question and losing focus. Have we agreed that tunnel runways are a bad idea?
Are they not going to mass produce conventional jets? Because then the price difference would be based on fuel necessary to haul the VTOL components.
Yes and none of those problems are solved by burying your runways. Instead you have gigantic holes that cost more, are more dangerous and require active venting of exhaust fumes, lighting and cleaning. For no benefit. Doesn’t that sound like a shitty idea to you?
Only if you hit the mountain.
You’ll also notice that lots of things stop being used over time. Seen any large propellor driven aircraft these days? How many new cars have window cranks these days? Its not because electric motors are cheaper than a crank that they’re now the default on cars, with window cranks not even being an option.
If it means that an airline (which have pretty much always been money losers, as I understand it) can reduce the types of planes in its fleet (thus saving money, not only on volume discounts, but on training operations, and parts inventories as well), handle the same (or greater) volume of passengers its presently doing, and land at the same or more airports than it currently does, then the fact that part of the VTOL components will spend much of their time as dead weight, won’t really matter. BA recently sent a jet with no passengers on it, on a transatlantic flight, simply because they needed the plane on the other side of the ocean. (There was cargo on the plane, so it wasn’t completely empty, but still.) They got blasted for it because of the carbon emissions made by the jet.
Nope. I’ll agree that its not something we’ll do any time in the near future, and 50 years from now might not see such a thing, but I’ve so far not seen anything to completely rule it out as of yet.
Yes, but the decision to make the swap over to VTOL-only designs will not be based solely on fuel costs. Other factors, like I mentioned above, will come into play.
IIRC, Boston’s Big Dig cost overruns were caused more by things like bribes and graft, than they were any technological hitches. As for the “no benefit,” its a little too early to tell about that. We may see similar engineering projects done by other cities in the future. Nashville has been considering the concept for around the year 2050 (burying the roads, that is), and it makes even less sense to do it here, since there’s only a few inches or less of soil before you hit bedrock.
Quoth Tuckerfan:
On the other hand, though, on a military aircraft, a technology which makes it more likely that the plane will kill its crew just might be worthwhile, if it makes it correspondingly less likely that the other guy’s plane will kill your crew. That tradeoff doesn’t really exist for civilian aircraft.
Yes, the military does have wider safety margins than civilian operations, but the military works hard at keeping the crews of expensive aircraft alive. I’ve never seen a passenger plane with ejection seats.
This is exactly the point I was going to make to refute your statement quoted by Chronos. Because fighter planes have ejector seats, in some sense the design can afford to have a small flaw (vis: inherent unstability corrected by computer), because in the one in a billion event that the system fails, the pilot will usually be able to escape unharmed. A similar failure on a jet-liner is almost certain to result in hundreds of deaths. Therefore, this is a good idea for fighter planes and a bad idea for passenger planes.
The point is that combat aviation is inherently risky, and going into that line of work means assuming an ever-present risk of accidental death even in peacetime, let alone death or injury in war. Crashing a 50,000 lb. airplane traveling at 100 knots into the heaving deck of a moving aircraft carrier and calling it “a landing” is a perfect example. The margin for error is practically zero, and people die doing it even under optimal conditions.
Civilian aviation carries a risk of death or injury for passengers that’s so low it’s practically 0. Margins for error are large, and all forms of risk are deliberately and obsessively minimized during the design of equipment and procedures. That’s why, for instance, most airlines use short-field takeoff procedures even on very long runways so that in the event of a mechanical problem they still have room to abort the takeoff safely.
Making something technically feasible doesn’t make it desirable in a failure-intolerant setting like commercial aviation.
Wow, that’s something I had never noticed before! Thanks for pointing that out!
I’ve seen a photo of a US carrier launching a Hellcat from the hangar deck. I thought that was nutty…but now that I think about it, it would be a great way to get an massive airstrike off the carrier in a hurry!