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Transportation Earth Science

Dutch Scientist Proposes Circular Runways For Airport Efficiency (curbed.com) 340

Posted by BeauHD from the what-goes-around-comes-around dept.
An anonymous reader quotes a report from Fast Company: While airport terminal architecture has a solid history of style and innovation, rarely is a proposal put forth to utterly redesign the runway. But that's precisely the aim of Henk Hesselink, a Dutch scientist working with the Netherlands Aerospace Center. Dubbed the "endless runway," Hesselink's brainchild is a 360-degree landing strip measuring more than two miles in diameter. Since airplanes would be able to approach and take off from any direction around the proposed circle, they wouldn't have to fight against crosswinds. And three planes would be able to take off or land at the same time. Hesselink's team uses flight simulators and computerized calculations to test the unconventional design, and have determined that round airports would be more efficient than existing layouts. With a central terminal, the airport would only use about a third of the land of the typical airport with the same airplane capacity. And there's an added benefit to those living near airports: Flight paths could be more distributed, and thereby making plane noise more tolerable. BBC produced a video detailing Hesselink's circular runway concept. The concept is fascinating but there are many questions the video does not answer. Phil Derner Jr. from NYC Aviation writes via Business Insider about some of those unanswered questions in his article titled "Why the circular runway concept wouldn't work." The fundamental issues discussed in his report include banked runway issues, curved runway issues, navigation issues, and airspace issues. What do you think of Hesselink's concept? Do you think it is preposterous or shows promise?
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Dutch Scientist Proposes Circular Runways For Airport Efficiency

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  • A computer doesn't give a shit if the runway is straight or curved, because it can handle a little more left (or whatever) while it's managing dozens of other things. But a human can't do that. You want to make pilots have to account for bank and curvature in addition to everything else? That's obviously a shit idea.

    • A computer doesn't give a shit if the runway is straight or curved, because it can handle a little more left (or whatever) while it's managing dozens of other things. But a human can't do that. You want to make pilots have to account for bank and curvature in addition to everything else? That's obviously a shit idea.

      I don't think it is that hard. Then again I am not a pilot, and I am guessing you are neither, but I know of a few mountain airports where some fine navigation is required to land safely, and that appears to work.

      • I don't think it is that hard. Then again I am not a pilot, and I am guessing you are neither,

        Okay, have you ever landed a 747 in a simulation? I did it on a Mac IIci with a mouse at about 8 fps, so it's not very like real flying, but it's a nice illustration of how complicated it is — especially since it was non-trivial even with all hazards turned off.

        • You did it alone, which makes it far more difficult. A real 747 has, depending on the age, one or two other people to help handle all of the operations on landing. The pilot who has the controls is responsible for only the basic controls and monitoring airspeed and sink rate. The other pilot (or the computer) handles everything else.

          Still, as a pilot, I'm really not keen on this idea. One of the benefits of the straight runway method is an extremely predictable location of all aircraft. You know where traff

    • Re: (Score:2, Insightful)

      by Anonymous Coward

      Not even with autoland. The aircraft would be landing with a curved path, and crosswinds (especially strong and gusty ones) would be more of a problem, since the aircraft is constantly changing heading during the rollout (same for takeoff), thus the crosswind is constantly changing its direction relative to the aircraft, thus adding one more factor into a situation already a potential problem.

      This wouldn't be a problem for a Piper Cub in no-wind conditions, but I can foresee all kinds of headaches for an ai

      • I would think the landing would still be straight, the pilot would have to start turning while braking to account for the curve. Or maybe they could adopt some of the ideas by creating a "circle" formed by a series of intersecting straight lines which curve into the circle. It would take more space around the circle but might still have some advantages.

    • Re:Only viable if all planes land themselves (Score:4, Interesting)

      by jofas ( 1081977 ) on Tuesday March 28, 2017 @08:21AM (#54126321)
      It's not just about that. In a catastrophic situation, there are now centripedal forces at play complicating recovery from a blown tire or engine malfunction, which results in increased danger to passenger life. And speaking of tires, I'm sure the several thousand more landing gear tire changes will offset the time efficiency gained. Airports are not just about efficiency, their product is transportation and safety is a component thereof.

