News Circular Runways.

[Notebook]

Thought it was a late Lirpa Loof, it seems not.

http://www.bbc.co.uk/news/magazine-39643292

Last month we published a video arguing the case for circular runways at airports, as part of a series called World Hacks. It took off and went viral.
The video has had more than 36 million views on Facebook and generated heated debate on social media - including within the aviation community. Many people are sceptical about the concept.

 

[C3PO]

Does it have electrolytes?

 

[Andy44]

Does it have electrolytes?

It has what plants want.

---------- Post added at 01:51 PM ---------- Previous post was at 01:50 PM ----------

When I first saw this I thought it was an April Fools' joke.

But this appears to be a serious idea...h:

 

[C3PO]

To calculate the correct camber, you have the know the speed and radius. AFAIK planes do not always touch down at the same speed.

What exactly are the advantages? I can only see one! RWY length. Listing the disadvantages would look like an essay. I'd rather land in a F9 stage on a barge than on this. :facts:

 

[Mojave]

This seems like one of those ideas that is interesting and efficient on paper, but would be wildly impractical in any real-world capacity. Maybe it'd work well for highly-specific aviation needs, or in military settings; however, for commercial aviation? All I see are problems even when considering the slightest incident.

Circular runways? More like circular reasoning - it's just as bad.

 

[RisingFury]

Yea, I don't know why people keep falling for crap like this. The lack of physics education and critical thinking is apparent.

 

[Mojave]

Yea, I don't know why people keep falling for crap like this. The lack of physics education and critical thinking is apparent.

I don't think it's necessarily a lack of physics education. It IS an interesting concept, but completely ridiculous for the audience they're selling for. The critical thought processing is lacking; though, as anyone with the slightest knowledge of how airports work can ascertain what problems you're going to have when a jumbo jet's gear fails and spreads FOD over 1/3 of your single, circular runway when the unwieldy curvature sends the speeding air frame spinning out of control. Not to mention the other simultaneous arrivals and departures that will be caught up in the accident.

I'm saying when you up the one runway you're operating from, it's not just the airplane that's crashing and burning. This is a financial mess.

It's very efficient until the first wreck.

 

[Urwumpe]

The problem is not physics, the problem is operations...

 

[C3PO]

It's very efficient until the first wreck.

Or a windy day.

---------- Post added at 07:55 PM ---------- Previous post was at 07:51 PM ----------

For the younger audience:

 

[jedidia]

What exactly are the advantages? I can only see one! RWY length.

As far as I gather from the article, the main advantage would lie in multiple aircraft being able to use the runway at the same time.
Also, it might open up more flexibility for approach paths.

It's certainly thinking outside the box, but the concept would need a darn lot of very expensive practical tests with empty planes and crazy pilots before I would comfortably trust it.

 

[ADSWNJ]

In the name of science, I think we Orbitnauts should try it out with some XR-2 and XR-5 landings! Anyone up for building it? It's a nice challenge for Glideslope as well! I would mark it up with 18 thresholds, at 20 degree marks around the track, and have 18 SIDs and STARs for it. I liked the idea of the ILS rotating on a track!

For real life - who knows? I think it's a radical out-of-the-box idea. Move the touchdown point around the circle to head into wind. Rejected takeoffs are much safer. In fact - you can reject at all points including after take-off, so long as you fly an arc to stay over the centerline. I'm wondering if you could do a double-helix of departures and arrivals?

If you had two circles, one for taxiway and the other for the active, then in case of a problem, you swap over the active, and you have say 350 degrees of the other still useable. Definitely workable.

 

[steph]

Might work with drones. . I vaguely remember a documentary about something similar. Some spinning structure, with many "arms", quite similar in looks to a chain roundabout (or the "octopus" kind, whichever were popular in your area :lol: ), would spin and capture any incoming drone/spaceship with one of its many arms.
Upon capture, the arm would lower, decreasing the angular speed and allowing the drone to be captured at low speed by another mechanism. After refit , it would again be attached to one of the "arms", which would centrifugally extend and release it at flying speed

Yup...this went off the rails fast. Not something you'd wish for a manned aircraft.

 

[Thunder Chicken]

For the same amount of real estate you could build two straight runways elevated on casters that could always be oriented into the wind. Bolt the ILS onto it and you just need to report the runway orientation to the pilots.

Or you could just, you know, pave a runway in the direction of the prevailing wind and call it good.

 

[Artlav]

How the heck would you line up an approach to this? Would there be beacon lines spaced at every few degrees?

How are they going to address hitting it? On a regular runway you can be a little short or quite a bit long, here it's hit-a-spot or die.