    • I'm looking for more input of highly technical details, suggestions, and criticisms from dilletantes.

    • Comment removed (Score:4, Insightful)

      by account_deleted ( 4530225 ) on Tuesday March 28, 2017 @08:37AM (#54126437)
      Comment removed based on user account deletion

    • Steering a great big heavy vehicle, on little bitty tires, at high speed around a curve with snow or ice on it...I'd buy a ticket to watch that.

    • An even bigger problem is the cognitive workload for ATC and pilots who have to constantly adapt to new runway directions and approach types. I'm certainly not an aviation safety expert but this looks like a giant new source of human error possibilities to me. I also wonder how they would integrate circular runways into the current system of approach charts who describe more or less fixed vectors and maneuvers that pilots fly at most airports.

    • A computer doesn't give a shit if the runway is straight or curved, because it can handle a little more left (or whatever) while it's managing dozens of other things. But a human can't do that. You want to make pilots have to account for bank and curvature in addition to everything else?

      I'm only mildly concerned about that under normal conditions. But when there's ice, snow, poor visibility, a landing gear that won't drop, a deficiency in the plane's control surfaces, illness in the cockpit, or any of a couple dozen other problems that plague fliers and aircraft, then you're right - it's a shit idea.

    • A computer doesn't give a shit if the runway is straight or curved, because it can handle a little more left (or whatever) while it's managing dozens of other things.

      An autoland system in aircraft depends on the local airport navigation system - either Instrument Landing System (ILS) cat III or Microwave Landing System (MLS).. An ILS or MLS installation cannot be easily moved, and is usually tuned and adjusted for a specific runway.

      For this to be viable, it would have to be implemented in conjunction with a Ground Based Augmentation System [wikipedia.org] (GBAS), an augmentation to GPS navigation which could provide guidance from any runway direction. However, GBAS does not currently

    • Re: (Score:2)

      by AmiMoJo ( 196126 )

      Why bother tilting it at all? Just make it a pentagon some other multi-sided shape with straight sections. Could even have the lines crossing each other in places to reduce the amount of land used.

      • You just described a conventional airport! Perhaps that was the intention... :D

      • Re: (Score:2)

        by CAOgdin ( 984672 )

        If you're taking that approach, why not just a circular runway, 2 miles across, giving you a 2-mile long runway in every direction?

        See, I can fantasize, too.

    • It's just a training issue

    • But a human can't do that. You want to make pilots have to account for bank and curvature in addition to everything else? That's obviously a shit idea.

      Once a plane has touched the ground getting it to slow down is no more difficult than driving a car. Also you realise the radius of curvature is over 1mile right. Even a NASCAR driver would fall asleep at how little they need to turn to get around this runway.

    • > A computer doesn't give a shit if the runway is straight or curved, because it can handle a little more left (or whatever) while it's managing dozens of other things.

      It's not "a little more left", it's nearly a 1G turn at the proposed dimensions - about the maximum turn rate an airliner will ever do outside of test flights.

      Just as important, probably, it would mean rolling the broad side of the wings into a cross wind. This is hard to explain in words, but imagine the wind is coming from the left. Wi

  • Safety issues? (Score:5, Insightful)

    by JoshuaZ ( 1134087 ) on Tuesday March 28, 2017 @08:07AM (#54126215) Homepage
    One of the major issues seems to be what happens when a plane comes in too fast. Straight runways handle that well. It is hard to handle that with circular runways. There are a lot of other safety advantages of the standard setup.

    • Re: (Score:2, Interesting)

      by Anonymous Coward

      I was in a plane on a flight back from France a few months back and even there the cowboy pilot started accellerating before he'd even finished leaving the taxi way to straighten up onto the runway. Net effect? Plane tilting violently and almost tipping.

      A circular runway only exacerbates the problem of cowboys like that who think they're in a race car that defies the laws of physics.

      I daren't even imagine the carnage on an icy day.

    • Re: (Score:2, Interesting)

      by freeze128 ( 544774 )
      When landing a large commercial airliner, the runway would curve before the nose wheel even touched down (which is where the steering is). The pilot would then need to bank the plan to make the curve. This could cause the wingtips to dig into the ground if banked too much. It might not be fatal, but I bet it would wreck a lot of planes. Which would be EXPENSIVE. Do you think the airlines would go for a concept that would be expensive? I bet they wouldn't.

  • Traffic? (Score:5, Insightful)

    by Carewolf ( 581105 ) on Tuesday March 28, 2017 @08:10AM (#54126241) Homepage

    I love how he places his drawning in the middle of nowhere with no roads or train tracks, or even neighby restraints on the layout of the land. Sure you can pull all that underground, but he seems to just ignore it.

    • Ummm, have you seen an airport with train tracks through it?

    • Sure you can pull all that underground, but he seems to just ignore it.

      He's Dutch. Have you been to Schipol? There are two major highways that cross under the runway. It's a minor annoyance to work around at best.

      Actually I much prefer the A2 which crosses underneath a dijk used by cruise liners. It's quite a different feeling to take a slight dip under a 180000T ship than under a traintrack.

  • More =/= better (Score:5, Insightful)

    by MrLogic17 ( 233498 ) on Tuesday March 28, 2017 @08:19AM (#54126305) Journal

    My first thought was: how the heck are you going to keep this runway clear of snow? You've gone from a single (or dual) short strip to a (pi*2mi)= 6.28 mile loop. That's a lot of runway to plow.

    Then there's the long taxi time from the outside to the terminal in the center. That's a 1 mile radius taxi. Lots of wasted time.

    Then there's the poor saps living around the airport. Instead of a well-defined small number of houses with noise pollution, you've spread it all over a huge area. Lots more people to complain. I doubt people want to build houses *inside* that 2 mile loop of land, so the footprint of this beast will be impractical for an airport near anything existing at all.

    And if there's a consistent level of wind (from any direction), that "3 at the some time" argument goes away, and you're back to a small strip of usable runway, at least until the wind dies down.

  • Circular runways have been discussed in two posts on Quora (www.quora.com) which have yet to be merged.

  • It's proven once again (Score:5, Informative)

    by santax ( 1541065 ) on Tuesday March 28, 2017 @08:26AM (#54126351)
    We Dutchies have the best marijuana in the world. Assuming he wasn't actually sober when he came up with the idea.

  • "Every time you solve one problem, you create two more." * My guess is that circular runways would solve a few problems and create dozens more.

    * I went looking for the source of that quote. Couldn't find it, but it appears in Popular Science, May 1942.

    https://books.google.com/books... [google.com]

  • He's never worked at an airport (Score:5, Interesting)

    by Nidi62 ( 1525137 ) on Tuesday March 28, 2017 @08:36AM (#54126427)
    This is great and all during the day and in clear weather, but constantly changing approach vectors means you can't have any approach lights unless you have a ring of lights around the whole ring that extends at least an additional 1000 ft. So your "3km" footprint for the whole airport is now about 5km. Either that or all landings with less than 1 mile visibility would require autoland. You'd also need to have a system that dynamically turns the lights on/off as approach vectors change. You'd also have to completely redesign the airport charts and the approach vector would already have to be known 30-60 minutes out so that the crew can do a landing briefing which might negate the benefits of using a round runway as the winds could shift in that timeframe so you still have crosswind. You'd have to cross the runway for access to hangars, maintenance facilities, cargo warehouses, etc which most likely wouldn't fit inside the ring. Which means you are losing a quarter of your landing space pretty much constantly to allow aircraft to be towed across, cargo to be delivered to/from flights, etc.

    • This is great and all during the day and in clear weather, but constantly changing approach vectors means you can't have any approach lights unless you have a ring of lights around the whole ring that extends at least an additional 1000 ft. So your "3km" footprint for the whole airport is now about 5km.