How are they going to address centrifugal forces and the fact that landing gear is not designed for continuous side loads?

How are they going to address slippery conditions?

Finally, how is this better that just having 4 non-intersecting runways in a square?

 

[ADSWNJ]

How the heck would you line up an approach to this? Would there be beacon lines spaced at every few degrees?

How are they going to address hitting it? On a regular runway you can be a little short or quite a bit long, here it's hit-a-spot or die.

I could imagine two ways this could work:

1. Set up a number of straight approach vectors (e.g. at 20 degree, 30 degree, or 60 degree intervals. Maybe smaller intervals on the prevailing wind side.

2. Do a circle-to-land approach, where the plane tightens its arc to match the runway radius.

How are they going to address centrifugal forces and the fact that landing gear is not designed for continuous side loads?

How are they going to address slippery conditions?

That's the point of the banking, I think. Done properly, the bank would offset the centrifugal force. With a good bank, there will not be standing water on the runway, so that's potentially an advantage.

Finally, how is this better that just having 4 non-intersecting runways in a square?

4 non-intersecting runways is a good analogy. Increasing the segments approaches the circle.

Why is the circle better in theory:
1. Reduce crosswind landings and takeoffs.
2. No need for reverse thrust
3. You can abort at any speed, without having to apply maximum braking
4. You can take off at multiple points on the circle in lower wind scenarios, driving higher working loads.
5. Better tower visibility at all points on the runway

Will it happen? Almost certainly not, but I love the new thinking.

 

[C3PO]

I suspect this is meant to be flown mostly by computers, maybe without pilots at all. Sort of a Jetsons future thingie.

The problem is that the world changes too fast for extra long term plans. A good example would be "future" aviation in the 1930's. Everyone believed that flying boats were the future, because nobody would be mad enough to suggest building runways all around the world.

Then a thing called WWII happened.

 

[Mojave]

2. No need for reverse thrust
3. You can abort at any speed, without having to apply maximum braking
4. You can take off at multiple points on the circle in lower wind scenarios

I understand the logic, but these practices can't be true in non-ideal conditions - which are kind of the conditions the designer of the circular runway is trying to champion the proficiency in.

What happens when you don't stop before hitting the jet ahead of you on the runway during an abort? There may not be enough time to taxi the other plane off the runway, or get it rolling forward. This is most-assuredly a potential problem given the designer anticipates the airport working multiple flights on the runway at any given time.

Even if takeoff position spacing is at the ideal distance, freak accidents can occur putting multiple flights in jeopardy. More importantly, the way he wants to use his airport is going to increase the workload for ATC, and make traffic management something of a nightmare if they truly want to use the runway's circular design for any-point landing. Exceedingly so in LAX or LAS traffic conditions. The idea is superb until you realize an entire rework of pilot/ground doctrine is needed before a facility like this can ever see use in even a private setting.

This is an endeavor requiring at least a decade of scenario-play.

 

[ADSWNJ]

I'm sure there's a million what-if's like this. I just instinctively like the fresh thinking. If ever it were to be considered, I suspect a scale-mock up would be needed for drones, etc.

Regarding the spacing - if the circle is an 11km circumference (3.5km diameter), then you have a 36000 ft ring. I assume you could make say an 8000 ft safety buffer for overruns, on 2 x 10,000 ft runways. That's about as good a safety margin as you could need. Have planes line up on the inner loop, or on a taxiway, such that there's only one taking off, one lining up and holding, and one landing at any one time.

I repeat - I have no idea if this is practical, but I would love to see it simulated.

 

[Hielor]

I'm sure there's a million what-if's like this. I just instinctively like the fresh thinking. If ever it were to be considered, I suspect a scale-mock up would be needed for drones, etc.

Regarding the spacing - if the circle is an 11km circumference (3.5km diameter), then you have a 36000 ft ring. I assume you could make say an 8000 ft safety buffer for overruns, on 2 x 10,000 ft runways. That's about as good a safety margin as you could need. Have planes line up on the inner loop, or on a taxiway, such that there's only one taking off, one lining up and holding, and one landing at any one time.

I repeat - I have no idea if this is practical, but I would love to see it simulated.

Except, in a windy situation, you've only really got one runway, unless you have planes going around the circle in different directions, in which case you only have two...

The amount of pavement (and infill to create the bank) it would take to do this could be far better spent just making a few runways aligned with the prevailing winds.

 

[boogabooga]

To people worried about banking: how level do you think existing runways actually are?

http://www.orbiter-forum.com/showthread.php?p=541271&highlight=runway#post541271