      All of your points are excellent. I'm going to assume that with multiple planes approaching, that we'll need multiple color approach lights. "502 Heavy, your approach color is fuschia."

      Circular runways are a half-baked idea. And like all half baked ideas, it creates more problems than it solves.

  • Dutch crackpot proposes unworkable concept (Score:4, Informative)

    by Baron_Yam ( 643147 ) on Tuesday March 28, 2017 @08:40AM (#54126465)

    For the one benefit of your initial landing possibly being inline with the prevailing wind, you're adding dozens of safety issues, inefficiencies, and implementation issues.

    • For the one benefit of your initial landing possibly being inline with the prevailing wind, you're adding dozens of safety issues, inefficiencies, and implementation issues.

      As a thought experiment, this circular runway is interesting. But for any other purpose than the one you pointed out, it doesn't have much use. I can envision approaches that will take the plane around most of the circumference of the runway before making the long trek to the hanger as well.

  • Isn't there a circular airfield in Lithuania already? Pochunai or some place like that? Grass airfield for light aircraft, but the point is the same.

  • Completely unfeasible (Score:3, Insightful)

    by Anonymous Coward on Tuesday March 28, 2017 @08:41AM (#54126475)

    This idea was studied in the 1940's, and was rejected then, it's still a bad idea.

    The video is pretty funny, they say you can always take off and land into the wind, but then state you can take off or land 3 planes at once at different places along the circle, but that would require one of those planes to land in a 60 degree crosswind, and the other to land in a 60 degree quartering tailwind, unless you had the planes on crossing approach paths (a really, really bad idea). A rejected landing would either put the plane right into another's approach/departure path or put wake turbulence right into short final approach of another aircraft. Wake turbulence from a heavy plane can flip a smaller plane, an A380 flipped a business jet 3 times flying 1000 feet below it last week*, the business jet landed, but the airframe is totalled. Another one also nearly flipped a 737 about the same distance away**. Ignoring it is idiotic, wake turbulence is at it's worst with heavy planes at low speeds, and drifts downwards and outwards. 3 simultaneous take offs still has the problem that if one plane takes off directly into the wind, the other 2 have to take off with a 60 degree crosswind & 30 degree tailwind unless you cross departure paths, at the other extreme it's a 30 degree crosswind into the wind, 90 degree crosswind, and a 30 degree crosswind/60 degree tailwind. You also put wake turbulence into the approach path of the next runway. You really can only use 2 runways on the circle if you account for the wind. Maybe I'm missing something, but I've made a bunch of diagrams and haven't found a solution that actually works for using 3 runways and accounting for the wind with non-crossing flight paths.

    All the other potential benefits mentioned ignore the wind as a factor. It also later ups the capacity to doing the work 4 runways without explaining why. But let's ignore all the flaws in the concept itself and think about building one anyway.

    11,480 foot runways would fit inside of the space of the circle, and you could build 3 at the same width for less concrete that the circle would use. But the circular runway looks a bit wider then needed, so you probably can get 4 standard runways out of the same area of concrete, probably a lot more since you don't need 50 taxiways. Even if that's not the case, 4 normal runways would use less land, and would not require building an enormous banking underneath the concrete, or the reinforced tunnels under the runways for passengers, cargo and equipment. The banking doesn't sound expensive until you realize that there's about 7 miles of it. The tunnels would need to be able to withstand a fully loaded A380 doing repeated hard touchdowns on it (remember, they can land anywhere on the circle) plus a safety factor, and be large enough for everything the airport needs. There would need to be enough land to build it near a large enough city to require an airport this size, which usually don't have large areas of inexpensive land available. And where are the cars parking?

    6 runways - 3 pairs in a triangular format, with terminals and parking, uses far less land than the circular format, and is much easier to expand. The 3.5km runway idea mentioned earlier would use 5.3 km^2 or area for the triangular runways, where as a circular 3.5km diameter runway would require 9.6 km^2 of land, and in the picture much more than half of that area is for the runway and taxiways. You can fit a lot of terminals and parking in the 4.3km^2 you have left over with the triangular runways (and that does not include the area in the center of the triangle). And why would you want the terminal in the middle? It makes ingress/egress more difficult, for little to no benefit. On days with any wind (which is the vast majority of them), you'd only be using one pair of runways/2 upwind paths on the circle.

    A complete, well thought out presentation of a bad idea is still a bad idea. They use the wind to justify one "benefit", but then pretend the wind doesn't exist as it is a massive problem to nearly

    • Let's go folks, mod this AC post up to where it belongs.

      I didn't even think of the "no expansion" problem the circular airport would have.

    • Re: (Score:2)

      by green1 ( 322787 )

      Exactly.

      Triangular runway formats have been around forever, they have almost all the advantages of the circular runway, with none of the disadvantages.

      The one point that is made that does make a lot of sense though is putting the terminal in the middle of the triangle, something rarely done. You could have the access roads at the points of the triangle, or as tunnels (not impossible, many runways have tunnels under them already)

      Done right, it would decrease the average distance planes need to taxi (saving t

  • So many flaws.... (Score:5, Interesting)

    by Eloking ( 877834 ) on Tuesday March 28, 2017 @08:43AM (#54126499)

    Oh boys, where to begin.

    The obvious one is to take off and land while turning, but this could be corrected with a few straight runway connected around the circle (Kinda like an "angled" sun shape). I'm actually surprised they didn't propose that instead. Of course, that also mean you'll need a lot more space.

    Then there's the air traffic management, it's going to be a pain since all plane that either lift-off or land will use the "same" runway at the same time.

    Furthermore, if you want a 3.5 km diameter circle, that mean that you'll need to put a lot of infrastructure "undergound". Highway, parking, car renting etc. That's a lot of digging and a lot of concrete.

    Also, I have serious doubt it'll raise the traffic. a 747 need over 2 kilometer for landing and take-off. A 3.5 km diameter mean 11 km circumference. So if you're really efficient, you'll have to shut down like ¼ of the runway. In other word, you'll only be able to run 2 corridor of landing and 2 corridor for lift-off at all time at ~90 angle. And that mean you bring back the problem you have been trying to solve in the first place.

    So yeah, a lot of new problems only to solve one that isn't that bad to begin with.

    • take off and land while turning

      Given the radius of curvature this is a non-issue.

      Then there's the air traffic management

      It will be but not for the reason you mentioned. More the problem would be that runways are identified by their headings so managing this will necessitate a complete change in the way aircraft are directed to approach and land at an airport. The management will be easy, the change will not.

      Furthermore, if you want a 3.5 km diameter circle, that mean that you'll need to put a lot of infrastructure "undergound". Highway, parking, car renting etc. That's a lot of digging and a lot of concrete.

      Not at all, only the primary access to the terminal needs to be underground. Something that a lot of airports have already. Heck Schipol has 2 major highways and multiple

    • You could make it an octagon shape where four segments (wind permitting) can be used simultaneously. Access and egress tunnels aren't that expensive to build. In fact most large airports already have them along with shuttle trains to move people between terminals, et cetera. I'm not saying that this is actually the ideal solution, but airports are not very efficient in terms of overhead. It often takes more time to get to the airport and board than it does to actually fly.

  • Airspace management issues aren't considered (Score:3)

    by lordlod ( 458156 ) on Tuesday March 28, 2017 @08:44AM (#54126505)

    Landing on a runway with a curve is certainly doable, I've known pilots to land on all sorts of odd surfaces. Many of the issues about traction etc. can be trivially solved by making the circle a bit bigger.

    The excitement of managing the airspace is touched upon in the Business Insider article but not really fleshed out and I believe handling it in practice would diminish many of the suggested benefits.

    The standard single runway is currently managed with a basic queue (simplified version). The planes circle in large loop around the airport. The airspace controller lines them up on a fixed marker above the end of the runway and they are passed on to the control tower for the landing. Take off is the same in reverse, they lift off, fly to a fixed marker and are then handed from the tower to the airspace controller.

    Running a circular runway with three approaches would be doable, you would have three fixed approach markers, the same process would be used. Issues like turbulence from adjacent planes would need to be managed but this is standard in a multi-runway airport and would actually be greatly improved compared to two parallel approaches.

    Once you start rotating the approaches with the wind things start getting far more exciting. Dynamic marker points aren't going to work, too much communication required and futzing around to communicate the approach point to every plane. So you are going to have to have multiple fixed sets, keeping it simple with only 3 options, 3 approach markers, 3 departure markers you have a total of 27 waypoints in a tight area around the airport. The odds of a plane flying to the wrong waypoint is huge (multiply it out by the number of flights a day, the number of passengers in a plane etc) and the consequences catastrophic, without extensive changes to the way planes are managed the risks are just far too high.

    • This is conceptually true, but flights don't generally circle anymore (except in bad weather). The approaching flights are slowed down so that they stream in. Saves fuel and makes it easier for ATC.

  • Conflict? (Score:5, Insightful)

    by QuietLagoon ( 813062 ) on Tuesday March 28, 2017 @08:48AM (#54126543)

    ...they wouldn't have to fight against crosswinds. And three planes would be able to take off or land at the same time...

    If three are landing at the same time, I'd say that at least one is fighting cross-winds.

  • I've got a better idea. (Score:5, Insightful)

    by Verdatum ( 1257828 ) on Tuesday March 28, 2017 @08:50AM (#54126563)
    Instead of a loop, we should make the runway a Möbius strip! That way, planes can taxi along both sides of the tarmac, allowing it to last twice as long!!
    • Or an equatorial runway that encompasses the entire Earth. That way, they wouldn't need to turn while landing.

  • A circular runway has too many problems as others have pointed out: Weather making the runway slippery, the need for approach lights, etc. So why not stick with straight runways, but gain the advantage of a circular runways by putting the entire airport on a giant turntable? Then you can rotate the runways to always be at the optimal alignment for the wind. :)

    • Re:Rotating Airport (Score:5, Interesting)

      by crow ( 16139 ) on Tuesday March 28, 2017 @08:58AM (#54126643) Homepage Journal

      On a serious note, you can approximate this by simply paving an entire square mile. I once heard that Lawrence Livermore National Laboratory was such an airport in WWII, allowing damaged aircraft to land without having to line up for a runway. I don't know if that's true or not (it was a naval air base according to Wikipedia, so it might be), but the idea may be valid.

      If you have a location with high winds that approach from many directions, and you have a wide open area, then something along these lines would work. Of course, there aren't going to be many locations where you have those wind conditions and the space, so you could approximate it with several different runways aligned based on the predominant wind conditions. That would work great! And that's pretty much exactly what they do at all major airports.

  • what about the 1960's plan for ohare? (Score:4, Interesting)

    by Joe_Dragon ( 2206452 ) on Tuesday March 28, 2017 @08:52AM (#54126587)

    http://archives.chicagotribune... [chicagotribune.com]

  • How do you get to the terminal? Does everything go through tunnels or do cars wait at the strip like a train crossing?

  • 3 KM? (Score:3)

    by Drethon ( 1445051 ) on Tuesday March 28, 2017 @09:02AM (#54126673)

    I could be doing my math wrong but the Nardo Ring is about 4KM in diameter https://en.wikipedia.org/wiki/... [wikipedia.org]?

    The fastest a car, with suspension for cornering, can go on the highest banked part of the track is 240 km/h. A Boeing 747 takes off at 260+ km/h.

    So the banking would have to be increased to prevent possible tipping but approaching a runway on a bank, or taking off, seems like it would have serious stall issues.

    A non banked runway could avoid this but what kind of suspension would an aircraft need (could it be done with a tricycle?) to handle the amount the aircraft would want to roll. Plus on approach, you would have to slew with the rudder, at those speeds is there enough force from the air to keep the aircraft from sliding sideways or would you have to slew twice as much as the runway angle or more so the engines would be driving the turn?

  • Of course it'll work (Score:5, Interesting)

    by oobayly ( 1056050 ) on Tuesday March 28, 2017 @09:03AM (#54126681)

    My local gliding club is a great big grass area. They have six winch points, but can shift the launch point to suit the wind. It also makes emergency landings safer as you have a huge area to aim for. The question isn't "will it work", it's "is paving the area worth it", and I very much doubt it. Take Dallas/Fort Worth for example - it has 7 runways. The total paved area of those runways is about 147 hectares (0.6 sq miles), assuming the average width is 60m.

    To fit just a single 4,085m runway in a circle the paved area would have to be 1310 hectares (5.1 sq miles) - an increase of almost 800% on the current paved area. It would be even greater as the circle would need to be bigger to have parallel 4,085m runways. Granted, I'm not including taxiways, but even so I can't see it being economic.

  • Already tested by the Navy in 1964 (Score:5, Informative)

    by AdamInParadise ( 257888 ) on Tuesday March 28, 2017 @09:28AM (#54126853) Homepage

    The Navy tried that already in 1964. Popular Science ran an article about it: https://books.google.fr/books?... [google.fr]

  • Did he check the math? (Score:5, Insightful)

    by Solandri ( 704621 ) on Tuesday March 28, 2017 @09:34AM (#54126901)
    Centripital force is

    F = mv^2/r

    or a = v^2/r

    At a typical takeoff speed of 150 knots [aerospaceweb.org], the lateral acceleration needed to keep the plane centered on a round runway with a 1.5km radius is 3.97 m/s^2, or 0.40g. On a freeway you'd just tilt the roadway based on the expected transit speed (about 24 degrees for 0.40g). But with a circular runway, planes are going to be traversing every part of it at all speeds from 0 to 150 knots, so there's no single tilt which will eliminate the problem. Likewise, during the takeoff roll the required lateral force will increase with velocity. So you can't just tilt the wheel/joystick at a certain angle and hold it there while taking off. You have to constantly adjust it as your velocity increases.

    If a plane has to make a no-flaps emergency landing at 200 knots (which also happened to be about the regular takeoff speed of Concorde), now you're talking a lateral force of 7.06 m/s^2, or 0.72g. Which brings us to why runways are straight in the first place. It's not because it's easier to design and build. It's because it's a stable travel path. If for whatever reason during takeoff or landing the plane's controls stop working, the plane will want to go straight. Making the runway straight means the plane naturally (and with a little luck) will stay on the runway. Making the runway round means if you lose that lateral force being applied by your control surfaces for whatever reason, the plane is guaranteed to depart the runway at speed.

  • Dumb. (Score:2)

    by dcw3 ( 649211 )

    Just my $.02 as a private pilot...

    The claim that 3 planes could be landing at once is only valid if the winds are cooperating...you don't land with a tailwind. With any serious wind, you've now limited everything to a single queue because the planes will all need to go single file into the wind.

  • 1. Dig a big hole.

    2. Build all the support infrastructure in the hole - parking, terminals, support vehicles, etc.

    3. Cover the hole and pave a big circle over it.

    4. Put the tower right in the middle of the circle.

    5. Mount lasers on the tower.

    6. Use the lasers to 'paint' runway markers wherever you want based on the wind conditions.

    7. Have 'pop up' structures to expose runway entrances to the underground complex on an unused portion of runway.

    Ta-da!

  • The linked Business Insider article breaks down every objection I had and confirms they're worse than I thought. I like his conclusion, too: It won't work, but it's good to see people coming up with new ideas. You never know what might come out of it.

  • ...logged flight time has seen these ideas crop up time, after time, after time. The radical change in pilot skills required, the creation of entire new solutions to low-visibility landing navigation signals, and the fact that it only applies to commercial airports (small airstrips take less space than the circle (unless you're willing to accept wing bank angles over 30 degrees during the most critical phase of flight) mean mostly only major destination passenger-service airports would be appropriate. Fin

  • Comment removed based on user account deletion

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